dust/src/parser.rs

use std::{cell::RefCell, collections::HashMap};

use chumsky::{input::SpannedInput, pratt::*, prelude::*};

use crate::{
    abstract_tree::*,
    error::Error,
    lexer::{Control, Operator, Token},
};

pub type ParserInput<'src> =
    SpannedInput<Token<'src>, SimpleSpan, &'src [(Token<'src>, SimpleSpan)]>;

pub fn parse<'src>(
    tokens: &'src [(Token<'src>, SimpleSpan)],
) -> Result<Vec<WithPosition<Statement>>, Vec<Error>> {
    parser()
        .parse(tokens.spanned((tokens.len()..tokens.len()).into()))
        .into_result()
        .map_err(|errors| errors.into_iter().map(|error| error.into()).collect())
}

pub fn parser<'src>() -> impl Parser<
    'src,
    ParserInput<'src>,
    Vec<WithPosition<Statement>>,
    extra::Err<Rich<'src, Token<'src>, SimpleSpan>>,
> {
    let identifiers: RefCell<HashMap<&str, Identifier>> = RefCell::new(HashMap::new());

    let identifier = select! {
        Token::Identifier(text) => {
            let mut identifiers = identifiers.borrow_mut();

            if let Some(identifier) = identifiers.get(&text) {
                identifier.clone()
            } else {
                let new = Identifier::new(text);

                identifiers.insert(text, new.clone());

                new
            }
        }
    };

    let positioned_identifier = identifier
        .clone()
        .map_with(|identifier, state| identifier.with_position(state.span()));

    let basic_value = select! {
        Token::Boolean(boolean) => ValueNode::Boolean(boolean),
        Token::Float(float) => ValueNode::Float(float),
        Token::Integer(integer) => ValueNode::Integer(integer),
        Token::String(string) => ValueNode::String(string.to_string()),
    }
    .map_with(|value, state| Expression::Value(value).with_position(state.span()));

    let r#type = recursive(|r#type| {
        let function_type = r#type
            .clone()
            .separated_by(just(Token::Control(Control::Comma)))
            .collect()
            .delimited_by(
                just(Token::Control(Control::ParenOpen)),
                just(Token::Control(Control::ParenClose)),
            )
            .then_ignore(just(Token::Control(Control::Arrow)))
            .then(r#type.clone())
            .map(|(parameter_types, return_type)| Type::Function {
                parameter_types,
                return_type: Box::new(return_type),
            });

        let list_of = just(Token::Keyword("list"))
            .ignore_then(r#type.clone().delimited_by(
                just(Token::Control(Control::ParenOpen)),
                just(Token::Control(Control::ParenClose)),
            ))
            .map(|item_type| Type::ListOf(Box::new(item_type)));

        let list_exact = r#type
            .clone()
            .separated_by(just(Token::Control(Control::Comma)))
            .collect()
            .delimited_by(
                just(Token::Control(Control::SquareOpen)),
                just(Token::Control(Control::SquareClose)),
            )
            .map(|types| Type::ListExact(types));

        choice((
            function_type,
            list_of,
            list_exact,
            just(Token::Keyword("any")).to(Type::Any),
            just(Token::Keyword("bool")).to(Type::Boolean),
            just(Token::Keyword("float")).to(Type::Float),
            just(Token::Keyword("int")).to(Type::Integer),
            just(Token::Keyword("none")).to(Type::None),
            just(Token::Keyword("range")).to(Type::Range),
            just(Token::Keyword("str")).to(Type::String),
            just(Token::Keyword("list")).to(Type::List),
        ))
    })
    .map_with(|r#type, state| r#type.with_position(state.span()));

    let type_specification = just(Token::Control(Control::Colon)).ignore_then(r#type.clone());

    let positioned_statement = recursive(|positioned_statement| {
        let block = positioned_statement
            .clone()
            .repeated()
            .collect()
            .delimited_by(
                just(Token::Control(Control::CurlyOpen)),
                just(Token::Control(Control::CurlyClose)),
            )
            .map(|statements| Block::new(statements));

        let positioned_expression = recursive(|positioned_expression| {
            let identifier_expression = identifier.clone().map_with(|identifier, state| {
                Expression::Identifier(identifier).with_position(state.span())
            });

            let raw_integer = select! {
                Token::Integer(integer) => integer
            };

            let range = raw_integer
                .clone()
                .then_ignore(just(Token::Control(Control::DoubleDot)))
                .then(raw_integer)
                .map_with(|(start, end), state| {
                    Expression::Value(ValueNode::Range(start..end)).with_position(state.span())
                });

            let list = positioned_expression
                .clone()
                .separated_by(just(Token::Control(Control::Comma)))
                .allow_trailing()
                .collect()
                .delimited_by(
                    just(Token::Control(Control::SquareOpen)),
                    just(Token::Control(Control::SquareClose)),
                )
                .map_with(|list, state| {
                    Expression::Value(ValueNode::List(list)).with_position(state.span())
                });

            let map_assignment = identifier
                .clone()
                .then(type_specification.clone().or_not())
                .then_ignore(just(Token::Operator(Operator::Assign)))
                .then(positioned_expression.clone())
                .map(|((identifier, r#type), expression)| (identifier, r#type, expression));

            let map = map_assignment
                .separated_by(just(Token::Control(Control::Comma)).or_not())
                .allow_trailing()
                .collect()
                .delimited_by(
                    just(Token::Control(Control::CurlyOpen)),
                    just(Token::Control(Control::CurlyClose)),
                )
                .map_with(|map_assigment_list, state| {
                    Expression::Value(ValueNode::Map(map_assigment_list))
                        .with_position(state.span())
                });

            let function = identifier
                .clone()
                .then(type_specification.clone())
                .separated_by(just(Token::Control(Control::Comma)))
                .collect()
                .delimited_by(
                    just(Token::Control(Control::ParenOpen)),
                    just(Token::Control(Control::ParenClose)),
                )
                .then(type_specification.clone())
                .then(block.clone())
                .map_with(|((parameters, return_type), body), state| {
                    Expression::Value(ValueNode::Function {
                        parameters,
                        return_type,
                        body: body.with_position(state.span()),
                    })
                    .with_position(state.span())
                });

            let atom = choice((
                function.clone(),
                identifier_expression.clone(),
                basic_value.clone(),
                list.clone(),
                map.clone(),
                positioned_expression.clone().delimited_by(
                    just(Token::Control(Control::ParenOpen)),
                    just(Token::Control(Control::ParenClose)),
                ),
            ));

            use Operator::*;

            let logic_math_indexes_and_function_calls = atom.pratt((
                prefix(2, just(Token::Operator(Not)), |_, expression, span| {
                    Expression::Logic(Box::new(Logic::Not(expression))).with_position(span)
                }),
                postfix(
                    2,
                    positioned_expression.clone().delimited_by(
                        just(Token::Control(Control::SquareOpen)),
                        just(Token::Control(Control::SquareClose)),
                    ),
                    |left, right, span| {
                        Expression::ListIndex(Box::new(ListIndex::new(left, right)))
                            .with_position(span)
                    },
                ),
                postfix(
                    3,
                    positioned_expression
                        .clone()
                        .separated_by(just(Token::Control(Control::Comma)))
                        .collect()
                        .delimited_by(
                            just(Token::Control(Control::ParenOpen)),
                            just(Token::Control(Control::ParenClose)),
                        ),
                    |op, expression, span| {
                        Expression::FunctionCall(FunctionCall::new(op, expression))
                            .with_position(span)
                    },
                ),
                infix(
                    left(4),
                    just(Token::Control(Control::Dot)),
                    |left, _, right, span| {
                        Expression::MapIndex(Box::new(MapIndex::new(left, right)))
                            .with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(Equal)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::Equal(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(NotEqual)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::NotEqual(left, right)))
                            .with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(Greater)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::Greater(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(Less)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::Less(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(GreaterOrEqual)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::GreaterOrEqual(left, right)))
                            .with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(LessOrEqual)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::LessOrEqual(left, right)))
                            .with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(And)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::And(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(Or)),
                    |left, _, right, span| {
                        Expression::Logic(Box::new(Logic::Or(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(Add)),
                    |left, _, right, span| {
                        Expression::Math(Box::new(Math::Add(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(Subtract)),
                    |left, _, right, span| {
                        Expression::Math(Box::new(Math::Subtract(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(2),
                    just(Token::Operator(Multiply)),
                    |left, _, right, span| {
                        Expression::Math(Box::new(Math::Multiply(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(2),
                    just(Token::Operator(Divide)),
                    |left, _, right, span| {
                        Expression::Math(Box::new(Math::Divide(left, right))).with_position(span)
                    },
                ),
                infix(
                    left(1),
                    just(Token::Operator(Modulo)),
                    |left, _, right, span| {
                        Expression::Math(Box::new(Math::Modulo(left, right))).with_position(span)
                    },
                ),
            ));

            choice((
                range,
                logic_math_indexes_and_function_calls,
                function,
                list,
                map,
                basic_value,
                identifier_expression,
            ))
        });

        let expression_statement =
            positioned_expression
                .clone()
                .map(|WithPosition { node, position }| {
                    Statement::Expression(node).with_position(position)
                });

        let r#break = just(Token::Keyword("break"))
            .map_with(|_, state| Statement::Break.with_position(state.span()));

        let assignment = positioned_identifier
            .clone()
            .then(type_specification.clone().or_not())
            .then(choice((
                just(Token::Operator(Operator::Assign)).to(AssignmentOperator::Assign),
                just(Token::Operator(Operator::AddAssign)).to(AssignmentOperator::AddAssign),
                just(Token::Operator(Operator::SubAssign)).to(AssignmentOperator::SubAssign),
            )))
            .then(positioned_statement.clone())
            .map_with(|(((identifier, r#type), operator), statement), state| {
                Statement::Assignment(Assignment::new(identifier, r#type, operator, statement))
                    .with_position(state.span())
            });

        let block_statement = block
            .clone()
            .map_with(|block, state| Statement::Block(block).with_position(state.span()));

        let r#loop = positioned_statement
            .clone()
            .repeated()
            .at_least(1)
            .collect()
            .delimited_by(
                just(Token::Keyword("loop")).then(just(Token::Control(Control::CurlyOpen))),
                just(Token::Control(Control::CurlyClose)),
            )
            .map_with(|statements, state| {
                Statement::Loop(Loop::new(statements)).with_position(state.span())
            });

        let r#while = just(Token::Keyword("while"))
            .ignore_then(positioned_expression.clone())
            .then(
                positioned_statement
                    .clone()
                    .repeated()
                    .collect()
                    .delimited_by(
                        just(Token::Control(Control::CurlyOpen)),
                        just(Token::Control(Control::CurlyClose)),
                    ),
            )
            .map_with(|(expression, statements), state| {
                Statement::While(While::new(expression, statements)).with_position(state.span())
            });

        let if_else = just(Token::Keyword("if"))
            .ignore_then(positioned_expression.clone())
            .then(block.clone())
            .then(
                just(Token::Keyword("else"))
                    .ignore_then(block.clone())
                    .or_not(),
            )
            .map_with(|((if_expression, if_block), else_block), state| {
                Statement::IfElse(IfElse::new(if_expression, if_block, else_block))
                    .with_position(state.span())
            });

        let structure_field = identifier.clone().then(type_specification.clone());

        let structure_definition = just(Token::Keyword("struct"))
            .ignore_then(identifier.clone())
            .then(
                structure_field
                    .separated_by(just(Token::Control(Control::Comma)))
                    .allow_trailing()
                    .collect()
                    .delimited_by(
                        just(Token::Control(Control::CurlyOpen)),
                        just(Token::Control(Control::CurlyClose)),
                    ),
            )
            .map_with(|(name, fields), state| {
                Statement::StructureDefinition(StructureDefinition::new(name, fields))
                    .with_position(state.span())
            });

        choice((
            structure_definition,
            if_else,
            assignment,
            expression_statement,
            r#break,
            block_statement,
            r#loop,
            r#while,
        ))
        .then_ignore(just(Token::Control(Control::Semicolon)).or_not())
    });

    positioned_statement.repeated().collect()
}

#[cfg(test)]
mod tests {
    use crate::lexer::lex;

    use super::*;

    #[test]
    fn structure_definition() {
        assert_eq!(
            parse(
                &lex("
                    struct Foo {
                        bar : int,
                        baz : str,
                    }
                ")
                .unwrap()
            )
            .unwrap()[0]
                .node,
            Statement::StructureDefinition(StructureDefinition::new(
                Identifier::new("Foo"),
                vec![
                    (
                        Identifier::new("bar"),
                        Type::Integer.with_position((64, 67))
                    ),
                    (
                        Identifier::new("baz"),
                        Type::String.with_position((99, 102))
                    ),
                ]
            ))
        )
    }

    #[test]
    fn map_index() {
        assert_eq!(
            parse(&lex("{ x = 42}.x").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::MapIndex(Box::new(MapIndex::new(
                Expression::Value(ValueNode::Map(vec![(
                    Identifier::new("x"),
                    None,
                    Expression::Value(ValueNode::Integer(42)).with_position((6, 8))
                )]))
                .with_position((0, 9)),
                Expression::Identifier(Identifier::new("x")).with_position((10, 11))
            ))))
        );
        assert_eq!(
            parse(&lex("foo.x").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::MapIndex(Box::new(MapIndex::new(
                Expression::Identifier(Identifier::new("foo")).with_position((0, 3)),
                Expression::Identifier(Identifier::new("x")).with_position((4, 5))
            ))))
        );
    }

    #[test]
    fn r#while() {
        assert_eq!(
            parse(&lex("while true { output('hi') }").unwrap()).unwrap()[0].node,
            Statement::While(While::new(
                Expression::Value(ValueNode::Boolean(true)).with_position((6, 11)),
                vec![
                    Statement::Expression(Expression::FunctionCall(FunctionCall::new(
                        Expression::Identifier(Identifier::new("output")).with_position((13, 19)),
                        vec![Expression::Value(ValueNode::String("hi".to_string()))
                            .with_position((20, 24))]
                    )))
                    .with_position((13, 26))
                ]
            ))
        )
    }

    #[test]
    fn boolean_type() {
        assert_eq!(
            parse(&lex("foobar : bool = true").unwrap()).unwrap()[0].node,
            Statement::Assignment(Assignment::new(
                Identifier::new("foobar").with_position((0, 6)),
                Some(Type::Boolean.with_position((9, 14))),
                AssignmentOperator::Assign,
                Statement::Expression(Expression::Value(ValueNode::Boolean(true)))
                    .with_position((16, 20))
            ),)
        );
    }

    #[test]
    fn list_type() {
        assert_eq!(
            parse(&lex("foobar: list = []").unwrap()).unwrap()[0].node,
            Statement::Assignment(Assignment::new(
                Identifier::new("foobar").with_position((0, 6)),
                Some(Type::List.with_position((8, 13))),
                AssignmentOperator::Assign,
                Statement::Expression(Expression::Value(ValueNode::List(vec![])))
                    .with_position((15, 17))
            ),)
        );
    }

    #[test]
    fn list_of_type() {
        assert_eq!(
            parse(&lex("foobar : list(bool) = [true]").unwrap()).unwrap()[0].node,
            Statement::Assignment(Assignment::new(
                Identifier::new("foobar").with_position((0, 6)),
                Some(Type::ListOf(Box::new(Type::Boolean)).with_position((9, 20))),
                AssignmentOperator::Assign,
                Statement::Expression(Expression::Value(ValueNode::List(vec![Expression::Value(
                    ValueNode::Boolean(true)
                )
                .with_position((23, 27))])))
                .with_position((22, 28))
            ))
        );
    }

    #[test]
    fn list_exact_type() {
        assert_eq!(
            parse(&lex("foobar : [bool, str] = [true, '42']").unwrap()).unwrap()[0],
            Statement::Assignment(Assignment::new(
                Identifier::new("foobar").with_position((0, 6)),
                Some(Type::ListExact(vec![Type::Boolean, Type::String]).with_position((9, 21))),
                AssignmentOperator::Assign,
                Statement::Expression(Expression::Value(ValueNode::List(vec![
                    Expression::Value(ValueNode::Boolean(true)).with_position((24, 28)),
                    Expression::Value(ValueNode::String("42".to_string())).with_position((30, 34))
                ])))
                .with_position((23, 35))
            ),)
            .with_position((0, 35))
        );
    }

    #[test]
    fn function_type() {
        assert_eq!(
            parse(&lex("foobar : () -> any = some_function").unwrap()).unwrap()[0].node,
            Statement::Assignment(Assignment::new(
                Identifier::new("foobar").with_position((0, 6)),
                Some(
                    Type::Function {
                        parameter_types: vec![],
                        return_type: Box::new(Type::Any)
                    }
                    .with_position((9, 19))
                ),
                AssignmentOperator::Assign,
                Statement::Expression(Expression::Identifier(Identifier::new("some_function")))
                    .with_position((21, 34))
            ),)
        );
    }

    #[test]
    fn function_call() {
        assert_eq!(
            parse(&lex("output()").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::FunctionCall(FunctionCall::new(
                Expression::Identifier(Identifier::new("output")).with_position((0, 6)),
                Vec::with_capacity(0),
            )))
        )
    }

    #[test]
    fn range() {
        assert_eq!(
            parse(&lex("1..10").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Range(1..10)))
        )
    }

    #[test]
    fn function() {
        assert_eq!(
            parse(&lex("(x: int) : int { x }").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Function {
                parameters: vec![(Identifier::new("x"), Type::Integer.with_position((4, 7)))],
                return_type: Type::Integer.with_position((11, 15)),
                body: Block::new(vec![Statement::Expression(Expression::Identifier(
                    Identifier::new("x")
                ),)
                .with_position((17, 18))])
                .with_position((0, 20))
            }),)
        )
    }

    #[test]
    fn r#if() {
        assert_eq!(
            parse(&lex("if true { 'foo' }").unwrap()).unwrap()[0].node,
            Statement::IfElse(IfElse::new(
                Expression::Value(ValueNode::Boolean(true)).with_position((3, 8)),
                Block::new(vec![Statement::Expression(Expression::Value(
                    ValueNode::String("foo".to_string())
                ),)
                .with_position((10, 15))]),
                None
            ),)
        );
    }

    #[test]
    fn if_else() {
        assert_eq!(
            parse(&lex("if true {'foo' } else { 'bar' }").unwrap()).unwrap()[0].node,
            Statement::IfElse(IfElse::new(
                Expression::Value(ValueNode::Boolean(true)).with_position((3, 8)),
                Block::new(vec![Statement::Expression(Expression::Value(
                    ValueNode::String("foo".to_string())
                ),)
                .with_position((9, 14))]),
                Some(Block::new(vec![Statement::Expression(Expression::Value(
                    ValueNode::String("bar".to_string())
                ),)
                .with_position((24, 29))]))
            ),)
        )
    }

    #[test]
    fn map() {
        assert_eq!(
            parse(&lex("{ foo = 'bar' }").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Map(vec![(
                Identifier::new("foo"),
                None,
                Expression::Value(ValueNode::String("bar".to_string())).with_position((8, 13))
            )])),)
        );
        assert_eq!(
            parse(&lex("{ x = 1, y = 2, }").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Map(vec![
                (
                    Identifier::new("x"),
                    None,
                    Expression::Value(ValueNode::Integer(1)).with_position((6, 7))
                ),
                (
                    Identifier::new("y"),
                    None,
                    Expression::Value(ValueNode::Integer(2)).with_position((13, 14))
                ),
            ])),)
        );
        assert_eq!(
            parse(&lex("{ x = 1 y = 2 }").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Map(vec![
                (
                    Identifier::new("x"),
                    None,
                    Expression::Value(ValueNode::Integer(1)).with_position((6, 7))
                ),
                (
                    Identifier::new("y"),
                    None,
                    Expression::Value(ValueNode::Integer(2)).with_position((12, 13))
                ),
            ])),)
        );
    }

    #[test]
    fn math() {
        assert_eq!(
            parse(&lex("1 + 1").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Math(Box::new(Math::Add(
                Expression::Value(ValueNode::Integer(1)).with_position((0, 1)),
                Expression::Value(ValueNode::Integer(1)).with_position((4, 5))
            ))),)
        );
    }

    #[test]
    fn r#loop() {
        assert_eq!(
            parse(&lex("loop { 42 }").unwrap()).unwrap()[0].node,
            Statement::Loop(Loop::new(vec![Statement::Expression(Expression::Value(
                ValueNode::Integer(42)
            ),)
            .with_position((7, 9))]),)
        );
        assert_eq!(
            parse(&lex("loop { if i > 2 { break } else { i += 1 } }").unwrap()).unwrap()[0].node,
            Statement::Loop(Loop::new(vec![Statement::IfElse(IfElse::new(
                Expression::Logic(Box::new(Logic::Greater(
                    Expression::Identifier(Identifier::new("i")).with_position((10, 11)),
                    Expression::Value(ValueNode::Integer(2)).with_position((14, 15))
                )))
                .with_position((10, 15)),
                Block::new(vec![Statement::Break.with_position((18, 24))]),
                Some(Block::new(vec![Statement::Assignment(Assignment::new(
                    Identifier::new("i").with_position((33, 34)),
                    None,
                    AssignmentOperator::AddAssign,
                    Statement::Expression(Expression::Value(ValueNode::Integer(1)))
                        .with_position((38, 39))
                ))
                .with_position((33, 39))]))
            ),)
            .with_position((7, 42))]))
        );
    }

    #[test]
    fn block() {
        assert_eq!(
            parse(&lex("{ x }").unwrap()).unwrap()[0].node,
            Statement::Block(Block::new(vec![Statement::Expression(
                Expression::Identifier(Identifier::new("x")),
            )
            .with_position((2, 3))]),)
        );

        assert_eq!(
            parse(
                &lex("
                {
                    x;
                    y;
                    z
                }
                ")
                .unwrap()
            )
            .unwrap()[0]
                .node,
            Statement::Block(Block::new(vec![
                Statement::Expression(Expression::Identifier(Identifier::new("x")))
                    .with_position((39, 40)),
                Statement::Expression(Expression::Identifier(Identifier::new("y")))
                    .with_position((62, 63)),
                Statement::Expression(Expression::Identifier(Identifier::new("z")))
                    .with_position((85, 86)),
            ]),)
        );

        assert_eq!(
            parse(
                &lex("
                {
                    1 == 1
                    z
                }
                ")
                .unwrap()
            )
            .unwrap()[0]
                .node,
            Statement::Block(Block::new(vec![
                Statement::Expression(Expression::Logic(Box::new(Logic::Equal(
                    Expression::Value(ValueNode::Integer(1)).with_position((39, 40)),
                    Expression::Value(ValueNode::Integer(1)).with_position((44, 45))
                ))),)
                .with_position((39, 45)),
                Statement::Expression(Expression::Identifier(Identifier::new("z")))
                    .with_position((66, 67)),
            ]),)
        );
    }

    #[test]
    fn identifier() {
        assert_eq!(
            parse(&lex("x").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Identifier(Identifier::new("x")))
        );
        assert_eq!(
            parse(&lex("foobar").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Identifier(Identifier::new("foobar")))
        );
        assert_eq!(
            parse(&lex("HELLO").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Identifier(Identifier::new("HELLO")))
        );
    }

    #[test]
    fn assignment() {
        assert_eq!(
            parse(&lex("foobar = 1").unwrap()).unwrap()[0].node,
            Statement::Assignment(Assignment::new(
                Identifier::new("foobar").with_position((0, 6)),
                None,
                AssignmentOperator::Assign,
                Statement::Expression(Expression::Value(ValueNode::Integer(1)))
                    .with_position((9, 10))
            ),)
        );
    }

    #[test]
    fn assignment_with_type() {
        assert_eq!(
            parse(&lex("foobar: int = 1").unwrap()).unwrap()[0].node,
            Statement::Assignment(Assignment::new(
                Identifier::new("foobar").with_position((0, 6)),
                Some(Type::Integer.with_position((8, 12))),
                AssignmentOperator::Assign,
                Statement::Expression(Expression::Value(ValueNode::Integer(1)))
                    .with_position((14, 15))
            ),)
        );
    }

    #[test]
    fn logic() {
        assert_eq!(
            parse(&lex("x == 1").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Logic(Box::new(Logic::Equal(
                Expression::Identifier(Identifier::new("x")).with_position((0, 1)),
                Expression::Value(ValueNode::Integer(1)).with_position((5, 6)),
            ))),)
        );

        assert_eq!(
            parse(&lex("(x == 1) && (y == 2)").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Logic(Box::new(Logic::And(
                Expression::Logic(Box::new(Logic::Equal(
                    Expression::Identifier(Identifier::new("x")).with_position((1, 2)),
                    Expression::Value(ValueNode::Integer(1)).with_position((6, 7)),
                )))
                .with_position((1, 7)),
                Expression::Logic(Box::new(Logic::Equal(
                    Expression::Identifier(Identifier::new("y")).with_position((13, 14)),
                    Expression::Value(ValueNode::Integer(2)).with_position((18, 19)),
                )))
                .with_position((13, 19)),
            ))),)
        );

        assert_eq!(
            parse(&lex("(x == 1) && (y == 2) && true").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Logic(Box::new(Logic::And(
                Expression::Logic(Box::new(Logic::And(
                    Expression::Logic(Box::new(Logic::Equal(
                        Expression::Identifier(Identifier::new("x")).with_position((1, 2)),
                        Expression::Value(ValueNode::Integer(1)).with_position((6, 7))
                    )))
                    .with_position((1, 7)),
                    Expression::Logic(Box::new(Logic::Equal(
                        Expression::Identifier(Identifier::new("y")).with_position((13, 14)),
                        Expression::Value(ValueNode::Integer(2)).with_position((18, 19))
                    )))
                    .with_position((13, 19)),
                )))
                .with_position((0, 21)),
                Expression::Value(ValueNode::Boolean(true)).with_position((24, 28))
            ))),)
        );
    }

    #[test]
    fn list() {
        assert_eq!(
            parse(&lex("[]").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::List(Vec::with_capacity(0))),)
        );
        assert_eq!(
            parse(&lex("[42]").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::List(vec![Expression::Value(
                ValueNode::Integer(42)
            )
            .with_position((1, 3))])),)
        );
        assert_eq!(
            parse(&lex("[42, 'foo', 'bar', [1, 2, 3,]]").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::List(vec![
                Expression::Value(ValueNode::Integer(42)).with_position((1, 3)),
                Expression::Value(ValueNode::String("foo".to_string())).with_position((5, 10)),
                Expression::Value(ValueNode::String("bar".to_string())).with_position((12, 17)),
                Expression::Value(ValueNode::List(vec![
                    Expression::Value(ValueNode::Integer(1)).with_position((20, 21)),
                    Expression::Value(ValueNode::Integer(2)).with_position((23, 24)),
                    Expression::Value(ValueNode::Integer(3)).with_position((26, 27)),
                ]))
                .with_position((19, 29))
            ])),)
        );
    }

    #[test]
    fn r#true() {
        assert_eq!(
            parse(&lex("true").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Boolean(true)))
        );
    }

    #[test]
    fn r#false() {
        assert_eq!(
            parse(&lex("false").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Boolean(false)))
        );
    }

    #[test]
    fn positive_float() {
        assert_eq!(
            parse(&lex("0.0").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(0.0)))
        );
        assert_eq!(
            parse(&lex("42.0").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(42.0)))
        );

        let max_float = f64::MAX.to_string() + ".0";

        assert_eq!(
            parse(&lex(&max_float).unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(f64::MAX)))
        );

        let min_positive_float = f64::MIN_POSITIVE.to_string();

        assert_eq!(
            parse(&lex(&min_positive_float).unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(f64::MIN_POSITIVE)),)
        );
    }

    #[test]
    fn negative_float() {
        assert_eq!(
            parse(&lex("-0.0").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(-0.0)))
        );
        assert_eq!(
            parse(&lex("-42.0").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(-42.0)))
        );

        let min_float = f64::MIN.to_string() + ".0";

        assert_eq!(
            parse(&lex(&min_float).unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(f64::MIN)))
        );

        let max_negative_float = format!("-{}", f64::MIN_POSITIVE);

        assert_eq!(
            parse(&lex(&max_negative_float).unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(-f64::MIN_POSITIVE)),)
        );
    }

    #[test]
    fn other_float() {
        assert_eq!(
            parse(&lex("Infinity").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(f64::INFINITY)))
        );
        assert_eq!(
            parse(&lex("-Infinity").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Float(f64::NEG_INFINITY)),)
        );

        if let Statement::Expression(Expression::Value(ValueNode::Float(float))) =
            &parse(&lex("NaN").unwrap()).unwrap()[0].node
        {
            assert!(float.is_nan());
        } else {
            panic!("Expected a float.");
        }
    }

    #[test]
    fn positive_integer() {
        for i in 0..10 {
            let source = i.to_string();
            let tokens = lex(&source).unwrap();
            let statements = parse(&tokens).unwrap();

            assert_eq!(
                statements[0].node,
                Statement::Expression(Expression::Value(ValueNode::Integer(i)))
            )
        }

        assert_eq!(
            parse(&lex("42").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Integer(42)))
        );

        let maximum_integer = i64::MAX.to_string();

        assert_eq!(
            parse(&lex(&maximum_integer).unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Integer(i64::MAX)))
        );
    }

    #[test]
    fn negative_integer() {
        for i in -9..1 {
            let source = i.to_string();
            let tokens = lex(&source).unwrap();
            let statements = parse(&tokens).unwrap();

            assert_eq!(
                statements[0].node,
                Statement::Expression(Expression::Value(ValueNode::Integer(i)))
            )
        }

        assert_eq!(
            parse(&lex("-42").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Integer(-42)))
        );

        let minimum_integer = i64::MIN.to_string();

        assert_eq!(
            parse(&lex(&minimum_integer).unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::Integer(i64::MIN)))
        );
    }

    #[test]
    fn double_quoted_string() {
        assert_eq!(
            parse(&lex("\"\"").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("".to_string())))
        );
        assert_eq!(
            parse(&lex("\"42\"").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("42".to_string())),)
        );
        assert_eq!(
            parse(&lex("\"foobar\"").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("foobar".to_string())),)
        );
    }

    #[test]
    fn single_quoted_string() {
        assert_eq!(
            parse(&lex("''").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("".to_string())))
        );
        assert_eq!(
            parse(&lex("'42'").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("42".to_string())),)
        );
        assert_eq!(
            parse(&lex("'foobar'").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("foobar".to_string())),)
        );
    }

    #[test]
    fn grave_quoted_string() {
        assert_eq!(
            parse(&lex("``").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("".to_string())))
        );
        assert_eq!(
            parse(&lex("`42`").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("42".to_string())),)
        );
        assert_eq!(
            parse(&lex("`foobar`").unwrap()).unwrap()[0].node,
            Statement::Expression(Expression::Value(ValueNode::String("foobar".to_string())),)
        );
    }
}