Implemnts the commands in webdriver to preform searching of elements on a page.

chrome/test/webdriver/commands/find_element_commands.cc

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/test/webdriver/commands/find_element_commands.h"
+
+#include <sstream>
+#include <string>
+
+#include "base/string_number_conversions.h"
+#include "base/utf_string_conversions.h"
+#include "base/values.h"
+#include "third_party/webdriver/atoms.h"
+#include "chrome/test/webdriver/error_codes.h"
+#include "chrome/test/webdriver/utility_functions.h"
+
+namespace webdriver {
+
+bool FindElementCommand::Init(Response* const response) {
+  if (!WebDriverCommand::Init(response)) {
+    SET_WEBDRIVER_ERROR(response, "Failure on Init for find element",
+                       kInternalServerError);

[Paweł Hajdan Jr., 2010/11/09 11:19:32]

nit: align

[Joe, 2010/11/10 02:37:05]

Done.

+    return false;
+  }
+
+  if (!GetStringASCIIParameter("using", &use_) ||
+      !GetStringASCIIParameter("value", &value_)) {
+    SET_WEBDRIVER_ERROR(response,
+        "Request is missing required 'using' and/or 'value' data", kBadRequest);
+    return false;
+  }
+
+  // TODO(jmikhail): The findElement(s) atom should handle this conversion.
+  if ("class name" == use_) {
+    use_ = "className";
+  } else if ("link text" == use_) {
+    use_ = "linkText";
+  } else if ("partial link text" == use_) {
+    use_ = "partialLinkText";
+  } else if ("tag name" == use_) {
+    use_ = "tagName";
+  }
+
+  // Searching under a custom root if the URL pattern is
+  // "/session/$session/element/$id/element(s)"
+  root_element_id_ = GetPathVariable(4);
+
+  return true;
+}
+
+void FindElementCommand::ExecutePost(Response* const response) {
+  scoped_ptr<ListValue> args(new ListValue());
+  DictionaryValue* locator = new DictionaryValue();
+  ErrorCode error;
+  std::wstring jscript;
+  Value* result = NULL;
+  bool done = false;
+
+  // Set the command we are using to locate the value beging searched for.
+  locator->SetString(use_, value_);
+  args->Append(locator);
+  args->Append(root_element_id_.size() == 0 ? Value::CreateNullValue() :
+      WebDriverCommand::GetElementIdAsDictionaryValue(root_element_id_));
+  if (find_one_element_) {
+    jscript = build_atom(FIND_ELEMENT, sizeof FIND_ELEMENT);
+    jscript.append(L"var result = findElement(arguments[0], arguments[1]);")
+           .append(L"if (!result) {")
+           .append(L"var e = Error('Unable to locate element');")
+           .append(L"e.code = ")
+           .append(UTF8ToWide(base::IntToString(kNoSuchElement)))
+           .append(L";throw e;")
+           .append(L"} else { return result; }");
+  } else {
+    jscript = build_atom(FIND_ELEMENTS, sizeof FIND_ELEMENT);
+    jscript.append(L"return findElements(arguments[0], arguments[1]);");
+  }
+
+  // The element search needs to loop until at least one element is found or the
+  // session's implicit wait timeout expires, whichever occurs first.
+  base::Time start_time = base::Time::Now();
+
+  while (!done) {
+    if (result) {
+      delete result;
+      result = NULL;
+    }
+
+    error = session_->ExecuteScript(jscript, args.get(), &result);
+    if (error == kSuccess) {
+      // If searching for many elements, make sure we found at least one before
+      // stopping.
+      done = find_one_element_ ||
+             (result->GetType() == Value::TYPE_LIST &&
+             static_cast<ListValue*>(result)->GetSize() > 0);
+    } else if (error != kNoSuchElement) {
+      SET_WEBDRIVER_ERROR(response, "Internal error in find_element atom",
+                          kInternalServerError);
+      return;
+    }
+
+    int64 ellapsed_time = (base::Time::Now() - start_time).InMilliseconds();
+    done = done || ellapsed_time > session_->implicit_wait();
+    PlatformThread::Sleep(250);  // Prevent a busy loop that eats the cpu.

[Paweł Hajdan Jr., 2010/11/09 11:19:32]

This is the bad sleep'n'probe pattern. Can we wait on the browser side instead?

[Joe, 2010/11/10 02:37:05]

From what I understand a script on the page could change the elements on the
page. So a polling search is the only deterministic method that could work for
all cases without requiring every webpage host to modify for a chrome specific
hook.

On 2010/11/09 11:19:32, Paweł Hajdan Jr. wrote:

[Paweł Hajdan Jr., 2010/11/10 12:18:45]

I don't think so. Let's at least explore our possibilities on waiting properly.
The rendering engine surely is aware of all of those changes. We need to make it
fire a notification that we can listen for. We can even listen for a "DOM
changed" notification, and only then re-evaluate our filter, instead of just
sleeping for a while.

+  }
+
+  response->set_value(result);
+  response->set_status(error);
+}
+
+}  // namespace webdriver
+