Module lualite::parser::expression

Expand description

Expression parsers

The primary parser to use in this module is expression, which will parse any expression. It’s used in the examples below. The other parsers in this module will only parse a specific type of expression. For example function_call will only parse an expressions where a function call is the root of the expression tree.

Examples:

let source_code = "x + 1.0 * y";
let (_remaining, parsed_ast) = expression(source_code).expect("parse error");

let expected_ast = Expression::Binary {
  left: Box::new(Expression::Identifier(Identifier("x".to_owned()))),
  op: BinaryOperator::Add,
  right: Box::new(Expression::Binary {
    left: Box::new(Expression::Float(FloatLiteral(1.0_f64))),
    op: BinaryOperator::Mul,
    right: Box::new(Expression::Identifier(Identifier("y".to_owned()))),
  })
};

assert_eq!(parsed_ast, expected_ast);

Order of operations can be changed with parentheses:

let source_code = "(x + 1.0) * y";
let (_remaining, parsed_ast) = expression(source_code).expect("parse error");

let expected_ast = Expression::Binary {
  left: Box::new(Expression::Binary {
    left: Box::new(Expression::Identifier(Identifier("x".to_owned()))),
    op: BinaryOperator::Add,
    right: Box::new(Expression::Float(FloatLiteral(1.0_f64))),
  }),
  op: BinaryOperator::Mul,
  right: Box::new(Expression::Identifier(Identifier("y".to_owned()))),
};

assert_eq!(parsed_ast, expected_ast);