[debugger] step on every assignment in destructuring bind.

R=caitpotter88@gmail.com, littledan@chromium.org

Review URL: https://codereview.chromium.org/1542813003

Cr-Commit-Position: refs/heads/master@{#33009}

src/parsing/parser.h

@@ -1077,7 +1077,9 @@ class Parser : public ParserBase<ParserTraits> {
     void RecurseIntoSubpattern(AstNode* pattern, Expression* value) {
       Expression* old_value = current_value_;
       current_value_ = value;
+      recursion_level_++;
       pattern->Accept(this);
+      recursion_level_--;
       current_value_ = old_value;
     }
 
@@ -1089,6 +1091,7 @@ class Parser : public ParserBase<ParserTraits> {
     bool IsAssignmentContext() const { return IsAssignmentContext(context_); }
     bool IsAssignmentContext(PatternContext c) const;
     bool IsBindingContext(PatternContext c) const;
+    bool IsSubPattern() const { return recursion_level_ > 1; }
     PatternContext SetAssignmentContextIfNeeded(Expression* node);
     PatternContext SetInitializerContextIfNeeded(Expression* node);
 
@@ -1110,6 +1113,7 @@ class Parser : public ParserBase<ParserTraits> {
     const DeclarationDescriptor* descriptor_;
     ZoneList<const AstRawString*>* names_;
     Expression* current_value_;
+    int recursion_level_;
     bool* ok_;
   };
 

src/parsing/pattern-rewriter.cc

@@ -26,6 +26,7 @@ void Parser::PatternRewriter::DeclareAndInitializeVariables(
   rewriter.descriptor_ = declaration_descriptor;
   rewriter.names_ = names;
   rewriter.ok_ = ok;
+  rewriter.recursion_level_ = 0;
 
   rewriter.RecurseIntoSubpattern(rewriter.pattern_, declaration->initializer);
 }
@@ -46,6 +47,7 @@ void Parser::PatternRewriter::RewriteDestructuringAssignment(
   rewriter.descriptor_ = nullptr;
   rewriter.names_ = nullptr;
   rewriter.ok_ = &ok;
+  rewriter.recursion_level_ = 0;
 
   rewriter.RecurseIntoSubpattern(rewriter.pattern_, nullptr);
   DCHECK(ok);
@@ -280,11 +282,12 @@ void Parser::PatternRewriter::VisitVariableProxy(VariableProxy* pattern) {
     DCHECK_NOT_NULL(proxy);
     DCHECK_NOT_NULL(proxy->var());
     DCHECK_NOT_NULL(value);
-    Assignment* assignment = factory()->NewAssignment(
-        Token::INIT, proxy, value, descriptor_->initialization_pos);
+    // Add break location for destructured sub-pattern.
+    int pos = IsSubPattern() ? pattern->position() : RelocInfo::kNoPosition;
+    Assignment* assignment =
+        factory()->NewAssignment(Token::INIT, proxy, value, pos);
     block_->statements()->Add(
-        factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition),
-        zone());
+        factory()->NewExpressionStatement(assignment, pos), zone());
     value = NULL;
   }
 
@@ -296,11 +299,12 @@ void Parser::PatternRewriter::VisitVariableProxy(VariableProxy* pattern) {
     // if they are inside a 'with' statement - they may change a 'with' object
     // property).
     VariableProxy* proxy = initialization_scope->NewUnresolved(factory(), name);
-    Assignment* assignment = factory()->NewAssignment(
-        Token::INIT, proxy, value, descriptor_->initialization_pos);
+    // Add break location for destructured sub-pattern.
+    int pos = IsSubPattern() ? pattern->position() : RelocInfo::kNoPosition;
+    Assignment* assignment =
+        factory()->NewAssignment(Token::INIT, proxy, value, pos);
     block_->statements()->Add(
-        factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition),
-        zone());
+        factory()->NewExpressionStatement(assignment, pos), zone());
   }
 }
 

test/mjsunit/harmony/debug-step-destructuring-bind.js

@@ -0,0 +1,110 @@
+// Copyright 2015 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.
+
+// Flags: --expose-debug-as debug --harmony-destructuring-bind
+
+var exception = null;
+var Debug = debug.Debug;
+var break_count = 0;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    var source = exec_state.frame(0).sourceLineText();
+    print(source, break_count);
+    assertTrue(source.indexOf(`B${break_count++}`) > 0);
+    if (source.indexOf("assertEquals") > 0) {
+      exec_state.prepareStep(Debug.StepAction.StepNext);
+    } else {
+      exec_state.prepareStep(Debug.StepAction.StepIn);
+    }
+  } catch (e) {
+    exception = e;
+    print(e);
+  }
+};
+
+Debug.setListener(listener);
+
+var id = x => x;                                  // B9 B10 B36 B37
+
+function test() {
+  debugger;                                       // B0
+  function fx1([
+                a,                                // B2
+                b                                 // B3
+              ]) {
+    assertEquals([1, 2], [a, b]);                 // B4
+  }                                               // B5
+  fx1([1, 2, 3]);                                 // B1
+
+  function f2([
+                a,                                // B7
+                b = id(3)                         // B8
+              ]) {
+    assertEquals([4, 3], [a, b]);                 // B11
+  }                                               // B12
+  f2([4]);                                        // B6
+
+  function f3({
+                x: a,                             // B14
+                y: b                              // B15
+              }) {
+    assertEquals([5, 6], [a, b]);                 // B16
+  }                                               // B17
+  f3({y: 6, x: 5});                               // B13
+
+  function f4([
+                a,                                // B19
+                {
+                  b,                              // B20
+                  c,                              // B21
+                }
+              ]) {
+    assertEquals([2, 4, 6], [a, b, c]);           // B22
+  }                                               // B23
+  f4([2, {c: 6, b: 4}]);                          // B18
+
+  function f5([
+                {
+                  a,                              // B25
+                  b = 7                           // B26
+                },
+                c = 3                             // B27
+              ] = [{a:1}]) {
+    assertEquals([1, 7, 3], [a, b, c]);           // B28
+  }                                               // B29
+  f5();                                           // B24
+
+  var name = "x";                                 // B30
+  function f6({
+                [id(name)]: a,                    // B34 B35
+                b = a                             // B38
+              }) {
+    assertEquals([9, 9], [a, b]);                 // B39
+  }                                               // B40
+  var o6 = {};                                    // B31
+  o6[name] = 9;                                   // B32
+  f6(o6);                                         // B33
+
+  try {
+    throw [3, 4];                                 // B41
+  } catch ([
+             a,                                   // B42
+             b,                                   // B43
+             c = 6                                // B44
+           ]) {
+    assertEquals([3, 4, 6], [a, b, c]);           // B45
+  }
+
+  var {                                           // B46
+    x: a,                                         // B47
+    y: b = 9                                      // B48
+  } = { x: 4 };
+  assertEquals([4, 9], [a, b]);                   // B49
+}                                                 // B50
+
+test();
+Debug.setListener(null);                          // B51
+assertNull(exception);