crftng-intrprtrs/src/ast/expression/mod.rs

mod binary_expr;
pub mod expression_node;
mod grouping_expr;
mod literal_expr;
pub mod operator;
mod unary_expr;
mod variable_expr;

pub use binary_expr::BinaryExpr;
pub use grouping_expr::GroupingExpr;
use itertools::PeekingNext;
pub use literal_expr::Literal;
pub use unary_expr::UnaryExpr;
pub use variable_expr::VariableExpr;

use super::parser::{InnerASTParsingError, Parser, Result};
use crate::lexer::token::{self, TokenType};

use from_variants::FromVariants;
use match_any::match_any;
use std::fmt::Debug;

#[derive(FromVariants)]
pub enum ExpressionNode {
	BinaryExpr(BinaryExpr),
	GroupingExpr(GroupingExpr),
	Literal(Literal),
	Variable(VariableExpr),
	UnaryExpr(UnaryExpr),
}

macro_rules! all_variants {
	($expr:expr, $val_name:ident => $expr_arm:expr) => {
		{
		use match_any::match_any;
		use $crate::ast::expression::*;
		match_any!($expr,
			   ExpressionNode::BinaryExpr($val_name) |
			   ExpressionNode::GroupingExpr($val_name) |
			   ExpressionNode::Literal($val_name) |
			   ExpressionNode::Variable($val_name) |
			   ExpressionNode::UnaryExpr($val_name) => $expr_arm)
		}
	};
}
pub(crate) use all_variants;

impl Debug for ExpressionNode {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		all_variants!(self, n => n.fmt(f))
	}
}

impl<'a, T: Iterator<Item = token::Token<'a>>> Parser<'a, T> {
	pub fn expression(&mut self) -> Result<ExpressionNode> {
		self.equality()
	}
	pub(super) fn primary(&mut self) -> Result<ExpressionNode> {
		let token = self.token_iter.next();
		let node = match token.token_type {
			TokenType::False => ExpressionNode::Literal(Literal::Bool(false)),
			TokenType::True => ExpressionNode::Literal(Literal::Bool(true)),
			TokenType::Int(i) => ExpressionNode::Literal(Literal::Int(i)),
			TokenType::String(i) => ExpressionNode::Literal(Literal::String(i)),
			TokenType::Float(f) => ExpressionNode::Literal(Literal::Float(f)),
			TokenType::Nil => ExpressionNode::Literal(Literal::Nil),
			TokenType::LeftParen => {
				let expr = self.expression()?;
				let group = GroupingExpr::new(Box::new(expr));
				match self
					.token_iter
					.peeking_next(|v| matches!(v.token_type, TokenType::RightParen))
				{
					Some(_) => return Ok(group.into()),
					None => return Err(token.location.wrap(InnerASTParsingError::UnmatchedBrace)),
				}
			}
			TokenType::Identifier(var_name) => VariableExpr::new(var_name).into(),
			a => return Err(token.location.wrap(InnerASTParsingError::IncorrectToken(a))),
		};
		Ok(node)
	}
}

#[cfg(test)]
mod tests {
	use super::*;
	use operator::{Operator, UnaryOperator};

	#[test]
	fn expression_node_ast_printer() {
		let ast = ExpressionNode::BinaryExpr(BinaryExpr {
			left: Box::new(ExpressionNode::UnaryExpr(UnaryExpr {
				operator: UnaryOperator::Bang,
				right: Box::new(ExpressionNode::Literal(Literal::Int(1))),
			})),
			operator: Operator::EqualEqual,
			right: Box::new(ExpressionNode::Literal(Literal::Int(0))),
		});
		let formated = format!("{:?}", ast);
		assert_eq!("(== (! Int(1)) Int(0))", formated);
	}
}