Add testcase for Strign::ComputeHash function

The qcalculatehash_p.h private header also has been added to provide
function calculatehash for qml and the new testcase.

Change-Id: I1a0cf6052f596438f50bb5d2899ceaaae3e2e477
Reviewed-by: Simon Hausmann <[email protected]>

src/v8/qcalculatehash_p.h

@@ -0,0 +1,140 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtV8 module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef CALCULATEHASH_P_H
+#define CALCULATEHASH_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qglobal.h>
+#include <QtCore/qstring.h>
+
+QT_BEGIN_NAMESPACE
+
+// This is a reimplementation of V8's string hash algorithm.  It is significantly
+// faster to do it here than call into V8, but it adds the maintenance burden of
+// ensuring that the two hashes are identical.  We Q_ASSERT() that the two return
+// the same value.  If these asserts start to fail, the hash code needs to be
+// synced with V8.
+namespace HashedString {
+    static const int kMaxArrayIndexSize = 10;
+    static const int kMaxHashCalcLength = 16383;
+    static const int kNofHashBitFields = 2;
+    static const int kHashShift = kNofHashBitFields;
+    static const int kIsNotArrayIndexMask = 1 << 1;
+    static const int kArrayIndexValueBits = 24;
+    static const int kArrayIndexHashLengthShift = kArrayIndexValueBits + kNofHashBitFields;
+    static const int kMaxCachedArrayIndexLength = 7;
+};
+
+template <typename schar>
+uint32_t calculateHash(const schar* chars, int length) {
+    if (length > HashedString::kMaxHashCalcLength) {
+        // V8 trivial hash
+        return (length << HashedString::kHashShift) | HashedString::kIsNotArrayIndexMask;
+    }
+
+    uint32_t raw_running_hash = 0;
+    uint32_t array_index = 0;
+    bool is_array_index = (0 < length && length <= HashedString::kMaxArrayIndexSize);
+    bool is_first_char = true;
+
+    int ii = 0;
+    for (;is_array_index && ii < length; ++ii) {
+        quint32 c = *chars++;
+
+        raw_running_hash += c;
+        raw_running_hash += (raw_running_hash << 10);
+        raw_running_hash ^= (raw_running_hash >> 6);
+
+        if (c < '0' || c > '9') {
+            is_array_index = false;
+        } else {
+            int d = c - '0';
+            if (is_first_char) {
+                is_first_char = false;
+                if (c == '0' && length > 1) {
+                    is_array_index = false;
+                    continue;
+                }
+            }
+            if (array_index > 429496729U - ((d + 2) >> 3)) {
+                is_array_index = false;
+            } else {
+                array_index = array_index * 10 + d;
+            }
+        }
+    }
+
+    for (;ii < length; ++ii) {
+        raw_running_hash += *chars++;
+        raw_running_hash += (raw_running_hash << 10);
+        raw_running_hash ^= (raw_running_hash >> 6);
+    }
+
+    if (is_array_index) {
+        array_index <<= HashedString::kHashShift;
+        array_index |= length << HashedString::kArrayIndexHashLengthShift;
+        return array_index;
+    } else {
+        raw_running_hash += (raw_running_hash << 3);
+        raw_running_hash ^= (raw_running_hash >> 11);
+        raw_running_hash += (raw_running_hash << 15);
+        if (raw_running_hash == 0) {
+            raw_running_hash = 27;
+        }
+
+        return (raw_running_hash << HashedString::kHashShift) | HashedString::kIsNotArrayIndexMask;
+    }
+}
+
+QT_END_NAMESPACE
+
+#endif // CALCULATEHASH_P_H

sync.profile

@@ -2,7 +2,7 @@
     "QtV8" => "$basedir/src/v8",
 );
 %moduleheaders = ( # restrict the module headers to those found in relative path
-    "QtV8" => "../3rdparty/v8/include",
+    "QtV8" => "../3rdparty/v8/include;../v8",
 );
 @allmoduleheadersprivate = (
     "QtV8"

tests/auto/v8/tst_v8.cpp

@@ -67,6 +67,7 @@ private slots:
     void fallbackpropertyhandler_in_prototype();
     void fallbackpropertyhandler_nonempty();
     void completehash();
+    void stringhashcomparison();
 };
 
 void tst_v8::eval()
@@ -134,6 +135,11 @@ void tst_v8::completehash()
     QVERIFY(v8test_completehash());
 }
 
+void tst_v8::stringhashcomparison()
+{
+    QVERIFY(v8test_stringhashcomparison());
+}
+
 int main(int argc, char *argv[])
 {
     V8::SetFlagsFromCommandLine(&argc, argv, true);

tests/auto/v8/v8main.cpp

@@ -72,6 +72,7 @@ int main(int argc, char *argv[])
     RUN_TEST(fallbackpropertyhandler_callbacks);
     RUN_TEST(fallbackpropertyhandler_in_prototype);
     RUN_TEST(fallbackpropertyhandler_nonempty);
+    RUN_TEST(stringhashcomparison);
 
     return exit_status;
 }

tests/auto/v8/v8test.cpp

@@ -40,6 +40,7 @@
 ****************************************************************************/
 
 #include "v8test.h"
+#include <private/qcalculatehash_p.h>
 
 using namespace v8;
 
@@ -1089,3 +1090,56 @@ bool v8test_completehash()
 
     ENDTEST();
 }
+
+bool v8test_stringhashcomparison()
+{
+    BEGINTEST();
+
+    // Initialize V8 random seed for string hashing
+    HandleScope handle_scope;
+    Persistent<Context> context = Context::New();
+    Context::Scope context_scope(context);
+
+    quint32 hash1;
+    uint32_t hash2;
+    int length, rand;
+
+    const char* text;
+    QString qtext;
+
+    char textRand[HashedString::kMaxHashCalcLength + 1];
+    QString qtextRand;
+
+    text = "tipli";
+    qtext = QString(text);
+    length = strlen(text);
+
+    hash1 = calculateHash((uint8_t*)text, length) >> HashedString::kHashShift;
+    hash2 = String::ComputeHash((char*)text, length);
+    VERIFY(hash1 == hash2);
+
+    hash1 = calculateHash<quint16>((quint16*)qtext.constData(), length) >> HashedString::kHashShift;
+    hash2 = String::ComputeHash((uint16_t*)qtext.constData(), length);
+    VERIFY(hash1 == hash2);
+
+    // Check V8 trivial hash
+    length = HashedString::kMaxHashCalcLength + 1;
+    for (int i = 0; i < length; i++) {
+        rand = qrand() % 255 + 1;
+        textRand[i] = (char)rand;
+    }
+    qtextRand = QString(textRand);
+
+    hash1 = calculateHash((uint8_t*)textRand, length) >> HashedString::kHashShift;
+    hash2 = String::ComputeHash((char*)textRand, length);
+    VERIFY(hash1 == hash2);
+
+    hash1 = calculateHash<quint16>((quint16*)qtextRand.constData(), length) >> HashedString::kHashShift;
+    hash2 = String::ComputeHash((uint16_t*)qtextRand.constData(), length);
+    VERIFY(hash1 == hash2);
+
+cleanup:
+    context.Dispose();
+
+    ENDTEST();
+}

tests/auto/v8/v8test.h

@@ -61,6 +61,7 @@ bool v8test_fallbackpropertyhandler_callbacks();
 bool v8test_fallbackpropertyhandler_in_prototype();
 bool v8test_fallbackpropertyhandler_nonempty();
 bool v8test_completehash();
+bool v8test_stringhashcomparison();
 
 #endif // V8TEST_H