- Revision
- 259785
- Author
- [email protected]
- Date
- 2020-04-09 00:57:16 -0700 (Thu, 09 Apr 2020)
Log Message
Remove unnecessary explicit parsing for mo@maxsize value "infinity"
https://bugs.webkit.org/show_bug.cgi?id=202720
Patch by Delan Azabani <[email protected]> on 2020-04-09
Reviewed by Frédéric Wang.
In MathML 2, the default mo@maxsize was infinity [1], unless some other
default was given by mstyle@maxsize [2]. The sole purpose of "infinity"
was to give authors a way to set mo@maxsize to infinity when some other
mstyle@maxsize was set.
MathML Core removes mstyle@maxsize [3][4], such that "infinity" has the
same semantics as any other missing or invalid mo@maxsize, so the spec
has been simplified to make infinity an anonymous value [5][6].
No functional change, because WebKit has never supported mstyle@maxsize
anyway. To verify that there's no functional change:
1. Search for references to LengthType::Infinity, and observe that the
mo@maxsize parser in MathMLOperatorElement::maxSize is the only
place where a Length of ::type infinity is created
2. Search for references to that method, and observe that the only
caller (RenderMathMLOperator::maxSize) passes intMaxForLayoutUnit
(infinity) to toUserUnits as the referenceValue
3. Go to the definition of toUserUnits, and observe that the refer-
enceValue is used as the ParsingFailed default
4. Step 1 shows that no other attributes would be affected by removing
LengthType::Infinity, and steps 2 and 3 show that mo@maxsize treats
invalid values as infinity, therefore it's safe to remove both the
"infinity" parsing code and the underlying LengthType variant
[1] https://www.w3.org/TR/MathML2/chapter3.html#id.3.2.5.2
[2] https://www.w3.org/TR/MathML2/chapter3.html#presm.mstyle
[3] https://mathml-refresh.github.io/mathml-core/#style-change-mstyle
[4] https://github.com/mathml-refresh/mathml/issues/1
[5] https://mathml-refresh.github.io/mathml-core/#dictionary-based-attributes
[6] https://github.com/mathml-refresh/mathml/issues/107
No new tests, because no functional change.
* mathml/MathMLElement.h: Remove LengthType::Infinity.
* mathml/MathMLOperatorElement.cpp:
(WebCore::MathMLOperatorElement::maxSize): Remove explicit branch on "infinity". Replace what remains with an equivalent cachedMathMLLength call.
* rendering/mathml/RenderMathMLBlock.cpp:
(WebCore::toUserUnits): Remove explicit branch on LengthType::Infinity.
* rendering/mathml/RenderMathMLOperator.cpp:
(WebCore::RenderMathMLOperator::maxSize): Update comment to refer to the default value in the same way as the spec.
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (259784 => 259785)
--- trunk/Source/WebCore/ChangeLog 2020-04-09 07:34:46 UTC (rev 259784)
+++ trunk/Source/WebCore/ChangeLog 2020-04-09 07:57:16 UTC (rev 259785)
@@ -1,3 +1,52 @@
+2020-04-09 Delan Azabani <[email protected]>
+
+ Remove unnecessary explicit parsing for mo@maxsize value "infinity"
+ https://bugs.webkit.org/show_bug.cgi?id=202720
+
+ Reviewed by Frédéric Wang.
+
+ In MathML 2, the default mo@maxsize was infinity [1], unless some other
+ default was given by mstyle@maxsize [2]. The sole purpose of "infinity"
+ was to give authors a way to set mo@maxsize to infinity when some other
+ mstyle@maxsize was set.
+
+ MathML Core removes mstyle@maxsize [3][4], such that "infinity" has the
+ same semantics as any other missing or invalid mo@maxsize, so the spec
+ has been simplified to make infinity an anonymous value [5][6].
+
+ No functional change, because WebKit has never supported mstyle@maxsize
+ anyway. To verify that there's no functional change:
+
+ 1. Search for references to LengthType::Infinity, and observe that the
+ mo@maxsize parser in MathMLOperatorElement::maxSize is the only
+ place where a Length of ::type infinity is created
+ 2. Search for references to that method, and observe that the only
+ caller (RenderMathMLOperator::maxSize) passes intMaxForLayoutUnit
+ (infinity) to toUserUnits as the referenceValue
+ 3. Go to the definition of toUserUnits, and observe that the refer-
+ enceValue is used as the ParsingFailed default
+ 4. Step 1 shows that no other attributes would be affected by removing
+ LengthType::Infinity, and steps 2 and 3 show that mo@maxsize treats
+ invalid values as infinity, therefore it's safe to remove both the
+ "infinity" parsing code and the underlying LengthType variant
+
+ [1] https://www.w3.org/TR/MathML2/chapter3.html#id.3.2.5.2
+ [2] https://www.w3.org/TR/MathML2/chapter3.html#presm.mstyle
+ [3] https://mathml-refresh.github.io/mathml-core/#style-change-mstyle
+ [4] https://github.com/mathml-refresh/mathml/issues/1
+ [5] https://mathml-refresh.github.io/mathml-core/#dictionary-based-attributes
+ [6] https://github.com/mathml-refresh/mathml/issues/107
+
+ No new tests, because no functional change.
+
+ * mathml/MathMLElement.h: Remove LengthType::Infinity.
+ * mathml/MathMLOperatorElement.cpp:
+ (WebCore::MathMLOperatorElement::maxSize): Remove explicit branch on "infinity". Replace what remains with an equivalent cachedMathMLLength call.
+ * rendering/mathml/RenderMathMLBlock.cpp:
+ (WebCore::toUserUnits): Remove explicit branch on LengthType::Infinity.
+ * rendering/mathml/RenderMathMLOperator.cpp:
+ (WebCore::RenderMathMLOperator::maxSize): Update comment to refer to the default value in the same way as the spec.
+
2020-04-08 Chris Dumez <[email protected]>
querySelector("#\u0000") should match an element with ID U+FFFD
Modified: trunk/Source/WebCore/mathml/MathMLElement.h (259784 => 259785)
--- trunk/Source/WebCore/mathml/MathMLElement.h 2020-04-09 07:34:46 UTC (rev 259784)
+++ trunk/Source/WebCore/mathml/MathMLElement.h 2020-04-09 07:57:16 UTC (rev 259785)
@@ -52,7 +52,7 @@
// MathML lengths (https://www.w3.org/TR/MathML3/chapter2.html#fund.units)
// TeX's Math Unit is used internally for named spaces (1 mu = 1/18 em).
// Unitless values are interpreted as a multiple of a reference value.
- enum class LengthType { Cm, Em, Ex, In, MathUnit, Mm, ParsingFailed, Pc, Percentage, Pt, Px, UnitLess, Infinity };
+ enum class LengthType { Cm, Em, Ex, In, MathUnit, Mm, ParsingFailed, Pc, Percentage, Pt, Px, UnitLess };
struct Length {
LengthType type { LengthType::ParsingFailed };
float value { 0 };
Modified: trunk/Source/WebCore/mathml/MathMLOperatorElement.cpp (259784 => 259785)
--- trunk/Source/WebCore/mathml/MathMLOperatorElement.cpp 2020-04-09 07:34:46 UTC (rev 259784)
+++ trunk/Source/WebCore/mathml/MathMLOperatorElement.cpp 2020-04-09 07:57:16 UTC (rev 259785)
@@ -198,18 +198,7 @@
const MathMLElement::Length& MathMLOperatorElement::maxSize()
{
- if (m_maxSize)
- return m_maxSize.value();
-
- const AtomString& value = attributeWithoutSynchronization(MathMLNames::maxsizeAttr);
- if (value == "infinity") {
- Length maxsize;
- maxsize.type = LengthType::Infinity;
- m_maxSize = maxsize;
- } else
- m_maxSize = parseMathMLLength(value);
-
- return m_maxSize.value();
+ return cachedMathMLLength(MathMLNames::maxsizeAttr, m_maxSize);
}
void MathMLOperatorElement::childrenChanged(const ChildChange& change)
Modified: trunk/Source/WebCore/rendering/mathml/RenderMathMLBlock.cpp (259784 => 259785)
--- trunk/Source/WebCore/rendering/mathml/RenderMathMLBlock.cpp 2020-04-09 07:34:46 UTC (rev 259784)
+++ trunk/Source/WebCore/rendering/mathml/RenderMathMLBlock.cpp 2020-04-09 07:57:16 UTC (rev 259785)
@@ -170,8 +170,6 @@
return LayoutUnit(referenceValue * length.value);
case MathMLElement::LengthType::ParsingFailed:
return referenceValue;
- case MathMLElement::LengthType::Infinity:
- return intMaxForLayoutUnit;
default:
ASSERT_NOT_REACHED();
return referenceValue;
Modified: trunk/Source/WebCore/rendering/mathml/RenderMathMLOperator.cpp (259784 => 259785)
--- trunk/Source/WebCore/rendering/mathml/RenderMathMLOperator.cpp 2020-04-09 07:34:46 UTC (rev 259784)
+++ trunk/Source/WebCore/rendering/mathml/RenderMathMLOperator.cpp 2020-04-09 07:57:16 UTC (rev 259785)
@@ -107,7 +107,7 @@
LayoutUnit RenderMathMLOperator::maxSize() const
{
- LayoutUnit maxSize = intMaxForLayoutUnit; // Default maxsize is "infinity".
+ LayoutUnit maxSize = intMaxForLayoutUnit; // Default maxsize is ∞.
maxSize = toUserUnits(element().maxSize(), style(), maxSize);
return std::max<LayoutUnit>(0, maxSize);
}
