A thread-safe Media Query Parser

Source/core/css/parser/MediaQueryToken.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/css/parser/MediaQueryToken.h"
+
+#include "wtf/HashMap.h"
+#include "wtf/text/StringHash.h"
+
+namespace WebCore {
+
+typedef HashMap<String, CSSPrimitiveValue::UnitTypes> UnitTable;
+
+UnitTable createUnitTable()
+{
+    UnitTable table;
+    table.set(String("em"), CSSPrimitiveValue::CSS_EMS);

[eseidel, 2014/03/11 20:14:19]

Should this funtion be on CSSPrimtiveValue?  If we add a type to
CSSPrimitiveValue should it automatically work here?

CSSPritiveValue::allTypes() or some such?  We do something like this for static
strings, etc.

This is static data, we shouldn't need to allocate it on the heap.

Unless we do these lookups a lot, we can suffer the O(N) lookup cost and just
use a flat table isntead of a hash.

[Yoav Weiss, 2014/03/12 20:39:00]

Maybe the best way to do that is through some CSSUnits.in and the build scripts
that'd create this table on Init? What do you think?

[eseidel, 2014/03/13 00:49:36]

OK.  Just file a bug and table that for a later CL then. :)

+    table.set(String("ex"), CSSPrimitiveValue::CSS_EXS);
+    table.set(String("px"), CSSPrimitiveValue::CSS_PX);
+    table.set(String("cm"), CSSPrimitiveValue::CSS_CM);
+    table.set(String("mm"), CSSPrimitiveValue::CSS_MM);
+    table.set(String("in"), CSSPrimitiveValue::CSS_IN);
+    table.set(String("pt"), CSSPrimitiveValue::CSS_PT);
+    table.set(String("pc"), CSSPrimitiveValue::CSS_PC);
+    table.set(String("deg"), CSSPrimitiveValue::CSS_DEG);
+    table.set(String("rad"), CSSPrimitiveValue::CSS_RAD);
+    table.set(String("grad"), CSSPrimitiveValue::CSS_GRAD);
+    table.set(String("ms"), CSSPrimitiveValue::CSS_MS);
+    table.set(String("s"), CSSPrimitiveValue::CSS_S);
+    table.set(String("hz"), CSSPrimitiveValue::CSS_HZ);
+    table.set(String("khz"), CSSPrimitiveValue::CSS_KHZ);
+    table.set(String("dpi"), CSSPrimitiveValue::CSS_DPI);
+    table.set(String("dpcm"), CSSPrimitiveValue::CSS_DPCM);
+    table.set(String("dppx"), CSSPrimitiveValue::CSS_DPPX);
+    table.set(String("vw"), CSSPrimitiveValue::CSS_VW);
+    table.set(String("vh"), CSSPrimitiveValue::CSS_VH);
+    table.set(String("vmax"), CSSPrimitiveValue::CSS_VMIN);
+    table.set(String("vmin"), CSSPrimitiveValue::CSS_VMAX);
+    return table;
+}
+
+static UnitTable& getUnitTable()
+{
+    DEFINE_STATIC_LOCAL(UnitTable, unitTable, (createUnitTable()));
+    return unitTable;
+}
+
+MediaQueryToken::MediaQueryToken(MediaQueryTokenType type)
+    : m_type(type)
+    , m_delimiter(0)
+    , m_unit(CSSPrimitiveValue::CSS_UNKNOWN)
+{
+}
+
+// Just a helper used for Delimiter tokens.
+MediaQueryToken::MediaQueryToken(MediaQueryTokenType type, UChar c)
+    : m_type(type)
+    , m_delimiter(c)
+    , m_unit(CSSPrimitiveValue::CSS_UNKNOWN)
+{
+    ASSERT(m_type == DelimiterToken);
+}
+
+MediaQueryToken::MediaQueryToken(MediaQueryTokenType type, String value)
+    : m_type(type)
+    , m_value(value)
+    , m_delimiter(0)
+    , m_unit(CSSPrimitiveValue::CSS_UNKNOWN)
+{
+}
+
+MediaQueryToken::MediaQueryToken(MediaQueryTokenType type, double numericValue, NumericValueType numericValueType)
+    : m_type(type)
+    , m_delimiter(0)
+    , m_numericValueType(numericValueType)
+    , m_numericValue(numericValue)
+    , m_unit(CSSPrimitiveValue::CSS_NUMBER)
+{
+    ASSERT(type == NumberToken);
+}
+
+void MediaQueryToken::convertToDimensionWithUnit(String unit)
+{
+    ASSERT(m_type == NumberToken);
+    m_type = DimensionToken;
+    m_unit = getUnitTable().get(unit.lower());
+}
+
+void MediaQueryToken::convertToPercentage()
+{
+    ASSERT(m_type == NumberToken);
+    m_type = PercentageToken;
+    m_unit = CSSPrimitiveValue::CSS_PERCENTAGE;
+}
+
+} // namespace WebCore