1 files changed, 162 insertions, 0 deletions
diff --git a/dhall/src/grammar.lalrpop b/dhall/src/grammar.lalrpop
new file mode 100644
index 0000000..150961f
--- /dev/null
+++ b/dhall/src/grammar.lalrpop
@@ -0,0 +1,162 @@
+use std::collections::BTreeMap;
+use std::iter;
+use std::iter::FromIterator;
+
+use crate::core;
+use crate::core::bx;
+use crate::core::Expr::*;
+use crate::core::BuiltinType::*;
+use crate::grammar_util::*;
+use crate::lexer::*;
+
+grammar<'input>;
+
+extern {
+    type Location = usize;
+    type Error = LexicalError;
+
+    enum Tok<'input> {
+        Pi => Tok::Pi,
+        Lambda => Tok::Lambda,
+        Combine => Tok::Combine,
+        "->" => Tok::Arrow,
+
+        Int => Tok::Integer(<isize>),
+        Nat => Tok::Natural(<usize>),
+        Text => Tok::Text(<String>),
+        Bool => Tok::Bool(<bool>),
+        Label => Tok::Identifier(<&'input str>),
+        Const => Tok::Const(<core::Const>),
+        Let => Tok::Keyword(Keyword::Let),
+        In => Tok::Keyword(Keyword::In),
+        If => Tok::Keyword(Keyword::If),
+        Then => Tok::Keyword(Keyword::Then),
+        Else => Tok::Keyword(Keyword::Else),
+        List => Tok::ListLike(ListLike::List),
+        Optional => Tok::ListLike(ListLike::Optional),
+        Builtin => Tok::Builtin(<Builtin>),
+
+        "{" => Tok::BraceL,
+        "}" => Tok::BraceR,
+        "[" => Tok::BracketL,
+        "]" => Tok::BracketR,
+        "(" => Tok::ParenL,
+        ")" => Tok::ParenR,
+        "&&" => Tok::BoolAnd,
+        "||" => Tok::BoolOr,
+        "==" => Tok::CompareEQ,
+        "!=" => Tok::CompareNE,
+        "++" => Tok::Append,
+        "*" => Tok::Times,
+        "+" => Tok::Plus,
+        "," => Tok::Comma,
+        "." => Tok::Dot,
+        ":" => Tok::Ascription,
+        "=" => Tok::Equals,
+    }
+}
+
+pub Expr: BoxExpr<'input> = { // exprA
+    <ExprB> ":" <Expr> => bx(Annot(<>)),
+    ExprB,
+};
+
+ExprB: BoxExpr<'input> = {
+    Lambda "(" <Label> ":" <Expr> ")" "->" <ExprB> => bx(Lam(<>)),
+    Pi "(" <Label> ":" <Expr> ")" "->" <ExprB> => bx(Pi(<>)),
+    If <Expr> Then <ExprB> Else <ExprC> => bx(BoolIf(<>)),
+    <ExprC> "->" <ExprB> => bx(Pi("_", <>)),
+    Let <Label> <(":" <Expr>)?> "=" <Expr> In <ExprB> => bx(Let(<>)),
+    "[" <a:Elems> "]" ":" <b:ListLike> <c:ExprE> => bx(b(c, a)),
+    ExprC,
+};
+
+ListLike: ExprListFn<'input> = {
+    List => ListLit,
+    Optional => OptionalLit,
+};
+
+BoolOr: ExprOpFn<'input> = { "||" => BoolOr };
+NaturalPlus: ExprOpFn<'input> = { "+" => NaturalPlus };
+TextAppend: ExprOpFn<'input> = { "++" => TextAppend };
+BoolAnd: ExprOpFn<'input> = { "&&" => BoolAnd };
+CombineOp: ExprOpFn<'input> = { Combine => Combine };
+NaturalTimes: ExprOpFn<'input> = { "*" => NaturalTimes };
+BoolEQ: ExprOpFn<'input> = { "==" => BoolEQ };
+BoolNE: ExprOpFn<'input> = { "!=" => BoolNE };
+
+Tier<NextTier, Op>: BoxExpr<'input> = {
+    <a:NextTier> <f:Op> <b:Tier<NextTier, Op>> => bx(f(a, b)),
+    // <b:Tier<NextTier, Op>> <f:Op> <a:NextTier> => bx(f(a, b)),
+    NextTier,
+};
+
+ExprC = Tier<ExprC1, BoolOr>;
+ExprC1 = Tier<ExprC2, NaturalPlus>;
+ExprC2 = Tier<ExprC3, TextAppend>;
+ExprC3 = Tier<ExprC4, BoolAnd>;
+ExprC4 = Tier<ExprC5, CombineOp>;
+ExprC5 = Tier<ExprC6, NaturalTimes>;
+ExprC6 = Tier<ExprC7, BoolEQ>;
+ExprC7 = Tier<ExprD, BoolNE>;
+
+ExprD: BoxExpr<'input> = {
+    <v:(ExprE)+> => {
+        let mut it = v.into_iter();
+        let f = it.next().unwrap();
+        it.fold(f, |f, x| bx(App(f, x)))
+    }
+};
+
+ExprE: BoxExpr<'input> = {
+    <a:ExprF> <fields:("." <Label>)*> => {
+        fields.into_iter().fold(a, |x, f| bx(Field(x, f)))
+    },
+};
+
+ExprF: BoxExpr<'input> = {
+    Nat => bx(NaturalLit(<>)),
+    Int => bx(IntegerLit(<>)),
+    Text => bx(TextLit(<>)),
+    Label => bx(Var(core::V(<>, 0))), // FIXME support var@n syntax
+    Const => bx(Const(<>)),
+    List => bx(BuiltinType(List)),
+    Optional => bx(BuiltinType(Optional)),
+    Builtin => bx(builtin_expr(<>)),
+    Bool => bx(BoolLit(<>)),
+    Record,
+    RecordLit,
+    "(" <Expr> ")",
+};
+
+SepBy<S, T>: iter::Chain<::std::vec::IntoIter<T>, ::std::option::IntoIter<T>> = {
+    <v:(<T> S)*> <last:T?> => v.into_iter().chain(last.into_iter()),
+};
+
+SepBy1<S, T>: iter::Chain<::std::vec::IntoIter<T>, iter::Once<T>> = {
+    <v:(<T> S)*> <last:T> => v.into_iter().chain(iter::once(last)),
+};
+
+Elems: Vec<ParsedExpr<'input>> = {
+    <v:SepBy<",", Expr>> => {
+        v.into_iter()
+         .map(|b| *b)
+         .collect::<Vec<_>>()
+    }
+};
+
+RecordLit: BoxExpr<'input> = {
+    "{" "=" "}" => bx(RecordLit(BTreeMap::new())),
+    "{" <FieldValues> "}" => bx(RecordLit(BTreeMap::from_iter(<>))),
+};
+
+Record: BoxExpr<'input> = {
+    "{" <FieldTypes> "}" => bx(Record(BTreeMap::from_iter(<>))),
+};
+
+FieldValues = SepBy1<",", Field<"=">>;
+FieldTypes = SepBy<",", Field<":">>;
+
+Field<Sep>: (&'input str, ParsedExpr<'input>) = {
+    <a:Label> Sep <b:Expr> => (a, *b),
+};