zen_expression/parser/

parser.rs

use bumpalo::collections::Vec as BumpVec;
use bumpalo::Bump;
use nohash_hasher::BuildNoHashHasher;
use rust_decimal::Decimal;
use std::cell::{Cell, RefCell};
use std::collections::HashMap;
use std::fmt::Debug;
use std::marker::PhantomData;
use std::ops::Deref;

use crate::lexer::{
    Bracket, ComparisonOperator, Identifier, Operator, QuotationMark, TemplateString, Token,
    TokenKind,
};
use crate::parser::ast::{AstNodeError, Node};
use crate::parser::builtin::{Arity, BuiltInFunction};
use crate::parser::error::ParserError;
use crate::parser::standard::Standard;
use crate::parser::unary::Unary;
use crate::parser::NodeMetadata;

macro_rules! expect {
    ($self:ident, $token:expr) => {
        if let Some(error_node) = $self.expect($token) {
            return error_node;
        }
    };
}
macro_rules! afmt {
    ($self:expr, $($arg:tt)*) => {{
        let formatted = format!($($arg)*);
        $self.bump.alloc_str(formatted.as_str())
    }}
}

#[derive(Debug)]
pub struct BaseParser;

#[derive(Debug)]
pub struct Parser<'arena, 'token_ref, Flavor> {
    tokens: &'token_ref [Token<'arena>],
    current: Cell<Option<&'token_ref Token<'arena>>>,
    pub(crate) bump: &'arena Bump,
    position: Cell<usize>,
    depth: Cell<u8>,
    marker_flavor: PhantomData<Flavor>,
    has_range_operator: bool,
    pub(crate) node_metadata:
        Option<RefCell<HashMap<usize, NodeMetadata, BuildNoHashHasher<usize>>>>,
}

impl<'arena, 'token_ref> Parser<'arena, 'token_ref, BaseParser> {
    pub fn try_new(
        tokens: &'token_ref [Token<'arena>],
        bump: &'arena Bump,
    ) -> Result<Self, ParserError> {
        let current = tokens.get(0);
        let has_range_operator = tokens
            .iter()
            .any(|t| t.kind == TokenKind::Operator(Operator::Range));

        Ok(Self {
            tokens,
            bump,
            current: Cell::new(current),
            depth: Cell::new(0),
            position: Cell::new(0),
            has_range_operator,
            node_metadata: None,
            marker_flavor: PhantomData,
        })
    }

    pub fn standard(self) -> Parser<'arena, 'token_ref, Standard> {
        Parser {
            tokens: self.tokens,
            bump: self.bump,
            current: self.current,
            depth: self.depth,
            position: self.position,
            has_range_operator: self.has_range_operator,
            node_metadata: self.node_metadata,
            marker_flavor: PhantomData,
        }
    }

    pub fn unary(self) -> Parser<'arena, 'token_ref, Unary> {
        Parser {
            tokens: self.tokens,
            bump: self.bump,
            current: self.current,
            depth: self.depth,
            position: self.position,
            has_range_operator: self.has_range_operator,
            node_metadata: self.node_metadata,
            marker_flavor: PhantomData,
        }
    }
}

impl<'arena, 'token_ref, Flavor> Parser<'arena, 'token_ref, Flavor> {
    pub fn with_metadata(mut self) -> Parser<'arena, 'token_ref, Flavor> {
        self.node_metadata = Some(Default::default());
        self
    }

    pub(crate) fn current(&self) -> Option<&Token<'arena>> {
        self.current.get()
    }

    pub(crate) fn current_kind(&self) -> Option<&TokenKind> {
        self.current.get().map(|token| &token.kind)
    }

    fn token_start(&self) -> u32 {
        match self.current() {
            None => self.tokens.last().map(|t| t.span.1).unwrap_or_default(),
            Some(t) => t.span.0,
        }
    }

    #[allow(dead_code)]
    fn token_end(&self) -> u32 {
        match self.current() {
            None => self.tokens.last().map(|t| t.span.1).unwrap_or_default(),
            Some(t) => t.span.1,
        }
    }

    pub(crate) fn prev_token_end(&self) -> u32 {
        let Some(pos) = self.position().checked_sub(1) else {
            return self.token_start();
        };

        match self.tokens.get(pos) {
            None => self.token_start(),
            Some(t) => t.span.1,
        }
    }

    fn position(&self) -> usize {
        self.position.get()
    }

    fn set_position(&self, position: usize) -> bool {
        let target_token = self.tokens.get(position);

        self.position.set(position);
        self.current.set(target_token);

        target_token.is_some()
    }

    pub(crate) fn depth(&self) -> u8 {
        self.depth.get()
    }

    pub(crate) fn is_done(&self) -> bool {
        self.current.get().is_none()
    }

    pub(crate) fn node<F>(&self, node: Node<'arena>, gen_metadata: F) -> &'arena Node<'arena>
    where
        F: FnOnce(MetadataHelper<'_, 'arena>) -> NodeMetadata,
    {
        let node = self.bump.alloc(node);
        if let Some(node_metadata) = &self.node_metadata {
            let metadata = {
                let nm = node_metadata.borrow();
                gen_metadata(MetadataHelper {
                    node_metadata: nm.deref(),
                    arena: PhantomData::<&'arena ()>,
                })
            };

            let mut nm = node_metadata.borrow_mut();
            nm.insert(node as *const Node as usize, metadata);
        };

        node
    }

    pub(crate) fn error(&self, error: AstNodeError<'arena>) -> &'arena Node<'arena> {
        self.node(Node::Error { error, node: None }, |_| NodeMetadata {
            span: (self.prev_token_end(), self.prev_token_end()),
        })
    }

    pub(crate) fn error_with_node(
        &self,
        error: AstNodeError<'arena>,
        node: &'arena Node<'arena>,
    ) -> &'arena Node<'arena> {
        self.node(
            Node::Error {
                error,
                node: Some(node),
            },
            |_| NodeMetadata { span: (0, 0) },
        )
    }

    pub(crate) fn next(&self) {
        let new_position = self.position.get() + 1;

        self.position.set(new_position);
        self.current.set(self.tokens.get(new_position));
    }

    pub(crate) fn expect(&self, kind: TokenKind) -> Option<&'arena Node<'arena>> {
        let token = self.current();
        if token.is_some_and(|t| t.kind == kind) {
            self.next();
            return None;
        }

        Some(
            self.error(AstNodeError::UnexpectedToken {
                expected: afmt!(self, "{kind}"),
                received: token
                    .map(|t| afmt!(self, "{}", t.kind))
                    .unwrap_or_else(|| afmt!(self, "None")),
                span: token.map(|t| t.span).unwrap_or((0, 0)),
            }),
        )
    }

    pub(crate) fn number(&self) -> &'arena Node<'arena> {
        let Some(token) = self.current() else {
            return self.error(AstNodeError::MissingToken {
                expected: afmt!(self, "Number"),
                position: self.position(),
            });
        };

        let Ok(decimal) = Decimal::from_str_exact(token.value) else {
            return self.error(AstNodeError::InvalidNumber {
                number: afmt!(self, "{}", token.value),
                span: token.span,
            });
        };

        self.next();
        self.node(Node::Number(decimal), |_| NodeMetadata { span: token.span })
    }

    pub(crate) fn bool(&self) -> &'arena Node<'arena> {
        let Some(token) = self.current() else {
            return self.error(AstNodeError::MissingToken {
                expected: afmt!(self, "Boolean"),
                position: self.position(),
            });
        };

        let TokenKind::Boolean(boolean) = token.kind else {
            return self.error(AstNodeError::InvalidBoolean {
                boolean: afmt!(self, "{}", token.value),
                span: token.span,
            });
        };

        self.next();
        self.node(Node::Bool(boolean), |_| NodeMetadata { span: token.span })
    }

    pub(crate) fn null(&self) -> &'arena Node<'arena> {
        let Some(token) = self.current() else {
            return self.error(AstNodeError::MissingToken {
                expected: afmt!(self, "Null"),
                position: self.position(),
            });
        };

        if token.kind != TokenKind::Identifier(Identifier::Null) {
            return self.error(AstNodeError::UnexpectedIdentifier {
                expected: afmt!(self, "Null"),
                received: afmt!(self, "{}", token.value),
                span: token.span,
            });
        }

        self.next();
        self.node(Node::Null, |_| NodeMetadata { span: token.span })
    }

    pub(crate) fn simple_string(&self, quote_mark: &QuotationMark) -> &'arena Node<'arena> {
        expect!(self, TokenKind::QuotationMark(quote_mark.clone()));
        let string_value = self.current();

        let error_literal = self.expect(TokenKind::Literal);
        let error_mark_end = self.expect(TokenKind::QuotationMark(quote_mark.clone()));

        error_literal
            .or(error_mark_end)
            .or(string_value.map(|t| {
                self.node(Node::String(t.value), |_| NodeMetadata {
                    span: (t.span.0 - 1, t.span.1 + 1),
                })
            }))
            .unwrap_or_else(|| {
                self.error(AstNodeError::Custom {
                    message: afmt!(
                        self,
                        "Failed to parse string `{}`",
                        string_value.map(|s| s.value).unwrap_or_default()
                    ),
                    span: string_value
                        .map(|s| s.span)
                        .unwrap_or((self.prev_token_end(), self.prev_token_end())),
                })
            })
    }

    pub(crate) fn template_string<F>(&self, expression_parser: F) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        expect!(self, TokenKind::QuotationMark(QuotationMark::Backtick));

        let Some(mut current_token) = self.current() else {
            return self.error(AstNodeError::MissingToken {
                expected: afmt!(self, "Backtick (`)"),
                position: self.position(),
            });
        };

        let mut span = (current_token.span.0 - 1, 0u32);

        let mut nodes = BumpVec::new_in(self.bump);
        while TokenKind::QuotationMark(QuotationMark::Backtick) != current_token.kind {
            match current_token.kind {
                TokenKind::TemplateString(template) => match template {
                    TemplateString::ExpressionStart => {
                        self.next();
                        nodes.push(expression_parser(ParserContext::Global));
                    }
                    TemplateString::ExpressionEnd => {
                        self.next();
                    }
                },
                TokenKind::Literal => {
                    nodes.push(
                        self.node(Node::String(current_token.value), |_| NodeMetadata {
                            span: current_token.span,
                        }),
                    );
                    self.next();
                }
                _ => {
                    return self.error(AstNodeError::UnexpectedToken {
                        expected: afmt!(self, "Valid TemplateString token"),
                        received: afmt!(self, "{}", current_token.kind),
                        span: current_token.span,
                    })
                }
            }

            if let Some(ct) = self.current() {
                current_token = ct;
                span.1 = ct.span.1;
            } else {
                break;
            }
        }

        expect!(self, TokenKind::QuotationMark(QuotationMark::Backtick));
        self.node(Node::TemplateString(nodes.into_bump_slice()), |_| {
            NodeMetadata { span }
        })
    }

    pub(crate) fn with_postfix<F>(
        &self,
        node: &'arena Node<'arena>,
        expression_parser: F,
    ) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let Some(postfix_token) = self.current() else {
            return node;
        };

        let postfix_kind = PostfixKind::from(postfix_token);

        let processed_token = match postfix_kind {
            PostfixKind::Other => return node,
            PostfixKind::MemberAccess => {
                self.next();
                let property_token = self.current();
                self.next();

                let property = match property_token {
                    None => self.error_with_node(
                        AstNodeError::Custom {
                            message: afmt!(self, "Expected a property"),
                            span: (self.prev_token_end(), self.prev_token_end()),
                        },
                        node,
                    ),
                    Some(t) => match is_valid_property(t) {
                        true => self.node(Node::String(t.value), |_| NodeMetadata { span: t.span }),
                        false => self.error_with_node(
                            AstNodeError::InvalidProperty {
                                property: afmt!(self, "{}", t.value),
                                span: t.span,
                            },
                            node,
                        ),
                    },
                };

                self.node(Node::Member { node, property }, |h| NodeMetadata {
                    span: h.span(node, property).unwrap_or_default(),
                })
            }
            PostfixKind::PropertyAccess => {
                self.next();
                let mut from: Option<&'arena Node<'arena>> = None;
                let mut to: Option<&'arena Node<'arena>> = None;

                let Some(mut c) = self.current() else {
                    return self.error_with_node(
                        AstNodeError::Custom {
                            message: afmt!(self, "Expected a property"),
                            span: (self.prev_token_end(), self.prev_token_end()),
                        },
                        node,
                    );
                };

                if c.kind == TokenKind::Operator(Operator::Slice) {
                    self.next();

                    let Some(cc) = self.current() else {
                        return self.error_with_node(
                            AstNodeError::Custom {
                                message: afmt!(self, "Unexpected token"),
                                span: (self.prev_token_end(), self.prev_token_end()),
                            },
                            node,
                        );
                    };
                    c = cc;

                    if c.kind != TokenKind::Bracket(Bracket::RightSquareBracket) {
                        to = Some(expression_parser(ParserContext::Global));
                    }

                    expect!(self, TokenKind::Bracket(Bracket::RightSquareBracket));
                    self.node(Node::Slice { node, to, from }, |h| NodeMetadata {
                        span: (
                            h.metadata(node).map(|m| m.span.0).unwrap_or_default(),
                            self.prev_token_end(),
                        ),
                    })
                } else {
                    let from_node = expression_parser(ParserContext::Global);
                    from = Some(from_node);
                    let Some(cc) = self.current() else {
                        return self.error_with_node(
                            AstNodeError::Custom {
                                message: afmt!(self, "Unexpected token"),
                                span: (self.prev_token_end(), self.prev_token_end()),
                            },
                            self.node(
                                Node::Member {
                                    node,
                                    property: from_node,
                                },
                                |h| NodeMetadata {
                                    span: h.span(node, from_node).unwrap_or_default(),
                                },
                            ),
                        );
                    };
                    c = cc;

                    if c.kind == TokenKind::Operator(Operator::Slice) {
                        self.next();
                        let Some(cc) = self.current() else {
                            return self.error_with_node(
                                AstNodeError::Custom {
                                    message: afmt!(self, "Invalid slice syntax"),
                                    span: (self.prev_token_end(), self.prev_token_end()),
                                },
                                self.node(Node::Slice { node, from, to }, |h| NodeMetadata {
                                    span: h.span(node, from_node).unwrap_or_default(),
                                }),
                            );
                        };
                        c = cc;

                        if c.kind != TokenKind::Bracket(Bracket::RightSquareBracket) {
                            to = Some(expression_parser(ParserContext::Global));
                        }

                        expect!(self, TokenKind::Bracket(Bracket::RightSquareBracket));
                        self.node(Node::Slice { node, from, to }, |h| NodeMetadata {
                            span: (
                                h.metadata(node).map(|m| m.span.0).unwrap_or_default(),
                                self.prev_token_end(),
                            ),
                        })
                    } else {
                        // Slice operator [:] was not found,
                        // it should be just an index node.
                        expect!(self, TokenKind::Bracket(Bracket::RightSquareBracket));
                        self.node(
                            Node::Member {
                                node,
                                property: from.unwrap_or_else(|| {
                                    return self.error_with_node(
                                        AstNodeError::Custom {
                                            message: afmt!(self, "Invalid index property"),
                                            span: (self.prev_token_end(), self.prev_token_end()),
                                        },
                                        node,
                                    );
                                }),
                            },
                            |h| NodeMetadata {
                                span: (
                                    h.metadata(node).map(|m| m.span.0).unwrap_or_default(),
                                    self.prev_token_end(),
                                ),
                            },
                        )
                    }
                }
            }
        };

        self.with_postfix(processed_token, expression_parser)
    }

    /// Closure
    pub(crate) fn closure<F>(&self, expression_parser: F) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let start = self.token_start();

        self.depth.set(self.depth.get() + 1);
        let node = expression_parser(ParserContext::Closure);
        self.depth.set(self.depth.get() - 1);

        self.node(Node::Closure(node), |_| NodeMetadata {
            span: (start, self.prev_token_end()),
        })
    }

    /// Identifier expression
    /// Either <Identifier> or <Identifier Expression>
    pub(crate) fn identifier<F>(&self, expression_parser: F) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let Some(token) = self.current() else {
            return self.error(AstNodeError::MissingToken {
                expected: afmt!(self, "Identifier"),
                position: self.position(),
            });
        };

        match token.kind {
            TokenKind::Identifier(_) | TokenKind::Literal => {
                // ok
            }
            _ => {
                return self.error(AstNodeError::Custom {
                    message: afmt!(self, "Expected an `identifier`, received `{}`.", token.kind),
                    span: token.span,
                });
            }
        }

        let Some(identifier_token) = self.current() else {
            return self.error(AstNodeError::Custom {
                message: afmt!(self, "Expected an `identifier`."),
                span: (self.prev_token_end(), self.prev_token_end()),
            });
        };
        self.next();

        let current_token = self.current();
        if current_token.map(|t| t.kind) != Some(TokenKind::Bracket(Bracket::LeftParenthesis)) {
            let identifier_node = match identifier_token.kind {
                TokenKind::Identifier(Identifier::RootReference) => {
                    self.node(Node::Root, |_| NodeMetadata {
                        span: identifier_token.span,
                    })
                }
                _ => self.node(Node::Identifier(identifier_token.value), |_| NodeMetadata {
                    span: identifier_token.span,
                }),
            };

            return self.with_postfix(identifier_node, expression_parser);
        }

        // Potentially it might be a built-in expression
        let Ok(builtin) = BuiltInFunction::try_from(identifier_token.value) else {
            return self.error(AstNodeError::UnknownBuiltIn {
                name: afmt!(self, "{}", identifier_token.value),
                span: identifier_token.span,
            });
        };

        self.next();
        let builtin_node = match builtin.arity() {
            Arity::Single => {
                let arg = expression_parser(ParserContext::Global);
                self.expect(TokenKind::Bracket(Bracket::RightParenthesis));

                Node::BuiltIn {
                    kind: builtin,
                    arguments: self.bump.alloc_slice_copy(&[arg]),
                }
            }
            Arity::Dual => {
                let arg1 = expression_parser(ParserContext::Global);
                self.expect(TokenKind::Operator(Operator::Comma));
                let arg2 = expression_parser(ParserContext::Global);
                self.expect(TokenKind::Bracket(Bracket::RightParenthesis));

                Node::BuiltIn {
                    kind: builtin,
                    arguments: self.bump.alloc_slice_copy(&[arg1, arg2]),
                }
            }
            Arity::Closure => {
                let arg1 = expression_parser(ParserContext::Global);

                self.expect(TokenKind::Operator(Operator::Comma));
                let arg2 = self.closure(&expression_parser);
                self.expect(TokenKind::Bracket(Bracket::RightParenthesis));

                Node::BuiltIn {
                    kind: builtin,
                    arguments: self.bump.alloc_slice_copy(&[arg1, arg2]),
                }
            }
        };

        self.with_postfix(
            self.node(builtin_node, |_| NodeMetadata {
                span: (identifier_token.span.0, self.prev_token_end()),
            }),
            expression_parser,
        )
    }

    /// Interval node
    pub(crate) fn interval<F>(&self, expression_parser: F) -> Option<&'arena Node<'arena>>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        // Performance optimisation: skip if expression does not contain an interval for faster evaluation
        if !self.has_range_operator {
            return None;
        }

        let TokenKind::Bracket(_) = &self.current()?.kind else {
            return None;
        };

        let initial_position = self.position();
        let TokenKind::Bracket(left_bracket) = &self.current()?.kind else {
            self.set_position(initial_position);
            return None;
        };

        self.next();
        let left = expression_parser(ParserContext::Global);
        if left.has_error() {
            self.set_position(initial_position);
            return None;
        };

        if let Some(_) = self.expect(TokenKind::Operator(Operator::Range)) {
            self.set_position(initial_position);
            return None;
        };

        let right = expression_parser(ParserContext::Global);
        if right.has_error() {
            self.set_position(initial_position);
            return None;
        };

        let TokenKind::Bracket(right_bracket) = &self.current()?.kind else {
            self.set_position(initial_position);
            return None;
        };

        self.next();

        let interval_node = self.node(
            Node::Interval {
                left,
                right,
                left_bracket: *left_bracket,
                right_bracket: *right_bracket,
            },
            |_| NodeMetadata {
                span: (initial_position as u32, self.position() as u32),
            },
        );

        Some(self.with_postfix(interval_node, expression_parser))
    }

    /// Array nodes
    pub(crate) fn array<F>(&self, expression_parser: F) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let Some(current_token) = self.current() else {
            return self.error(AstNodeError::MissingToken {
                expected: afmt!(self, "Array"),
                position: self.position(),
            });
        };

        if current_token.kind != TokenKind::Bracket(Bracket::LeftSquareBracket) {
            return self.error(AstNodeError::UnexpectedToken {
                expected: afmt!(self, "{}", TokenKind::Bracket(Bracket::LeftSquareBracket)),
                received: afmt!(self, "{}", current_token.kind),
                span: current_token.span,
            });
        }

        self.next();
        let mut nodes = BumpVec::new_in(self.bump);
        while !(self.current().map(|t| t.kind)
            == Some(TokenKind::Bracket(Bracket::RightSquareBracket)))
        {
            if !nodes.is_empty() {
                expect!(self, TokenKind::Operator(Operator::Comma));
                if self.current().map(|t| t.kind)
                    == Some(TokenKind::Bracket(Bracket::RightSquareBracket))
                {
                    break;
                }
            }

            nodes.push(expression_parser(ParserContext::Global));
        }

        expect!(self, TokenKind::Bracket(Bracket::RightSquareBracket));

        let node = Node::Array(nodes.into_bump_slice());

        self.with_postfix(
            self.node(node, |_| NodeMetadata {
                span: (current_token.span.0, self.prev_token_end()),
            }),
            expression_parser,
        )
    }

    pub(crate) fn object<F>(&self, expression_parser: F) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let span_start = self.token_start();
        expect!(self, TokenKind::Bracket(Bracket::LeftCurlyBracket));

        let mut key_value_pairs = BumpVec::new_in(self.bump);
        if let Some(TokenKind::Bracket(Bracket::RightCurlyBracket)) = self.current().map(|t| t.kind)
        {
            self.next();
            return self.node(Node::Object(key_value_pairs.into_bump_slice()), |_| {
                NodeMetadata {
                    span: (span_start, self.prev_token_end()),
                }
            });
        }

        loop {
            let key = self.object_key(&expression_parser);
            expect!(self, TokenKind::Operator(Operator::Slice));
            let value = expression_parser(ParserContext::Global);

            key_value_pairs.push((key, value));

            let Some(current_token) = self.current() else {
                break;
            };

            match current_token.kind {
                TokenKind::Operator(Operator::Comma) => {
                    expect!(self, TokenKind::Operator(Operator::Comma));
                }
                TokenKind::Bracket(Bracket::RightCurlyBracket) => break,
                _ => {
                    return self.error(AstNodeError::Custom {
                        message: afmt!(self, "Invalid object syntax"),
                        span: current_token.span,
                    })
                }
            }
        }

        expect!(self, TokenKind::Bracket(Bracket::RightCurlyBracket));
        self.node(Node::Object(key_value_pairs.into_bump_slice()), |_| {
            NodeMetadata {
                span: (span_start, self.prev_token_end()),
            }
        })
    }

    pub(crate) fn object_key<F>(&self, expression_parser: F) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let Some(key_token) = self.current() else {
            return self.error(AstNodeError::Custom {
                message: afmt!(self, "Expected an object key"),
                span: (self.prev_token_end(), self.prev_token_end()),
            });
        };

        let key = match key_token.kind {
            TokenKind::Identifier(identifier) => {
                self.next();
                self.node(Node::String(identifier.into()), |_| NodeMetadata {
                    span: key_token.span,
                })
            }
            TokenKind::Boolean(boolean) => match boolean {
                true => {
                    self.next();
                    self.node(Node::String("true"), |_| NodeMetadata {
                        span: key_token.span,
                    })
                }
                false => {
                    self.next();
                    self.node(Node::String("false"), |_| NodeMetadata {
                        span: key_token.span,
                    })
                }
            },
            TokenKind::Number => {
                self.next();
                self.node(Node::String(key_token.value), |_| NodeMetadata {
                    span: key_token.span,
                })
            }
            TokenKind::Literal => {
                self.next();
                self.node(Node::String(key_token.value), |_| NodeMetadata {
                    span: key_token.span,
                })
            }
            TokenKind::Bracket(bracket) => match bracket {
                Bracket::LeftSquareBracket => {
                    expect!(self, TokenKind::Bracket(Bracket::LeftSquareBracket));
                    let token = expression_parser(ParserContext::Global);
                    expect!(self, TokenKind::Bracket(Bracket::RightSquareBracket));

                    token
                }
                _ => {
                    return self.error(AstNodeError::Custom {
                        message: afmt!(self, "Operator is not supported as object key"),
                        span: key_token.span,
                    })
                }
            },
            TokenKind::QuotationMark(qm) => match qm {
                QuotationMark::SingleQuote => self.simple_string(&QuotationMark::SingleQuote),
                QuotationMark::DoubleQuote => self.simple_string(&QuotationMark::DoubleQuote),
                QuotationMark::Backtick => {
                    return self.error(AstNodeError::Custom {
                        message: afmt!(
                            self,
                            "TemplateString expression not supported as object key"
                        ),
                        span: key_token.span,
                    })
                }
            },
            TokenKind::TemplateString(_) => {
                return self.error(AstNodeError::Custom {
                    message: afmt!(
                        self,
                        "TemplateString expression not supported as object key"
                    ),
                    span: key_token.span,
                })
            }
            TokenKind::Operator(_) => {
                return self.error(AstNodeError::Custom {
                    message: afmt!(self, "Operator is not supported as object key"),
                    span: key_token.span,
                })
            }
        };

        key
    }

    /// Conditional
    /// condition_node ? on_true : on_false
    pub(crate) fn conditional<F>(
        &self,
        condition: &'arena Node<'arena>,
        expression_parser: F,
    ) -> Option<&'arena Node<'arena>>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let Some(current_token) = self.current() else {
            return None;
        };
        if current_token.kind != TokenKind::Operator(Operator::QuestionMark) {
            return None;
        }

        self.next();

        let on_true = expression_parser(ParserContext::Global);
        if let Some(error_node) = self.expect(TokenKind::Operator(Operator::Slice)) {
            return Some(error_node);
        }

        let on_false = expression_parser(ParserContext::Global);

        let conditional_node = Node::Conditional {
            condition,
            on_true,
            on_false,
        };

        Some(self.node(conditional_node, |_| NodeMetadata {
            span: (current_token.span.0, self.prev_token_end()),
        }))
    }

    /// Literal - number, string, array etc.
    pub(crate) fn literal<F>(&self, expression_parser: F) -> &'arena Node<'arena>
    where
        F: Fn(ParserContext) -> &'arena Node<'arena>,
    {
        let Some(current_token) = self.current() else {
            return self.error(AstNodeError::Custom {
                message: afmt!(self, "Expected a literal"),
                span: (self.prev_token_end(), self.prev_token_end()),
            });
        };

        match &current_token.kind {
            TokenKind::Identifier(identifier) => match identifier {
                Identifier::Null => self.null(),
                _ => self.identifier(&expression_parser),
            },
            TokenKind::Literal => self.identifier(&expression_parser),
            TokenKind::Boolean(_) => self.bool(),
            TokenKind::Number => self.number(),
            TokenKind::QuotationMark(quote_mark) => match quote_mark {
                QuotationMark::SingleQuote | QuotationMark::DoubleQuote => {
                    self.simple_string(quote_mark)
                }
                QuotationMark::Backtick => self.template_string(&expression_parser),
            },
            TokenKind::Bracket(bracket) => match bracket {
                Bracket::LeftParenthesis
                | Bracket::RightParenthesis
                | Bracket::RightSquareBracket => {
                    self.interval(&expression_parser).unwrap_or_else(|| {
                        self.error(AstNodeError::Custom {
                            message: afmt!(self, "Invalid syntax"),
                            span: (self.prev_token_end(), self.prev_token_end()),
                        })
                    })
                }
                Bracket::LeftSquareBracket => self
                    .interval(&expression_parser)
                    .unwrap_or_else(|| self.array(&expression_parser)),
                Bracket::LeftCurlyBracket => self.object(&expression_parser),
                Bracket::RightCurlyBracket => self.error(AstNodeError::Custom {
                    message: afmt!(self, "Unexpected RightCurlyBracket token"),
                    span: current_token.span,
                }),
            },
            TokenKind::Operator(_) => self.error(AstNodeError::Custom {
                message: afmt!(self, "Unexpected Operator token"),
                span: current_token.span,
            }),
            TokenKind::TemplateString(_) => self.error(AstNodeError::Custom {
                message: afmt!(self, "Unexpected TemplateString token"),
                span: current_token.span,
            }),
        }
    }
}

fn is_valid_property(token: &Token) -> bool {
    match &token.kind {
        TokenKind::Identifier(_) => true,
        TokenKind::Literal => true,
        TokenKind::Operator(operator) => match operator {
            Operator::Logical(_) => true,
            Operator::Comparison(comparison) => matches!(comparison, ComparisonOperator::In),
            _ => false,
        },
        _ => false,
    }
}

#[derive(Debug)]
enum PostfixKind {
    MemberAccess,
    PropertyAccess,
    Other,
}

impl From<&Token<'_>> for PostfixKind {
    fn from(token: &Token) -> Self {
        match &token.kind {
            TokenKind::Bracket(Bracket::LeftSquareBracket) => Self::PropertyAccess,
            TokenKind::Operator(Operator::Dot) => Self::MemberAccess,
            _ => Self::Other,
        }
    }
}

pub(crate) struct MetadataHelper<'a, 'arena> {
    node_metadata: &'a HashMap<usize, NodeMetadata, BuildNoHashHasher<usize>>,
    arena: PhantomData<&'arena ()>,
}

impl<'a, 'arena> MetadataHelper<'a, 'arena> {
    pub(crate) fn span(
        &self,
        left: &'arena Node<'arena>,
        right: &'arena Node<'arena>,
    ) -> Option<(u32, u32)> {
        Some((self.metadata(left)?.span.0, self.metadata(right)?.span.1))
    }

    pub(crate) fn metadata(&self, n: &'arena Node<'arena>) -> Option<&NodeMetadata> {
        self.node_metadata.get(&self.address(n))
    }

    fn address(&self, n: &'arena Node<'arena>) -> usize {
        n as *const Node as usize
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum ParserContext {
    Global,
    Closure,
}