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#![allow(clippy::cognitive_complexity)] #![allow(clippy::many_single_char_names)] #![allow(clippy::needless_doctest_main)] #![allow(clippy::new_without_default)] #![allow(clippy::range_plus_one)] #![allow(clippy::too_many_arguments)] #![allow(clippy::type_complexity)] #![allow(clippy::unnecessary_wraps)] //! `lrpar` provides a Yacc-compatible parser (where grammars can be generated at //! compile-time or run-time). It can take in traditional `.y` files and convert //! them into an idiomatic Rust parser. More details can be found in the [grmtools //! book](https://softdevteam.github.io/grmtools/master/book); the //! [quickstart guide](https://softdevteam.github.io/grmtools/master/book/quickstart.html) //! is a good place to start. //! //! //! ## Example //! //! Let's assume we want to statically generate a parser for a simple calculator //! language (and let's also assume we are able to use //! [`lrlex`](https://softdevteam.github.io/grmtools/master/book/lrlex.html) for the //! lexer). We need to add a `build.rs` file to our project which tells `lrpar` to //! statically compile the lexer and parser files: //! //! ```text //! use cfgrammar::yacc::YaccKind; //! use lrlex::LexerBuilder; //! use lrpar::CTParserBuilder; //! //! fn main() -> Result<(), Box<dyn std::error::Error>> { //! let lex_rule_ids_map = CTParserBuilder::new() //! .yacckind(YaccKind::Grmtools) //! .process_file_in_src("calc.y")?; //! LexerBuilder::new() //! .rule_ids_map(lex_rule_ids_map) //! .process_file_in_src("calc.l")?; //! Ok(()) //! } //! ``` //! //! where `src/calc.l` is as follows: //! //! ```text //! %% //! [0-9]+ "INT" //! \+ "+" //! \* "*" //! \( "(" //! \) ")" //! [\t ]+ ; //! ``` //! //! and `src/calc.y` is as follows: //! //! ```text //! %start Expr //! %avoid_insert "INT" //! %% //! Expr -> Result<u64, ()>: //! Expr '+' Term { Ok($1? + $3?) } //! | Term { $1 } //! ; //! //! Term -> Result<u64, ()>: //! Term '*' Factor { Ok($1? * $3?) } //! | Factor { $1 } //! ; //! //! Factor -> Result<u64, ()>: //! '(' Expr ')' { $2 } //! | 'INT' //! { //! let v = $1.map_err(|_| ())?; //! parse_int($lexer.span_str(v.span())) //! } //! ; //! %% //! // Any functions here are in scope for all the grammar actions above. //! //! fn parse_int(s: &str) -> Result<u64, ()> { //! match s.parse::<u64>() { //! Ok(val) => Ok(val), //! Err(_) => { //! eprintln!("{} cannot be represented as a u64", s); //! Err(()) //! } //! } //! } //! ``` //! //! Because we specified that our Yacc file is in `Grmtools` format, each rule has a //! separate Rust type to which all its functions conform (in this case, all the //! rules have the same type, but that's not a requirement). //! //! A simple `src/main.rs` is as follows: //! //! ```text //! use std::io::{self, BufRead, Write}; //! //! use lrlex::lrlex_mod; //! use lrpar::lrpar_mod; //! //! // Using `lrlex_mod!` brings the lexer for `calc.l` into scope. By default the module name //! // will be `calc_l` (i.e. the file name, minus any extensions, with a suffix of `_l`). //! lrlex_mod!("calc.l"); //! // Using `lrpar_mod!` brings the parser for `calc.y` into scope. By default the module name //! // will be `calc_y` (i.e. the file name, minus any extensions, with a suffix of `_y`). //! lrpar_mod!("calc.y"); //! //! fn main() { //! // Get the `LexerDef` for the `calc` language. //! let lexerdef = calc_l::lexerdef(); //! let stdin = io::stdin(); //! loop { //! print!(">>> "); //! io::stdout().flush().ok(); //! match stdin.lock().lines().next() { //! Some(Ok(ref l)) => { //! if l.trim().is_empty() { //! continue; //! } //! // Now we create a lexer with the `lexer` method with which we can lex an input. //! let lexer = lexerdef.lexer(l); //! // Pass the lexer to the parser and lex and parse the input. //! let (res, errs) = calc_y::parse(&lexer); //! for e in errs { //! println!("{}", e.pp(&lexer, &calc_y::token_epp)); //! } //! match res { //! Some(Ok(r)) => println!("Result: {}", r), //! _ => eprintln!("Unable to evaluate expression.") //! } //! } //! _ => break //! } //! } //! } //! ``` //! //! We can now `cargo run` our project and evaluate simple expressions: //! //! ```text //! >>> 2 + 3 //! Result: 5 //! >>> 2 + 3 * 4 //! Result: 14 //! >>> (2 + 3) * 4 //! Result: 20 //! ``` //! //! `lrpar` also comes with advanced [error //! recovery](https://softdevteam.github.io/grmtools/master/book/errorrecovery.html) built-in: //! //! ```text //! >>> 2 + + 3 //! Parsing error at line 1 column 5. Repair sequences found: //! 1: Delete + //! 2: Insert INT //! Result: 5 //! >>> 2 + 3 3 //! Parsing error at line 1 column 7. Repair sequences found: //! 1: Insert * //! 2: Insert + //! 3: Delete 3 //! Result: 11 //! >>> 2 + 3 4 5 //! Parsing error at line 1 column 7. Repair sequences found: //! 1: Insert *, Delete 4 //! 2: Insert +, Delete 4 //! 3: Delete 4, Delete 5 //! 4: Insert +, Shift 4, Delete 5 //! 5: Insert +, Shift 4, Insert + //! 6: Insert *, Shift 4, Delete 5 //! 7: Insert *, Shift 4, Insert * //! 8: Insert *, Shift 4, Insert + //! 9: Insert +, Shift 4, Insert * //! Result: 17 //! ``` mod cpctplus; #[doc(hidden)] pub mod ctbuilder; mod dijkstra; #[doc(hidden)] pub mod lex; pub use crate::lex::{LexError, Lexeme, Lexer, NonStreamingLexer}; #[doc(hidden)] pub mod parser; pub use crate::{ ctbuilder::{CTParserBuilder, Visibility}, parser::{LexParseError, Node, ParseError, ParseRepair, RTParserBuilder, RecoveryKind}, }; /// A convenience macro for including statically compiled `.y` files. A file `src/a/b/c.y` which is /// statically compiled by lrpar can then be used in a crate with `lrpar_mod!("a/b/c.y")`. #[macro_export] macro_rules! lrpar_mod { ($path:expr) => { include!(concat!(env!("OUT_DIR"), "/", $path, ".rs")); }; } #[doc(hidden)] pub use cfgrammar::RIdx; /// A `Span` records what portion of the user's input something (e.g. a lexeme or production) /// references (i.e. the `Span` doesn't hold a reference / copy of the actual input). #[derive(Clone, Copy, Debug, Eq, PartialEq)] pub struct Span { start: usize, end: usize, } impl Span { /// Create a new span starting at byte `start` and ending at byte `end`. /// /// # Panics /// /// If `end` is less than `start`. pub fn new(start: usize, end: usize) -> Self { if end < start { panic!("Span starts ({}) after it ends ({})!", start, end); } Span { start, end } } /// Byte offset of the start of the span. pub fn start(&self) -> usize { self.start } /// Byte offset of the end of the span. pub fn end(&self) -> usize { self.end } /// Length in bytes of the span. pub fn len(&self) -> usize { self.end - self.start } /// Returns `true` if this `Span` covers 0 bytes, or `false` otherwise. pub fn is_empty(&self) -> bool { self.len() == 0 } }