ezno-parser 0.1.7

Parser and AST definitions for Ezno
Documentation
use iterator_endiate::EndiateIteratorExt;
use source_map::Span;
use tokenizer_lib::{sized_tokens::TokenStart, TokenReader};
use visitable_derive::Visitable;

use crate::{
	derive_ASTNode,
	expressions::{ExpressionOrBlock, MultipleExpression},
	ASTNode, TSXToken, TypeAnnotation,
};

#[apply(derive_ASTNode)]
#[derive(Debug, PartialEq, Clone, Visitable, get_field_by_type::GetFieldByType)]
#[get_field_by_type_target(Span)]
pub struct IsExpression {
	pub matcher: Box<MultipleExpression>,
	pub branches: Vec<(TypeAnnotation, ExpressionOrBlock)>,
	pub position: Span,
}

impl ASTNode for IsExpression {
	fn from_reader(
		reader: &mut impl tokenizer_lib::TokenReader<crate::TSXToken, crate::TokenStart>,
		state: &mut crate::ParsingState,
		options: &crate::ParseOptions,
	) -> crate::ParseResult<Self> {
		let start = state.expect_keyword(reader, crate::TSXKeyword::Is)?;
		is_expression_from_reader_sub_is_keyword(reader, state, options, start)
	}

	fn to_string_from_buffer<T: source_map::ToString>(
		&self,
		buf: &mut T,
		options: &crate::ToStringOptions,
		local: crate::LocalToStringInformation,
	) {
		buf.push_str("is (");
		self.matcher.to_string_from_buffer(buf, options, local);
		buf.push_str(") {");
		for (at_end, (l, r)) in self.branches.iter().endiate() {
			l.to_string_from_buffer(buf, options, local);
			buf.push_str(" => ");
			r.to_string_from_buffer(buf, options, local);
			if !at_end {
				buf.push_str(", ");
			}
		}
		buf.push('}');
	}

	fn get_position(&self) -> Span {
		self.position
	}
}

pub(crate) fn is_expression_from_reader_sub_is_keyword(
	reader: &mut impl TokenReader<crate::TSXToken, crate::TokenStart>,
	state: &mut crate::ParsingState,
	options: &crate::ParseOptions,
	start: TokenStart,
) -> Result<IsExpression, crate::ParseError> {
	reader.expect_next(TSXToken::OpenParentheses)?;
	let matcher = MultipleExpression::from_reader(reader, state, options)?;
	reader.expect_next(TSXToken::CloseParentheses)?;
	reader.expect_next(TSXToken::OpenBrace)?;
	let mut branches = Vec::new();
	loop {
		// Function important here for
		let type_annotation = TypeAnnotation::from_reader_with_config(
			reader,
			state,
			options,
			Some(crate::type_annotations::TypeOperatorKind::Function),
			None,
		)?;
		reader.expect_next(TSXToken::Arrow)?;
		let body = ExpressionOrBlock::from_reader(reader, state, options)?;
		if let Some(token) = reader.conditional_next(|t| matches!(t, TSXToken::CloseBrace)) {
			branches.push((type_annotation, body));
			return Ok(IsExpression {
				position: start.union(token.get_end()),
				matcher: Box::new(matcher),
				branches,
			});
		}
		if matches!(body, ExpressionOrBlock::Expression(..)) {
			reader.expect_next(TSXToken::Comma)?;
		}
		branches.push((type_annotation, body));
	}
}