diff options
Diffstat (limited to 'src/grammar.pest')
| -rw-r--r-- | src/grammar.pest | 165 |
1 files changed, 107 insertions, 58 deletions
diff --git a/src/grammar.pest b/src/grammar.pest index 405ab39..d97caba 100644 --- a/src/grammar.pest +++ b/src/grammar.pest @@ -1,6 +1,6 @@ // pest. The Elegant Parser // Copyright (c) 2018 Dragoș Tiselice -// +// // Licensed under the Apache License, Version 2.0 // <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT // license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your @@ -16,97 +16,126 @@ //! future (e.g. by increasing MSRV and non_exhaustive annotations). /// The top-level rule of a grammar. -grammar_rules = _{ SOI ~ grammar_doc* ~ (grammar_rule)+ ~ EOI } +grammar_rules = _{ SOI ~ grammar_doc* ~ grammar_rule* ~ EOI } /// A rule of a grammar. grammar_rule = { - identifier ~ assignment_operator ~ modifier? ~ - opening_brace ~ expression ~ closing_brace | - line_doc + identifier ~ assignment_operator ~ modifier? ~ opening_brace ~ expression ~ closing_brace + | line_doc } /// Assignment operator. assignment_operator = { "=" } + /// Opening brace for a rule. -opening_brace = { "{" } +opening_brace = { "{" } + /// Closing brace for a rule. -closing_brace = { "}" } +closing_brace = { "}" } + /// Opening parenthesis for a branch, PUSH, etc. -opening_paren = { "(" } +opening_paren = { "(" } + /// Closing parenthesis for a branch, PUSH, etc. -closing_paren = { ")" } +closing_paren = { ")" } + /// Opening bracket for PEEK (slice inside). -opening_brack = { "[" } +opening_brack = { "[" } + /// Closing bracket for PEEK (slice inside). -closing_brack = { "]" } +closing_brack = { "]" } /// A rule modifier. modifier = _{ - silent_modifier | - atomic_modifier | - compound_atomic_modifier | - non_atomic_modifier + silent_modifier + | atomic_modifier + | compound_atomic_modifier + | non_atomic_modifier } /// Silent rule prefix. -silent_modifier = { "_" } +silent_modifier = { "_" } + /// Atomic rule prefix. -atomic_modifier = { "@" } +atomic_modifier = { "@" } + /// Compound atomic rule prefix. compound_atomic_modifier = { "$" } + /// Non-atomic rule prefix. -non_atomic_modifier = { "!" } +non_atomic_modifier = { "!" } + +/// A tag label. +tag_id = @{ "#" ~ ("_" | alpha) ~ ("_" | alpha_num)* } + +/// For assigning labels to nodes. +node_tag = _{ tag_id ~ assignment_operator } /// A rule expression. -expression = { choice_operator? ~ term ~ (infix_operator ~ term)* } +expression = { choice_operator? ~ term ~ (infix_operator ~ term)* } + /// A rule term. -term = { prefix_operator* ~ node ~ postfix_operator* } +term = { node_tag? ~ prefix_operator* ~ node ~ postfix_operator* } + /// A rule node (inside terms). -node = _{ opening_paren ~ expression ~ closing_paren | terminal } +node = _{ opening_paren ~ expression ~ closing_paren | terminal } + /// A terminal expression. -terminal = _{ _push | peek_slice | identifier | string | insensitive_string | range } +terminal = _{ _push | peek_slice | identifier | string | insensitive_string | range } /// Possible predicates for a rule. -prefix_operator = _{ positive_predicate_operator | negative_predicate_operator } +prefix_operator = _{ positive_predicate_operator | negative_predicate_operator } + /// Branches or sequences. -infix_operator = _{ sequence_operator | choice_operator } +infix_operator = _{ sequence_operator | choice_operator } + /// Possible modifiers for a rule. postfix_operator = _{ - optional_operator | - repeat_operator | - repeat_once_operator | - repeat_exact | - repeat_min | - repeat_max | - repeat_min_max + optional_operator + | repeat_operator + | repeat_once_operator + | repeat_exact + | repeat_min + | repeat_max + | repeat_min_max } /// A positive predicate. positive_predicate_operator = { "&" } + /// A negative predicate. negative_predicate_operator = { "!" } + /// A sequence operator. -sequence_operator = { "~" } +sequence_operator = { "~" } + /// A choice operator. -choice_operator = { "|" } +choice_operator = { "|" } + /// An optional operator. -optional_operator = { "?" } +optional_operator = { "?" } + /// A repeat operator. -repeat_operator = { "*" } +repeat_operator = { "*" } + /// A repeat at least once operator. -repeat_once_operator = { "+" } +repeat_once_operator = { "+" } /// A repeat exact times. -repeat_exact = { opening_brace ~ number ~ closing_brace } +repeat_exact = { opening_brace ~ number ~ closing_brace } + /// A repeat at least times. -repeat_min = { opening_brace ~ number ~ comma ~ closing_brace } +repeat_min = { opening_brace ~ number ~ comma ~ closing_brace } + /// A repeat at most times. -repeat_max = { opening_brace ~ comma ~ number ~ closing_brace } +repeat_max = { opening_brace ~ comma ~ number ~ closing_brace } + /// A repeat in a range. repeat_min_max = { opening_brace ~ number ~ comma ~ number ~ closing_brace } /// A number. number = @{ '0'..'9'+ } + /// An integer number (positive or negative). integer = @{ number | "-" ~ "0"* ~ '1'..'9' ~ number? } @@ -115,62 +144,82 @@ comma = { "," } /// A PUSH expression. _push = { "PUSH" ~ opening_paren ~ expression ~ closing_paren } + /// A PEEK expression. peek_slice = { "PEEK" ~ opening_brack ~ integer? ~ range_operator ~ integer? ~ closing_brack } /// An identifier. identifier = @{ !"PUSH" ~ ("_" | alpha) ~ ("_" | alpha_num)* } + /// An alpha character. -alpha = _{ 'a'..'z' | 'A'..'Z' } +alpha = _{ 'a'..'z' | 'A'..'Z' } + /// An alphanumeric character. -alpha_num = _{ alpha | '0'..'9' } +alpha_num = _{ alpha | '0'..'9' } /// A string. -string = ${ quote ~ inner_str ~ quote } +string = ${ quote ~ inner_str ~ quote } + /// An insensitive string. -insensitive_string = { "^" ~ string } +insensitive_string = { "^" ~ string } + /// A character range. -range = { character ~ range_operator ~ character } +range = { character ~ range_operator ~ character } + /// A single quoted character -character = ${ single_quote ~ inner_chr ~ single_quote } +character = ${ single_quote ~ inner_chr ~ single_quote } /// A quoted string. inner_str = @{ (!("\"" | "\\") ~ ANY)* ~ (escape ~ inner_str)? } + /// An escaped or any character. inner_chr = @{ escape | ANY } + /// An escape sequence. -escape = @{ "\\" ~ ("\"" | "\\" | "r" | "n" | "t" | "0" | "'" | code | unicode) } +escape = @{ "\\" ~ ("\"" | "\\" | "r" | "n" | "t" | "0" | "'" | code | unicode) } + /// A hexadecimal code. -code = @{ "x" ~ hex_digit{2} } +code = @{ "x" ~ hex_digit{2} } + /// A unicode code. -unicode = @{ "u" ~ opening_brace ~ hex_digit{2, 6} ~ closing_brace } +unicode = @{ "u" ~ opening_brace ~ hex_digit{2, 6} ~ closing_brace } + /// A hexadecimal digit. hex_digit = @{ '0'..'9' | 'a'..'f' | 'A'..'F' } /// A double quote. -quote = { "\"" } +quote = { "\"" } + /// A single quote. -single_quote = { "'" } +single_quote = { "'" } + /// A range operator. range_operator = { ".." } /// A newline character. -newline = _{ "\n" | "\r\n" } +newline = _{ "\n" | "\r\n" } + /// A whitespace character. -WHITESPACE = _{ " " | "\t" | newline } +WHITESPACE = _{ " " | "\t" | newline } + /// A single line comment. -line_comment = _{ ("//" ~ !("/" | "!") ~ (!newline ~ ANY)*) } +line_comment = _{ ("//" ~ !("/" | "!") ~ (!newline ~ ANY)*) } + /// A multi-line comment. -block_comment = _{ "/*" ~ (block_comment | !"*/" ~ ANY)* ~ "*/" } +block_comment = _{ "/*" ~ (block_comment | !"*/" ~ ANY)* ~ "*/" } + /// A grammar comment. -COMMENT = _{ block_comment | line_comment } +COMMENT = _{ block_comment | line_comment } // ref: https://doc.rust-lang.org/reference/comments.html /// A space character. -space = _{ " " | "\t" } +space = _{ " " | "\t" } + /// A top-level comment. grammar_doc = ${ "//!" ~ space? ~ inner_doc } + /// A rule comment. -line_doc = ${ "///" ~ space? ~ !"/" ~ inner_doc } +line_doc = ${ "///" ~ space? ~ inner_doc } + /// A comment content. -inner_doc = @{ (!newline ~ ANY)* } +inner_doc = @{ (!newline ~ ANY)* } |