28 lines
1.3 KiB
Rust
28 lines
1.3 KiB
Rust
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use crate::parser::{NyashParser, ParseError};
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use crate::parser::common::ParserUtils;
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use crate::tokenizer::TokenType;
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use crate::ast::{ASTNode, BinaryOperator, Span};
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impl NyashParser {
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pub(crate) fn expr_parse_term(&mut self) -> Result<ASTNode, ParseError> {
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let mut expr = self.expr_parse_shift()?;
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while self.match_token(&TokenType::PLUS) || self.match_token(&TokenType::MINUS) {
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let operator = match &self.current_token().token_type {
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TokenType::PLUS => BinaryOperator::Add,
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TokenType::MINUS => BinaryOperator::Subtract,
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_ => unreachable!(),
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};
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self.advance();
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let right = self.expr_parse_shift()?;
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if std::env::var("NYASH_GRAMMAR_DIFF").ok().as_deref() == Some("1") {
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let name = match operator { BinaryOperator::Add=>"add", BinaryOperator::Subtract=>"sub", _=>"term" };
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let ok = crate::grammar::engine::get().syntax_is_allowed_binop(name);
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if !ok { eprintln!("[GRAMMAR-DIFF][Parser] binop '{}' not allowed by syntax rules", name); }
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}
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expr = ASTNode::BinaryOp { operator, left: Box::new(expr), right: Box::new(right), span: Span::unknown() };
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}
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Ok(expr)
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}
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}
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