Impl experimental pipe operators

`|>` and `<|` operators are introduced as experimental feature "pipe-operator" since Nix 2.24. Ref: <https://github.com/NixOS/nix/blob/2.24.0/doc/manual/src/language/operators.md#pipe-operators> Co-authored-by: Kira Malinova <[email protected]>
oxalica · Nov 19, 2024 · 52304da · 52304da
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diff --git a/crates/ide/src/ide/syntax_highlighting.rs b/crates/ide/src/ide/syntax_highlighting.rs
@@ -51,6 +51,7 @@ pub enum HlOperator {
     Comparison,
     Arithmetic,
     Aggregation,
+    Pipe,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
@@ -161,6 +162,7 @@ pub(crate) fn highlight(
             }
             T![+] | T![-] | T![*] | T![/] => HlTag::Operator(HlOperator::Arithmetic),
             T![++] | T!["//"] => HlTag::Operator(HlOperator::Aggregation),
+            T![|>] | T![<|] => HlTag::Operator(HlOperator::Pipe),
             T!['{'] | T!['}'] | T!["${"] => HlTag::Punct(HlPunct::Brace),
             T!['['] | T![']'] => HlTag::Punct(HlPunct::Bracket),
             T!['('] | T![')'] => HlTag::Punct(HlPunct::Paren),

diff --git a/crates/ide/src/ty/infer.rs b/crates/ide/src/ty/infer.rs
@@ -213,6 +213,17 @@ impl<'db> InferCtx<'db> {
                 self.unify_var(then_ty, else_ty);
                 then_ty
             }
+            &Expr::Apply(lam, arg)
+            | &Expr::Binary(Some(BinaryOpKind::PipeRight), arg, lam)
+            | &Expr::Binary(Some(BinaryOpKind::PipeLeft), lam, arg) => {
+                let param_ty = self.new_ty_var();
+                let ret_ty = self.new_ty_var();
+                let lam_ty = self.infer_expr(lam);
+                self.unify_var_ty(lam_ty, Ty::Lambda(param_ty, ret_ty));
+                let arg_ty = self.infer_expr(arg);
+                self.unify_var(arg_ty, param_ty);
+                ret_ty
+            }
             &Expr::Binary(op, lhs, rhs) => {
                 let lhs_ty = self.infer_expr(lhs);
                 let rhs_ty = self.infer_expr(rhs);
@@ -256,6 +267,8 @@ impl<'db> InferCtx<'db> {
                         self.unify_var(rhs_ty, ret_ty);
                         ret_ty
                     }
+                    // Already handled by the outer match.
+                    BinaryOpKind::PipeLeft | BinaryOpKind::PipeRight => unreachable!(),
                 }
             }
             &Expr::Unary(op, arg) => {
@@ -270,15 +283,6 @@ impl<'db> InferCtx<'db> {
                     Some(UnaryOpKind::Negate) => arg_ty,
                 }
             }
-            &Expr::Apply(lam, arg) => {
-                let param_ty = self.new_ty_var();
-                let ret_ty = self.new_ty_var();
-                let lam_ty = self.infer_expr(lam);
-                self.unify_var_ty(lam_ty, Ty::Lambda(param_ty, ret_ty));
-                let arg_ty = self.infer_expr(arg);
-                self.unify_var(arg_ty, param_ty);
-                ret_ty
-            }
             Expr::HasAttr(set_expr, path) => {
                 // TODO: Store the information of referenced paths somehow.
                 self.infer_expr(*set_expr);

diff --git a/crates/ide/src/ty/tests.rs b/crates/ide/src/ty/tests.rs
@@ -179,6 +179,12 @@ fn select() {
     );
 }
 
+#[test]
+fn pipe() {
+    check("f: 1 |> f", expect!["(int → ?) → ?"]);
+    check("f: f <| 1", expect!["(int → ?) → ?"]);
+}
+
 #[test]
 fn external() {
     check_all_expect(

diff --git a/crates/syntax/src/ast.rs b/crates/syntax/src/ast.rs
@@ -25,6 +25,9 @@ pub enum BinaryOpKind {
     Sub,
     Mul,
     Div,
+
+    PipeLeft,
+    PipeRight,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -263,16 +266,20 @@ impl Expr {
     }
 
     pub fn contains_without_paren(&self, inner: &Self) -> bool {
-        fn bp(e: &Expr) -> Option<u8> {
+        const MIN_BP: i8 = i8::MIN;
+        const MAX_BP: i8 = i8::MAX;
+
+        fn bp(e: &Expr) -> Option<i8> {
             Some(match e {
                 Expr::With(_)
                 | Expr::Lambda(_)
                 | Expr::LetIn(_)
                 | Expr::IfThenElse(_)
-                | Expr::Assert(_) => TOPLEVEL,
+                | Expr::Assert(_) => MIN_BP,
 
                 // Binary and unary ops. They follow `infix_bp` in parser.
                 Expr::BinaryOp(e) => match e.op_kind()? {
+                    BinaryOpKind::PipeLeft | BinaryOpKind::PipeRight => 0,
                     BinaryOpKind::Imply => 1,
                     BinaryOpKind::Or => 3,
                     BinaryOpKind::And => 5,
@@ -307,18 +314,15 @@ impl Expr {
                 | Expr::Ref(_) => 29,
 
                 // Special. See below.
-                Expr::Paren(_) => PAREN,
+                Expr::Paren(_) => MAX_BP,
             })
         }
 
-        const TOPLEVEL: u8 = 0;
-        const PAREN: u8 = 31;
-
         match (bp(self), bp(inner)) {
             // Special case 1: `Paren`s can safely contain or be contained by anything.
-            (Some(PAREN), _) | (_, Some(PAREN)) => true,
+            (Some(MAX_BP), _) | (_, Some(MAX_BP)) => true,
             // Special case 2: top-levels can contain each other without ambiguity.
-            (Some(TOPLEVEL), Some(TOPLEVEL)) => true,
+            (Some(MIN_BP), Some(MIN_BP)) => true,
             // Otherwise, expressions with lower binding power contain higher ones.
             (Some(outer), Some(inner)) => outer < inner,
             // `false` by default.
@@ -382,6 +386,8 @@ asts! {
                 let op = match tok.kind() {
                     T![->] => BinaryOpKind::Imply,
                     T![&&] => BinaryOpKind::And,
+                    T![|>] => BinaryOpKind::PipeRight,
+                    T![<|] => BinaryOpKind::PipeLeft,
                     T![||] => BinaryOpKind::Or,
                     T![==] => BinaryOpKind::Equal,
                     T![!=] => BinaryOpKind::NotEqual,

diff --git a/crates/syntax/src/kind.rs b/crates/syntax/src/kind.rs
@@ -111,9 +111,11 @@ def! {
     EQ2 = [==],
     GT_EQ = [>=],
     LT_EQ = [<=],
+    LT_OR = [<|],
     MINUS_GT = [->],
     NOT_EQ = [!=],
     OR2 = [||],
+    OR_GT = [|>],
     PLUS2 = [++],
     QUOTE2 = ["''"],
     SLASH2 = ["//"],

diff --git a/crates/syntax/src/lexer.rs b/crates/syntax/src/lexer.rs
@@ -109,6 +109,8 @@ regex_dfa! {
         QUOTE2 = r"''",
 
         DOT3 = r"\.\.\.",
+        OR_GT = r"\|>",
+        LT_OR = r"<\|",
         MINUS_GT = r"->",
         OR2 = r"\|\|",
         AND2 = r"&&",
@@ -654,4 +656,18 @@ mod tests {
             "#]],
         );
     }
+
+    #[test]
+    fn pipe() {
+        check_lex(
+            "1<|2|>3",
+            expect![[r#"
+                INT "1"
+                LT_OR "<|"
+                INT "2"
+                OR_GT "|>"
+                INT "3"
+            "#]],
+        );
+    }
 }
diff --git a/crates/syntax/src/parser.rs b/crates/syntax/src/parser.rs
@@ -367,12 +367,12 @@ impl<'i> Parser<'i> {
     /// Operator level expression (low priority).
     /// Maybe consume nothing.
     fn expr_operator_opt(&mut self) {
-        self.expr_bp(0);
+        self.expr_bp(i8::MIN);
     }
 
     // Pratt parser.
     // Ref: https://matklad.github.io/2020/04/13/simple-but-powerful-pratt-parsing.html
-    fn expr_bp(&mut self, min_bp: u8) {
+    fn expr_bp(&mut self, min_bp: i8) {
         // Always consume whitespace first, even though not `allow_prefix`.
         let Some(tok) = self.peek_non_ws() else {
             self.error(ErrorKind::ExpectExpr);
@@ -847,7 +847,7 @@ impl SyntaxKind {
     }
 
     #[rustfmt::skip]
-    fn prefix_bp(self) -> Option<u8> {
+    fn prefix_bp(self) -> Option<i8> {
         // See `infix_bp`.
         Some(match self {
             T![!] => 13,
@@ -857,7 +857,7 @@ impl SyntaxKind {
     }
 
     #[rustfmt::skip]
-    fn postfix_bp(self) -> Option<u8> {
+    fn postfix_bp(self) -> Option<i8> {
         // See `infix_bp`.
         Some(match self {
             T![?] => 21,
@@ -866,8 +866,10 @@ impl SyntaxKind {
     }
 
     #[rustfmt::skip]
-    fn infix_bp(self) -> Option<(u8, u8)> {
+    fn infix_bp(self) -> Option<(i8, i8)> {
         Some(match self {
+            T![|>] => (-1, 0),
+            T![<|] => (0, -1),
             T![->] => (2, 1),
             T![||] => (3, 4),
             T![&&] => (5, 6),
@@ -892,4 +894,4 @@ impl SyntaxKind {
     }
 }
 
-const APPLY_RBP: u8 = 26;
+const APPLY_RBP: i8 = 26;
diff --git a/crates/syntax/test_data/parser/ok/0010-pipe.ast b/crates/syntax/test_data/parser/ok/0010-pipe.ast
@@ -0,0 +1,39 @@
+[email protected]
+  [email protected]
+    [email protected] "["
+    [email protected]
+      [email protected] "("
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected] "1"
+            [email protected] "->"
+            [email protected]
+              [email protected] "2"
+          [email protected] "|>"
+          [email protected]
+            [email protected] "3"
+        [email protected] "|>"
+        [email protected]
+          [email protected] "4"
+      [email protected] ")"
+    [email protected]
+      [email protected] "("
+      [email protected]
+        [email protected]
+          [email protected] "5"
+        [email protected] "<|"
+        [email protected]
+          [email protected]
+            [email protected] "6"
+          [email protected] "<|"
+          [email protected]
+            [email protected]
+              [email protected] "7"
+            [email protected] "->"
+            [email protected]
+              [email protected] "8"
+      [email protected] ")"
+    [email protected] "]"
+  [email protected] "\n"
diff --git a/crates/syntax/test_data/parser/ok/0010-pipe.nix b/crates/syntax/test_data/parser/ok/0010-pipe.nix
@@ -0,0 +1 @@
+[(1->2|>3|>4)(5<|6<|7->8)]