pest_generator/
lib.rs

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1// pest. The Elegant Parser
2// Copyright (c) 2018 Dragoș Tiselice
3//
4// Licensed under the Apache License, Version 2.0
5// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT
6// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
7// option. All files in the project carrying such notice may not be copied,
8// modified, or distributed except according to those terms.
9
10#![doc(
11    html_root_url = "https://docs.rs/pest_derive",
12    html_logo_url = "https://raw.githubusercontent.com/pest-parser/pest/master/pest-logo.svg",
13    html_favicon_url = "https://raw.githubusercontent.com/pest-parser/pest/master/pest-logo.svg"
14)]
15#![warn(missing_docs, rust_2018_idioms, unused_qualifications)]
16#![recursion_limit = "256"]
17//! # pest generator
18//!
19//! This crate generates code from ASTs (which is used in the `pest_derive` crate).
20
21#[macro_use]
22extern crate quote;
23
24use std::env;
25use std::fs::File;
26use std::io::{self, Read};
27use std::path::Path;
28
29use generator::generate;
30use proc_macro2::TokenStream;
31use syn::DeriveInput;
32
33#[macro_use]
34mod macros;
35
36#[cfg(feature = "export-internal")]
37pub mod docs;
38#[cfg(not(feature = "export-internal"))]
39mod docs;
40
41#[cfg(feature = "export-internal")]
42pub mod generator;
43#[cfg(not(feature = "export-internal"))]
44mod generator;
45
46#[cfg(feature = "export-internal")]
47pub mod parse_derive;
48#[cfg(not(feature = "export-internal"))]
49mod parse_derive;
50
51use crate::parse_derive::{parse_derive, GrammarSource};
52use pest_meta::parser::{self, rename_meta_rule, Rule};
53use pest_meta::{optimizer, unwrap_or_report, validator};
54
55/// Processes the derive/proc macro input and generates the corresponding parser based
56/// on the parsed grammar. If `include_grammar` is set to true, it'll generate an explicit
57/// "include_str" statement (done in pest_derive, but turned off in the local bootstrap).
58pub fn derive_parser(input: TokenStream, include_grammar: bool) -> TokenStream {
59    let ast: DeriveInput = syn::parse2(input).unwrap();
60    let (parsed_derive, contents) = parse_derive(ast);
61
62    // Grammar presented in a view of a string.
63    let mut data = String::new();
64    let mut paths = vec![];
65
66    for content in contents {
67        let (_data, _path) = match content {
68            GrammarSource::File(ref path) => {
69                let root = env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| ".".into());
70
71                // Check whether we can find a file at the path relative to the CARGO_MANIFEST_DIR
72                // first.
73                //
74                // If we cannot find the expected file over there, fallback to the
75                // `CARGO_MANIFEST_DIR/src`, which is the old default and kept for convenience
76                // reasons.
77                // TODO: This could be refactored once `std::path::absolute()` get's stabilized.
78                // https://doc.rust-lang.org/std/path/fn.absolute.html
79                let path = if Path::new(&root).join(path).exists() {
80                    Path::new(&root).join(path)
81                } else {
82                    Path::new(&root).join("src/").join(path)
83                };
84
85                let file_name = match path.file_name() {
86                    Some(file_name) => file_name,
87                    None => panic!("grammar attribute should point to a file"),
88                };
89
90                let data = match read_file(&path) {
91                    Ok(data) => data,
92                    Err(error) => panic!("error opening {:?}: {}", file_name, error),
93                };
94                (data, Some(path.clone()))
95            }
96            GrammarSource::Inline(content) => (content, None),
97        };
98
99        data.push_str(&_data);
100        if let Some(path) = _path {
101            paths.push(path);
102        }
103    }
104
105    // `Rule::grammar_rules` is taken from meta/srd/parser.rs.
106    let pairs = match parser::parse(Rule::grammar_rules, &data) {
107        Ok(pairs) => pairs,
108        Err(error) => panic!("error parsing \n{}", error.renamed_rules(rename_meta_rule)),
109    };
110
111    let defaults = unwrap_or_report(validator::validate_pairs(pairs.clone()));
112    let doc_comment = docs::consume(pairs.clone());
113    let ast = unwrap_or_report(parser::consume_rules(pairs));
114    let optimized = optimizer::optimize(ast);
115
116    generate(
117        parsed_derive,
118        paths,
119        optimized,
120        defaults,
121        &doc_comment,
122        include_grammar,
123    )
124}
125
126fn read_file<P: AsRef<Path>>(path: P) -> io::Result<String> {
127    let mut file = File::open(path.as_ref())?;
128    let mut string = String::new();
129    file.read_to_string(&mut string)?;
130    Ok(string)
131}
132
133#[cfg(test)]
134mod tests {
135
136    #[doc = "Matches dar\n\nMatch dar description\n"]
137    #[test]
138    fn test_generate_doc() {
139        let input = quote! {
140            #[derive(Parser)]
141            #[non_exhaustive]
142            #[grammar = "../tests/test.pest"]
143            pub struct TestParser;
144        };
145
146        let token = super::derive_parser(input, true);
147
148        let expected = quote! {
149            #[doc = "A parser for JSON file.\nAnd this is a example for JSON parser.\n\n    indent-4-space\n"]
150            #[allow(dead_code, non_camel_case_types, clippy::upper_case_acronyms)]
151            #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
152            #[non_exhaustive]
153            pub enum Rule {
154                #[doc = "Matches foo str, e.g.: `foo`"]
155                r#foo,
156                #[doc = "Matches bar str\n\n  Indent 2, e.g: `bar` or `foobar`"]
157                r#bar,
158                r#bar1,
159                #[doc = "Matches dar\n\nMatch dar description\n"]
160                r#dar
161            }
162        };
163
164        assert!(
165            token.to_string().contains(expected.to_string().as_str()),
166            "{}\n\nExpected to contains:\n{}",
167            token,
168            expected
169        );
170    }
171}
pest_generator/lib.rs

pest_generator/
lib.rs
