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diff --git a/doc/libconfig.texi b/doc/libconfig.texi new file mode 100644 index 0000000..9645077 --- /dev/null +++ b/doc/libconfig.texi @@ -0,0 +1,2452 @@ +\input texinfo.tex @c -*-texinfo-*- +@c +@c %**start of header + +@c All text is ignored before the setfilename. +@setfilename libconfig.info +@settitle libconfig + +@set edition 1.7.3 +@set update-date 20 Jun 2021 +@set subtitle-text A Library For Processing Structured Configuration Files +@set author-text Mark A.@: Lindner + +@comment %**end of header + +@firstparagraphindent insert + +@dircategory Software libraries +@direntry +* libconfig: (libconfig). A Library For Processing Structured Configuration Files +@end direntry + + +@tex +\global\emergencystretch = .3\hsize +@end tex + +@setchapternewpage odd + +@titlepage + +@title libconfig +@subtitle @value{subtitle-text} +@subtitle Version @value{edition} +@subtitle @value{update-date} + +@author @value{author-text} + +@page +@vskip 0pt plus 1filll +Copyright @copyright{} 2004-2021 Mark A Lindner + +Permission is granted to make and distribute verbatim copies of +this manual provided the copyright notice and this permission notice +are preserved on all copies. + +Permission is granted to copy and distribute modified versions of this +manual under the conditions for verbatim copying, provided that the entire +resulting derived work is distributed under the terms of a permission +notice identical to this one. + +@end titlepage + +@c Give the HTML output a title page that somewhat resembles the printed one +@ifhtml +@html +<hr noshade size=6 color="black"> +<div align=right>@value{subtitle-text}<br> +Version @value{edition}<br> +@value{update-date}</div> +<br><br><br><br> +<font size=+1>@value{author-text}</font> +<hr size=3 noshade color="black"> +<br><br> +@end html +@end ifhtml + +@contents + +@ifnottex +@node Top +@comment node-name, next, previous, up +@top libconfig +@end ifnottex + +@menu +* Introduction:: +* Configuration Files:: +* The C API:: +* The C++ API:: +* Example Programs:: +* Other Bindings and Implementations:: +* License:: +* Configuration File Grammar:: +* Function Index:: +* Type Index:: +* Concept Index:: +@end menu + +@node Introduction, Configuration Files, Top, Top +@comment node-name, next, previous, up +@menu +* Why Another Configuration File Library?:: +* Using the Library from a C Program:: +* Using the Library from a C++ Program:: +* Multithreading Issues:: +* Internationalization Issues:: +* Compiling Using pkg-config:: +* Version Test Macros:: +@end menu +@chapter Introduction + +@i{Libconfig} is a library for reading, manipulating, and writing +structured configuration files. The library features a fully +reentrant parser and includes bindings for both the C and C++ +programming languages. + +The library runs on modern POSIX-compilant systems, such as Linux, +Solaris, and Mac OS X (Darwin), as well as on Microsoft Windows +2000/XP and later (with either Microsoft Visual Studio 2005 or later, +or the GNU toolchain via the MinGW environment). + +@node Why Another Configuration File Library?, Using the Library from a C Program, , Introduction +@comment node-name, next, previous, up +@section Why Another Configuration File Library? + +There are several open-source configuration file libraries available +as of this writing. This library was written because each of those +libraries falls short in one or more ways. The main features of +@i{libconfig} that set it apart from the other libraries are: + +@itemize @bullet + +@item A fully reentrant parser. Independent configurations can be parsed in concurrent threads at the same time. + +@item Both C @i{and} C++ bindings, as well as hooks to allow for the creation of wrappers in other languages. + +@item A simple, structured configuration file format that is more +readable and compact than XML and more flexible than the obsolete but +prevalent Windows ``INI'' file format. + +@item A low-footprint implementation (just 37K for the C library and 76K for +the C++ library) that is suitable for memory-constrained systems. + +@item Proper documentation. + +@end itemize + +@node Using the Library from a C Program, Using the Library from a C++ Program, Why Another Configuration File Library?, Introduction +@comment node-name, next, previous, up +@section Using the Library from a C Program + +To use the library from C code, include the following preprocessor +directive in your source files: + +@sp 1 +@smallexample +#include <libconfig.h> +@end smallexample +@sp 1 + +To link with the library, specify @samp{-lconfig} as an argument to the +linker. + +@node Using the Library from a C++ Program, Multithreading Issues, Using the Library from a C Program, Introduction +@comment node-name, next, previous, up +@section Using the Library from a C++ Program + +To use the library from C++, include the following preprocessor +directive in your source files: + +@sp 1 +@smallexample +#include <libconfig.h++> +@end smallexample +@sp 1 + +Or, alternatively: + +@sp 1 +@smallexample +#include <libconfig.hh> +@end smallexample +@sp 1 +@page +The C++ API classes are defined in the namespace @samp{libconfig}, hence the +following statement may optionally be used: + +@sp 1 +@smallexample +using namespace libconfig; +@end smallexample +@sp 1 + +To link with the library, specify @samp{-lconfig++} as an argument to +the linker. + +@node Multithreading Issues, Internationalization Issues, Using the Library from a C++ Program, Introduction +@comment node-name, next, previous, up +@section Multithreading Issues + +@i{Libconfig} is fully @dfn{reentrant}; the functions in the library +do not make use of global variables and do not maintain state between +successive calls. Therefore two independent configurations may be safely +manipulated concurrently by two distinct threads. + +@i{Libconfig} is not @dfn{thread-safe}. The library is not aware of +the presence of threads and knows nothing about the host system's +threading model. Therefore, if an instance of a configuration is to be +accessed from multiple threads, it must be suitably protected by +synchronization mechanisms like read-write locks or mutexes; the +standard rules for safe multithreaded access to shared data must be +observed. + +@i{Libconfig} is not @dfn{async-safe}. Calls should not be made into +the library from signal handlers, because some of the C library +routines that it uses may not be async-safe. + +@i{Libconfig} is not guaranteed to be @dfn{cancel-safe}. Since it is +not aware of the host system's threading model, the library does not +contain any thread cancellation points. In most cases this will not be +an issue for multithreaded programs. However, be aware that some of +the routines in the library (namely those that read/write +configurations from/to files or streams) perform I/O using C library +routines which may potentially block; whether or not these C library +routines are cancel-safe depends on the host system. + +@node Internationalization Issues, Compiling Using pkg-config, Multithreading Issues, Introduction +@comment node-name, next, previous, up +@section Internationalization Issues + +@cindex Unicode +@cindex UTF-8 +@i{Libconfig} does not natively support Unicode configuration files, +but string values may contain Unicode text encoded in UTF-8; such +strings will be treated as ordinary 8-bit ASCII text by the +library. It is the responsibility of the calling program to perform +the necessary conversions to/from wide (@t{wchar_t}) strings using the +wide string conversion functions such as @t{mbsrtowcs()} and +@t{wcsrtombs()} or the @t{iconv()} function of the @i{libiconv} +library. + +@cindex locale +The textual representation of a floating point value varies by +locale. However, the @i{libconfig} grammar specifies that +floating point values are represented using a period (`.') as the +radix symbol; this is consistent with the grammar of most programming +languages. When a configuration is read in or written out, +@i{libconfig} temporarily changes the @t{LC_NUMERIC} category of the +locale of the calling thread to the ``C'' locale to ensure consistent +handling of floating point values regardless of the locale(s) in use +by the calling program. + +Note that the MinGW environment does not (as of this writing) provide +functions for changing the locale of the calling thread. Therefore, +when using @i{libconfig} in that environment, the calling program is +responsible for changing the @t{LC_NUMERIC} category of the locale to +the "C" locale before reading or writing a configuration. + +@node Compiling Using pkg-config, Version Test Macros, Internationalization Issues, Introduction +@comment node-name, next, previous, up +@section Compiling Using pkg-config + +@cindex pkg-config +On UNIX systems you can use the @i{pkg-config} utility (version 0.20 +or later) to automatically select the appropriate compiler and linker +switches for @i{libconfig}. Ensure that the environment variable +@code{PKG_CONFIG_PATH} contains the absolute path to the +@file{lib/pkgconfig} subdirectory of the @i{libconfig} installation. Then, +you can compile and link C programs with @i{libconfig} as follows: + +@smallexample +gcc `pkg-config --cflags libconfig` myprogram.c -o myprogram \ + `pkg-config --libs libconfig` +@end smallexample +@sp 1 + +And similarly, for C++ programs: + +@smallexample +g++ `pkg-config --cflags libconfig++` myprogram.cpp -o myprogram \ + `pkg-config --libs libconfig++` +@end smallexample + +@sp 1 +Note the backticks in the above examples. + +When using @b{autoconf}, the @code{PKG_CHECK_MODULES} m4 macro may be used to check for the presence of a given version of @i{libconfig}, and set the appropriate Makefile variables automatically. For example: + +@smallexample +PKG_CHECK_MODULES([LIBCONFIGXX], [libconfig++ >= 1.4],, + AC_MSG_ERROR([libconfig++ 1.4 or newer not found.]) +) +@end smallexample + +In the above example, if @i{libconfig++} version 1.4 or newer is found, +the Makefile variables @code{LIBCONFIGXX_LIBS} and @code{LIBCONFIGXX_CFLAGS} will be +set to the appropriate compiler and linker flags for compiling with +@i{libconfig}, and if it is not found, the configure script will abort +with an error to that effect. + +@node Version Test Macros, , Compiling Using pkg-config, Introduction +@comment node-name, next, previous, up +@section Version Test Macros + +The @file{libconfig.h} header declares the following macros: + +@defmac LIBCONFIG_VER_MAJOR +@defmacx LIBCONFIG_VER_MINOR +@defmacx LIBCONFIG_VER_REVISION + +These macros represent the major version, minor version, and revision +of the @i{libconfig} library. For example, in @i{libconfig} 1.4 these +are defined as @samp{1}, @samp{4}, and @samp{0}, respectively. These +macros can be used in preprocessor directives to determine which +@i{libconfig} features and/or APIs are present. For example: + +@smallexample +#if (((LIBCONFIG_VER_MAJOR == 1) && (LIBCONFIG_VER_MINOR >= 4)) \ + || (LIBCONFIG_VER_MAJOR > 1)) + /* use features present in libconfig 1.4 and later */ +#endif +@end smallexample + +These macros were introduced in @i{libconfig} 1.4. + +@end defmac + +Similarly, the @file{libconfig.h++} header declares the following macros: + +@defmac LIBCONFIGXX_VER_MAJOR +@defmacx LIBCONFIGXX_VER_MINOR +@defmacx LIBCONFIGXX_VER_REVISION + +These macros represent the major version, minor version, and revision +of the @i{libconfig++} library. + +@end defmac + +@node Configuration Files, The C API, Introduction, Top +@comment node-name, next, previous, up +@menu +* Settings:: +* Groups:: +* Arrays:: +* Lists:: +* Integer Values:: +* 64-bit Integer Values:: +* Floating Point Values:: +* Boolean Values:: +* String Values:: +* Comments:: +* Include Directives:: +@end menu +@chapter Configuration Files + +@i{Libconfig} supports structured, hierarchical configurations. These +configurations can be read from and written to files and manipulated +in memory. + +@cindex setting +@cindex value +@cindex scalar value +@cindex array +@cindex group +@cindex list +@cindex configuration +A @dfn{configuration} consists of a group of @dfn{settings}, which +associate names with values. A @dfn{value} can be one of the +following: + +@itemize @bullet +@item A @dfn{scalar value}: integer, 64-bit integer, floating-point number, boolean, +or string +@item An @dfn{array}, which is a sequence of scalar values, all of which must have the same type +@item A @dfn{group}, which is a collection of settings +@item A @dfn{list}, which is a sequence of values of any type, including other lists +@end itemize + +Consider the following configuration file for a hypothetical GUI +application, which illustrates all of the elements of the configuration +file grammar. + +@sp 1 +@cartouche +@smallexample +# Example application configuration file + +version = "1.0"; + +application: +@{ + window: + @{ + title = "My Application"; + size = @{ w = 640; h = 480; @}; + pos = @{ x = 350; y = 250; @}; + @}; + + list = ( ( "abc", 123, true ), 1.234, ( /* an empty list */ ) ); + + books = ( @{ title = "Treasure Island"; + author = "Robert Louis Stevenson"; + price = 29.95; + qty = 5; @}, + @{ title = "Snow Crash"; + author = "Neal Stephenson"; + price = 9.99; + qty = 8; @} ); + + misc: + @{ + pi = 3.141592654; + bigint = 9223372036854775807L; + columns = [ "Last Name", "First Name", "MI" ]; + bitmask = 0x1FC3; // hex + umask = 0027; // octal. Range limited to that of "int" + @}; +@}; +@end smallexample +@end cartouche +@sp 1 + +@cindex path +Settings can be uniquely identified within the configuration by a +@dfn{path}. The path is a dot-separated sequence of names, beginning +at a top-level group and ending at the setting itself. Each name in +the path is the name of a setting; if the setting has no name because +it is an element in a list or array, an integer index in square +brackets can be used as the name. + +For example, in our hypothetical configuration file, the path to the +@code{x} setting is @code{application.window.pos.x}; the path to the +@code{version} setting is simply @code{version}; and the path to the +@code{title} setting of the second book in the @code{books} list is +@code{application.books.[1].title}. + +The datatype of a value is determined from the format of the value +itself. If the value is enclosed in double quotes, it is treated as a +string. If it looks like an integer or floating point number, it is +treated as such. If it is one of the values @code{TRUE}, @code{true}, +@code{FALSE}, or @code{false} (or any other mixed-case version of +those tokens, e.g., @code{True} or @code{FaLsE}), it is treated as a +boolean. If it consists of a comma-separated list of values enclosed +in square brackets, it is treated as an array. And if it consists of a +comma-separated list of values enclosed in parentheses, it is treated +as a list. Any value which does not meet any of these criteria is +considered invalid and results in a parse error. + +All names are case-sensitive. They may consist only of alphanumeric +characters, dashes (@samp{-}), underscores (@samp{_}), and asterisks +(@samp{*}), and must begin with a letter or asterisk. No other +characters are allowed. + +In C and C++, integer, 64-bit integer, floating point, and string +values are mapped to the native types @code{int}, @code{long long}, +@code{double}, and @code{const char *}, respectively. The boolean type +is mapped to @code{int} in C and @code{bool} in C++. + +The following sections describe the elements of the configuration file +grammar in additional detail. + +@node Settings, Groups, , Configuration Files +@comment node-name, next, previous, up +@section Settings + +A setting has the form: + +@i{name} @b{=} @i{value} @b{;} + +or: + +@i{name} @b{:} @i{value} @b{;} + +The trailing semicolon is optional. Whitespace is not significant. + +The value may be a scalar value, an array, a group, or a list. + +@node Groups, Arrays, Settings, Configuration Files +@comment node-name, next, previous, up +@section Groups + +A group has the form: + +@b{@{} + @i{settings ...} +@b{@}} + +Groups can contain any number of settings, but each setting must have +a unique name within the group. + +@node Arrays, Lists, Groups, Configuration Files +@comment node-name, next, previous, up +@section Arrays + +An array has the form: + +@b{[} @i{value}@b{,} @i{value ...} @b{]} + +An array may have zero or more elements, but the elements must all be +scalar values of the same type. + +The last element in an array may be followed by a comma, which will be ignored. + +@node Lists, Integer Values, Arrays, Configuration Files +@comment node-name, next, previous, up +@section Lists + +A list has the form: + +@b{(} @i{value}@b{,} @i{value ...} @b{)} + +A list may have zero or more elements, each of which can be a scalar +value, an array, a group, or another list. + +The last element in a list may be followed by a comma, which will be ignored. + +@node Integer Values, 64-bit Integer Values, Lists, Configuration Files +@comment node-name, next, previous, up +@section Integer Values + +Integers can be represented in one of two ways: as a series of one or +more decimal digits (@samp{0} - @samp{9}), with an optional leading +sign character (@samp{+} or @samp{-}); or as a hexadecimal value +consisting of the characters @samp{0x} followed by a series of one or +more hexadecimal digits (@samp{0} - @samp{9}, @samp{A} - @samp{F}, +@samp{a} - @samp{f}). Additionally, octal notation integers (that is, +those having a leading zero with non-zero value) are also allowed. + +@node 64-bit Integer Values, Floating Point Values, Integer Values, Configuration Files +@comment node-name, next, previous, up +@section 64-bit Integer Values + +Long long (64-bit) integers are represented identically to integers, +except that an `L' character is appended to indicate a 64-bit +value. For example, @samp{0L} indicates a 64-bit integer value 0. As +of version 1.5 of the library, the trailing `L' is optional; if the +integer value exceeds the range of a 32-bit integer, it will +automatically be interpreted as a 64-bit integer. + +The @i{integer} and @i{64-bit integer} setting types are interchangeable to the +extent that a conversion between the corresponding native types would not +result in an overflow or underflow. For example, a @i{long long} value can be +written to a setting that has an @i{integer} type, if that value is within the +range of an @i{int}. This rule applies to every API function or method that +reads a value from or writes a value to a setting: if the type conversion would +not result in an overflow or underflow, then the call will succeed, and +otherwise it will fail. This behavior was not well-defined prior to version 1.7 +of the library. + +@node Floating Point Values, Boolean Values, 64-bit Integer Values, Configuration Files +@comment node-name, next, previous, up +@section Floating Point Values + +Floating point values consist of a series of one or more digits, one +decimal point, an optional leading sign character (@samp{+} or +@samp{-}), and an optional exponent. An exponent consists of the +letter @samp{E} or @samp{e}, an optional sign character, and a series +of one or more digits. + +@node Boolean Values, String Values, Floating Point Values, Configuration Files +@comment node-name, next, previous, up +@section Boolean Values + +Boolean values may have one of the following values: @samp{true}, +@samp{false}, or any mixed-case variation thereof. + +@node String Values, Comments, Boolean Values, Configuration Files +@comment node-name, next, previous, up +@section String Values + +@cindex escape sequence +String values consist of arbitrary text delimited by double +quotes. Literal double quotes can be escaped by preceding them with a +backslash: @samp{\"}. The escape sequences @samp{\\}, @samp{\f}, +@samp{\n}, @samp{\r}, and @samp{\t} are also recognized, and have the +usual meaning. + +In addition, the @samp{\x} escape sequence is supported; this sequence +must be followed by @i{exactly two} hexadecimal digits, which represent an +8-bit ASCII value. For example, @samp{\xFF} represents the character +with ASCII code 0xFF. + +No other escape sequences are currently supported. + +Adjacent strings are automatically concatenated, as in C/C++ source +code. This is useful for formatting very long strings as sequences of +shorter strings. For example, the following constructs are equivalent: + +@itemize @bullet +@item +@code{"The quick brown fox jumped over the lazy dog."} + +@item +@code{"The quick brown fox"} @* +@code{" jumped over the lazy dog."} + +@item +@code{"The quick" /* comment */ " brown fox " // another comment} @* +@code{"jumped over the lazy dog."} + +@end itemize +@page +@node Comments, Include Directives, String Values, Configuration Files +@comment node-name, next, previous, up +@section Comments + +@cindex comment +Three types of comments are allowed within a configuration: + +@itemize @bullet + +@item Script-style comments. All text beginning with a @samp{#} character +to the end of the line is ignored. + +@item C-style comments. All text, including line breaks, between a starting +@samp{/*} sequence and an ending @samp{*/} sequence is ignored. + +@item C++-style comments. All text beginning with a @samp{//} sequence to the +end of the line is ignored. + +@end itemize + +As expected, comment delimiters appearing within quoted strings are +treated as literal text. + +Comments are ignored when the configuration is read in, so they are +not treated as part of the configuration. Therefore if the +configuration is written back out to a stream, any comments that were +present in the original configuration will be lost. + + +@node Include Directives, , Comments, Configuration Files +@comment node-name, next, previous, up +@section Include Directives + +@cindex include directive +A configuration file may ``include'' the contents of other files +using an @i{include directive}. This directive has the effect of +inlining the contents of the named file(s) at the point of inclusion. + +An include directive must appear on its own line in the input. It has +the form: + +@b{@@include "}@i{path}@b{"} + +@cindex include function +The interpretation of @i{path} depends on the currently registered +@i{include function}. The default include function prepends the include +directory, if any, to @i{path}, and then interprets the result as a single, +literal file path. The application may supply its own include function which +does variable substitution, wildcard expansion, or other transformations, +returning a list of zero or more paths to files whose contents should be inlined +at the point of inclusion. + +Any backslashes or double quotes in the path must be escaped as +@samp{\\} and @samp{\"}, respectively. + +For example, consider the following two configuration files: + +@cartouche +@smallexample +# file: quote.cfg +quote = "Criticism may not be agreeable, but it is necessary." + " It fulfils the same function as pain in the human" + " body. It calls attention to an unhealthy state of" + " things.\n" + "\t--Winston Churchill"; +@end smallexample +@end cartouche + +@cartouche +@smallexample +# file: test.cfg +info: @{ + name = "Winston Churchill"; + @@include "quote.cfg" + country = "UK"; +@}; +@end smallexample +@end cartouche + +The resulting configuration will be equivalent to one in which the +contents of the file @samp{quote.cfg} appeared at the point where the +include directive is placed. + +Include files may be nested to a maximum of 10 levels; exceeding this +limit results in a parse error. + +When the path argument to an @b{@@include} directive is a relative +path, then it will be interpreted as being relative to the include +directory that has been been set by means of +@code{config_set_include_dir()}. If no include directory has been set, +then it will be taken as being relative to the program's current +working directory. + +Like comments, include directives are not part of the configuration +file syntax. They are processed before the configuration itself is +parsed. Therefore, they are not preserved when the configuration is +written back out to a stream. There is presently no support for +programmatically inserting include directives into a configuration. + +@node The C API, The C++ API, Configuration Files, Top +@comment node-name, next, previous, up +@chapter The C API + +@tindex config_t +@tindex config_setting_t +This chapter describes the C library API. The type @i{config_t} +represents a configuration, and the type @i{config_setting_t} represents +a configuration setting. + +The boolean values @code{CONFIG_TRUE} and @code{CONFIG_FALSE} are +macros defined as @code{(1)} and @code{(0)}, respectively. + +@deftypefun void config_init (@w{config_t * @var{config}}) +@deftypefunx void config_destroy (@w{config_t * @var{config}}) + +These functions initialize and destroy the configuration object @var{config}. + +@code{config_init()} initializes the @i{config_t} structure pointed to by +@var{config} as a new, empty configuration. + +@code{config_destroy()} destroys the configuration @var{config}, +deallocating all memory associated with the configuration, but does not +attempt to deallocate the @i{config_t} structure itself. + +@end deftypefun + +@deftypefun void config_clear (@w{config_t * @var{config}}) + +@b{Since @i{v1.7}} + +This function clears the configuration @var{config}. All child settings of the +root setting are recursively destroyed. All other attributes of the configuration +are left unchanged. + +@end deftypefun + +@deftypefun int config_read (@w{config_t * @var{config}}, @w{FILE * @var{stream}}) + +This function reads and parses a configuration from the given +@var{stream} into the configuration object @var{config}. It returns +@code{CONFIG_TRUE} on success, or @code{CONFIG_FALSE} on failure; the +@code{config_error_text()}, @code{config_error_file()}, +@code{config_error_line()}, and @code{config_error_type()} functions, +described below, can be used to obtain information about the error. + +@end deftypefun + +@deftypefun int config_read_file (@w{config_t * @var{config}}, @w{const char * @var{filename}}) + +This function reads and parses a configuration from the file named +@var{filename} into the configuration object @var{config}. It returns +@code{CONFIG_TRUE} on success, or @code{CONFIG_FALSE} on failure; the +@code{config_error_text()} and @code{config_error_line()} functions, +described below, can be used to obtain information about the error. + +@end deftypefun + +@deftypefun int config_read_string (@w{config_t * @var{config}}, @w{const char * @var{str}}) + +This function reads and parses a configuration from the string +@var{str} into the configuration object @var{config}. It returns +@code{CONFIG_TRUE} on success, or @code{CONFIG_FALSE} on failure; the +@code{config_error_text()} and @code{config_error_line()} functions, +described below, can be used to obtain information about the error. + +@end deftypefun + +@deftypefun void config_write (@w{const config_t * @var{config}}, @w{FILE * @var{stream}}) + +This function writes the configuration @var{config} to the given +@var{stream}. + +@end deftypefun + +@deftypefun int config_write_file (@w{config_t * @var{config}}, @w{const char * @var{filename}}) + +This function writes the configuration @var{config} to the file named +@var{filename}. It returns @code{CONFIG_TRUE} on success, or +@code{CONFIG_FALSE} on failure. + +@end deftypefun + +@deftypefun {const char *} config_error_text (@w{const config_t * @var{config}}) +@deftypefunx {const char *} config_error_file (@w{const config_t * @var{config}}) +@deftypefunx int config_error_line (@w{const config_t * @var{config}}) + +These functions, which are implemented as macros, return the text, +filename, and line number of the parse error, if one occurred during a +call to @code{config_read()}, @code{config_read_string()}, or +@code{config_read_file()}. Storage for the strings returned by +@code{config_error_text()} and @code{config_error_file()} are managed +by the library and released automatically when the configuration is +destroyed; these strings must not be freed by the caller. If the error +occurred in text that was read from a string or stream, +@code{config_error_file()} will return NULL. + +@end deftypefun + +@deftypefun config_error_t config_error_type (@w{const config_t * @var{config}}) +@tindex config_error_t +This function, which is implemented as a macro, returns the type of +error that occurred during the last call to one of the read or write +functions. The @var{config_error_t} type is an enumeration with the +following values: @code{CONFIG_ERR_NONE}, @code{CONFIG_ERR_FILE_IO}, +@code{CONFIG_ERR_PARSE}. These represent success, a file I/O error, +and a parsing error, respectively. + +@end deftypefun + +@deftypefun void config_set_include_dir (@w{config_t *@var{config}}, @w{const char *@var{include_dir}}) +@deftypefunx {const char *} config_get_include_dir (@w{const config_t *@var{config}}) + +@code{config_set_include_dir()} specifies the include directory, +@var{include_dir}, relative to which the files specified in +@samp{@@include} directives will be located for the configuration +@var{config}. By default, there is no include directory, and all +include files are expected to be relative to the current working +directory. If @var{include_dir} is @code{NULL}, the default behavior +is reinstated. + +For example, if the include directory is set to @file{/usr/local/etc}, +the include directive @samp{@@include "configs/extra.cfg"} would include the +file @file{/usr/local/etc/configs/extra.cfg}. + +@code{config_get_include_dir()} returns the current include directory for the +configuration @var{config}, or @code{NULL} if none is set. + +@end deftypefun + +@deftypefun void config_set_include_func (@w{config_include_fn_t @var{func}}) + +@b{Since @i{v1.7}} + +Specifies the include function @var{func} to use when processing +include directives. If @var{func} is @code{NULL}, the default include function, +@code{config_default_include_func()}, will be reinstated. + +@tindex config_include_fn_t +The type @i{config_include_fn_t} is a type alias +for a function whose signature is: + +@deftypefun @w{const char **} func (@w{config_t *@var{config}}, @w{const char *@var{include_dir}}, @w{const char *@var{path}}, @w{const char **@var{error}}) + +The function receives the configuration @var{config}, the +configuration's current include directory @var{include_dir}, the +argument to the include directive @var{path}; and a pointer at which +to return an error message @var{error}. + +On success, the function should return a @code{NULL}-terminated array +of paths. Any relative paths must be relative to the program's current +working directory. The contents of these files will be inlined at the point +of inclusion, in the order that the paths appear in the +array. Both the array and its elements should be heap allocated; the +library will take ownership of and eventually free the strings in the +array and the array itself. + +On failure, the function should return @code{NULL} and set @var{*error} to a +static error string which should be used as the parse error for the +configuration; the library does not take ownership of or free this string. + +The default include function, @code{config_default_include_func()}, +simply returns a @code{NULL}-terminated array containing either a copy +of @var{path} if it's an absolute path, or a concatenation of +@var{include_dir} and @var{path} if it's a relative path. + +@end deftypefun + +Application-supplied include functions can perform custom tasks like wildcard +expansion or variable substitution. For example, consider the include directive: + +@cartouche +@smallexample +@@include "configs/*.cfg" +@end smallexample +@end cartouche + +The include function would be invoked with the path @samp{configs/*.cfg} and +could do wildcard expansion on that path, returning a list of paths to files +with the file extension @samp{.cfg} in the subdirectory @samp{configs}. Each of +these files would then be inlined at the location of the include directive. + +Tasks like wildcard expansion and variable substitution are non-trivial to +implement and typically require platform-specific code. In the interests of +keeping the library as compact and platform-independent as possible, +implementations of such include functions are not included. + +@end deftypefun + +@deftypefun {unsigned short} config_get_float_precision(@w{config_t *@var{config}}) +@deftypefunx void config_set_float_precision(@w{config_t *@var{config}}, @w{unsigned short @var{digits}}) + +@b{Since @i{v1.6}} + +These functions get and set the number of decimal digits to output after the +radix character when writing the configuration to a file or stream. + +Valid values for @var{digits} range from 0 (no decimals) to about 15 +(implementation defined). This parameter has no effect on parsing. + +The default float precision is 6. + +@end deftypefun + +@deftypefun int config_get_options (@w{config_t *@var{config}}) +@deftypefunx void config_set_options (@w{config_t *@var{config}}, @w{int @var{options}}) + +These functions get and set the options for the configuration +@var{config}. The options affect how configurations are read and +written. The following options are defined: + +@table @code + +@item CONFIG_OPTION_AUTOCONVERT +Turning this option on enables number auto-conversion for +the configuration. When this feature is enabled, an attempt to retrieve a +floating point setting's value into an integer (or vice versa), or +store an integer to a floating point setting's value (or vice versa) +will cause the library to silently perform the necessary conversion +(possibly leading to loss of data), rather than reporting failure. By +default this option is turned off. + +@item CONFIG_OPTION_SEMICOLON_SEPARATORS +This option controls whether a semicolon (`;') is output after each setting +when the configuration is written to a file or stream. (The semicolon +separators are optional in the configuration syntax.) By default this +option is turned on. + +@item CONFIG_OPTION_COLON_ASSIGNMENT_FOR_GROUPS +This option controls whether a colon (`:') is output between each +group setting's name and its value when the configuration is written to +a file or stream. If the option is turned off, an equals sign (`=') is +output instead. (These tokens are interchangeable in the configuration +syntax.) By default this option is turned on. + +@item CONFIG_OPTION_COLON_ASSIGNMENT_FOR_NON_GROUPS +This option controls whether a colon (`:') is output between each +non-group setting's name and its value when the configuration is written +to a file or stream. If the option is turned off, an equals sign (`=') +is output instead. (These tokens are interchangeable in the configuration +syntax.) By default this option is turned off. + +@item CONFIG_OPTION_OPEN_BRACE_ON_SEPARATE_LINE +This option controls whether an open brace (`@{') will be written on its own +line when the configuration is written to a file or stream. If the option is +turned off, the brace will be written at the end of the previous line. +By default this option is turned on. + +@item CONFIG_OPTION_ALLOW_SCIENTIFIC_NOTATION +(@b{Since @i{v1.7}}) +This option controls whether scientific notation may be used as appropriate +when writing floating point values (corresponding to @code{printf()} +@samp{%g} format) or should never be used (corresponding to @code{printf()} +@samp{%f} format). By default this option is turned off. + +@item CONFIG_OPTION_FSYNC +(@b{Since @i{v1.7.1}}) +This option controls whether the @code{config_write_file()} function performs +an @i{fsync} operation after writing the configuration and before closing the +file. By default this option is turned off. + +@item CONFIG_OPTION_ALLOW_OVERRIDES +(@b{Since @i{v1.7.3}}) +This option controls whether duplicate settings override previous settings +with the same name. If this option is turned off, duplicate settings are +rejected. By default this option is turned off. + +@end table + +@end deftypefun + +@deftypefun int config_get_option (@w{config_t *@var{config}}, @w{int @var{option}}) +@deftypefunx void config_set_option (@w{config_t *@var{config}}, @w{int @var{option}}, @w{int @var{flag}}) + +@b{Since @i{v1.7}} + +These functions get and set the given @var{option} of the configuration +@var{config}. The option is enabled if @var{flag} is @code{CONFIG_TRUE} and +disabled if it is @code{CONFIG_FALSE}. + +See @code{config_set_options()} above for the list of available options. + +@end deftypefun + + +@deftypefun int config_get_auto_convert (@w{const config_t *@var{config}}) +@deftypefunx void config_set_auto_convert (@w{config_t *@var{config}}, @w{int @var{flag}}) + +These functions get and set the @code{CONFIG_OPTION_AUTO_CONVERT} +option. They are obsoleted by the @code{config_set_option()} and +@code{config_get_option()} functions described above. + +@end deftypefun + +@deftypefun short config_get_default_format (@w{config_t * @var{config}}) +@deftypefunx void config_set_default_format (@w{config_t * @var{config}}, @w{short @var{format}}) + +These functions, which are implemented as macros, get and set the +default external format for settings in the configuration +@var{config}. If a non-default format has not been set for a setting +with @code{config_setting_set_format()}, this configuration-wide +default format will be used instead when that setting is written to a +file or stream. + +@end deftypefun + +@deftypefun {unsigned short} config_get_tab_width (@w{const config_t * @var{config}}) +@deftypefunx void config_set_tab_width (@w{config_t * @var{config}}, @w{unsigned short @var{width}}) + +These functions, which are implemented as macros, get and set the tab +width for the configuration @var{config}. The tab width affects the +formatting of the configuration when it is written to a file or +stream: each level of nesting is indented by @var{width} spaces, or +by a single tab character if @var{width} is 0. The tab width has no +effect on parsing. + +Valid tab widths range from 0 to 15. The default tab width is 2. + +@end deftypefun + +@deftypefun int config_lookup_int (@w{const config_t * @var{config}}, @w{const char * @var{path}}, @w{int * @var{value}}) +@deftypefunx int config_lookup_int64 (@w{const config_t * @var{config}}, @w{const char * @var{path}}, @w{long long * @var{value}}) +@deftypefunx int config_lookup_float (@w{const config_t * @var{config}}, @w{const char * @var{path}}, @w{double * @var{value}}) +@deftypefunx int config_lookup_bool (@w{const config_t * @var{config}}, @w{const char * @var{path}}, @w{int * @var{value}}) +@deftypefunx int config_lookup_string (@w{const config_t * @var{config}}, @w{const char * @var{path}}, @w{const char ** @var{value}}) + +These functions look up the value of the setting in the configuration +@var{config} specified by the path @var{path}. They store the value of +the setting at @var{value} and return @code{CONFIG_TRUE} on +success. If the setting was not found or if the type of the value did +not match the type requested, they leave the data pointed to by +@var{value} unmodified and return @code{CONFIG_FALSE}. + +Storage for the string returned by @code{config_lookup_string()} is +managed by the library and released automatically when the setting is +destroyed or when the setting's value is changed; the string must not +be freed by the caller. + +@end deftypefun + +@deftypefun {config_setting_t *} config_lookup (@w{const config_t * @var{config}}, @w{const char * @var{path}}) + +This function locates the setting in the configuration @var{config} +specified by the path @var{path}. It returns a pointer to the +@code{config_setting_t} structure on success, or @code{NULL} if the +setting was not found. + +@end deftypefun + +@deftypefun {config_setting_t *} config_setting_lookup (@w{const config_setting_t * @var{setting}}, @w{const char * @var{path}}) + +This function locates a setting by a path @var{path} relative to +the setting @var{setting}. It returns a pointer to the +@code{config_setting_t} structure on success, or @code{NULL} if the +setting was not found. + +@end deftypefun + +@deftypefun int config_setting_get_int (@w{const config_setting_t * @var{setting}}) +@deftypefunx {long long} config_setting_get_int64 (@w{const config_setting_t * @var{setting}}) +@deftypefunx double config_setting_get_float (@w{const config_setting_t * @var{setting}}) +@deftypefunx int config_setting_get_bool (@w{const config_setting_t * @var{setting}}) +@deftypefunx {const char *} config_setting_get_string (@w{const config_setting_t * @var{setting}}) + +These functions return the value of the given @var{setting}. If the +type of the setting does not match the type requested, a 0 or +@code{NULL} value is returned. Storage for the string returned by +@code{config_setting_get_string()} is managed by the library and +released automatically when the setting is destroyed or when the +setting's value is changed; the string must not be freed by the +caller. + +@end deftypefun +@deftypefun int config_setting_set_int (@w{config_setting_t * @var{setting}}, @w{int @var{value}}) +@deftypefunx int config_setting_set_int64 (@w{config_setting_t * @var{setting}}, @w{long long @var{value}}) +@deftypefunx int config_setting_set_float (@w{config_setting_t * @var{setting}}, @w{double @var{value}}) +@deftypefunx int config_setting_set_bool (@w{config_setting_t * @var{setting}}, @w{int @var{value}}) +@deftypefunx int config_setting_set_string (@w{config_setting_t * @var{setting}}, @w{const char * @var{value}}) + +These functions set the value of the given @var{setting} to +@var{value}. On success, they return @code{CONFIG_TRUE}. If +the setting does not match the type of the value, they return +@code{CONFIG_FALSE}. @code{config_setting_set_string()} makes a copy +of the passed string @var{value}, so it may be subsequently freed or +modified by the caller without affecting the value of the setting. + +@end deftypefun + +@deftypefun int config_setting_lookup_int (@w{const config_setting_t * @var{setting}}, @w{const char * @var{name}}, @w{int * @var{value}}) +@deftypefunx int config_setting_lookup_int64 (@w{const config_setting_t * @var{setting}}, @w{const char * @var{name}}, @w{long long * @var{value}}) +@deftypefunx int config_setting_lookup_float (@w{const config_setting_t * @var{setting}}, @w{const char * @var{name}}, @w{double * @var{value}}) +@deftypefunx int config_setting_lookup_bool (@w{const config_setting_t * @var{setting}}, @w{const char * @var{name}}, @w{int * @var{value}}) +@deftypefunx int config_setting_lookup_string (@w{const config_setting_t * @var{setting}}, @w{const char * @var{name}}, @w{const char ** @var{value}}) + +These functions look up the value of the child setting named +@var{name} of the setting @var{setting}. They store the value at +@var{value} and return @code{CONFIG_TRUE} on success. If the setting +was not found or if the type of the value did not match the type +requested, they leave the data pointed to by @var{value} unmodified +and return @code{CONFIG_FALSE}. + +Storage for the string returned by @code{config_setting_lookup_string()} is +managed by the library and released automatically when the setting is +destroyed or when the setting's value is changed; the string must not +be freed by the caller. + +@end deftypefun + +@deftypefun short config_setting_get_format (@w{config_setting_t * @var{setting}}) +@deftypefunx int config_setting_set_format (@w{config_setting_t * @var{setting}}, @w{short @var{format}}) + +These functions get and set the external format for the setting @var{setting}. + +@tindex SettingFormat +@cindex format + +The @var{format} must be one of the constants +@code{CONFIG_FORMAT_DEFAULT} or @code{CONFIG_FORMAT_HEX}. All settings +support the @code{CONFIG_FORMAT_DEFAULT} format. The +@code{CONFIG_FORMAT_HEX} format specifies hexadecimal formatting for +integer values, and hence only applies to settings of type +@code{CONFIG_TYPE_INT} and @code{CONFIG_TYPE_INT64}. If @var{format} +is invalid for the given setting, it is ignored. + +If a non-default format has not been set for the setting, @code{config_setting_get_format()} returns the default format for the configuration, as set by @code{config_set_default_format()}. + +@code{config_setting_set_format()} returns @code{CONFIG_TRUE} on +success and @code{CONFIG_FALSE} on failure. + +@end deftypefun + + +@deftypefun {config_setting_t *} config_setting_get_member (@w{config_setting_t * @var{setting}}, @w{const char * @var{name}}) + +This function fetches the child setting named @var{name} from the group +@var{setting}. It returns the requested setting on success, or +@code{NULL} if the setting was not found or if @var{setting} is not a +group. + +@end deftypefun + +@deftypefun {config_setting_t *} config_setting_get_elem (@w{const config_setting_t * @var{setting}}, @w{unsigned int @var{index}}) + +This function fetches the element at the given index @var{index} in the +setting @var{setting}, which must be an array, list, or group. It returns the +requested setting on success, or @code{NULL} if @var{index} is out of +range or if @var{setting} is not an array, list, or group. + +@end deftypefun + +@deftypefun int config_setting_get_int_elem (@w{const config_setting_t * @var{setting}}, @w{int @var{index}}) +@deftypefunx {long long} config_setting_get_int64_elem (@w{const config_setting_t * @var{setting}}, @w{int @var{index}}) +@deftypefunx double config_setting_get_float_elem (@w{const config_setting_t * @var{setting}}, @w{int @var{index}}) +@deftypefunx int config_setting_get_bool_elem (@w{const config_setting_t * @var{setting}}, @w{int @var{index}}) +@deftypefunx {const char *} config_setting_get_string_elem (@w{const config_setting_t * @var{setting}}, @w{int @var{index}}) + +These functions return the value at the specified index @var{index} in the +setting @var{setting}. If the setting is not an array or list, or if +the type of the element does not match the type requested, or if +@var{index} is out of range, they return 0 or @code{NULL}. Storage for +the string returned by @code{config_setting_get_string_elem()} is +managed by the library and released automatically when the setting is +destroyed or when its value is changed; the string must not be freed +by the caller. +@end deftypefun + +@deftypefun {config_setting_t *} config_setting_set_int_elem (@w{config_setting_t * @var{setting}}, @w{int @var{index}}, @w{int @var{value}}) +@deftypefunx {config_setting_t *} config_setting_set_int64_elem (@w{config_setting_t * @var{setting}}, @w{int @var{index}}, @w{long long @var{value}}) +@deftypefunx {config_setting_t *} config_setting_set_float_elem (@w{config_setting_t * @var{setting}}, @w{int @var{index}}, @w{double @var{value}}) +@deftypefunx {config_setting_t *} config_setting_set_bool_elem (@w{config_setting_t * @var{setting}}, @w{int @var{index}}, @w{int @var{value}}) +@deftypefunx {config_setting_t *} config_setting_set_string_elem (@w{config_setting_t * @var{setting}}, @w{int @var{index}}, @w{const char * @var{value}}) + +These functions set the value at the specified index @var{index} in the +setting @var{setting} to @var{value}. If @var{index} is negative, a +new element is added to the end of the array or list. On success, +these functions return a pointer to the setting representing the +element. If the setting is not an array or list, or if the setting is +an array and the type of the array does not match the type of the +value, or if @var{index} is out of range, they return +@code{NULL}. @code{config_setting_set_string_elem()} makes a copy of +the passed string @var{value}, so it may be subsequently freed or +modified by the caller without affecting the value of the setting. +@end deftypefun + +@deftypefun {config_setting_t *} config_setting_add (@w{config_setting_t * @var{parent}}, @w{const char * @var{name}}, @w{int @var{type}}) + +This function adds a new child setting or element to the setting +@var{parent}, which must be a group, array, or list. If @var{parent} +is an array or list, the @var{name} parameter is ignored and may be +@code{NULL}. + +The function returns the new setting on success, or @code{NULL} if +@var{parent} is not a group, array, or list; or if there is already a +child setting of @var{parent} named @var{name}; or if @var{type} is +invalid. If @var{type} is a scalar type, the new setting will have a +default value of 0, 0.0, @code{false}, or @code{NULL}, as appropriate. +@end deftypefun + +@deftypefun int config_setting_remove (@w{config_setting_t * @var{parent}}, @w{const char * @var{name}}) + +This function removes and destroys the setting named @var{name} from +the parent setting @var{parent}, which must be a group. Any child +settings of the setting are recursively destroyed as well. + +The @var{name} parameter can also specify a setting @i{path} relative to +the provided @var{parent}. +(In that case, the setting will be looked up and removed.) + +The function returns @code{CONFIG_TRUE} on success. If @var{parent} is +not a group, or if it has no setting with the given name, it returns +@code{CONFIG_FALSE}. + +@end deftypefun + +@deftypefun int config_setting_remove_elem (@w{config_setting_t * @var{parent}}, @w{unsigned int @var{index}}) + +This function removes the child setting at the given index @var{index} from +the setting @var{parent}, which must be a group, list, or array. Any +child settings of the removed setting are recursively destroyed as +well. + +The function returns @code{CONFIG_TRUE} on success. If @var{parent} is +not a group, list, or array, or if @var{index} is out of range, it returns +@code{CONFIG_FALSE}. + +@end deftypefun + +@deftypefun {config_setting_t *} config_root_setting (@w{const config_t * @var{config}}) + +This function, which is implemented as a macro, returns the root setting for the configuration @var{config}. The root setting is a group. + +@end deftypefun + +@deftypefun {const char *} config_setting_name (@w{const config_setting_t * @var{setting}}) + +This function returns the name of the given @var{setting}, or +@code{NULL} if the setting has no name. Storage for the returned +string is managed by the library and released automatically when the +setting is destroyed; the string must not be freed by the caller. + +@end deftypefun + +@deftypefun {config_setting_t *} config_setting_parent (@w{const config_setting_t * @var{setting}}) + +This function returns the parent setting of the given @var{setting}, +or @code{NULL} if @var{setting} is the root setting. + +@end deftypefun + +@deftypefun int config_setting_is_root (@w{const config_setting_t * @var{setting}}) + +This function returns @code{CONFIG_TRUE} if the given @var{setting} is +the root setting, and @code{CONFIG_FALSE} otherwise. + +@end deftypefun + +@deftypefun int config_setting_index (@w{const config_setting_t * @var{setting}}) + +This function returns the index of the given @var{setting} within its +parent setting. If @var{setting} is the root setting, this function +returns -1. + +@end deftypefun + +@deftypefun int config_setting_length (@w{const config_setting_t * @var{setting}}) + +This function returns the number of settings in a group, or the number of +elements in a list or array. For other types of settings, it returns +0. + +@end deftypefun + +@deftypefun int config_setting_type (@w{const config_setting_t * @var{setting}}) + +This function returns the type of the given @var{setting}. The return +value is one of the constants +@code{CONFIG_TYPE_INT}, @code{CONFIG_TYPE_INT64}, @code{CONFIG_TYPE_FLOAT}, +@code{CONFIG_TYPE_STRING}, @code{CONFIG_TYPE_BOOL}, +@code{CONFIG_TYPE_ARRAY}, @code{CONFIG_TYPE_LIST}, or @code{CONFIG_TYPE_GROUP}. + +@end deftypefun + +@deftypefun int config_setting_is_group (@w{const config_setting_t * @var{setting}}) +@deftypefunx int config_setting_is_array (@w{const config_setting_t * @var{setting}}) +@deftypefunx int config_setting_is_list (@w{const config_setting_t * @var{setting}}) + +These convenience functions, which are implemented as macros, test if +the setting @var{setting} is of a given type. They return +@code{CONFIG_TRUE} or @code{CONFIG_FALSE}. + +@end deftypefun + +@deftypefun int config_setting_is_aggregate (@w{const config_setting_t * @var{setting}}) +@deftypefunx int config_setting_is_scalar (@w{const config_setting_t * @var{setting}}) +@deftypefunx int config_setting_is_number (@w{const config_setting_t * @var{setting}}) + +@cindex aggregate value +These convenience functions, some of which are implemented as macros, test if +the setting @var{setting} is of an aggregate type (a group, array, or +list), of a scalar type (integer, 64-bit integer, floating point, +boolean, or string), and of a number (integer, 64-bit integer, or +floating point), respectively. They return @code{CONFIG_TRUE} or +@code{CONFIG_FALSE}. + +@end deftypefun + +@deftypefun {const char *} config_setting_source_file (@w{const config_setting_t * @var{setting}}) + +This function returns the name of the file from which the setting +@var{setting} was read, or NULL if the setting was not read from a +file. This information is useful for reporting application-level +errors. Storage for the returned string is managed by the library and +released automatically when the configuration is destroyed; the +string must not be freed by the caller. + +@end deftypefun + +@deftypefun {unsigned int} config_setting_source_line (@w{const config_setting_t * @var{setting}}) + +This function returns the line number of the configuration file or +stream at which the setting @var{setting} was read, or 0 if no line +number is available. This information is useful for reporting +application-level errors. + +@end deftypefun + +@deftypefun void config_set_hook (@w{config_t * @var{config}}, @w{void * @var{hook}}) +@deftypefunx {void *} config_get_hook (@w{const config_t * @var{config}}) + +@b{Since @i{v1.7}} + +@cindex hook +These functions make it possible to attach arbitrary data to a configuration +structure, for instance a ``wrapper'' or ``peer'' object written in +another programming language. + +@end deftypefun + +@deftypefun void config_setting_set_hook (@w{config_setting_t * @var{setting}}, @w{void * @var{hook}}) +@deftypefunx {void *} config_setting_get_hook (@w{const config_setting_t * @var{setting}}) + +@cindex hook +These functions make it possible to attach arbitrary data to each +setting structure, for instance a ``wrapper'' or ``peer'' object written in +another programming language. The destructor function, if one has been +supplied via a call to @code{config_set_destructor()}, will be called +by the library to dispose of this data when the setting itself is +destroyed. There is no default destructor. + +@end deftypefun + +@deftypefun void config_set_destructor (@w{config_t * @var{config}}, @w{void (* @var{destructor})(void *)}) + +@cindex destructor function +This function assigns the destructor function @var{destructor} for the +configuration @var{config}. This function accepts a single @code{void +*} argument and has no return value. See +@code{config_setting_set_hook()} above for more information. + +@end deftypefun + +@node The C++ API, Example Programs, The C API, Top +@comment node-name, next, previous, up +@chapter The C++ API + +@tindex Config +@tindex Setting +This chapter describes the C++ library API. The class @code{Config} +represents a configuration, and the class @code{Setting} represents a +configuration setting. Note that by design, neither of these classes +provides a public copy constructor or assignment operator. Therefore, +instances of these classes may only be passed between functions via +references or pointers. + +@tindex ConfigException +The library defines a group of exceptions, all of which extend the +common base exception @code{ConfigException}. + +@tindex SettingTypeException +A @code{SettingTypeException} is thrown when the type of a setting's +value does not match the type requested. + +@deftypemethod SettingTypeException {} SettingTypeException (@w{const Setting &@var{setting}}) +@deftypemethodx SettingTypeException {} SettingTypeException (@w{const Setting &@var{setting}}, @w{int @var{index}}) +@deftypemethodx SettingTypeException {} SettingTypeException (@w{const Setting &@var{setting}}, @w{const char *@var{name}}) + +These methods construct @code{SettingTypeException} objects for the given @var{setting} and/or member @var{index} or @var{name}. + +@end deftypemethod + +@tindex SettingNotFoundException +A @code{SettingNotFoundException} is thrown when a setting is not found. + +@deftypemethod SettingNotFoundException {} SettingNotFoundException (@w{const Setting &@var{setting}}, @w{int @var{index}}) +@deftypemethodx SettingNotFoundException {} SettingNotFoundException (@w{const Setting &@var{setting}}, @w{const char *@var{name}}) +@deftypemethodx SettingNotFoundException {} SettingNotFoundException (@w{const char *@var{path}}) + +These methods construct @code{SettingTypeException} objects for the given @var{setting} and member @var{index} or @var{name}, or path @var{path}. + +@end deftypemethod + +@tindex SettingNameException +A @code{SettingNameException} is thrown when an attempt is made to add +a new setting with a non-unique or invalid name. + +@deftypemethod SettingNameException {} SettingNameException (@w{const Setting &@var{setting}}, @w{const char *@var{name}}) + +This method constructs a @code{SettingNameExcpetion} object for the given @var{setting} and member name @var{name}. + +@end deftypemethod + +@tindex ParseException +A @code{ParseException} is thrown when a parse error occurs while +reading a configuration from a stream. + +@deftypemethod ParseException {} ParseException (@w{const char *@var{file}}, @w{int @var{line}}, @w{const char *@var{error}}) + +This method constructs a @code{ParseException} object with the given filename @var{file}, line number @var{line}, and error message @var{error}. + +@end deftypemethod + +@tindex FileIOException +A @code{FileIOException} is thrown when an I/O error occurs while +reading/writing a configuration from/to a file. + +@tindex SettingException +@code{SettingTypeException}, @code{SettingNotFoundException}, and +@code{SettingNameException} all extend the common base +exception @code{SettingException}, which provides the following method: + +@deftypemethod SettingException {const char *} getPath () const + +This method returns the path to the setting associated with the exception, or +@code{NULL} if there is no applicable path. + +@end deftypemethod + +The remainder of this chapter describes the methods for manipulating +configurations and configuration settings. + +@deftypemethod Config {} Config () +@deftypemethodx Config {} ~Config () + +These methods create and destroy @code{Config} objects. + +@end deftypemethod + +@deftypemethod Config void clear () + +@b{Since @i{v1.7}} + +This method clears the configuration. All child settings of the root +setting are recursively destroyed. All other attributes of the +configuration are left unchanged. + +@end deftypemethod + +@deftypemethod Config void read (@w{FILE * @var{stream}}) +@deftypemethodx Config void write (@w{FILE * @var{stream}}) const + +The @code{read()} method reads and parses a configuration from the given +@var{stream}. A @code{ParseException} is thrown if a parse error occurs. + +The @code{write()} method writes the configuration to the given @var{stream}. + +@end deftypemethod + +@deftypemethod Config void readFile (@w{const char * @var{filename}}) +@deftypemethodx Config void readFile (@w{const std::string &@var{filename}}) + +The @code{readFile()} method reads and parses a configuration from the +file named @var{filename}. A @code{ParseException} is thrown if a +parse error occurs. A @code{FileIOException} is thrown if the file +cannot be read. + +@end deftypemethod + +@deftypemethod Config void writeFile (@w{const char * @var{filename}}) +@deftypemethodx Config void writeFile (@w{const std::string &@var{filename}}) + +The @code{writeFile()} method writes the configuration to the file +named @var{filename}. A @code{FileIOException} is thrown if the file cannot +be written. + +@end deftypemethod + +@deftypemethod Config void readString (@w{const char * @var{str}}) +@deftypemethodx Config void readString (@w{const std::string &@var{str}}) + +These methods read and parse a configuration from the string +@var{str}. A @code{ParseException} is thrown if a parse error occurs. + +@end deftypemethod + +@deftypemethod ParseException {const char *} getError () const +@deftypemethodx ParseException {const char *} getFile () const +@deftypemethodx ParseException int getLine () const + +If a call to @code{readFile()}, @code{readString()}, or @code{read()} +resulted in a @code{ParseException}, these methods can be called on +the exception object to obtain the text, filename, and line number of +the parse error. Storage for the strings returned by @code{getError()} +and @code{getFile()} are managed by the library; the strings must not +be freed by the caller. + +@end deftypemethod + +@deftypemethod Config void setIncludeDir (@w{const char *@var{includeDir}}) +@deftypemethodx Config {const char *} getIncludeDir () const + +The @code{setIncludeDir()} method specifies the include directory, +@var{includeDir}, relative to which the files specified in +@samp{@@include} directives will be located for the configuration. By +default, there is no include directory, and all include files are +expected to be relative to the current working directory. If +@var{includeDir} is @code{NULL}, the default behavior is reinstated. + +For example, if the include directory is set to @file{/usr/local/etc}, +the include directive @samp{@@include "configs/extra.cfg"} would include the +file @file{/usr/local/etc/configs/extra.cfg}. + +@code{getIncludeDir()} returns the current include directory for the +configuration, or @code{NULL} if none is set. + +@end deftypemethod + +@deftypemethod Config {virtual const char **} evaluateIncludePath (@w{const char * @var{path}}, @w{const char ** @var{error}}) + +@b{Since @i{v1.7}} + +This method is called to evaluate the path of an @code{@@include} directive. +The @var{path} is the literal path argument of the directive. The method may +be overridden in a subclass to perform tasks like wildcard expansion and +variable substitution. + +On success, the method should return a @code{NULL}-terminated array of paths. +Any relative paths must be relative to the program's current working directory. +The contents of these files will be inlined at the point of inclusion, in the +order that the paths appear in the array. Both the array and its elements should +be heap allocated; the library will take ownership of and eventually free the +strings in the array and the array itself. + +On failure, the function should return @code{NULL} and set @var{*error} to a +static error string which should be used as the parse error for the +configuration; the library does not take ownership of or free this string. + +The default implementation simply returns a @code{NULL}-terminated array +containing either a copy of @var{path} if it's an absolute path, or a +concatenation of the include directory and @var{path} if it's a relative path. + +For more information see @code{config_set_include_func()} above. + +@end deftypemethod + +@deftypemethod Config int getOptions () const +@deftypemethodx Config void setOptions (int @var{options}) + +@tindex Config::Option +These methods get and set the options for the configuration. The +options affect how configurations are read and written. The parameter +@var{options} should be a bitwise-OR of the following @var{Config::Option} +enumeration values: + +@table @code + +@item Config::OptionAutoConvert +Turning this option on enables number auto-conversion for +the configuration. When this feature is enabled, an attempt to retrieve a +floating point setting's value into an integer (or vice versa), or +store an integer to a floating point setting's value (or vice versa) +will cause the library to silently perform the necessary conversion +(possibly leading to loss of data), rather than reporting failure. By +default this option is turned off. + +@item Config::OptionSemicolonSeparators +This option controls whether a semicolon (`;') is output after each setting +when the configuration is written to a file or stream. (The semicolon +separators are optional in the configuration syntax.) By default this +option is turned on. + +@item Config::OptionColonAssignmentForGroups +This option controls whether a colon (`:') is output between each +group setting's name and its value when the configuration is written to +a file or stream. If the option is turned off, an equals sign (`=') is +output instead. (These tokens are interchangeable in the configuration +syntax.) By default this option is turned on. + +@item Config::OptionColonAssignmentForNonGroups +This option controls whether a colon (`:') is output between each +non-group setting's name and its value when the configuration is written +to a file or stream. If the option is turned off, an equals sign (`=') +is output instead. (These tokens are interchangeable in the configuration +syntax.) By default this option is turned off. + +@item Config::OptionOpenBraceOnSeparateLine +This option controls whether an open brace (`@{') will be written on its own +line when the configuration is written to a file or stream. If the option is +turned off, the brace will be written at the end of the previous line. +By default this option is turned on. + +@item Config::OptionAllowScientificNotation +(@b{Since @i{v1.7}}) +This option controls whether scientific notation may be used as appropriate +when writing floating point values (corresponding to @code{printf()} +@samp{%g} format) or should never be used (corresponding to @code{printf()} +@samp{%f} format). By default this option is turned off. + +@item Config::OptionFsync +(@b{Since @i{v1.7.1}}) +This option controls whether the @code{writeFile()} method performs an @i{fsync} +operation after writing the configuration and before closing the file. By +default this option is turned off. + +@item Config::OptionAllowOverrides +(@b{Since @i{v1.7.3}}) +This option controls whether duplicate settings override previous settings +with the same name. If this option is turned off, duplicate settings are +rejected. By default this option is turned off. + +@end table + +@end deftypemethod + +@deftypemethod Config bool getOption (@w{Config::Option @var{option}}) const +@deftypemethodx Config void setOption (@w{Config::Option @var{option}}, @w{bool @var{flag}}) + +@b{Since @i{v1.7}} + +These methods get and set the option @var{option} for the configuration. The +option is enabled if @var{flag} is @code{true} and disabled if it is +@code{false}. + +See @code{setOptions()} above for the list of available options. + +@end deftypemethod + +@deftypemethod Config bool getAutoConvert () const +@deftypemethodx Config void setAutoConvert (bool @var{flag}) + +These methods get and set the @code{OptionAutoConvert} option. They +are obsoleted by the @code{setOption()} and @code{getOption()} +methods described above. + +@end deftypemethod + +@deftypemethod Config Setting::Format getDefaultFormat () const +@deftypemethodx Config void setDefaultFormat (@w{Setting::Format @var{format}}) + +These methods get and set the default external format for settings in +the configuration. If a non-default format has not been set for a +setting with @code{Setting::setFormat()}, this configuration-wide +default format will be used instead when that setting is written to a +file or stream. + +@end deftypemethod + +@deftypemethod Config {unsigned short} getTabWidth () const +@deftypemethodx Config void setTabWidth (@w{unsigned short @var{width}}) + +These methods get and set the tab width for the configuration. The tab +width affects the formatting of the configuration when it is written +to a file or stream: each level of nesting is indented by @var{width} +spaces, or by a single tab character if @var{width} is 0. The tab +width has no effect on parsing. + +Valid tab widths range from 0 to 15. The default tab width is 2. + +@end deftypemethod + +@deftypemethod Config {unsigned short} getFloatPrecision () const +@deftypemethodx Config void setFloatPrecision (@w{unsigned short @var{width}}) + +These methods get and set the float precision for the configuration. +This parameter influences the formatting of floating point settings in +the configuration when it is written to a file or stream. +Float precision has no effect on parsing. + +Valid precisions range from 0 to about 15 (implementation dependent), +though the library will accept and store values up to 255. + +@end deftypemethod + +@deftypemethod Config {Setting &} getRoot () const + +This method returns the root setting for the configuration, which is a group. + +@end deftypemethod + +@deftypemethod Config {Setting &} lookup (@w{const std::string &@var{path}}) const +@deftypemethodx Config {Setting &} lookup (@w{const char * @var{path}}) const + +These methods locate the setting specified by the path @var{path}. If +the requested setting is not found, a @code{SettingNotFoundException} is +thrown. + +@end deftypemethod +@deftypemethod Config bool exists (@w{const std::string &@var{path}}) const +@deftypemethodx Config bool exists (@w{const char *@var{path}}) const + +These methods test if a setting with the given @var{path} exists in +the configuration. They return @code{true} if the setting exists, and +@code{false} otherwise. These methods do not throw exceptions. + +@end deftypemethod + +@deftypemethod Config bool lookupValue (@w{const char *@var{path}}, @w{bool &@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{bool &@var{value}}) const + +@deftypemethodx Config bool lookupValue (@w{const char *@var{path}}, @w{int &@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{int &@var{value}}) const + +@deftypemethodx Config bool lookupValue (@w{const char *@var{path}}, @w{unsigned int &@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{unsigned int &@var{value}}) const + +@deftypemethodx Config bool lookupValue (@w{const char *@var{path}}, @w{long long &@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{long long &@var{value}}) const + +@deftypemethodx Config bool lookupValue (@w{const char *@var{path}}, @w{float &@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{float &@var{value}}) const + +@deftypemethodx Config bool lookupValue (@w{const char *@var{path}}, @w{double &@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{double &@var{value}}) const + +@deftypemethodx Config bool lookupValue (@w{const char *@var{path}}, @w{const char *&@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{const char *&@var{value}}) const + +@deftypemethodx Config bool lookupValue (@w{const char *@var{path}}, @w{std::string &@var{value}}) const +@deftypemethodx Config bool lookupValue (@w{const std::string &@var{path}}, @w{std::string &@var{value}}) const + +These are convenience methods for looking up the value of a setting +with the given @var{path}. If the setting is found and is of an +appropriate type, the value is stored in @var{value} and the method +returns @code{true}. Otherwise, @var{value} is left unmodified and the +method returns @code{false}. These methods do not throw exceptions. + +Storage for @w{@i{const char *}} values is managed by the library and +released automatically when the setting is destroyed or when its value +is changed; the string must not be freed by the caller. For safety and +convenience, always assigning string values to a @code{std::string} is +suggested. + +Since these methods have boolean return values and do not throw +exceptions, they can be used within boolean logic expressions. The following +example presents a concise way to look up three values at once and +perform error handling if any of them are not found or are of the +wrong type: + +@sp 1 +@cartouche +@smallexample +int var1; +double var2; +const char *var3; + +if(config.lookupValue("values.var1", var1) + && config.lookupValue("values.var2", var2) + && config.lookupValue("values.var3", var3)) +@{ + // use var1, var2, var3 +@} +else +@{ + // error handling here +@} +@end smallexample +@end cartouche + +This approach also takes advantage of the short-circuit evaluation rules +of C++, e.g., if the first lookup fails (returning @code{false}), the +remaining lookups are skipped entirely. + +@end deftypemethod + +@deftypemethod Setting {} {operator bool ()} const +@deftypemethodx Setting {} {operator int ()} const +@deftypemethodx Setting {} {operator unsigned int ()} const +@deftypemethodx Setting {} {operator long ()} const +@deftypemethodx Setting {} {operator unsigned long ()} const +@deftypemethodx Setting {} {operator long long ()} const +@deftypemethodx Setting {} {operator unsigned long long ()} const +@deftypemethodx Setting {} {operator float ()} const +@deftypemethodx Setting {} {operator double ()} const +@deftypemethodx Setting {} {operator const char * ()} const +@deftypemethodx Setting {} {operator std::string ()} const +@deftypemethodx Setting {const char *} c_str () const + +These cast operators allow a @code{Setting} object to be assigned to a +variable of type @i{bool} if it is of type @code{TypeBoolean}; +@i{int}, @i{unsigned int}; @code{long long} or @code{unsigned long long} if +it is of type @code{TypeInt64}, @i{float} or @i{double} if it is of type +@code{TypeFloat}; or @w{@i{const char *}} or @i{std::string} if it is +of type @code{TypeString}. + +Values of type @code{TypeInt} or @code{TypeInt64} may be assigned to +variables of type @i{long}, or @i{unsigned long}, depending on the +sizes of those types on the host system. + +Storage for @w{@i{const char *}} return values is managed by the +library and released automatically when the setting is destroyed or +when its value is changed; the string must not be freed by the +caller. For safety and convenience, always assigning string return +values to a @code{std::string} is suggested. + +The following examples demonstrate this usage: + +@cartouche +@smallexample +long width = config.lookup("application.window.size.w"); + +bool splashScreen = config.lookup("application.splash_screen"); + +std::string title = config.lookup("application.window.title"); +@end smallexample +@end cartouche + +Note that certain conversions can lead to loss of precision or +clipping of values, e.g., assigning a negative value to an @i{unsigned +int} (in which case the value will be treated as 0), or a +double-precision value to a @i{float}. The library does not treat +these lossy conversions as errors. + +Perhaps surprisingly, the following code in particular will cause a +compiler error: + +@cartouche +@smallexample +std::string title; +. +. +. +title = config.lookup("application.window.title"); +@end smallexample +@end cartouche + +This is because the assignment operator of @code{std::string} is being +invoked with a @code{Setting &} as an argument. The compiler is unable +to make an implicit conversion because both the @code{const char *} +and the @code{std::string} cast operators of @code{Setting} are +equally appropriate. This is not a bug in @i{libconfig}; providing +only the @code{const char *} cast operator would resolve this +particular ambiguity, but would cause assignments to +@code{std::string} like the one in the previous example to produce a +compiler error. (To understand why, see section 11.4.1 of @i{The C++ +Programming Language}.) + +The solution to this problem is to use an explicit conversion that +avoids the construction of an intermediate @code{std::string} object, +as follows: + +@cartouche +@smallexample +std::string title; +. +. +. +title = (const char *)config.lookup("application.window.title"); +@end smallexample +@end cartouche + +Or, alternatively, use the @code{c_str()} method, which has the same effect: + +@cartouche +@smallexample +std::string title; +. +. +. +title = config.lookup("application.window.title").c_str(); +@end smallexample +@end cartouche + +If the assignment is invalid due to a type mismatch, a +@code{SettingTypeException} is thrown. + +@end deftypemethod + +@deftypemethod Setting {Setting &} operator= (@w{bool @var{value}}) +@deftypemethodx Setting {Setting &} operator= (@w{int @var{value}}) +@deftypemethodx Setting {Setting &} operator= (@w{long @var{value}}) +@deftypemethodx Setting {Setting &} operator= (@w{const long long &@var{value}}) +@deftypemethodx Setting {Setting &} operator= (@w{float @var{value}}) +@deftypemethodx Setting {Setting &} operator= (@w{const double &@var{value}}) +@deftypemethodx Setting {Setting &} operator= (@w{const char *@var{value}}) +@deftypemethodx Setting {Setting &} operator= (@w{const std::string &@var{value}}) + +These assignment operators allow values of type @i{bool}, @i{int}, +@i{long}, @i{long long}, @i{float}, @i{double}, @i{const char *}, and +@i{std::string} to be assigned to a setting. In the case of strings, +the library makes a copy of the passed string @var{value}, so it may +be subsequently freed or modified by the caller without affecting the +value of the setting. + +The following example code looks up a (presumably) integer setting +and changes its value: + +@cartouche +@smallexample +Setting &setting = config.lookup("application.window.size.w"); +setting = 1024; +@end smallexample +@end cartouche + +If the assignment is invalid due to a type mismatch, a +@code{SettingTypeException} is thrown. + +@end deftypemethod + +@deftypemethod Setting {Setting &} {operator[]} (@w{int @var{index}}) const +@deftypemethodx Setting {Setting &} {operator[]} (@w{const std::string &@var{name}}) const +@deftypemethodx Setting {Setting &} {operator[]} (@w{const char *@var{name}}) const + +A @code{Setting} object may be subscripted with an integer index +@var{index} if it is an array or list, or with either a string +@var{name} or an integer index @var{index} if it is a group. For example, +the following code would produce the string @samp{Last Name} when +applied to the example configuration in @ref{Configuration Files}. + +@cartouche +@smallexample +Setting& setting = config.lookup("application.misc"); +const char *s = setting["columns"][0]; +@end smallexample +@end cartouche + +If the setting is not an array, list, or group, a +@code{SettingTypeException} is thrown. If the subscript (@var{index} +or @var{name}) does not refer to a valid element, a +@code{SettingNotFoundException} is thrown. + +Iterating over a group's child settings with an integer index will +return the settings in the same order that they appear in the +configuration. + +@end deftypemethod + +@deftypemethod Setting {Setting &} lookup (@w{const char * @var{path}}) const +@deftypemethodx Setting {Setting &} lookup (@w{const std::string &@var{path}}) const + +These methods locate a setting by a path @var{path} relative to +this setting. If requested setting is not found, a +@code{SettingNotFoundException} is thrown. + +@end deftypemethod + +@deftypemethod Setting bool lookupValue (@w{const char *@var{name}}, @w{bool &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{bool &@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{int &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{int &@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{unsigned int &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{unsigned int &@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{long long &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{long long &@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{unsigned long long &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{unsigned long long &@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{float &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{float &@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{double &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{double &@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{const char *&@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{const char *&@var{value}}) const + +@deftypemethodx Setting bool lookupValue (@w{const char *@var{name}}, @w{std::string &@var{value}}) const +@deftypemethodx Setting bool lookupValue (@w{const std::string &@var{name}}, @w{std::string &@var{value}}) const + +These are convenience methods for looking up the value of a child setting +with the given @var{name}. If the setting is found and is of an +appropriate type, the value is stored in @var{value} and the method +returns @code{true}. Otherwise, @var{value} is left unmodified and the +method returns @code{false}. These methods do not throw exceptions. + +Storage for @w{@i{const char *}} values is managed by the library and +released automatically when the setting is destroyed or when its value +is changed; the string must not be freed by the caller. For safety and +convenience, always assigning string values to a @code{std::string} is +suggested. + +Since these methods have boolean return values and do not throw +exceptions, they can be used within boolean logic expressions. The following +example presents a concise way to look up three values at once and +perform error handling if any of them are not found or are of the +wrong type: + +@sp 1 +@cartouche +@smallexample +int var1; +double var2; +const char *var3; + +if(setting.lookupValue("var1", var1) + && setting.lookupValue("var2", var2) + && setting.lookupValue("var3", var3)) +@{ + // use var1, var2, var3 +@} +else +@{ + // error handling here +@} +@end smallexample +@end cartouche + +This approach also takes advantage of the short-circuit evaluation +rules of C++, e.g., if the first lookup fails (returning @code{false}), the +remaining lookups are skipped entirely. + +@end deftypemethod + +@deftypemethod Setting {Setting &} add (@w{const std::string &@var{name}}, @w{Setting::Type @var{type}}) +@deftypemethodx Setting {Setting &} add (@w{const char *@var{name}}, @w{Setting::Type @var{type}}) + +These methods add a new child setting with the given @var{name} and +@var{type} to the setting, which must be a group. They return a +reference to the new setting. If the setting already has a child +setting with the given name, or if the name is invalid, a +@code{SettingNameException} is thrown. If the setting is not a group, +a @code{SettingTypeException} is thrown. + +Once a setting has been created, neither its name nor type can be +changed. + +@end deftypemethod + +@deftypemethod Setting {Setting &} add (@w{Setting::Type @var{type}}) + +This method adds a new element to the setting, which must be of type +@code{TypeArray} or @code{TypeList}. If the setting is an array which +currently has zero elements, the @var{type} parameter (which must be +@code{TypeInt}, @code{TypeInt64}, @code{TypeFloat}, @code{TypeBool}, +or @code{TypeString}) determines the type for the array; otherwise it +must match the type of the existing elements in the array. + +The method returns the new setting on success. If @var{type} is a +scalar type, the new setting will have a default value of 0, 0.0, +@code{false}, or @code{NULL}, as appropriate. + +The method throws a @code{SettingTypeException} if the setting is not +an array or list, or if @var{type} is invalid. + +@end deftypemethod + +@deftypemethod Setting void remove (@w{const std::string &@var{name}}) +@deftypemethodx Setting void remove (@w{const char *@var{name}}) + +These methods remove the child setting with the given @var{name} from +the setting, which must be a group. Any child settings of the removed +setting are recursively destroyed as well. + +If the setting is not a group, a @code{SettingTypeException} is +thrown. If the setting does not have a child setting with the given +name, a @code{SettingNotFoundException} is thrown. + +@end deftypemethod + +@deftypemethod Setting void remove (@w{unsigned int @var{index}}) + +This method removes the child setting at the given index @var{index} from +the setting, which must be a group, list, or array. Any child settings +of the removed setting are recursively destroyed as well. + +If the setting is not a group, list, or array, a +@code{SettingTypeException} is thrown. If @var{index} is out of range, +a @code{SettingNotFoundException} is thrown. + +@end deftypemethod + +@deftypemethod Setting {const char *} getName () const + +This method returns the name of the setting, or @code{NULL} if the +setting has no name. Storage for the returned string is managed by the +library and released automatically when the setting is destroyed; the +string must not be freed by the caller. For safety and convenience, +consider assigning the return value to a @code{std::string}. + +@end deftypemethod + +@deftypemethod Setting {std::string} getPath () const + +This method returns the complete dot-separated path to the +setting. Settings which do not have a name (list and array elements) +are represented by their index in square brackets. + +@end deftypemethod + +@deftypemethod Setting {Setting &} getParent () const + +This method returns the parent setting of the setting. If the setting +is the root setting, a @code{SettingNotFoundException} is thrown. + +@end deftypemethod + +@deftypemethod Setting bool isRoot () const + +This method returns @code{true} if the setting is the root setting, and +@code{false} otherwise. + +@end deftypemethod + +@deftypemethod Setting int getIndex () const + +This method returns the index of the setting within its parent +setting. When applied to the root setting, this method returns -1. + +@end deftypemethod + +@deftypemethod Setting Setting::Type getType () const + +@tindex Setting::Type +This method returns the type of the setting. The +@code{Setting::Type} enumeration consists of the following constants: +@code{TypeInt}, @code{TypeInt64}, @code{TypeFloat}, @code{TypeString}, +@code{TypeBoolean}, @code{TypeArray}, @code{TypeList}, and +@code{TypeGroup}. + +@end deftypemethod + +@deftypemethod Setting Setting::Format getFormat () const +@deftypemethodx Setting void setFormat (@w{Setting::Format @var{format}}) + +These methods get and set the external format for the setting. + +@tindex Setting::Format +The @var{Setting::Format} enumeration consists of the following +constants: @code{FormatDefault} and @code{FormatHex}. All settings +support the @code{FormatDefault} format. The @code{FormatHex} format +specifies hexadecimal formatting for integer values, and hence only +applies to settings of type @code{TypeInt} and @code{TypeInt64}. If +@var{format} is invalid for the given setting, it is ignored. + +@end deftypemethod + +@deftypemethod Setting bool exists (@w{const std::string &@var{name}}) const +@deftypemethodx Setting bool exists (@w{const char *@var{name}}) const + +These methods test if the setting has a child setting with the given +@var{name}. They return @code{true} if the setting exists, and +@code{false} otherwise. These methods do not throw exceptions. + +@end deftypemethod +@page +@deftypemethod Setting iterator begin () +@deftypemethodx Setting iterator end () +@deftypemethodx Setting const_iterator begin () +@deftypemethodx Setting const_iterator end () + +These methods return STL-style iterators that can be used to enumerate +the child settings of a given setting. If the setting is not an array, list, +or group, they throw a @code{SettingTypeException}. + +@end deftypemethod + +@deftypemethod Setting int getLength () const + +This method returns the number of settings in a group, or the number of +elements in a list or array. For other types of settings, it returns +0. + +@end deftypemethod + +@deftypemethod Setting bool isGroup () const +@deftypemethodx Setting bool isArray () const +@deftypemethodx Setting bool isList () const + +These convenience methods test if a setting is of a given type. + +@end deftypemethod + +@deftypemethod Setting bool isAggregate () const +@deftypemethodx Setting bool isScalar () const +@deftypemethodx Setting bool isNumber () const +@deftypemethodx Setting bool isString () const + +These convenience methods test if a setting is of an aggregate type (a +group, array, or list), of a scalar type (integer, 64-bit integer, +floating point, boolean, or string), of a number (integer, 64-bit +integer, or floating point), and of a string respectively. + +@end deftypemethod + +@deftypemethod Setting {const char *} getSourceFile () const + +This method returns the name of the file from which the setting was +read, or NULL if the setting was not read from a file. This +information is useful for reporting application-level errors. Storage +for the returned string is managed by the library and released +automatically when the configuration is destroyed; the string must +not be freed by the caller. + +@end deftypemethod + +@deftypemethod Setting {unsigned int} getSourceLine () const + +This method returns the line number of the configuration file or +stream at which the setting @var{setting} was read, or 0 if no line +number is available. This information is useful for reporting +application-level errors. + +@end deftypemethod + +@node Example Programs, Other Bindings and Implementations, The C++ API, Top +@comment node-name, next, previous, up +@chapter Example Programs + +Practical example programs that illustrate how to use @i{libconfig} +from both C and C++ are included in the @file{examples} subdirectory +of the distribution. These examples include: + +@table @file + +@item examples/c/example1.c +An example C program that reads a configuration from an existing file +@file{example.cfg} (also located in @file{examples/c}) and displays +some of its contents. + +@item examples/c++/example1.cpp +The C++ equivalent of @file{example1.c}. + +@item examples/c/example2.c +An example C program that reads a configuration from an existing file +@file{example.cfg} (also located in @file{examples/c}), adds new +settings to the configuration, and writes the updated configuration to +another file. + +@item examples/c++/example2.cpp +The C++ equivalent of @file{example2.c} + +@item examples/c/example3.c +An example C program that constructs a new configuration in memory and writes it to a file. + +@item examples/c++/example3.cpp +The C++ equivalent of @file{example3.c} + +@item examples/c/example4.c +An example C program that uses a custom include function for processing +wildcard includes. Note that this code will not compile on Windows. + +@end table + +@node Other Bindings and Implementations, License, Example Programs, Top +@comment node-name, next, previous, up +@chapter Other Bindings and Implementations +@menu +* Bourne Shell:: +* D:: +* Haskell:: +* Java:: +* Lisp:: +* Perl:: +* Python:: +* Ruby:: +@end menu + +Various open-source libraries have been written that provide access to +@i{libconfig}-style configuration files from other programming languages. Some +of these libraries are wrappers which add new language bindings for +@i{libconfig} while others are syntax-compatible reimplementations in other +languages. + +Here is a list of some of these implementations. + +@node Bourne Shell, D, , Other Bindings and Implementations +@comment node-name, next, previous, up +@section Bourne Shell + +@L{}ukasz A. Grabowski's @i{ls-config} provides a means to read and write +values in @i{libconfig} configuration files from Bourne shell scripts. The +implementation is included in the @i{libconfig} git repository at +@url{https://github.com/hyperrealm/libconfig}, in the @file{contrib/ls-config} +subdirectory. + +@node D, Haskell, Bourne Shell, Other Bindings and Implementations +@comment node-name, next, previous, up +@section D + +Remi Thebault's @i{libconfig-d} is a port of @i{libconfig} to the D programming +language. It may be found at @url{https://code.dlang.org/packages/libconfig-d}. + +@node Haskell, Java, D, Other Bindings and Implementations +@comment node-name, next, previous, up +@section Haskell + +Matthew Peddie's @i{libconfig} provides Haskell bindings to +@i{libconfig}. It may be found at +@url{https://hackage.haskell.org/package/libconfig-0.3.0.0}. + +@node Java, Lisp, Haskell, Other Bindings and Implementations +@comment node-name, next, previous, up +@section Java + +Andrey V. Pleskach has a pure-Java implementation of @i{libconfig}. It may be +found on github at @url{https://github.com/willyborankin/libconfig}. + +@node Lisp, Perl, Java, Other Bindings and Implementations +@comment node-name, next, previous, up +@section Lisp + +Oleg Shalaev's @i{cl-libconfig} provides Common Lisp bindings for @i{libconfig}. +It may be found on github at @url{https://github.com/chalaev/cl-libconfig}. + +@node Perl, Python, Lisp, Other Bindings and Implementations +@comment node-name, next, previous, up +@section Perl + +The @i{Conf::Libconfig} module provides Perl bindings for @i{libconfig}. It may +be found on CPAN at @url{http://search.cpan.org/~cnangel/Conf-Libconfig-0.05/} +or on github at @url{https://github.com/cnangel/Conf-Libconfig}. + +@node Python, Ruby, Perl, Other Bindings and Implementations +@comment node-name, next, previous, up +@section Python + +Heiner Tholen's @i{pylibconfig2} is a Python library that is syntax-compatible +with @i{libconfig}. It may be found at +@url{https://pypi.python.org/pypi/pylibconfig2/0.1.2}. + +@sp 1 + +Christian Aichinger's @i{libconf} is another pure-Python implementation with a +more permissive license. It may be found at +@url{https://pypi.python.org/pypi/libconf} or on github at +@url{https://github.com/Grk0/python-libconf}. + +@sp 1 + +The @i{python-libconfig} wrapper provides Python bindings to @i{libconfig}. It +may be found on github at @url{https://github.com/cnangel/python-libconfig/}. + +@node Ruby, , Python, Other Bindings and Implementations +@comment node-name, next, previous, up +@section Ruby + +Christopher Mark Gore's @i{ruby-libconfig} is a Ruby library that provides Ruby +bindings for @i{libconfig}. It may be found at +@url{https://rubygems.org/gems/libconfig} or on github at +@url{https://github.com/cgore/ruby-libconfig}. + +@sp 1 + +There is also another Ruby wrapper, @i{libconfig-ruby}, that is included in +the @i{libconfig} git repository at @url{https://github.com/hyperrealm/libconfig}, +in the @file{contrib/libconfig-ruby} subdirectory. + +@node License, Configuration File Grammar, Other Bindings and Implementations, Top +@comment node-name, next, previous, up +@appendix License + +@include LGPL.texi + +@node Configuration File Grammar, Function Index, License, Top +@comment node-name, next, previous, up +@appendix Configuration File Grammar + +Below is the BNF grammar for configuration files. Comments and include +directives are not part of the grammar, so they are not included here. + +@sp 1 +@example +<configuration> ::= + <setting-list> + | <empty> + +<setting-list> ::= + <setting> + | <setting-list> <setting> + +<setting> ::= + <name> ( ":" | "=" ) <value> ( ";" | "," | <empty> ) + +<value> ::= + <scalar-value> + | <array> + | <list> + | <group> + +<value-list> ::= + <value> + | <value-list> "," <value> + | <value-list> "," + +<scalar-value> ::= + <boolean> + | <integer> + | <integer64> + | <hex> + | <hex64> + | <float> + | <string> + +<scalar-value-list> ::= + <scalar-value> + | <scalar-value-list> "," <scalar-value> + | <scalar-value-list> "," + +<array> ::= + "[" ( <scalar-value-list> | <empty> ) "]" + +<list> ::= + "(" ( <value-list> | <empty> ) ")" + +<group> ::= + "@{" ( <setting-list> | <empty> ) "@}" + +<empty> ::= +@end example + +@sp 2 +Terminals are defined below as regular expressions: +@sp 1 + +@multitable @columnfractions .2 .8 +@item @code{<boolean>} @tab +@code{([Tt][Rr][Uu][Ee])|([Ff][Aa][Ll][Ss][Ee])} +@item @code{<string>} @tab +@code{\"([^\"\\]|\\.)*\"} +@item @code{<name>} @tab +@code{[A-Za-z\*][-A-Za-z0-9_\*]*} +@item @code{<integer>} @tab +@code{[-+]?[0-9]+} +@item @code{<integer64>} @tab +@code{[-+]?[0-9]+L(L)?} +@item @code{<hex>} @tab +@code{0[Xx][0-9A-Fa-f]+} +@item @code{<hex64>} @tab +@code{0[Xx][0-9A-Fa-f]+(L(L)?)?} +@item @code{<float>} @tab +@code{([-+]?([0-9]*)?\.[0-9]*([eE][-+]?[0-9]+)?)|([-+]([0-9]+)(\.[0-9]*)?[eE][-+]?[0-9]+)} +@end multitable + +@sp 1 + +Note that adjacent strings are automatically concatenated. Non-printable +characters can be represented within strings using a sequence @samp{\xx}, +representing the ASCII value as two hex digits. + +@node Function Index, Type Index, Configuration File Grammar, Top +@comment node-name, next, previous, up +@unnumbered Function Index + +@printindex fn + +@node Type Index, Concept Index, Function Index, Top +@comment node-name, next, previous, up +@unnumbered Type Index + +@printindex tp + +@node Concept Index, , Type Index, Top +@comment node-name, next, previous, up +@unnumbered Concept Index + +@printindex cp + +@bye |