[debugger] Further stepping support in test wrapper

test/debugger/test-api.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 "use strict";
 
 // If true, prints all messages sent and received by inspector.
 const printProtocolMessages = false;
 
 // The active wrapper instance.
 let activeWrapper = undefined;
 
 // Receiver function called by inspector, delegating to active wrapper.
 function receive(message) {
   activeWrapper.receiveMessage(message);
 }
 
 class DebugWrapper {
   constructor() {
     // Message dictionary storing {id, message} pairs.
-    this.receivedMessages = {};
+    this.receivedMessages = new Map();
 
     // Each message dispatched by the Debug wrapper is assigned a unique number
     // using nextMessageId.
     this.nextMessageId = 0;
 
     // The listener method called on certain events.
     this.listener = undefined;
 
     // TODO(jgruber): Determine which of these are still required and possible.
     // Debug events which can occur in the V8 JavaScript engine.
     this.DebugEvent = { Break: 1
                       , Exception: 2
                       , NewFunction: 3
                       , BeforeCompile: 4
                       , AfterCompile: 5
                       , CompileError: 6
                       , AsyncTaskEvent: 7
                       };
 
+    // The different types of steps.
+    this.StepAction = { StepOut: 0
+                      , StepNext: 1
+                      , StepIn: 2
+                      , StepFrame: 3
+                      };
+
+    // A copy of the scope types from runtime-debug.cc.
+    // NOTE: these constants should be backward-compatible, so
+    // add new ones to the end of this list.
+    this.ScopeType = { Global:  0
+                     , Local:   1
+                     , With:    2
+                     , Closure: 3
+                     , Catch:   4
+                     , Block:   5
+                     , Script:  6
+                     , Eval:    7
+                     , Module:  8
+                     };
+
+    // Store the current script id so we can skip corresponding break events.
+    this.thisScriptId = %FunctionGetScriptId(receive);
+
     // Register as the active wrapper.
     assertTrue(activeWrapper === undefined);
     activeWrapper = this;
   }
 
   enable() { this.sendMessageForMethodChecked("Debugger.enable"); }
   disable() { this.sendMessageForMethodChecked("Debugger.disable"); }
 
   setListener(listener) { this.listener = listener; }
 
@@ skipping 18 matching lines @@
 
     const {msgid, msg} = this.createMessage(
         "Debugger.setBreakpoint",
         { location : { scriptId : scriptid.toString()
                      , lineNumber : loc.line
                      , columnNumber : loc.column
                      }
         });
     this.sendMessage(msg);
 
-    const reply = this.receivedMessages[msgid];
+    const reply = this.takeReplyChecked(msgid);
+    assertTrue(reply.result !== undefined);
     const breakid = reply.result.breakpointId;
     assertTrue(breakid !== undefined);
 
     return breakid;
   }
 
   clearBreakPoint(breakid) {
     const {msgid, msg} = this.createMessage(
         "Debugger.removeBreakpoint", { breakpointId : breakid });
     this.sendMessage(msg);
-    assertTrue(this.receivedMessages[msgid] !== undefined);
+    this.takeReplyChecked(msgid);
   }
 
   // Returns the serialized result of the given expression. For example:
   // {"type":"number", "value":33, "description":"33"}.
   evaluate(frameid, expression) {
     const {msgid, msg} = this.createMessage(
         "Debugger.evaluateOnCallFrame",
         { callFrameId : frameid
         , expression : expression
         });
     this.sendMessage(msg);
 
-    const reply = this.receivedMessages[msgid];
+    const reply = this.takeReplyChecked(msgid);
     return reply.result.result;
   }
 
   // --- Internal methods. -----------------------------------------------------
 
   getNextMessageId() {
     return this.nextMessageId++;
   }
 
   createMessage(method, params) {
@@ skipping 18 matching lines @@
   }
 
   sendMessage(message) {
     if (printProtocolMessages) print(message);
     send(message);
   }
 
   sendMessageForMethodChecked(method) {
     const {msgid, msg} = this.createMessage(method);
     this.sendMessage(msg);
-    assertTrue(this.receivedMessages[msgid] !== undefined);
+    this.takeReplyChecked(msgid);
+  }
+
+  takeReplyChecked(msgid) {
+    const reply = this.receivedMessages[msgid];
+    assertTrue(reply !== undefined);
+    delete this.receivedMessages[msgid];

[Yang, 2016/11/02 10:36:04]

I don't think this is how to use a Map. You would use the methods
Map.prototype.{set,get,delete}.

[jgruber, 2016/11/07 11:35:11]

Done.

+    return reply;
+  }
+
+  execStatePrepareStep(action) {
+    switch(action) {
+      case this.StepAction.StepOut: this.stepOut(); break;
+      case this.StepAction.StepNext: this.stepOver(); break;
+      case this.StepAction.StepIn: this.stepInto(); break;
+      default: %AbortJS("Unsupported StepAction"); break;
+    }
+  }
+
+  execStateScope(scope) {
+    // TODO(jgruber): Mapping
+    return { scopeType: () => scope.type
+           , scopeObject: () => scope.object

[Yang, 2016/11/02 10:36:04]

Can we have the comma on the previous line? Elsewhere too.

[jgruber, 2016/11/07 11:35:11]

Dang, thought I could sneak some nice haskell-style list formatting in. Done.

+           };
+  }
+
+  execStateFrame(frame) {
+    const scriptid = parseInt(frame.location.scriptId);
+    const line = frame.location.lineNumber;
+    const column = frame.location.columnNumber;
+    const loc = %ScriptLocationFromLine2(scriptid, line, column, 0);
+    const func = { name : () => frame.functionName };
+    return { sourceLineText : () => loc.sourceText
+           , functionName : () => frame.functionName
+           , func : () => func
+           , scopeCount : () => frame.scopeChain.length
+           , scope : (index) => this.execStateScope(frame.scopeChain[index])
+           };
   }
 
   // --- Message handlers. -----------------------------------------------------
 
   dispatchMessage(message) {
     const method = message.method;
     if (method == "Debugger.paused") {
       this.handleDebuggerPaused(message);
     } else if (method == "Debugger.scriptParsed") {
       this.handleDebuggerScriptParsed(message);
     }
   }
 
   handleDebuggerPaused(message) {
     const params = message.params;
 
+    // Skip break events in this file.
+    if (params.callFrames[0].location.scriptId == this.thisScriptId) return;
+
     // TODO(jgruber): Arguments as needed.
-    let execState = { frames: params.callFrames };
-    this.invokeListener(this.DebugEvent.Break, execState);
+    let execState = { frames : params.callFrames
+                    , prepareStep : this.execStatePrepareStep.bind(this)
+                    , frame : (index) => this.execStateFrame(index ? params.callFrames[index] : params.callFrames[0])
+                    , frameCount : () => params.callFrames.length

[Yang, 2016/11/02 10:36:04]

80-char limit.

[jgruber, 2016/11/07 11:35:11]

Done.

+                    };
+    let eventData = this.execStateFrame(params.callFrames[0]);
+    this.invokeListener(this.DebugEvent.Break, execState, eventData);
   }
 
   handleDebuggerScriptParsed(message) {
     const params = message.params;
     let eventData = { scriptId : params.scriptId
                     , eventType : this.DebugEvent.AfterCompile
                     }
 
     // TODO(jgruber): Arguments as needed. Still completely missing exec_state,
     // and eventData used to contain the script mirror instead of its id.
     this.invokeListener(this.DebugEvent.AfterCompile, undefined, eventData,
                         undefined);
   }
 
   invokeListener(event, exec_state, event_data, data) {
     if (this.listener) {
       this.listener(event, exec_state, event_data, data);
     }
   }
 }
+
+// Simulate the debug object generated by --expose-debug-as debug.
+var debug = { instance : undefined };
+Object.defineProperty(debug, 'Debug', { get: function() {
+  if (!debug.instance) {
+    debug.instance = new DebugWrapper();
+    debug.instance.enable();
+  }
+  return debug.instance;
+}});