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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;
use crate::token;
/*
* Parse python code.
* Grammar may be inspired by antlr grammar for python:
* https://github.com/antlr/grammars-v4/tree/master/python3
*/
macro_rules! do_lalr_parsing {
($input: expr, $pat: ident, $tok: ident) => {{
let lxr = lexer::make_tokenizer($input);
let marker_token = (Default::default(), token::Tok::$tok, Default::default());
let tokenizer = iter::once(Ok(marker_token)).chain(lxr);
match python::TopParser::new().parse(tokenizer) {
Err(err) => Err(ParseError::from(err)),
Ok(top) => {
if let ast::Top::$pat(x) = top {
Ok(x)
} else {
unreachable!()
}
}
}
}};
}
/// Parse a full python program, containing usually multiple lines.
pub fn parse_program(source: &str) -> Result<ast::Program, ParseError> {
do_lalr_parsing!(source, Program, StartProgram)
}
/// Parse a single statement.
pub fn parse_statement(source: &str) -> Result<Vec<ast::Statement>, ParseError> {
do_lalr_parsing!(source, Statement, StartStatement)
}
/// Parses a python expression
///
/// # Example
/// ```
/// extern crate num_bigint;
/// use num_bigint::BigInt;
/// use rustpython_parser::{parser, ast};
/// let expr = parser::parse_expression("1 + 2").unwrap();
///
/// assert_eq!(ast::Expression {
/// location: ast::Location::new(1, 3),
/// node: ast::ExpressionType::Binop {
/// a: Box::new(ast::Expression {
/// location: ast::Location::new(1, 1),
/// node: ast::ExpressionType::Number {
/// value: ast::Number::Integer { value: BigInt::from(1) }
/// }
/// }),
/// op: ast::Operator::Add,
/// b: Box::new(ast::Expression {
/// location: ast::Location::new(1, 5),
/// node: ast::ExpressionType::Number {
/// value: ast::Number::Integer { value: BigInt::from(2) }
/// }
/// })
/// }
/// },
/// expr);
///
/// ```
pub fn parse_expression(source: &str) -> Result<ast::Expression, ParseError> {
do_lalr_parsing!(source, Expression, StartExpression)
}
// Parse a given source code
pub fn parse(source: &str, mode: Mode) -> Result<ast::Top, ParseError> {
Ok(match mode {
Mode::Program => {
let ast = parse_program(source)?;
ast::Top::Program(ast)
}
Mode::Statement => {
let statement = parse_statement(source)?;
ast::Top::Statement(statement)
}
})
}
#[cfg(test)]
mod tests {
use super::ast;
use super::parse_expression;
use super::parse_program;
use super::parse_statement;
use num_bigint::BigInt;
fn mk_ident(name: &str, row: usize, col: usize) -> ast::Expression {
ast::Expression {
location: ast::Location::new(row, col),
node: ast::ExpressionType::Identifier {
name: name.to_owned(),
},
}
}
fn make_int(value: i32, row: usize, col: usize) -> ast::Expression {
ast::Expression {
location: ast::Location::new(row, col),
node: ast::ExpressionType::Number {
value: ast::Number::Integer {
value: BigInt::from(value),
},
},
}
}
fn make_string(value: &str, row: usize, col: usize) -> ast::Expression {
ast::Expression {
location: ast::Location::new(row, col),
node: ast::ExpressionType::String {
value: ast::StringGroup::Constant {
value: String::from(value),
},
},
}
}
fn as_statement(expr: ast::Expression) -> ast::Statement {
ast::Statement {
location: expr.location.clone(),
node: ast::StatementType::Expression { expression: expr },
}
}
#[test]
fn test_parse_empty() {
let parse_ast = parse_program(&String::from(""));
assert_eq!(parse_ast, Ok(ast::Program { statements: vec![] }))
}
#[test]
fn test_parse_print_hello() {
let source = String::from("print('Hello world')");
let parse_ast = parse_program(&source).unwrap();
assert_eq!(
parse_ast,
ast::Program {
statements: vec![ast::Statement {
location: ast::Location::new(1, 1),
node: ast::StatementType::Expression {
expression: ast::Expression {
location: ast::Location::new(1, 6),
node: ast::ExpressionType::Call {
function: Box::new(mk_ident("print", 1, 1)),
args: vec![make_string("Hello world", 1, 8)],
keywords: vec![],
}
},
},
},],
}
);
}
#[test]
fn test_parse_print_2() {
let source = String::from("print('Hello world', 2)");
let parse_ast = parse_program(&source).unwrap();
assert_eq!(
parse_ast,
ast::Program {
statements: vec![ast::Statement {
location: ast::Location::new(1, 1),
node: ast::StatementType::Expression {
expression: ast::Expression {
location: ast::Location::new(1, 6),
node: ast::ExpressionType::Call {
function: Box::new(mk_ident("print", 1, 1)),
args: vec![make_string("Hello world", 1, 8), make_int(2, 1, 22),],
keywords: vec![],
},
},
},
},],
}
);
}
#[test]
fn test_parse_kwargs() {
let source = String::from("my_func('positional', keyword=2)");
let parse_ast = parse_program(&source).unwrap();
assert_eq!(
parse_ast,
ast::Program {
statements: vec![ast::Statement {
location: ast::Location::new(1, 1),
node: ast::StatementType::Expression {
expression: ast::Expression {
location: ast::Location::new(1, 8),
node: ast::ExpressionType::Call {
function: Box::new(mk_ident("my_func", 1, 1)),
args: vec![make_string("positional", 1, 10)],
keywords: vec![ast::Keyword {
name: Some("keyword".to_string()),
value: make_int(2, 1, 31),
}],
}
},
},
},],
}
);
}
#[test]
fn test_parse_if_elif_else() {
let source = String::from("if 1: 10\nelif 2: 20\nelse: 30");
let parse_ast = parse_statement(&source).unwrap();
assert_eq!(
parse_ast,
vec![ast::Statement {
location: ast::Location::new(1, 1),
node: ast::StatementType::If {
test: make_int(1, 1, 4),
body: vec![as_statement(make_int(10, 1, 7))],
orelse: Some(vec![ast::Statement {
location: ast::Location::new(2, 1),
node: ast::StatementType::If {
test: make_int(2, 2, 6),
body: vec![as_statement(make_int(20, 2, 9))],
orelse: Some(vec![as_statement(make_int(30, 3, 7))]),
}
},]),
}
}]
);
}
#[test]
fn test_parse_lambda() {
let source = String::from("lambda x, y: x * y"); // lambda(x, y): x * y");
let parse_ast = parse_statement(&source);
assert_eq!(
parse_ast,
Ok(vec![as_statement(ast::Expression {
location: ast::Location::new(1, 1),
node: ast::ExpressionType::Lambda {
args: Box::new(ast::Parameters {
args: vec![
ast::Parameter {
location: ast::Location::new(1, 8),
arg: String::from("x"),
annotation: None,
},
ast::Parameter {
location: ast::Location::new(1, 11),
arg: String::from("y"),
annotation: None,
}
],
kwonlyargs: vec![],
vararg: ast::Varargs::None,
kwarg: ast::Varargs::None,
defaults: vec![],
kw_defaults: vec![],
}),
body: Box::new(ast::Expression {
location: ast::Location::new(1, 16),
node: ast::ExpressionType::Binop {
a: Box::new(mk_ident("x", 1, 14)),
op: ast::Operator::Mult,
b: Box::new(mk_ident("y", 1, 18))
}
})
}
})])
)
}
#[test]
fn test_parse_tuples() {
let source = String::from("a, b = 4, 5");
assert_eq!(
parse_statement(&source),
Ok(vec![ast::Statement {
location: ast::Location::new(1, 1),
node: ast::StatementType::Assign {
targets: vec![ast::Expression {
location: ast::Location::new(1, 1),
node: ast::ExpressionType::Tuple {
elements: vec![mk_ident("a", 1, 1), mk_ident("b", 1, 4),]
}
}],
value: ast::Expression {
location: ast::Location::new(1, 8),
node: ast::ExpressionType::Tuple {
elements: vec![make_int(4, 1, 8), make_int(5, 1, 11),]
}
}
}
}])
)
}
#[test]
fn test_parse_class() {
let source = String::from(
"class Foo(A, B):\n def __init__(self):\n pass\n def method_with_default(self, arg='default'):\n pass",
);
assert_eq!(
parse_statement(&source),
Ok(vec![ast::Statement {
location: ast::Location::new(1, 1),
node: ast::StatementType::ClassDef {
name: String::from("Foo"),
bases: vec![mk_ident("A", 1, 11), mk_ident("B", 1, 14)],
keywords: vec![],
body: vec![
ast::Statement {
location: ast::Location::new(2, 2),
node: ast::StatementType::FunctionDef {
is_async: false,
name: String::from("__init__"),
args: Box::new(ast::Parameters {
args: vec![ast::Parameter {
location: ast::Location::new(2, 15),
arg: String::from("self"),
annotation: None,
}],
kwonlyargs: vec![],
vararg: ast::Varargs::None,
kwarg: ast::Varargs::None,
defaults: vec![],
kw_defaults: vec![],
}),
body: vec![ast::Statement {
location: ast::Location::new(3, 3),
node: ast::StatementType::Pass,
}],
decorator_list: vec![],
returns: None,
}
},
ast::Statement {
location: ast::Location::new(4, 2),
node: ast::StatementType::FunctionDef {
is_async: false,
name: String::from("method_with_default"),
args: Box::new(ast::Parameters {
args: vec![
ast::Parameter {
location: ast::Location::new(4, 26),
arg: String::from("self"),
annotation: None,
},
ast::Parameter {
location: ast::Location::new(4, 32),
arg: String::from("arg"),
annotation: None,
}
],
kwonlyargs: vec![],
vararg: ast::Varargs::None,
kwarg: ast::Varargs::None,
defaults: vec![make_string("default", 4, 37)],
kw_defaults: vec![],
}),
body: vec![ast::Statement {
location: ast::Location::new(5, 3),
node: ast::StatementType::Pass,
}],
decorator_list: vec![],
returns: None,
}
}
],
decorator_list: vec![],
}
}])
)
}
#[test]
fn test_parse_list_comprehension() {
let source = String::from("[x for y in z]");
let parse_ast = parse_expression(&source).unwrap();
assert_eq!(
parse_ast,
ast::Expression {
location: ast::Location::new(1, 1),
node: ast::ExpressionType::Comprehension {
kind: Box::new(ast::ComprehensionKind::List {
element: mk_ident("x", 1, 2),
}),
generators: vec![ast::Comprehension {
location: ast::Location::new(1, 4),
target: mk_ident("y", 1, 8),
iter: mk_ident("z", 1, 13),
ifs: vec![],
is_async: false,
}],
}
}
);
}
#[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();
assert_eq!(
parse_ast,
ast::Expression {
location: ast::Location::new(1, 1),
node: ast::ExpressionType::Comprehension {
kind: Box::new(ast::ComprehensionKind::List {
element: mk_ident("x", 1, 2)
}),
generators: vec![
ast::Comprehension {
location: ast::Location::new(1, 4),
target: ast::Expression {
location: ast::Location::new(1, 8),
node: ast::ExpressionType::Tuple {
elements: vec![mk_ident("y", 1, 8), mk_ident("y2", 1, 11),],
}
},
iter: mk_ident("z", 1, 17),
ifs: vec![],
is_async: false,
},
ast::Comprehension {
location: ast::Location::new(1, 19),
target: mk_ident("a", 1, 23),
iter: mk_ident("b", 1, 28),
ifs: vec![
ast::Expression {
location: ast::Location::new(1, 35),
node: ast::ExpressionType::Compare {
vals: vec![mk_ident("a", 1, 33), make_int(5, 1, 37),],
ops: vec![ast::Comparison::Less],
}
},
ast::Expression {
location: ast::Location::new(1, 44),
node: ast::ExpressionType::Compare {
vals: vec![mk_ident("a", 1, 42), make_int(10, 1, 46),],
ops: vec![ast::Comparison::Greater],
},
},
],
is_async: false,
}
],
}
}
);
}
}