compound ops

6 files changed, 94 insertions, 16 deletions

diff --git a/src/grammar.ron b/src/grammar.ron
index 0a79eeb95..67022b296 100644
--- a/src/grammar.ron
+++ b/src/grammar.ron
@@ -37,6 +37,10 @@ Grammar(
         ["!=", "NEQ"],
         ["-", "MINUS"],
         ["->", "THIN_ARROW"],
+        ["<=", "LTEQ"],
+        [">=", "GTEQ"],
+        ["+=", "PLUSEQ"],
+        ["-=", "MINUSEQ"],
     ],
     keywords: [
         "use",
diff --git a/src/grammar/expressions/mod.rs b/src/grammar/expressions/mod.rs
index 15669f99d..baff0da52 100644
--- a/src/grammar/expressions/mod.rs
+++ b/src/grammar/expressions/mod.rs
@@ -33,19 +33,45 @@ struct Restrictions {
     forbid_structs: bool
 }
 
+enum Op {
+    Simple,
+    Composite(SyntaxKind, u8)
+}
+
 // test expr_binding_power
 // fn foo() {
 //     1 + 2 * 3 == 1 * 2 + 3;
 //     *x = 1 + 1;
 // }
-fn bp_of(op: SyntaxKind) -> u8 {
-    match op {
+
+// test compound_ops
+// fn foo() {
+//     x += 1;
+//     1 + 1 <= 2 * 3;
+//     z -= 3 >= 0;
+// }
+fn current_op(p: &Parser) -> (u8, Op) {
+    if p.at_compound2(L_ANGLE, EQ) {
+        return (2, Op::Composite(LTEQ, 2))
+    }
+    if p.at_compound2(R_ANGLE, EQ) {
+        return (2, Op::Composite(GTEQ, 2))
+    }
+    if p.at_compound2(PLUS, EQ) {
+        return (1, Op::Composite(PLUSEQ, 2))
+    }
+    if p.at_compound2(MINUS, EQ) {
+        return (1, Op::Composite(MINUSEQ, 2))
+    }
+
+    let bp = match p.current() {
         EQ => 1,
         EQEQ | NEQ => 2,
         MINUS | PLUS => 3,
         STAR | SLASH => 4,
-        _ => 0
-    }
+        _ => 0,
+    };
+    (bp, Op::Simple)
 }
 
 // Parses expression with binding power of at least bp.
@@ -56,10 +82,16 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) {
     };
 
     loop {
-        let op_bp = bp_of(p.current());
+        let (op_bp, op) = current_op(p);
         if op_bp < bp {
             break;
         }
+        match op {
+            Op::Simple => p.bump(),
+            Op::Composite(kind, n) => {
+                p.bump_compound(kind, n);
+            },
+        }
         lhs = bin_expr(p, r, lhs, op_bp);
     }
 }
@@ -254,12 +286,7 @@ fn struct_lit(p: &mut Parser) {
 }
 
 fn bin_expr(p: &mut Parser, r: Restrictions, lhs: CompletedMarker, bp: u8) -> CompletedMarker {
-    assert!(match p.current() {
-        MINUS | PLUS | STAR | SLASH | EQEQ | NEQ | EQ => true,
-        _ => false,
-    });
     let m = lhs.precede(p);
-    p.bump();
     expr_bp(p, r, bp);
     m.complete(p, BIN_EXPR)
 }
diff --git a/src/parser_api.rs b/src/parser_api.rs
index 95394e39d..fef21c5fd 100644
--- a/src/parser_api.rs
+++ b/src/parser_api.rs
@@ -58,6 +58,10 @@ impl<'t> Parser<'t> {
         self.current() == kind
     }
 
+    pub(crate) fn at_compound2(&self, c1: SyntaxKind, c2: SyntaxKind) -> bool {
+        self.0.at_compound2(c1, c2)
+    }
+
     /// Checks if the current token is contextual keyword with text `t`.
     pub(crate) fn at_contextual_kw(&self, t: &str) -> bool {
         self.0.at_kw(t)
@@ -85,6 +89,13 @@ impl<'t> Parser<'t> {
         self.0.bump_remap(kind);
     }
 
+    /// Advances the parser by `n` tokens, remapping its kind.
+    /// This is useful to create compound tokens from parts. For
+    /// example, an `<<` token is two consecutive remapped `<` tokens
+    pub(crate) fn bump_compound(&mut self, kind: SyntaxKind, n: u8) {
+        self.0.bump_compound(kind, n);
+    }
+
     /// Emit error with the `message`
     /// TODO: this should be much more fancy and support
     /// structured errors with spans and notes, like rustc
diff --git a/src/parser_impl/input.rs b/src/parser_impl/input.rs
index db76364b2..c0fe4d488 100644
--- a/src/parser_impl/input.rs
+++ b/src/parser_impl/input.rs
@@ -36,7 +36,22 @@ impl<'t> ParserInput<'t> {
         self.tokens[idx].kind
     }
 
-    #[allow(unused)]
+    pub fn len(&self, pos: InputPosition) -> TextUnit {
+        let idx = pos.0 as usize;
+        if !(idx < self.tokens.len()) {
+            return 0.into();
+        }
+        self.tokens[idx].len
+    }
+
+    pub fn start(&self, pos: InputPosition) -> TextUnit {
+        let idx = pos.0 as usize;
+        if !(idx < self.tokens.len()) {
+            return 0.into();
+        }
+        self.start_offsets[idx]
+    }
+
     pub fn text(&self, pos: InputPosition) -> &'t str {
         let idx = pos.0 as usize;
         if !(idx < self.tokens.len()) {
diff --git a/src/parser_impl/mod.rs b/src/parser_impl/mod.rs
index 2791c8da5..d640a7784 100644
--- a/src/parser_impl/mod.rs
+++ b/src/parser_impl/mod.rs
@@ -65,6 +65,11 @@ impl<'t> ParserImpl<'t> {
         self.events
     }
 
+    pub(super) fn at_compound2(&self, c1: SyntaxKind, c2: SyntaxKind) -> bool {
+        self.inp.kind(self.pos) == c1 && self.inp.kind(self.pos + 1) == c2
+            && self.inp.start(self.pos + 1) == self.inp.start(self.pos) + self.inp.len(self.pos)
+    }
+
     pub(super) fn nth(&self, n: u32) -> SyntaxKind {
         self.inp.kind(self.pos + n)
     }
@@ -87,7 +92,7 @@ impl<'t> ParserImpl<'t> {
         if kind == EOF {
             return;
         }
-        self.do_bump(kind);
+        self.do_bump(kind, 1);
     }
 
     pub(super) fn bump_remap(&mut self, kind: SyntaxKind) {
@@ -95,14 +100,18 @@ impl<'t> ParserImpl<'t> {
             // TODO: panic!?
             return;
         }
-        self.do_bump(kind);
+        self.do_bump(kind, 1);
+    }
+
+    pub(super) fn bump_compound(&mut self, kind: SyntaxKind, n: u8) {
+        self.do_bump(kind, n);
     }
 
-    fn do_bump(&mut self, kind: SyntaxKind) {
-        self.pos += 1;
+    fn do_bump(&mut self, kind: SyntaxKind, n_raw_tokens: u8) {
+        self.pos += u32::from(n_raw_tokens);
         self.event(Event::Token {
             kind,
-            n_raw_tokens: 1,
+            n_raw_tokens,
         });
     }
 
diff --git a/src/syntax_kinds/generated.rs b/src/syntax_kinds/generated.rs
index 8ac13fd63..8dfeb2b82 100644
--- a/src/syntax_kinds/generated.rs
+++ b/src/syntax_kinds/generated.rs
@@ -40,6 +40,10 @@ pub enum SyntaxKind {
     NEQ,
     MINUS,
     THIN_ARROW,
+    LTEQ,
+    GTEQ,
+    PLUSEQ,
+    MINUSEQ,
     USE_KW,
     FN_KW,
     STRUCT_KW,
@@ -261,6 +265,10 @@ impl SyntaxKind {
             NEQ => &SyntaxInfo { name: "NEQ" },
             MINUS => &SyntaxInfo { name: "MINUS" },
             THIN_ARROW => &SyntaxInfo { name: "THIN_ARROW" },
+            LTEQ => &SyntaxInfo { name: "LTEQ" },
+            GTEQ => &SyntaxInfo { name: "GTEQ" },
+            PLUSEQ => &SyntaxInfo { name: "PLUSEQ" },
+            MINUSEQ => &SyntaxInfo { name: "MINUSEQ" },
             USE_KW => &SyntaxInfo { name: "USE_KW" },
             FN_KW => &SyntaxInfo { name: "FN_KW" },
             STRUCT_KW => &SyntaxInfo { name: "STRUCT_KW" },
@@ -502,6 +510,10 @@ impl SyntaxKind {
             NEQ => "!=",
             MINUS => "-",
             THIN_ARROW => "->",
+            LTEQ => "<=",
+            GTEQ => ">=",
+            PLUSEQ => "+=",
+            MINUSEQ => "-=",
 
             USE_KW => "use",
             FN_KW => "fn",