64 lines
1.6 KiB
Plaintext
64 lines
1.6 KiB
Plaintext
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use std::str::FromStr;
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use crate::ast;
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grammar;
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pub LiteralInt: ast::LiteralInt = {
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r"[0-9]+" => ast::LiteralInt{value: i32::from_str(<>).unwrap()}
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};
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pub Identifier: ast::Identifier = {
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r"[A-Za-z][A-Za-z0-9_]*" => ast::Identifier{name: <>.to_string()}
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};
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pub Expression: Box<ast::Expression> = {
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<l:Expression> "+" <r:Factor> => Box::new(ast::Expression::Op(l, ast::Operator::Plus, r)),
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<l:Expression> "-" <r:Factor> => Box::new(ast::Expression::Op(l, ast::Operator::Minus, r)),
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Factor,
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}
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pub Factor: Box<ast::Expression> = {
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<l:Factor> "*" <r:Term> => Box::new(ast::Expression::Op(l, ast::Operator::Mul, r)),
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<l:Factor> "/" <r:Term> => Box::new(ast::Expression::Op(l, ast::Operator::Div, r)),
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Term,
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}
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pub Term: Box<ast::Expression> = {
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LiteralInt => Box::new(ast::Expression::LiteralInt(<>)),
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Identifier => Box::new(ast::Expression::Identifier(<>)),
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"(" <Expression> ")",
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}
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pub Block: ast::Block = {
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"{" <e:Expression> "}" => ast::Block{expression: e}
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}
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pub VariableDeclaration: ast::VariableDeclaration = {
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Identifier => ast::VariableDeclaration{name: <>}
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}
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pub Function: ast::Function = {
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"fn" <n:Identifier> "(" <args:Comma<VariableDeclaration>> ")" <b:Block> => ast::Function{name: n, arguments: args, block: b}
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}
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pub Program: ast::Program = {
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<fs:Function*> => ast::Program{functions: fs}
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}
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// From https://lalrpop.github.io/lalrpop/tutorial/006_macros.html
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// Comma seperated list of T with optional trailing comma
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Comma<T>: Vec<T> = {
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<v:(<T> ",")*> <e:T?> => match e {
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None => v,
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Some(e) => {
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let mut v = v;
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v.push(e);
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v
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}
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}
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};
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