From 3cde4b2dce74419be439b68c1f715a78aed7d6c4 Mon Sep 17 00:00:00 2001
From: Jason Orendorff <jorendorff@mozilla.com>
Date: Fri, 13 May 2011 22:08:26 -0500
Subject: [PATCH] Add Debug.prototype.getYoungestFrame.

---
 .../tests/debug/Debug-getYoungestFrame-01.js  | 20 ++++++++++++++++
 .../tests/debug/Debug-getYoungestFrame-02.js  | 23 +++++++++++++++++++
 js/src/jsdbg.cpp                              | 21 ++++++++++++++++-
 js/src/jsdbg.h                                | 17 ++++++++++++++
 4 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 js/src/jit-test/tests/debug/Debug-getYoungestFrame-01.js
 create mode 100644 js/src/jit-test/tests/debug/Debug-getYoungestFrame-02.js

diff --git a/js/src/jit-test/tests/debug/Debug-getYoungestFrame-01.js b/js/src/jit-test/tests/debug/Debug-getYoungestFrame-01.js
new file mode 100644
index 00000000000..77e630ad33b
--- /dev/null
+++ b/js/src/jit-test/tests/debug/Debug-getYoungestFrame-01.js
@@ -0,0 +1,20 @@
+// |jit-test| debug
+// getYoungestFrame basics.
+
+load(libdir + "asserts.js");
+
+var g = newGlobal('new-compartment');
+var dbg = new Debug(g);
+assertEq(dbg.getYoungestFrame(), null);
+
+var frame;
+function f() {
+    frame = dbg.getYoungestFrame();
+    assertEq(frame instanceof Debug.Frame, true);
+    assertEq(frame.type, "eval");
+    assertEq(frame.older, null);
+}
+g.h = this;
+g.eval("h.f()");
+assertEq(frame.live, false);
+assertThrowsInstanceOf(function () { frame.older; }, Error);
diff --git a/js/src/jit-test/tests/debug/Debug-getYoungestFrame-02.js b/js/src/jit-test/tests/debug/Debug-getYoungestFrame-02.js
new file mode 100644
index 00000000000..fdffa6aa401
--- /dev/null
+++ b/js/src/jit-test/tests/debug/Debug-getYoungestFrame-02.js
@@ -0,0 +1,23 @@
+// |jit-test| debug
+// Hooks and Debug.prototype.getYoungestFrame produce the same Frame object.
+
+var g = newGlobal('new-compartment');
+var dbg = Debug(g);
+var hits = 0;
+var savedFrame, savedCallee;
+dbg.hooks = {
+    debuggerHandler: function (frame) {
+        assertEq(frame, savedFrame);
+        assertEq(frame.live, true);
+        assertEq(frame.callee, savedCallee);
+        hits++;
+    }
+};
+g.h = function () {
+    savedFrame = dbg.getYoungestFrame();
+    savedCallee = savedFrame.callee;
+    assertEq(savedCallee.name, "f");
+};
+g.eval("function f() { h(); debugger; }");
+g.f();
+assertEq(hits, 1);
diff --git a/js/src/jsdbg.cpp b/js/src/jsdbg.cpp
index 2a6f3c900c9..9017adcb1a6 100644
--- a/js/src/jsdbg.cpp
+++ b/js/src/jsdbg.cpp
@@ -690,6 +690,20 @@ Debug::setUncaughtExceptionHook(JSContext *cx, uintN argc, Value *vp)
     return true;
 }
 
+JSBool
+Debug::getYoungestFrame(JSContext *cx, uintN argc, Value *vp)
+{
+    THISOBJ(cx, vp, Debug, "getYoungestFrame", thisobj, dbg);
+    StackFrame *fp = cx->fp();
+    while (fp && !dbg->observesFrame(fp))
+        fp = fp->prev();
+    if (!fp) {
+        vp->setNull();
+        return true;
+    }
+    return dbg->getScriptFrame(cx, fp, vp);
+}
+
 JSBool
 Debug::construct(JSContext *cx, uintN argc, Value *vp)
 {
@@ -755,6 +769,11 @@ JSPropertySpec Debug::properties[] = {
     JS_PS_END
 };
 
+JSFunctionSpec Debug::methods[] = {
+    JS_FN("getYoungestFrame", Debug::getYoungestFrame, 0, 0),
+    JS_FS_END
+};
+
 // === Debug.Frame
 
 Class DebugFrame_class = {
@@ -1102,7 +1121,7 @@ JS_DefineDebugObject(JSContext *cx, JSObject *obj)
 
     JSObject *debugCtor;
     JSObject *debugProto = js_InitClass(cx, obj, objProto, &Debug::jsclass, Debug::construct, 1,
-                                        Debug::properties, NULL, NULL, NULL, &debugCtor);
+                                        Debug::properties, Debug::methods, NULL, NULL, &debugCtor);
     if (!debugProto || !debugProto->ensureClassReservedSlots(cx))
         return false;
 
diff --git a/js/src/jsdbg.h b/js/src/jsdbg.h
index 825d890218e..98eb2cb0b96 100644
--- a/js/src/jsdbg.h
+++ b/js/src/jsdbg.h
@@ -88,8 +88,10 @@ class Debug {
     static JSBool setEnabled(JSContext *cx, uintN argc, Value *vp);
     static JSBool getUncaughtExceptionHook(JSContext *cx, uintN argc, Value *vp);
     static JSBool setUncaughtExceptionHook(JSContext *cx, uintN argc, Value *vp);
+    static JSBool getYoungestFrame(JSContext *cx, uintN argc, Value *vp);
     static JSBool construct(JSContext *cx, uintN argc, Value *vp);
     static JSPropertySpec properties[];
+    static JSFunctionSpec methods[];
 
     inline bool hasAnyLiveHooks() const;
 
@@ -101,6 +103,9 @@ class Debug {
                                      DebugObservesMethod observesEvent,
                                      DebugHandleMethod handleEvent);
 
+    inline bool observesScope(JSObject *obj) const;
+    inline bool observesFrame(StackFrame *fp) const;
+
     bool observesDebuggerStatement() const;
     JSTrapStatus handleDebuggerStatement(JSContext *cx, Value *vp);
 
@@ -189,6 +194,18 @@ Debug::hasAnyLiveHooks() const
     return observesDebuggerStatement();
 }
 
+bool
+Debug::observesScope(JSObject *obj) const
+{
+    return observesCompartment(obj->compartment());
+}
+
+bool
+Debug::observesFrame(StackFrame *fp) const
+{
+    return observesScope(&fp->scopeChain());
+}
+
 bool
 Debug::observesCompartment(JSCompartment *c) const
 {