Upgrade pest_generator to 2.5.1 am: f769896352 am: bad9552507 am: a8e786d08b

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/pest_generator/+/2345755

Change-Id: Icff7ad48b82480eb81f3b1722efcec3598e08c7a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

8 files changed, 187 insertions, 117 deletions

diff --git a/Android.bp b/Android.bp
index ccfa35c..f64f23b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,8 +1,6 @@
 // This file is generated by cargo2android.py --run --host-first-multilib.
 // Do not modify this file as changes will be overridden on upgrade.
 
-
-
 package {
     default_applicable_licenses: [
         "external_rust_crates_pest_generator_license",
@@ -45,9 +43,13 @@ rust_library_host {
     name: "libpest_generator",
     crate_name: "pest_generator",
     cargo_env_compat: true,
-    cargo_pkg_version: "2.1.3",
+    cargo_pkg_version: "2.5.1",
     srcs: ["src/lib.rs"],
-    edition: "2015",
+    edition: "2021",
+    features: [
+        "default",
+        "std",
+    ],
     rustlibs: [
         "libpest",
         "libpest_meta",
@@ -56,4 +58,8 @@ rust_library_host {
         "libsyn",
     ],
     compile_multilib: "first",
+    apex_available: [
+        "//apex_available:platform",
+        "//apex_available:anyapex",
+    ],
 }
diff --git a/Cargo.toml b/Cargo.toml
index 1ef45f9..e21784d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,30 +3,36 @@
 # When uploading crates to the registry Cargo will automatically
 # "normalize" Cargo.toml files for maximal compatibility
 # with all versions of Cargo and also rewrite `path` dependencies
-# to registry (e.g., crates.io) dependencies
+# to registry (e.g., crates.io) dependencies.
 #
-# If you believe there's an error in this file please file an
-# issue against the rust-lang/cargo repository. If you're
-# editing this file be aware that the upstream Cargo.toml
-# will likely look very different (and much more reasonable)
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
 
 [package]
+edition = "2021"
+rust-version = "1.56"
 name = "pest_generator"
-version = "2.1.3"
+version = "2.5.1"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
 description = "pest code generator"
-homepage = "https://pest-parser.github.io/"
+homepage = "https://pest.rs/"
 documentation = "https://docs.rs/pest"
 readme = "_README.md"
-keywords = ["pest", "generator"]
+keywords = [
+    "pest",
+    "generator",
+]
 categories = ["parsing"]
 license = "MIT/Apache-2.0"
 repository = "https://github.com/pest-parser/pest"
+
 [dependencies.pest]
-version = "2.1.0"
+version = "2.5.1"
+default-features = false
 
 [dependencies.pest_meta]
-version = "2.1.0"
+version = "2.5.1"
 
 [dependencies.proc-macro2]
 version = "1.0"
@@ -36,11 +42,7 @@ version = "1.0"
 
 [dependencies.syn]
 version = "1.0"
-[badges.codecov]
-repository = "pest-parser/pest"
-
-[badges.maintenance]
-status = "actively-developed"
 
-[badges.travis-ci]
-repository = "pest-parser/pest"
+[features]
+default = ["std"]
+std = ["pest/std"]
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index a70cb5f..1836fe0 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -1,24 +1,25 @@
 [package]
 name = "pest_generator"
 description = "pest code generator"
-version = "2.1.3"
+version = "2.5.1"
+edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
-homepage = "https://pest-parser.github.io/"
+homepage = "https://pest.rs/"
 repository = "https://github.com/pest-parser/pest"
 documentation = "https://docs.rs/pest"
 keywords = ["pest", "generator"]
 categories = ["parsing"]
 license = "MIT/Apache-2.0"
 readme = "_README.md"
+rust-version = "1.56"
+
+[features]
+default = ["std"]
+std = ["pest/std"]
 
 [dependencies]
-pest = { path = "../pest", version = "2.1.0" }
-pest_meta = { path = "../meta", version = "2.1.0" }
+pest = { path = "../pest", version = "2.5.1", default-features = false }
+pest_meta = { path = "../meta", version = "2.5.1" }
 proc-macro2 = "1.0"
 quote = "1.0"
 syn = "1.0"
-
-[badges]
-codecov = { repository = "pest-parser/pest" }
-maintenance = { status = "actively-developed" }
-travis-ci = { repository = "pest-parser/pest" }
diff --git a/METADATA b/METADATA
index 66a82b1..ce1af20 100644
--- a/METADATA
+++ b/METADATA
@@ -1,3 +1,7 @@
+# This project was upgraded with external_updater.
+# Usage: tools/external_updater/updater.sh update rust/crates/pest_generator
+# For more info, check https://cs.android.com/android/platform/superproject/+/master:tools/external_updater/README.md
+
 name: "pest_generator"
 description: "pest code generator"
 third_party {
@@ -7,14 +11,13 @@ third_party {
   }
   url {
     type: ARCHIVE
-    value: "https://static.crates.io/crates/pest_generator/pest_generator-2.1.3.crate"
+    value: "https://static.crates.io/crates/pest_generator/pest_generator-2.5.1.crate"
   }
-  version: "2.1.3"
-  # Dual-licensed, using the least restrictive per go/thirdpartylicenses#same.
+  version: "2.5.1"
   license_type: NOTICE
   last_upgrade_date {
     year: 2022
-    month: 1
-    day: 27
+    month: 12
+    day: 13
   }
 }
diff --git a/_README.md b/_README.md
index 8e55f29..da30ab7 100644
--- a/_README.md
+++ b/_README.md
@@ -1,16 +1,18 @@
+
 <p align="center">
   <img src="https://raw.github.com/pest-parser/pest/master/pest-logo.svg?sanitize=true" width="80%"/>
 </p>
 
 # pest. The Elegant Parser
 
-[![Join the chat at https://gitter.im/dragostis/pest](https://badges.gitter.im/dragostis/pest.svg)](https://gitter.im/dragostis/pest?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-[![Book](https://img.shields.io/badge/book-WIP-4d76ae.svg)](https://pest-parser.github.io/book)
+[![Join the chat at https://gitter.im/pest-parser/pest](https://badges.gitter.im/dragostis/pest.svg)](https://gitter.im/pest-parser/pest?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Book](https://img.shields.io/badge/book-WIP-4d76ae.svg)](https://pest.rs/book)
 [![Docs](https://docs.rs/pest/badge.svg)](https://docs.rs/pest)
 
-[![Build Status](https://travis-ci.org/pest-parser/pest.svg?branch=master)](https://travis-ci.org/pest-parser/pest)
+[![pest Continuous Integration](https://github.com/pest-parser/pest/actions/workflows/ci.yml/badge.svg)](https://github.com/pest-parser/pest/actions/workflows/ci.yml)
 [![codecov](https://codecov.io/gh/pest-parser/pest/branch/master/graph/badge.svg)](https://codecov.io/gh/pest-parser/pest)
-[![Fuzzit Status](https://app.fuzzit.dev/badge?org_id=pest-parser)](https://app.fuzzit.dev/orgs/pest-parser/dashboard)
+<a href="https://blog.rust-lang.org/2021/11/01/Rust-1.56.1.html"><img alt="Rustc Version 1.56.1+" src="https://img.shields.io/badge/rustc-1.56.1%2B-lightgrey.svg"/></a>
+
 [![Crates.io](https://img.shields.io/crates/d/pest.svg)](https://crates.io/crates/pest)
 [![Crates.io](https://img.shields.io/crates/v/pest.svg)](https://crates.io/crates/pest)
 
@@ -29,25 +31,28 @@ Other helpful resources:
 
 * API reference on [docs.rs]
 * play with grammars and share them on our [fiddle]
-* leave feedback, ask questions, or greet us on [Gitter]
+* find previous common questions answered or ask questions on [GitHub Discussions]
+* leave feedback, ask questions, or greet us on [Gitter] or [Discord]
 
-[book]: https://pest-parser.github.io/book
+[book]: https://pest.rs/book
 [docs.rs]: https://docs.rs/pest
-[fiddle]: https://pest-parser.github.io/#editor
-[Gitter]: https://gitter.im/dragostis/pest
+[fiddle]: https://pest.rs/#editor
+[Gitter]: https://gitter.im/pest-parser/pest
+[Discord]: https://discord.gg/XEGACtWpT2
+[GitHub Discussions]: https://github.com/pest-parser/pest/discussions
 
 ## Example
 
-The following is an example of a grammar for a list of alpha-numeric identifiers
-where the first identifier does not start with a digit:
+The following is an example of a grammar for a list of alphanumeric identifiers
+where all identifiers don't start with a digit:
 
 ```rust
 alpha = { 'a'..'z' | 'A'..'Z' }
 digit = { '0'..'9' }
 
-ident = { (alpha | digit)+ }
+ident = { !digit ~ (alpha | digit)+ }
 
-ident_list = _{ !digit ~ ident ~ (" " ~ ident)+ }
+ident_list = _{ ident ~ (" " ~ ident)* }
           // ^
           // ident_list rule is silent which means it produces no tokens
 ```
@@ -79,6 +84,9 @@ thread 'main' panicked at ' --> 1:1
   = expected ident', src/main.rs:12
 ```
 
+These error messages can be obtained from their default `Display` implementation,
+e.g. `panic!("{}", parser_result.unwrap_err())` or `println!("{}", e)`.
+
 ## Pairs API
 
 The grammar can be used to derive a `Parser` implementation automatically.
@@ -131,6 +139,25 @@ Letter:  b
 Digit:   2
 ```
 
+### Defining multiple parsers in a single file
+The current automatic `Parser` derivation will produce the `Rule` enum
+which would have name conflicts if one tried to define multiple such structs
+that automatically derive `Parser`. One possible way around it is to put each
+parser struct in a separate namespace:
+
+```rust
+mod a {
+    #[derive(Parser)]
+    #[grammar = "a.pest"]
+    pub struct ParserA;
+}
+mod b {
+    #[derive(Parser)]
+    #[grammar = "b.pest"]
+    pub struct ParserB;
+}
+```
+
 ## Other features
 
 * Precedence climbing
@@ -143,16 +170,18 @@ Digit:   2
 * [pest_meta](https://github.com/pest-parser/pest/blob/master/meta/src/grammar.pest) (bootstrapped)
 * [AshPaper](https://github.com/shnewto/ashpaper)
 * [brain](https://github.com/brain-lang/brain)
-* [Chelone](https://github.com/Aaronepower/chelone)
+* [cicada](https://github.com/mitnk/cicada)
 * [comrak](https://github.com/kivikakk/comrak)
 * [elastic-rs](https://github.com/cch123/elastic-rs)
 * [graphql-parser](https://github.com/Keats/graphql-parser)
 * [handlebars-rust](https://github.com/sunng87/handlebars-rust)
 * [hexdino](https://github.com/Luz/hexdino)
 * [Huia](https://gitlab.com/jimsy/huia/)
+* [insta](https://github.com/mitsuhiko/insta)
 * [jql](https://github.com/yamafaktory/jql)
 * [json5-rs](https://github.com/callum-oakley/json5-rs)
 * [mt940](https://github.com/svenstaro/mt940-rs)
+* [Myoxine](https://github.com/d3bate/myoxine)
 * [py_literal](https://github.com/jturner314/py_literal)
 * [rouler](https://github.com/jarcane/rouler)
 * [RuSh](https://github.com/lwandrebeck/RuSh)
@@ -162,6 +191,17 @@ Digit:   2
 * [ui_gen](https://github.com/emoon/ui_gen)
 * [ukhasnet-parser](https://github.com/adamgreig/ukhasnet-parser)
 * [ZoKrates](https://github.com/ZoKrates/ZoKrates)
+* [Vector](https://github.com/timberio/vector)
+* [AutoCorrect](https://github.com/huacnlee/autocorrect)
+* [yaml-peg](https://github.com/aofdev/yaml-peg)
+* [qubit](https://github.com/abhimanyu003/qubit)
+* [caith](https://github.com/Geobert/caith) (a dice roller crate)
+* [Melody](https://github.com/yoav-lavi/melody)
+
+## Minimum Supported Rust Version (MSRV)
+
+This library should always compile with default features on **Rust 1.56.1** 
+or **Rust 1.61** with `const_prec_climber`.
 
 ## Special thanks
 
diff --git a/src/generator.rs b/src/generator.rs
index bed56f3..f3da1ba 100644
--- a/src/generator.rs
+++ b/src/generator.rs
@@ -17,7 +17,6 @@ use pest_meta::ast::*;
 use pest_meta::optimizer::*;
 use pest_meta::UNICODE_PROPERTY_NAMES;
 
-#[allow(clippy::needless_pass_by_value)]
 pub fn generate(
     name: Ident,
     generics: &Generics,
@@ -52,17 +51,20 @@ pub fn generate(
 
     let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
 
+    let result = result_type();
+
     let parser_impl = quote! {
         #[allow(clippy::all)]
         impl #impl_generics ::pest::Parser<Rule> for #name #ty_generics #where_clause {
             fn parse<'i>(
                 rule: Rule,
                 input: &'i str
-            ) -> ::std::result::Result<
+            ) -> #result<
                 ::pest::iterators::Pairs<'i, Rule>,
                 ::pest::error::Error<Rule>
             > {
                 mod rules {
+                    #![allow(clippy::upper_case_acronyms)]
                     pub mod hidden {
                         use super::super::Rule;
                         #skip
@@ -98,7 +100,7 @@ fn generate_builtin_rules() -> Vec<(&'static str, TokenStream)> {
     let mut builtins = Vec::new();
 
     insert_builtin!(builtins, ANY, state.skip(1));
-    insert_public_builtin!(
+    insert_builtin!(
         builtins,
         EOI,
         state.rule(Rule::EOI, |state| state.end_of_input())
@@ -149,13 +151,15 @@ fn generate_builtin_rules() -> Vec<(&'static str, TokenStream)> {
             .or_else(|state| state.match_string("\r"))
     );
 
+    let box_ty = box_type();
+
     for property in UNICODE_PROPERTY_NAMES {
         let property_ident: Ident = syn::parse_str(property).unwrap();
         // insert manually for #property substitution
         builtins.push((property, quote! {
             #[inline]
             #[allow(dead_code, non_snake_case, unused_variables)]
-            fn #property_ident(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            fn #property_ident(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                 state.match_char_by(::pest::unicode::#property_ident)
             }
         }));
@@ -183,7 +187,7 @@ fn generate_enum(rules: &[OptimizedRule], uses_eoi: bool) -> TokenStream {
         .map(|rule| Ident::new(rule.name.as_str(), Span::call_site()));
     if uses_eoi {
         quote! {
-            #[allow(dead_code, non_camel_case_types)]
+            #[allow(dead_code, non_camel_case_types, clippy::upper_case_acronyms)]
             #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
             pub enum Rule {
                 EOI,
@@ -192,7 +196,7 @@ fn generate_enum(rules: &[OptimizedRule], uses_eoi: bool) -> TokenStream {
         }
     } else {
         quote! {
-            #[allow(dead_code, non_camel_case_types)]
+            #[allow(dead_code, non_camel_case_types, clippy::upper_case_acronyms)]
             #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
             pub enum Rule {
                 #( #rules ),*
@@ -239,11 +243,13 @@ fn generate_rule(rule: OptimizedRule) -> TokenStream {
         generate_expr(rule.expr)
     };
 
+    let box_ty = box_type();
+
     match rule.ty {
         RuleType::Normal => quote! {
             #[inline]
             #[allow(non_snake_case, unused_variables)]
-            pub fn #name(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            pub fn #name(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                 state.rule(Rule::#name, |state| {
                     #expr
                 })
@@ -252,14 +258,14 @@ fn generate_rule(rule: OptimizedRule) -> TokenStream {
         RuleType::Silent => quote! {
             #[inline]
             #[allow(non_snake_case, unused_variables)]
-            pub fn #name(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            pub fn #name(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                 #expr
             }
         },
         RuleType::Atomic => quote! {
             #[inline]
             #[allow(non_snake_case, unused_variables)]
-            pub fn #name(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            pub fn #name(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                 state.rule(Rule::#name, |state| {
                     state.atomic(::pest::Atomicity::Atomic, |state| {
                         #expr
@@ -270,7 +276,7 @@ fn generate_rule(rule: OptimizedRule) -> TokenStream {
         RuleType::CompoundAtomic => quote! {
             #[inline]
             #[allow(non_snake_case, unused_variables)]
-            pub fn #name(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            pub fn #name(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                 state.atomic(::pest::Atomicity::CompoundAtomic, |state| {
                     state.rule(Rule::#name, |state| {
                         #expr
@@ -281,7 +287,7 @@ fn generate_rule(rule: OptimizedRule) -> TokenStream {
         RuleType::NonAtomic => quote! {
             #[inline]
             #[allow(non_snake_case, unused_variables)]
-            pub fn #name(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            pub fn #name(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                 state.atomic(::pest::Atomicity::NonAtomic, |state| {
                     state.rule(Rule::#name, |state| {
                         #expr
@@ -619,13 +625,38 @@ struct QuoteOption<T>(Option<T>);
 
 impl<T: ToTokens> ToTokens for QuoteOption<T> {
     fn to_tokens(&self, tokens: &mut TokenStream) {
+        let option = option_type();
         tokens.append_all(match self.0 {
-            Some(ref t) => quote! { ::std::option::Option::Some(#t) },
-            None => quote! { ::std::option::Option::None },
+            Some(ref t) => quote! { #option::Some(#t) },
+            None => quote! { #option::None },
         });
     }
 }
 
+fn box_type() -> TokenStream {
+    #[cfg(feature = "std")]
+    quote! { ::std::boxed::Box }
+
+    #[cfg(not(feature = "std"))]
+    quote! { ::alloc::boxed::Box }
+}
+
+fn result_type() -> TokenStream {
+    #[cfg(feature = "std")]
+    quote! { ::std::result::Result }
+
+    #[cfg(not(feature = "std"))]
+    quote! { ::core::result::Result }
+}
+
+fn option_type() -> TokenStream {
+    #[cfg(feature = "std")]
+    quote! { ::std::option::Option }
+
+    #[cfg(not(feature = "std"))]
+    quote! { ::core::option::Option }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -641,7 +672,7 @@ mod tests {
         assert_eq!(
             generate_enum(&rules, false).to_string(),
             quote! {
-                #[allow(dead_code, non_camel_case_types)]
+                #[allow(dead_code, non_camel_case_types, clippy::upper_case_acronyms)]
                 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
                 pub enum Rule {
                     f
@@ -935,6 +966,8 @@ mod tests {
             expr: OptimizedExpr::Str("b".to_owned()),
         }];
         let defaults = vec!["ANY"];
+        let result = result_type();
+        let box_ty = box_type();
         let mut current_dir = std::env::current_dir().expect("Unable to get current directory");
         current_dir.push("test.pest");
         let test_path = current_dir.to_str().expect("path contains invalid unicode");
@@ -944,7 +977,7 @@ mod tests {
                 #[allow(non_upper_case_globals)]
                 const _PEST_GRAMMAR_MyParser: &'static str = include_str!(#test_path);
 
-                #[allow(dead_code, non_camel_case_types)]
+                #[allow(dead_code, non_camel_case_types, clippy::upper_case_acronyms)]
                 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
                 pub enum Rule {
                     a
@@ -955,17 +988,18 @@ mod tests {
                     fn parse<'i>(
                         rule: Rule,
                         input: &'i str
-                    ) -> ::std::result::Result<
+                    ) -> #result<
                         ::pest::iterators::Pairs<'i, Rule>,
                         ::pest::error::Error<Rule>
                     > {
                         mod rules {
+                            #![allow(clippy::upper_case_acronyms)]
                             pub mod hidden {
                                 use super::super::Rule;
 
                                 #[inline]
                                 #[allow(dead_code, non_snake_case, unused_variables)]
-                                pub fn skip(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+                                pub fn skip(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                                     Ok(state)
                                 }
                             }
@@ -975,13 +1009,13 @@ mod tests {
 
                                 #[inline]
                                 #[allow(non_snake_case, unused_variables)]
-                                pub fn a(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+                                pub fn a(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                                     state.match_string("b")
                                 }
 
                                 #[inline]
                                 #[allow(dead_code, non_snake_case, unused_variables)]
-                                pub fn ANY(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+                                pub fn ANY(state: #box_ty<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<#box_ty<::pest::ParserState<'_, Rule>>> {
                                     state.skip(1)
                                 }
                             }
diff --git a/src/lib.rs b/src/lib.rs
index 27b4d81..2a1203e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,17 +7,19 @@
 // option. All files in the project carrying such notice may not be copied,
 // modified, or distributed except according to those terms.
 
-#![doc(html_root_url = "https://docs.rs/pest_derive")]
+#![doc(
+    html_root_url = "https://docs.rs/pest_derive",
+    html_logo_url = "https://raw.githubusercontent.com/pest-parser/pest/master/pest-logo.svg",
+    html_favicon_url = "https://raw.githubusercontent.com/pest-parser/pest/master/pest-logo.svg"
+)]
+#![warn(missing_docs, rust_2018_idioms, unused_qualifications)]
 #![recursion_limit = "256"]
+//! # pest generator
+//!
+//! This crate generates code from ASTs (which is used in the `pest_derive` crate).
 
-extern crate pest;
-extern crate pest_meta;
-
-extern crate proc_macro;
-extern crate proc_macro2;
 #[macro_use]
 extern crate quote;
-extern crate syn;
 
 use std::env;
 use std::fs::File;
@@ -31,9 +33,12 @@ use syn::{Attribute, DeriveInput, Generics, Ident, Lit, Meta};
 mod macros;
 mod generator;
 
-use pest_meta::parser::{self, Rule};
+use pest_meta::parser::{self, rename_meta_rule, Rule};
 use pest_meta::{optimizer, unwrap_or_report, validator};
 
+/// Processes the derive/proc macro input and generates the corresponding parser based
+/// on the parsed grammar. If `include_grammar` is set to true, it'll generate an explicit
+/// "include_str" statement (done in pest_derive, but turned off in the local bootstrap).
 pub fn derive_parser(input: TokenStream, include_grammar: bool) -> TokenStream {
     let ast: DeriveInput = syn::parse2(input).unwrap();
     let (name, generics, content) = parse_derive(ast);
@@ -41,7 +46,21 @@ pub fn derive_parser(input: TokenStream, include_grammar: bool) -> TokenStream {
     let (data, path) = match content {
         GrammarSource::File(ref path) => {
             let root = env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| ".".into());
-            let path = Path::new(&root).join("src/").join(&path);
+
+            // Check whether we can find a file at the path relative to the CARGO_MANIFEST_DIR
+            // first.
+            //
+            // If we cannot find the expected file over there, fallback to the
+            // `CARGO_MANIFEST_DIR/src`, which is the old default and kept for convenience
+            // reasons.
+            // TODO: This could be refactored once `std::path::absolute()` get's stabilized.
+            // https://doc.rust-lang.org/std/path/fn.absolute.html
+            let path = if Path::new(&root).join(path).exists() {
+                Path::new(&root).join(path)
+            } else {
+                Path::new(&root).join("src/").join(path)
+            };
+
             let file_name = match path.file_name() {
                 Some(file_name) => file_name,
                 None => panic!("grammar attribute should point to a file"),
@@ -58,37 +77,7 @@ pub fn derive_parser(input: TokenStream, include_grammar: bool) -> TokenStream {
 
     let pairs = match parser::parse(Rule::grammar_rules, &data) {
         Ok(pairs) => pairs,
-        Err(error) => panic!(
-            "error parsing \n{}",
-            error.renamed_rules(|rule| match *rule {
-                Rule::grammar_rule => "rule".to_owned(),
-                Rule::_push => "PUSH".to_owned(),
-                Rule::assignment_operator => "`=`".to_owned(),
-                Rule::silent_modifier => "`_`".to_owned(),
-                Rule::atomic_modifier => "`@`".to_owned(),
-                Rule::compound_atomic_modifier => "`$`".to_owned(),
-                Rule::non_atomic_modifier => "`!`".to_owned(),
-                Rule::opening_brace => "`{`".to_owned(),
-                Rule::closing_brace => "`}`".to_owned(),
-                Rule::opening_brack => "`[`".to_owned(),
-                Rule::closing_brack => "`]`".to_owned(),
-                Rule::opening_paren => "`(`".to_owned(),
-                Rule::positive_predicate_operator => "`&`".to_owned(),
-                Rule::negative_predicate_operator => "`!`".to_owned(),
-                Rule::sequence_operator => "`&`".to_owned(),
-                Rule::choice_operator => "`|`".to_owned(),
-                Rule::optional_operator => "`?`".to_owned(),
-                Rule::repeat_operator => "`*`".to_owned(),
-                Rule::repeat_once_operator => "`+`".to_owned(),
-                Rule::comma => "`,`".to_owned(),
-                Rule::closing_paren => "`)`".to_owned(),
-                Rule::quote => "`\"`".to_owned(),
-                Rule::insensitive_string => "`^`".to_owned(),
-                Rule::range_operator => "`..`".to_owned(),
-                Rule::single_quote => "`'`".to_owned(),
-                other_rule => format!("{:?}", other_rule),
-            })
-        ),
+        Err(error) => panic!("error parsing \n{}", error.renamed_rules(rename_meta_rule)),
     };
 
     let defaults = unwrap_or_report(validator::validate_pairs(pairs.clone()));
@@ -155,7 +144,6 @@ fn get_attribute(attr: &Attribute) -> GrammarSource {
 mod tests {
     use super::parse_derive;
     use super::GrammarSource;
-    use syn;
 
     #[test]
     fn derive_inline_file() {
diff --git a/src/macros.rs b/src/macros.rs
index 9d02725..377f66e 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -13,30 +13,26 @@ macro_rules! insert_builtin {
     };
 }
 
-macro_rules! insert_public_builtin {
-    ($builtin: expr, $name: ident, $pattern: expr) => {
-        $builtin.push((stringify!($name), generate_public_rule!($name, $pattern)));
-    };
-}
-
+#[cfg(feature = "std")]
 macro_rules! generate_rule {
     ($name: ident, $pattern: expr) => {
         quote! {
             #[inline]
             #[allow(dead_code, non_snake_case, unused_variables)]
-            pub fn $name(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            pub fn $name(state: ::std::boxed::Box<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<::std::boxed::Box<::pest::ParserState<'_, Rule>>> {
                 $pattern
             }
         }
     }
 }
 
-macro_rules! generate_public_rule {
+#[cfg(not(feature = "std"))]
+macro_rules! generate_rule {
     ($name: ident, $pattern: expr) => {
         quote! {
             #[inline]
             #[allow(dead_code, non_snake_case, unused_variables)]
-            pub fn $name(state: Box<::pest::ParserState<Rule>>) -> ::pest::ParseResult<Box<::pest::ParserState<Rule>>> {
+            pub fn $name(state: ::alloc::boxed::Box<::pest::ParserState<'_, Rule>>) -> ::pest::ParseResult<::alloc::boxed::Box<::pest::ParserState<'_, Rule>>> {
                 $pattern
             }
         }