63 lines
1.4 KiB
Plaintext
63 lines
1.4 KiB
Plaintext
use crate::ast::*;
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grammar;
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pub Program: Vec<Decl<()>> = Decl* => <>;
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Decl: Decl<()> = {
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Func => Decl::Func(<>),
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};
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Func: Func<()> = {
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"fn" <name:Ident> "(" ")" "->" <return_ty:Type> "{" <stmts:Stmt*> "}" =>
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Func { name, return_ty, stmts },
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};
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Stmt: Stmt<()> = {
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"let" <name:Ident> <ty:ColonType?> "=" <expr:Expr> ";" =>
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Stmt::Let(name, ty, expr),
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"return" <expr:Expr?> ";" => Stmt::Return(expr),
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IfElse => Stmt::IfElse(<>),
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};
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ColonType: Type = ":" <ty:Type> => ty;
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IfElse: IfElse<()> =
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"if" <cond:Expr> "{" <body:Stmt*> "}" <else_clause:Else?> =>
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IfElse { cond, body, else_clause };
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Else: ElseClause<()> = "else" <else_clause:Else_> => else_clause;
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Else_: ElseClause<()> = {
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IfElse => ElseClause::If(Box::new(<>)),
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"{" <body:Stmt*> "}" => ElseClause::Body(body),
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};
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Expr: Expr<()> = {
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#[precedence(level = "0")]
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"(" <expr:Expr> ")" => expr,
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#[precedence(level = "0")]
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r"[0-9]+" => Expr { kind: ExprKind::Int(<>.parse::<i64>().unwrap()), ty: () },
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#[precedence(level = "0")]
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Ident => Expr { kind: ExprKind::Var(<>), ty: () },
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#[precedence(level = "13")]
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#[assoc(side = "none")]
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<left:Expr> <op:CompareOp> <right:Expr> => Expr {
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kind: ExprKind::BinOp(Box::new(left), op, Box::new(right)),
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ty: (),
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},
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};
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CompareOp: Op = {
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"<" => Op::LessThan,
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">" => Op::GreaterThan,
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};
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Type: Type = {
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"int" => Type::Int,
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};
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Ident: String = r"([A-Za-z][A-Za-z0-9_]*)|(_[A-Za-z0-9_]+)" => <>.to_string();
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