From 596face2745ccc11a959a530807ea3e36e9d1354 Mon Sep 17 00:00:00 2001
From: Graydon Hoare <graydon@mozilla.com>
Date: Fri, 4 Mar 2011 14:15:19 -0800
Subject: Parse (and generally ignore) constraints and constrained types.

---
 src/comp/front/ast.rs    |  9 +++++++
 src/comp/front/parser.rs | 68 +++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index e9dee7ec..a8bf4b00 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -231,8 +231,17 @@ tag ty_ {
     ty_path(path, option.t[def]);
     ty_mutable(@ty);
     ty_type;
+    ty_constr(@ty, vec[@constr]);
 }
 
+tag constr_arg_ {
+    carg_base;
+    carg_ident(ident);
+}
+type constr_arg = spanned[constr_arg_];
+type constr_ = rec(path path, vec[@constr_arg] args);
+type constr = spanned[constr_];
+
 type arg = rec(mode mode, @ty ty, ident ident, def_id id);
 type fn_decl = rec(effect effect,
                    vec[arg] inputs,
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index f80c3bd5..934764e6 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -199,6 +199,10 @@ impure fn parse_ty_fn(ast.proto proto, parser p,
     auto inputs = parse_seq[rec(ast.mode mode, @ast.ty ty)](token.LPAREN,
         token.RPAREN, some(token.COMMA), f, p);
 
+    // FIXME: dropping constrs on the floor at the moment.
+    // pick them up when they're used by typestate pass.
+    parse_constrs(p);
+
     let @ast.ty output;
     if (p.peek() == token.RARROW) {
         p.bump();
@@ -254,6 +258,62 @@ impure fn parse_ty_field(parser p) -> ast.ty_field {
     ret rec(ident=id, ty=ty);
 }
 
+impure fn parse_constr_arg(parser p) -> @ast.constr_arg {
+    auto lo = p.get_span();
+    auto carg = ast.carg_base;
+    if (p.peek() == token.BINOP(token.STAR)) {
+        p.bump();
+    } else {
+        carg = ast.carg_ident(parse_ident(p));
+    }
+    ret @spanned(lo, lo, carg);
+}
+
+impure fn parse_ty_constr(parser p) -> @ast.constr {
+    auto lo = p.get_span();
+    auto path = parse_path(p, GREEDY);
+    auto pf = parse_constr_arg;
+    auto args = parse_seq[@ast.constr_arg](token.LPAREN,
+                                         token.RPAREN,
+                                         some(token.COMMA), pf, p);
+    auto hi = args.span;
+    ret @spanned(lo, hi, rec(path=path, args=args.node));
+}
+
+impure fn parse_constrs(parser p) -> common.spanned[vec[@ast.constr]] {
+    auto lo = p.get_span();
+    auto hi = lo;
+    let vec[@ast.constr] constrs = vec();
+    if (p.peek() == token.COLON) {
+        p.bump();
+        let bool more = true;
+        while (more) {
+            alt (p.peek()) {
+                case (token.IDENT(_)) {
+                    auto constr = parse_ty_constr(p);
+                    hi = constr.span;
+                    append[@ast.constr](constrs, constr);
+                    if (p.peek() == token.COMMA) {
+                        p.bump();
+                        more = false;
+                    }
+                }
+                case (_) { more = false; }
+            }
+        }
+    }
+   ret spanned(lo, hi, constrs);
+}
+
+impure fn parse_ty_constrs(@ast.ty t, parser p) -> @ast.ty {
+   if (p.peek() == token.COLON) {
+       auto constrs = parse_constrs(p);
+       ret @spanned(t.span, constrs.span,
+                    ast.ty_constr(t, constrs.node));
+   }
+   ret t;
+}
+
 impure fn parse_ty(parser p) -> @ast.ty {
     auto lo = p.get_span();
     auto hi = lo;
@@ -368,7 +428,8 @@ impure fn parse_ty(parser p) -> @ast.ty {
             fail;
         }
     }
-    ret @spanned(lo, hi, t);
+
+    ret parse_ty_constrs(@spanned(lo, hi, t), p);
 }
 
 impure fn parse_arg(parser p) -> ast.arg {
@@ -1676,6 +1737,11 @@ impure fn parse_fn_decl(parser p, ast.effect eff) -> ast.fn_decl {
          pf, p);
 
     let @ast.ty output;
+
+    // FIXME: dropping constrs on the floor at the moment.
+    // pick them up when they're used by typestate pass.
+    parse_constrs(p);
+
     if (p.peek() == token.RARROW) {
         p.bump();
         output = parse_ty(p);
-- 
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