Allow access to scopes of suspended generator objects

The scopes of suspended generators can now be accessed through GeneratorMirror
(similar to FrameMirror).

BUG=v8:5235

Review-Url: https://codereview.chromium.org/2228393002
Cr-Commit-Position: refs/heads/master@{#38530}

src/debug/debug-scopes.cc

@@ -125,6 +125,19 @@ ScopeIterator::ScopeIterator(Isolate* isolate, Handle<JSFunction> function)
   UnwrapEvaluationContext();
 }
 
+ScopeIterator::ScopeIterator(Isolate* isolate,
+                             Handle<JSGeneratorObject> generator)
+    : isolate_(isolate),
+      frame_inspector_(NULL),
+      context_(generator->context()),
+      seen_script_scope_(false),
+      failed_(false) {
+  if (!generator->function()->shared()->IsSubjectToDebugging()) {
+    context_ = Handle<Context>();
+  }
+  UnwrapEvaluationContext();
+}
+
 void ScopeIterator::UnwrapEvaluationContext() {
   while (true) {
     if (context_.is_null()) return;
@@ -623,6 +636,7 @@ bool ScopeIterator::SetParameterValue(Handle<ScopeInfo> scope_info,
 bool ScopeIterator::SetStackVariableValue(Handle<ScopeInfo> scope_info,
                                           Handle<String> variable_name,
                                           Handle<Object> new_value) {
+  if (frame_inspector_ == nullptr) return false;
   JavaScriptFrame* frame = GetFrame();
   // Setting stack locals of optimized frames is not supported.
   if (frame->is_optimized()) return false;

src/debug/debug-scopes.h

@@ -43,6 +43,7 @@ class ScopeIterator {
                 Option options = DEFAULT);
 
   ScopeIterator(Isolate* isolate, Handle<JSFunction> function);
+  ScopeIterator(Isolate* isolate, Handle<JSGeneratorObject> generator);
 
   MUST_USE_RESULT MaybeHandle<JSObject> MaterializeScopeDetails();
 

src/debug/mirrors.js

@@ -1022,7 +1022,7 @@ FunctionMirror.prototype.scopeCount = function() {
 
 FunctionMirror.prototype.scope = function(index) {
   if (this.resolved()) {
-    return new ScopeMirror(UNDEFINED, this, index);
+    return new ScopeMirror(UNDEFINED, this, UNDEFINED, index);
   }
 };
 
@@ -1451,6 +1451,27 @@ GeneratorMirror.prototype.receiver = function() {
 };
 
 
+GeneratorMirror.prototype.scopeCount = function() {
+  // This value can change over time as the underlying generator is suspended
+  // at different locations.
+  return %GetGeneratorScopeCount(this.value());
+};
+
+
+GeneratorMirror.prototype.scope = function(index) {
+  return new ScopeMirror(UNDEFINED, UNDEFINED, this, index);
+};
+
+
+GeneratorMirror.prototype.allScopes = function() {
+  var scopes = [];
+  for (let i = 0; i < this.scopeCount(); i++) {
+    scopes.push(this.scope(i));
+  }
+  return scopes;
+};
+
+
 /**
  * Base mirror object for properties.
  * @param {ObjectMirror} mirror The mirror object having this property
@@ -1973,7 +1994,7 @@ FrameMirror.prototype.scopeCount = function() {
 
 
 FrameMirror.prototype.scope = function(index) {
-  return new ScopeMirror(this, UNDEFINED, index);
+  return new ScopeMirror(this, UNDEFINED, UNDEFINED, index);
 };
 
 
@@ -1984,7 +2005,8 @@ FrameMirror.prototype.allScopes = function(opt_ignore_nested_scopes) {
                                           !!opt_ignore_nested_scopes);
   var result = [];
   for (var i = 0; i < scopeDetails.length; ++i) {
-    result.push(new ScopeMirror(this, UNDEFINED, i, scopeDetails[i]));
+    result.push(new ScopeMirror(this, UNDEFINED, UNDEFINED, i,
+                                scopeDetails[i]));
   }
   return result;
 };
@@ -2163,7 +2185,7 @@ var kScopeDetailsStartPositionIndex = 3;
 var kScopeDetailsEndPositionIndex = 4;
 var kScopeDetailsFunctionIndex = 5;
 
-function ScopeDetails(frame, fun, index, opt_details) {
+function ScopeDetails(frame, fun, gen, index, opt_details) {
   if (frame) {
     this.break_id_ = frame.break_id_;
     this.details_ = opt_details ||
@@ -2173,10 +2195,15 @@ function ScopeDetails(frame, fun, index, opt_details) {
                                      index);
     this.frame_id_ = frame.details_.frameId();
     this.inlined_frame_id_ = frame.details_.inlinedFrameIndex();
-  } else {
+  } else if (fun) {
     this.details_ = opt_details || %GetFunctionScopeDetails(fun.value(), index);
     this.fun_value_ = fun.value();
     this.break_id_ = UNDEFINED;
+  } else {
+    this.details_ =
+      opt_details || %GetGeneratorScopeDetails(gen.value(), index);
+    this.gen_value_ = gen.value();
+    this.break_id_ = UNDEFINED;
   }
   this.index_ = index;
 }
@@ -2235,9 +2262,12 @@ ScopeDetails.prototype.setVariableValueImpl = function(name, new_value) {
     %CheckExecutionState(this.break_id_);
     raw_res = %SetScopeVariableValue(this.break_id_, this.frame_id_,
         this.inlined_frame_id_, this.index_, name, new_value);
-  } else {
+  } else if (!IS_UNDEFINED(this.fun_value_)) {
     raw_res = %SetScopeVariableValue(this.fun_value_, null, null, this.index_,
         name, new_value);
+  } else {
+    raw_res = %SetScopeVariableValue(this.gen_value_, null, null, this.index_,
+        name, new_value);
   }
   if (!raw_res) throw %make_error(kDebugger, "Failed to set variable value");
 };
@@ -2248,12 +2278,13 @@ ScopeDetails.prototype.setVariableValueImpl = function(name, new_value) {
  * be specified.
  * @param {FrameMirror} frame The frame this scope is a part of
  * @param {FunctionMirror} function The function this scope is a part of
+ * @param {GeneratorMirror} gen The generator this scope is a part of
  * @param {number} index The scope index in the frame
  * @param {Array=} opt_details Raw scope details data
  * @constructor
  * @extends Mirror
  */
-function ScopeMirror(frame, fun, index, opt_details) {
+function ScopeMirror(frame, fun, gen, index, opt_details) {
   %_Call(Mirror, this, MirrorType.SCOPE_TYPE);
   if (frame) {
     this.frame_index_ = frame.index_;
@@ -2261,7 +2292,7 @@ function ScopeMirror(frame, fun, index, opt_details) {
     this.frame_index_ = UNDEFINED;
   }
   this.scope_index_ = index;
-  this.details_ = new ScopeDetails(frame, fun, index, opt_details);
+  this.details_ = new ScopeDetails(frame, fun, gen, index, opt_details);
 }
 inherits(ScopeMirror, Mirror);
 

src/runtime/runtime-debug.cc

@@ -919,6 +919,48 @@ RUNTIME_FUNCTION(Runtime_GetFunctionScopeDetails) {
   RETURN_RESULT_OR_FAILURE(isolate, it.MaterializeScopeDetails());
 }
 
+RUNTIME_FUNCTION(Runtime_GetGeneratorScopeCount) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(1, args.length());
+
+  if (!args[0]->IsJSGeneratorObject()) return Smi::FromInt(0);
+
+  // Check arguments.
+  CONVERT_ARG_HANDLE_CHECKED(JSGeneratorObject, gen, 0);
+
+  // Count the visible scopes.
+  int n = 0;
+  for (ScopeIterator it(isolate, gen); !it.Done(); it.Next()) {
+    n++;
+  }
+
+  return Smi::FromInt(n);
+}
+
+RUNTIME_FUNCTION(Runtime_GetGeneratorScopeDetails) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+
+  if (!args[0]->IsJSGeneratorObject()) {
+    return *isolate->factory()->undefined_value();
+  }
+
+  // Check arguments.
+  CONVERT_ARG_HANDLE_CHECKED(JSGeneratorObject, gen, 0);
+  CONVERT_NUMBER_CHECKED(int, index, Int32, args[1]);
+
+  // Find the requested scope.
+  int n = 0;
+  ScopeIterator it(isolate, gen);
+  for (; !it.Done() && n < index; it.Next()) {
+    n++;
+  }
+  if (it.Done()) {
+    return isolate->heap()->undefined_value();
+  }
+
+  RETURN_RESULT_OR_FAILURE(isolate, it.MaterializeScopeDetails());
+}
 
 static bool SetScopeVariableValue(ScopeIterator* it, int index,
                                   Handle<String> variable_name,
@@ -967,10 +1009,14 @@ RUNTIME_FUNCTION(Runtime_SetScopeVariableValue) {
 
     ScopeIterator it(isolate, &frame_inspector);
     res = SetScopeVariableValue(&it, index, variable_name, new_value);
-  } else {
+  } else if (args[0]->IsJSFunction()) {
     CONVERT_ARG_HANDLE_CHECKED(JSFunction, fun, 0);
     ScopeIterator it(isolate, fun);
     res = SetScopeVariableValue(&it, index, variable_name, new_value);
+  } else {
+    CONVERT_ARG_HANDLE_CHECKED(JSGeneratorObject, gen, 0);
+    ScopeIterator it(isolate, gen);
+    res = SetScopeVariableValue(&it, index, variable_name, new_value);
   }
 
   return isolate->heap()->ToBoolean(res);

src/runtime/runtime.h

@@ -156,6 +156,8 @@ namespace internal {
   F(GetAllScopesDetails, 4, 1)                  \
   F(GetFunctionScopeCount, 1, 1)                \
   F(GetFunctionScopeDetails, 2, 1)              \
+  F(GetGeneratorScopeCount, 1, 1)               \
+  F(GetGeneratorScopeDetails, 2, 1)             \
   F(SetScopeVariableValue, 6, 1)                \
   F(DebugPrintScopes, 0, 1)                     \
   F(SetBreakPointsActive, 1, 1)                 \