Bug 1254893 - Add a .format property on Debugger.Script. (r=jimb)

js/src/doc/Debugger/Debugger.Script.md

@@ -128,6 +128,9 @@ from its prototype:
 :   This is `true` if this script's code is ECMAScript strict mode code, and
     `false` otherwise.
 
+`format`
+:   If the script is WebAssembly, this is `"wasm"`. Otherwise, this is `"js"`.
+
 ## Function Properties of the Debugger.Script Prototype Object
 
 The functions described below may only be called with a `this` value

js/src/vm/CommonPropertyNames.h

@@ -144,6 +144,7 @@
     macro(isExtensible, isExtensible, "isExtensible") \
     macro(iteratorIntrinsic, iteratorIntrinsic, "__iterator__") \
     macro(join, join, "join") \
+    macro(js, js, "js") \
     macro(keys, keys, "keys") \
     macro(label, label, "label") \
     macro(lastIndex, lastIndex, "lastIndex") \
@@ -269,6 +270,7 @@
     macro(var, var, "var") \
     macro(variable, variable, "variable") \
     macro(void0, void0, "(void 0)") \
+    macro(wasm, wasm, "wasm") \
     macro(watch, watch, "watch") \
     macro(WeakSet_add, WeakSet_add, "WeakSet_add") \
     macro(weekday, weekday, "weekday") \

js/src/vm/Debugger.cpp

@@ -5289,6 +5289,25 @@ DebuggerScript_getGlobal(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
+class DebuggerScriptGetFormatMatcher
+{
+    const JSAtomState& names_;
+  public:
+    explicit DebuggerScriptGetFormatMatcher(const JSAtomState& names) : names_(names) { }
+    using ReturnType = JSAtom*;
+    ReturnType match(HandleScript script) { return names_.js; }
+    ReturnType match(Handle<WasmModuleObject*> wasmModule) { return names_.wasm; }
+};
+
+static bool
+DebuggerScript_getFormat(JSContext* cx, unsigned argc, Value* vp)
+{
+    THIS_DEBUGSCRIPT_REFERENT(cx, argc, vp, "(get format)", args, obj, referent);
+    DebuggerScriptGetFormatMatcher matcher(cx->names());
+    args.rval().setString(referent.match(matcher));
+    return true;
+}
+
 static bool
 DebuggerScript_getChildScripts(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -6205,6 +6224,7 @@ static const JSPropertySpec DebuggerScript_properties[] = {
     JS_PSG("sourceStart", DebuggerScript_getSourceStart, 0),
     JS_PSG("sourceLength", DebuggerScript_getSourceLength, 0),
     JS_PSG("global", DebuggerScript_getGlobal, 0),
+    JS_PSG("format", DebuggerScript_getFormat, 0),
     JS_PS_END
 };