Web Animations: Add Interpolation class.

Source/core/animation/Interpolation.cpp

+// Copyright 2014 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 "config.h"
+#include "core/animation/Interpolation.h"
+
+namespace WebCore {
+
+void Interpolation::interpolate(double fraction) const
+{
+    if (m_cachedFraction != fraction) {
+        m_cachedValue = m_start->interpolate(*m_end, fraction);
+        m_cachedFraction = fraction;
+    }
+}
+
+namespace {
+
+bool typesMatch(const InterpolableValue* start, const InterpolableValue* end)
+{
+    if (start->isNumber())
+        return end->isNumber();
+    if (start->isBool())
+        return end->isBool();
+    const InterpolableList* startList = toInterpolableList(start);
+    const InterpolableList* endList = toInterpolableList(end);

[Timothy Loh, 2014/03/06 02:54:49]

Probably need to explicitly check for end->isList() here too if we're making the
check a release assert.

[shans, 2014/03/06 04:42:57]

Done.

+    if (startList->length() != endList->length())
+        return false;
+    for (size_t i = 0; i < startList->length(); ++i) {
+        if (!typesMatch(startList->get(i), endList->get(i)))
+            return false;
+    }
+    return true;
+}
+
+}
+
+Interpolation::Interpolation(PassOwnPtr<InterpolableValue> start, PassOwnPtr<InterpolableValue> end)

[alancutter (OOO until 2018), 2014/03/05 04:30:43]

Constructors are usually at the top of source files where possible.

[shans, 2014/03/06 04:42:57]

Done.

+    : m_start(start)
+    , m_end(end)
+    , m_cachedFraction(0)
+    , m_cachedValue(m_start->clone())
+{
+    ASSERT(typesMatch(m_start.get(), m_end.get()));

[dstockwell, 2014/03/06 02:12:19]

I thought this was going to be a release assert to make up for not having a
release assert in InterpolableList?

[shans, 2014/03/06 04:42:57]

Done.

+}
+
+}