nac3/nac3parser/src/parser.rs

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//! Python parsing.
//!
//! Use this module to parse python code into an AST.
//! There are three ways to parse python code. You could
//! parse a whole program, a single statement, or a single
//! expression.
use std::iter;
use crate::ast;
use crate::error::ParseError;
use crate::lexer;
pub use crate::mode::Mode;
use crate::python;
/*
* Parse python code.
* Grammar may be inspired by antlr grammar for python:
* https://github.com/antlr/grammars-v4/tree/master/python3
*/
/// Parse a full python program, containing usually multiple lines.
pub fn parse_program(source: &str) -> Result<ast::Suite, ParseError> {
parse(source, Mode::Module).map(|top| match top {
ast::Mod::Module { body, .. } => body,
_ => unreachable!(),
})
}
/// Parses a python expression
///
/// # Example
/// ```
/// extern crate num_bigint;
2021-11-03 17:11:00 +08:00
/// use nac3parser::{parser, ast};
/// let expr = parser::parse_expression("1 + 2").unwrap();
///
/// assert_eq!(
/// expr,
/// ast::Expr {
/// location: ast::Location::new(1, 3),
/// custom: (),
/// node: ast::ExprKind::BinOp {
/// left: Box::new(ast::Expr {
/// location: ast::Location::new(1, 1),
/// custom: (),
/// node: ast::ExprKind::Constant {
/// value: ast::Constant::Int(1.into()),
/// kind: None,
/// }
/// }),
/// op: ast::Operator::Add,
/// right: Box::new(ast::Expr {
/// location: ast::Location::new(1, 5),
/// custom: (),
/// node: ast::ExprKind::Constant {
/// value: ast::Constant::Int(2.into()),
/// kind: None,
/// }
/// })
/// }
/// },
/// );
///
/// ```
pub fn parse_expression(source: &str) -> Result<ast::Expr, ParseError> {
parse(source, Mode::Expression).map(|top| match top {
ast::Mod::Expression { body } => *body,
_ => unreachable!(),
})
}
// Parse a given source code
pub fn parse(source: &str, mode: Mode) -> Result<ast::Mod, ParseError> {
let lxr = lexer::make_tokenizer(source);
let marker_token = (Default::default(), mode.to_marker(), Default::default());
let tokenizer = iter::once(Ok(marker_token)).chain(lxr);
python::TopParser::new()
.parse(tokenizer)
.map_err(ParseError::from)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_parse_empty() {
let parse_ast = parse_program("").unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_print_hello() {
let source = String::from("print('Hello world')");
let parse_ast = parse_program(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_print_2() {
let source = String::from("print('Hello world', 2)");
let parse_ast = parse_program(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_kwargs() {
let source = String::from("my_func('positional', keyword=2)");
let parse_ast = parse_program(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_if_elif_else() {
let source = String::from("if 1: 10\nelif 2: 20\nelse: 30");
let parse_ast = parse_program(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_lambda() {
let source = "lambda x, y: x * y"; // lambda(x, y): x * y";
let parse_ast = parse_program(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_tuples() {
let source = "a, b = 4, 5";
insta::assert_debug_snapshot!(parse_program(&source).unwrap());
}
#[test]
fn test_parse_class() {
let source = "\
class Foo(A, B):
def __init__(self):
pass
def method_with_default(self, arg='default'):
pass";
insta::assert_debug_snapshot!(parse_program(&source).unwrap());
}
#[test]
fn test_parse_dict_comprehension() {
let source = String::from("{x1: x2 for y in z}");
let parse_ast = parse_expression(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_list_comprehension() {
let source = String::from("[x for y in z]");
let parse_ast = parse_expression(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
#[test]
fn test_parse_double_list_comprehension() {
let source = String::from("[x for y, y2 in z for a in b if a < 5 if a > 10]");
let parse_ast = parse_expression(&source).unwrap();
insta::assert_debug_snapshot!(parse_ast);
}
}