Made a generator for CSSPropertyDescriptor.cpp

third_party/WebKit/Source/core/css/CSSProperties.in

 // This file specifies all the CSS properties we support and the necessary
 // information for our code generation. The various supported arguments
 // are described below with example usage
 
 
 // - alias_for=other-property
 // Properties specifying alias_for should be virtually identical to the
 // properties they alias. Minor parsing differences are allowed as long as
 // the CSSValues created are of the same format of the aliased property.
 
 
 // - runtime_flag=CSSGridLayout
 // The flag on RuntimeEnabledFeatures conditionally enables the property.
 // This doesn't currently work with alias_for.
 
 
 // - descriptor_only
 // These are actually descriptors and not CSS properties. Properties with
 // the same name as a descriptor do not get this flag.
 
 
 // - longhands=property;other-property
 // The property is a shorthand for several other properties.
 
 
+// - api_class[=classname]
+// We have a CSSPropertyAPI interface which contains parsing functions for
+// properties, and will be implemented by all CSS properties. CSSPropertyDescriptor
+// is used to store function pointers for the parsing functions for a specific
+// property, and CSSPropertyDescriptors.cpp stores a static array of these
+// descriptors. Therefore when CSSPropertyDescriptors.cpp is being generated, we
+// need to know which properties CSSPropertyAPI has been implemented for.

[alancutter (OOO until 2018), 2016/12/12 00:00:07]

Too much low level implementation detail and takes too long to answer the
question "what is this parameter for?".

How about:
Specifies the existance (and optionally name) of a CSSPropertyAPI implementation
for the property to be used by make_css_property_descriptor.py.
See core/css/properties/CSSPropertyAPI.h for API details.

[aazzam, 2016/12/12 04:05:40]

done :)

+// * Add this flag if the API has been implemented for this property.

[alancutter (OOO until 2018), 2016/12/12 00:00:07]

Redundant with the third bullet point.

[aazzam, 2016/12/12 04:05:40]

done :)

+// * If the classname for this is different to the name of the property, specify a
+//   value for this flag. An example of this is when properties have similar parsing

[alancutter (OOO until 2018), 2016/12/12 00:00:07]

Give explicit examples of the default and the override behaviour of this
parameter.

[aazzam, 2016/12/12 04:05:40]

done :)

+//   logic, they are grouped together under one classname, and all properties with
+//   this flag inherit from a class with this name.

[alancutter (OOO until 2018), 2016/12/12 00:00:04]

No need for use case example.

[aazzam, 2016/12/12 04:05:40]

done :)

+// * Properties which have not been implemented do not get this flag.

[alancutter (OOO until 2018), 2016/12/12 00:00:04]

s/which have not been implemented/without a CSSPropertyAPI implementation/

[aazzam, 2016/12/12 04:05:40]

done :)

+// TODO(aazzam): When most properties have been implemented, modify this so that
+// properties with default classnames do not get this flag, and introduce a
+// 'not_implemented' flag instead.

[alancutter (OOO until 2018), 2016/12/12 00:00:07]

Awesome.

+
+
 // - keyword_only
 // These properties only store keyword values. This is used when
 // generating the ComputedStyle storage for the property. The initial
 // value for this property on a ComputedStyle is specified with the
 // initial_keyword flag below.
 // TODO(sashab, meade): Remove this once TypedOM types are specified for
 // every property, since this value can be inferred from that.
 
 
 // - keywords=[keyword1|keyword2]
@@ skipping 425 matching lines @@
 -webkit-border-before-color direction_aware
 -webkit-border-before-style direction_aware
 -webkit-border-before-width direction_aware
 -webkit-border-after-color direction_aware
 -webkit-border-after-style direction_aware
 -webkit-border-after-width direction_aware
 -webkit-margin-end direction_aware
 -webkit-margin-start direction_aware
 -webkit-margin-before direction_aware
 -webkit-margin-after direction_aware
--webkit-padding-end direction_aware
--webkit-padding-start direction_aware
--webkit-padding-before direction_aware
--webkit-padding-after direction_aware
+-webkit-padding-end direction_aware, api_class=WebkitPadding
+-webkit-padding-start direction_aware, api_class=WebkitPadding
+-webkit-padding-before direction_aware, api_class=WebkitPadding
+-webkit-padding-after direction_aware, api_class=WebkitPadding

[alancutter (OOO until 2018), 2016/12/12 00:00:04]

Let's make the name explicitly CSSPropertyAPIWebkitPadding for easier
searchability and less magic generator behaviour for users to have to look up in
order to use/read this.

[aazzam, 2016/12/12 04:05:40]

The reason I haven't done it this way is that in some cases in the tmpl file I
need an ID name e.g. "CSSPropertyWebkitPadding", and in others I need a class
name e.g. "CSSPropertyAPIWebkitPadding". Do you think it's okay to keep it this
way, or do you have an alternative suggestion? :)

 -webkit-logical-width direction_aware
 -webkit-logical-height direction_aware
 -webkit-min-logical-width direction_aware
 -webkit-min-logical-height direction_aware
 -webkit-max-logical-width direction_aware
 -webkit-max-logical-height direction_aware
 
 // Properties that we ignore in the StyleBuilder.
 // TODO(timloh): This seems wrong, most of these shouldn't reach the StyleBuilder
 
@@ skipping 132 matching lines @@
 -webkit-text-size-adjust alias_for=text-size-adjust
 -webkit-transform alias_for=transform
 -webkit-transform-origin alias_for=transform-origin
 -webkit-transform-style alias_for=transform-style
 -webkit-transition alias_for=transition
 -webkit-transition-delay alias_for=transition-delay
 -webkit-transition-duration alias_for=transition-duration
 -webkit-transition-property alias_for=transition-property
 -webkit-transition-timing-function alias_for=transition-timing-function
 -webkit-user-select alias_for=user-select