Part 1: Implement ES6 function name property semantics

Issue #78

1 files changed, 43 insertions, 11 deletions

diff --git a/js/src/jsfun.h b/js/src/jsfun.h
index 65da5e06f8..d45d112a5e 100644
--- a/js/src/jsfun.h
+++ b/js/src/jsfun.h
@@ -31,6 +31,12 @@ static const uint32_t JSSLOT_BOUND_FUNCTION_ARGS       = 4;
 static const char FunctionConstructorMedialSigils[] = ") {\n";
 static const char FunctionConstructorFinalBrace[] = "\n}";
 
+enum class FunctionPrefixKind {
+    None,
+    Get,
+    Set
+};
+
 class JSFunction : public js::NativeObject
 {
   public:
@@ -61,6 +67,9 @@ class JSFunction : public js::NativeObject
                                        function-statement) */
         SELF_HOSTED      = 0x0080,  /* function is self-hosted builtin and must not be
                                        decompilable nor constructible. */
+        HAS_COMPILE_TIME_NAME = 0x0100, /* function had no explicit name, but a
+                                           name was set by SetFunctionName
+                                           at compile time */
         INTERPRETED_LAZY = 0x0200,  /* function is interpreted but doesn't have a script yet */
         RESOLVED_LENGTH  = 0x0400,  /* f.length has been resolved (see fun_resolve). */
         RESOLVED_NAME    = 0x0800,  /* f.name has been resolved (see fun_resolve). */
@@ -94,7 +103,7 @@ class JSFunction : public js::NativeObject
         NO_XDR_FLAGS = RESOLVED_LENGTH | RESOLVED_NAME,
 
         STABLE_ACROSS_CLONES = CONSTRUCTOR | EXPR_BODY | HAS_GUESSED_ATOM | LAMBDA |
-                               SELF_HOSTED | FUNCTION_KIND_MASK
+                               SELF_HOSTED | HAS_COMPILE_TIME_NAME | FUNCTION_KIND_MASK
     };
 
     static_assert((INTERPRETED | INTERPRETED_LAZY) == js::JS_FUNCTION_INTERPRETED_BITS,
@@ -179,6 +188,7 @@ class JSFunction : public js::NativeObject
 
     /* Possible attributes of an interpreted function: */
     bool isExprBody()               const { return flags() & EXPR_BODY; }
+    bool hasCompileTimeName()       const { return flags() & HAS_COMPILE_TIME_NAME; }
     bool hasGuessedAtom()           const { return flags() & HAS_GUESSED_ATOM; }
     bool isLambda()                 const { return flags() & LAMBDA; }
     bool isBoundFunction()          const { return flags() & BOUND_FUN; }
@@ -220,7 +230,7 @@ class JSFunction : public js::NativeObject
     }
 
     bool isNamedLambda() const {
-        return isLambda() && displayAtom() && !hasGuessedAtom();
+        return isLambda() && displayAtom() && !hasCompileTimeName() && !hasGuessedAtom();
     }
 
     bool hasLexicalThis() const {
@@ -308,14 +318,12 @@ class JSFunction : public js::NativeObject
 
     JSAtom* getUnresolvedName(JSContext* cx);
 
-    JSAtom* name() const { return hasGuessedAtom() ? nullptr : atom_.get(); }
-
-    // Because display names (see Debugger.Object.displayName) are already stored
-    // on functions and will always contain a valid es6 function name, as described
-    // in "ECMA-262 (2016-02-27) 9.2.11 SetFunctionName," we have opted to save
-    // memory by parsing the existing display name when a function's name property
-    // is accessed.
-    JSAtom* functionName(JSContext* cx) const;
+    JSAtom* explicitName() const {
+        return (hasCompileTimeName() || hasGuessedAtom()) ? nullptr : atom_.get();
+    }
+    JSAtom* explicitOrCompileTimeName() const {
+        return hasGuessedAtom() ? nullptr : atom_.get();
+    }
 
     void initAtom(JSAtom* atom) { atom_.init(atom); }
 
@@ -325,9 +333,24 @@ class JSFunction : public js::NativeObject
         return atom_;
     }
 
+    void setCompileTimeName(JSAtom* atom) {
+        MOZ_ASSERT(!atom_);
+        MOZ_ASSERT(atom);
+        MOZ_ASSERT(!hasGuessedAtom());
+        MOZ_ASSERT(!isClassConstructor());
+        atom_ = atom;
+        flags_ |= HAS_COMPILE_TIME_NAME;
+    }
+    JSAtom* compileTimeName() const {
+        MOZ_ASSERT(hasCompileTimeName());
+        MOZ_ASSERT(atom_);
+        return atom_;
+    }
+
     void setGuessedAtom(JSAtom* atom) {
         MOZ_ASSERT(!atom_);
         MOZ_ASSERT(atom);
+        MOZ_ASSERT(!hasCompileTimeName());
         MOZ_ASSERT(!hasGuessedAtom());
         atom_ = atom;
         flags_ |= HAS_GUESSED_ATOM;
@@ -672,7 +695,16 @@ NewFunctionWithProto(ExclusiveContext* cx, JSNative native, unsigned nargs,
                      NewFunctionProtoHandling protoHandling = NewFunctionClassProto);
 
 extern JSAtom*
-IdToFunctionName(JSContext* cx, HandleId id, const char* prefix = nullptr);
+IdToFunctionName(JSContext* cx, HandleId id,
+                 FunctionPrefixKind prefixKind = FunctionPrefixKind::None);
+
+extern JSAtom*
+NameToFunctionName(ExclusiveContext* cx, HandleAtom name,
+                   FunctionPrefixKind prefixKind = FunctionPrefixKind::None);
+
+extern bool
+SetFunctionNameIfNoOwnName(JSContext* cx, HandleFunction fun, HandleValue name,
+                           FunctionPrefixKind prefixKind);
 
 extern JSFunction*
 DefineFunction(JSContext* cx, HandleObject obj, HandleId id, JSNative native,