52 lines
1.3 KiB
Plaintext
52 lines
1.3 KiB
Plaintext
use crate::ast::*;
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use std::rc::Rc;
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grammar<'s>();
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match {
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r"\s*" => { }, // The default whitespace skipping is disabled an `ignore pattern` is specified
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r";[^\n\r]*[\n\r]*" => { }, // Skip `;` comments
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_
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}
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pub(crate) File = {Lang? <Trees> }
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Trees = Tree+;
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pub(crate) Tree: Tree = {
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"(" <Tree+> ")" => Tree::Branch(<>),
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"(" "define" <Sym> <BTree> ")" => Tree::Define(<>),
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"(" "define" "(" <name:Sym> <args:Sym*> ")" <body:Trees> ")"
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=> Tree::Define(name, Box::new(Tree::Func(Rc::new(Func{args, body})))),
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"(" "if" <Tree> <Tree> <Tree> ")" => Tree::If(Box::new([<>])),
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"(" "lambda (" <args:Sym*> ")" <body:Trees> ")" => Tree::Func(Rc::new(Func{<>})),
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"(" "set!" <Sym> <BTree> ")" => Tree::Set(<>),
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Literal => Tree::Leaf(<>),
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}
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BTree = { Box<Tree> }
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Literal: Literal = {
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Sym => Literal::Sym(<>),
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Num => Literal::Num(<>),
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Bool => Literal::Bool(<>),
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}
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Box<T>: Box<T> = { T => Box::new(<>) }
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RcSlice<T>: Rc<[T]> = { T* => <>.into() }
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Rc<T>: Rc<T> = { T => Rc::new(<>) }
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Sym: String = { r"[A-Za-z!$%&*+\-./:<=>?@^_~][A-Za-z!$%&*+\-./:<=>?@^_~0-9]*" => <>.to_owned() }
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Num: f64 = { r"[0-9]+(\.[0-9]+)?" => <>.parse().unwrap() }
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Bool: bool = {
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"#t" => true,
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"#f" => false,
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}
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Lang: () = { "#lang" LangName }
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LangName = {
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// TODO: What should these be?
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"scheme",
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"r7rs",
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} |