Basic implementation of liveedit feature

test/mjsunit/debug-liveedit-2.js

+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
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+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-debug-as debug
+// Get the Debug object exposed from the debug context global object.
+
+
+Debug = debug.Debug
+
+
+eval(
+    "function ChooseAnimal(p) {\n " +
+    "  if (p == 7) {\n" + // Use p
+    "    return;\n" +
+    "  }\n" +
+    "  return function Chooser() {\n" +
+    "    return 'Cat';\n" +
+    "  };\n" +
+    "}\n"
+);
+
+var old_closure = ChooseAnimal(19);
+
+assertEquals("Cat", old_closure());
+
+var script = Debug.findScript(ChooseAnimal);
+
+var orig_animal = "'Cat'";
+var patch_pos = script.source.indexOf(orig_animal);
+var new_animal_patch = "'Capybara' + p";
+
+// We patch innermost function "Chooser".
+// However, this does not actually patch existing "Chooser" instances,
+// because old value of parameter "p" was not saved.
+// Instead it patches ChooseAnimal.
+var change_log = new Array();
+Debug.LiveEditChangeScript(script, patch_pos, orig_animal.length, new_animal_patch, change_log);
+print("Change log: " + JSON.stringify(change_log) + "\n");
+
+var new_closure = ChooseAnimal(19);
+// New instance of closure is patched.
+assertEquals("Capybara19", new_closure());
+
+// Old instance of closure is not patched.
+assertEquals("Cat", old_closure());
+