Issue 2399 part 1: In debugger allow modifying local variable values

src/debug-debugger.js

Index: src/debug-debugger.js
diff --git a/src/debug-debugger.js b/src/debug-debugger.js
index 163a0bd82959d9f248df5a673823378ed44c3820..dfad902d75a5c0a1f24c733e0b84955d46f258d1 100644
--- a/src/debug-debugger.js
+++ b/src/debug-debugger.js
@@ -1427,6 +1427,8 @@ DebugCommandProcessor.prototype.processDebugJSONRequest = function(
         this.scopesRequest_(request, response);
       } else if (request.command == 'scope') {
         this.scopeRequest_(request, response);
+      } else if (request.command == 'setVariableValue') {
+        this.setVariableValueRequest_(request, response);
       } else if (request.command == 'evaluate') {
         this.evaluateRequest_(request, response);
       } else if (lol_is_enabled && request.command == 'getobj') {
@@ -1953,11 +1955,12 @@ DebugCommandProcessor.prototype.frameRequest_ = function(request, response) {
 };
 
 
-DebugCommandProcessor.prototype.frameForScopeRequest_ = function(request) {
+DebugCommandProcessor.prototype.resolveFrameFromScopeDescription_ =
+    function(scope_description) {
   // Get the frame for which the scope or scopes are requested.
   // With no frameNumber argument use the currently selected frame.
-  if (request.arguments && !IS_UNDEFINED(request.arguments.frameNumber)) {
-    frame_index = request.arguments.frameNumber;
+  if (scope_description && !IS_UNDEFINED(scope_description.frameNumber)) {
+    frame_index = scope_description.frameNumber;
     if (frame_index < 0 || this.exec_state_.frameCount() <= frame_index) {
       throw new Error('Invalid frame number');
     }
@@ -1971,13 +1974,13 @@ DebugCommandProcessor.prototype.frameForScopeRequest_ = function(request) {
 // Gets scope host object from request. It is either a function
 // ('functionHandle' argument must be specified) or a stack frame
 // ('frameNumber' may be specified and the current frame is taken by default).
-DebugCommandProcessor.prototype.scopeHolderForScopeRequest_ =
-    function(request) {
-  if (request.arguments && "functionHandle" in request.arguments) {
-    if (!IS_NUMBER(request.arguments.functionHandle)) {
+DebugCommandProcessor.prototype.resolveScopeHolder_ =
+    function(scope_description) {
+  if (scope_description && "functionHandle" in scope_description) {
+    if (!IS_NUMBER(scope_description.functionHandle)) {
       throw new Error('Function handle must be a number');
     }
-    var function_mirror = LookupMirror(request.arguments.functionHandle);
+    var function_mirror = LookupMirror(scope_description.functionHandle);
     if (!function_mirror) {
       throw new Error('Failed to find function object by handle');
     }
@@ -1992,14 +1995,14 @@ DebugCommandProcessor.prototype.scopeHolderForScopeRequest_ =
     }
 
     // Get the frame for which the scopes are requested.
-    var frame = this.frameForScopeRequest_(request);
+    var frame = this.resolveFrameFromScopeDescription_(scope_description);
     return frame;
   }
 }
 
 
 DebugCommandProcessor.prototype.scopesRequest_ = function(request, response) {
-  var scope_holder = this.scopeHolderForScopeRequest_(request);
+  var scope_holder = this.resolveScopeHolder_(request.arguments);
 
   // Fill all scopes for this frame or function.
   var total_scopes = scope_holder.scopeCount();
@@ -2018,7 +2021,7 @@ DebugCommandProcessor.prototype.scopesRequest_ = function(request, response) {
 
 DebugCommandProcessor.prototype.scopeRequest_ = function(request, response) {
   // Get the frame or function for which the scope is requested.
-  var scope_holder = this.scopeHolderForScopeRequest_(request);
+  var scope_holder = this.resolveScopeHolder_(request.arguments);
 
   // With no scope argument just return top scope.
   var scope_index = 0;
@@ -2033,6 +2036,77 @@ DebugCommandProcessor.prototype.scopeRequest_ = function(request, response) {
 };
 
 
+// Reads value from protocol description. Description may be in form of type
+// (for singletons), raw value (primitive types supported in JSON),
+// string value description plus type (for primitive values) or handle id.
+// Returns raw value or throws exception.
+DebugCommandProcessor.resolveValue_ = function(value_description) {
+  if ("handle" in value_description) {
+    var value_mirror = LookupMirror(value_description.handle);
+    if (!value_mirror) {
+      throw new Error("Failed to resolve value by handle, ' #" +
+          mapping.handle + "# not found");
+    }
+    return value_mirror.value();
+  } else if ("stringDescription" in value_description) {
+    if (value_description.type == BOOLEAN_TYPE) {
+      return Boolean(value_description.stringDescription);
+    } else if (value_description.type == NUMBER_TYPE) {
+      return Number(value_description.stringDescription);
+    } if (value_description.type == STRING_TYPE) {
+      return String(value_description.stringDescription);
+    } else {
+      throw new Error("Unknown type");
+    }
+  } else if ("value" in value_description) {
+    return value_description.value;
+  } else if (value_description.type == UNDEFINED_TYPE) {
+    return void 0;
+  } else if (value_description.type == NULL_TYPE) {
+    return null;
+  } else {
+    throw new Error("Failed to parse value description");
+  }
+};
+
+
+DebugCommandProcessor.prototype.setVariableValueRequest_ =
+    function(request, response) {
+  if (!request.arguments) {
+    response.failed('Missing arguments');
+    return;
+  }
+
+  if (IS_UNDEFINED(request.arguments.name)) {
+    response.failed('Missing variable name');
+  }
+  var variable_name = request.arguments.name;
+
+  var scope_description = request.arguments.scope;
+
+  // Get the frame or function for which the scope is requested.
+  var scope_holder = this.resolveScopeHolder_(scope_description);
+
+  if (IS_UNDEFINED(scope_description.number)) {
+    response.failed('Missing scope number');
+  }
+  var scope_index = %ToNumber(scope_description.number);
+
+  var scope = scope_holder.scope(scope_index);
+
+  var new_value =
+      DebugCommandProcessor.resolveValue_(request.arguments.newValue);
+
+  scope.setVariableValue(variable_name, new_value);
+
+  var new_value_mirror = MakeMirror(new_value);
+
+  response.body = {
+    newValue: new_value_mirror
+  };
+};
+
+
 DebugCommandProcessor.prototype.evaluateRequest_ = function(request, response) {
   if (!request.arguments) {
     return response.failed('Missing arguments');
@@ -2663,3 +2737,7 @@ function ValueToProtocolValue_(value, mirror_serializer) {
   }
   return json;
 }
+
+Debug.TestApi = {
+  CommandProcessorResolveValue: DebugCommandProcessor.resolveValue_
+};