third_party/WebKit/Source/build/scripts/make_css_property_names.py

#!/usr/bin/env python

import subprocess
import sys

import css_properties
import in_generator
import license


HEADER_TEMPLATE = """
%(license)s

#ifndef %(class_name)s_h
#define %(class_name)s_h

#include "core/CoreExport.h"
#include "wtf/Assertions.h"
#include <stddef.h>

namespace WTF {
class AtomicString;
class String;
}

namespace blink {

enum CSSPropertyID {
    CSSPropertyInvalid = 0,
    // This isn't a property, but we need to know the position of @apply rules in style rules
    CSSPropertyApplyAtRule = 1,
    CSSPropertyVariable = 2,
%(property_enums)s
};

const int firstCSSProperty = %(first_property_id)s;
const int numCSSProperties = %(properties_count)s;
const int lastCSSProperty = %(last_property_id)d;
const int lastUnresolvedCSSProperty = %(last_unresolved_property_id)d;
const size_t maxCSSPropertyNameLength = %(max_name_length)d;

const char* getPropertyName(CSSPropertyID);
const WTF::AtomicString& getPropertyNameAtomicString(CSSPropertyID);
WTF::String getPropertyNameString(CSSPropertyID);
WTF::String getJSPropertyName(CSSPropertyID);

inline CSSPropertyID convertToCSSPropertyID(int value)
{
    ASSERT(value >= CSSPropertyInvalid && value <= lastCSSProperty);
    return static_cast<CSSPropertyID>(value);
}

inline CSSPropertyID resolveCSSPropertyID(CSSPropertyID id)
{
    return convertToCSSPropertyID(id & ~512);
}

inline bool isPropertyAlias(CSSPropertyID id) { return id & 512; }

CSSPropertyID unresolvedCSSPropertyID(const WTF::String&);

CSSPropertyID CORE_EXPORT cssPropertyID(const WTF::String&);

} // namespace blink

#endif // %(class_name)s_h
"""

GPERF_TEMPLATE = """
%%{
%(license)s

#include "%(class_name)s.h"
#include "core/css/HashTools.h"
#include <string.h>

#include "wtf/ASCIICType.h"
#include "wtf/text/AtomicString.h"
#include "wtf/text/WTFString.h"

#ifdef _MSC_VER
// Disable the warnings from casting a 64-bit pointer to 32-bit long
// warning C4302: 'type cast': truncation from 'char (*)[28]' to 'long'
// warning C4311: 'type cast': pointer truncation from 'char (*)[18]' to 'long'
#pragma warning(disable : 4302 4311)
#endif

namespace blink {
static const char propertyNameStringsPool[] = {
%(property_name_strings)s
};

static const unsigned short propertyNameStringsOffsets[] = {
%(property_name_offsets)s
};

%%}
%%struct-type
struct Property;
%%omit-struct-type
%%language=C++
%%readonly-tables
%%global-table
%%compare-strncmp
%%define class-name %(class_name)sHash
%%define lookup-function-name findPropertyImpl
%%define hash-function-name property_hash_function
%%define slot-name nameOffset
%%define word-array-name property_word_list
%%enum
%%%%
%(property_to_enum_map)s
%%%%
const Property* findProperty(register const char* str, register unsigned int len)
{
    return %(class_name)sHash::findPropertyImpl(str, len);
}

const char* getPropertyName(CSSPropertyID id)
{
    ASSERT(id >= firstCSSProperty && id <= lastUnresolvedCSSProperty);
    int index = id - firstCSSProperty;
    return propertyNameStringsPool + propertyNameStringsOffsets[index];
}

const AtomicString& getPropertyNameAtomicString(CSSPropertyID id)
{
    ASSERT(id >= firstCSSProperty && id <= lastUnresolvedCSSProperty);
    int index = id - firstCSSProperty;
    static AtomicString* propertyStrings = new AtomicString[lastUnresolvedCSSProperty]; // Intentionally never destroyed.
    AtomicString& propertyString = propertyStrings[index];
    if (propertyString.isNull())
        propertyString = AtomicString(propertyNameStringsPool + propertyNameStringsOffsets[index]);
    return propertyString;
}

String getPropertyNameString(CSSPropertyID id)
{
    // We share the StringImpl with the AtomicStrings.
    return getPropertyNameAtomicString(id).getString();
}

String getJSPropertyName(CSSPropertyID id)
{
    char result[maxCSSPropertyNameLength + 1];
    const char* cssPropertyName = getPropertyName(id);
    const char* propertyNamePointer = cssPropertyName;
    if (!propertyNamePointer)
        return emptyString();

    char* resultPointer = result;
    while (char character = *propertyNamePointer++) {
        if (character == '-') {
            char nextCharacter = *propertyNamePointer++;
            if (!nextCharacter)
                break;
            character = (propertyNamePointer - 2 != cssPropertyName) ? toASCIIUpper(nextCharacter) : nextCharacter;
        }
        *resultPointer++ = character;
    }
    *resultPointer = '\\0';
    return String(result);
}

CSSPropertyID cssPropertyID(const String& string)
{
    return resolveCSSPropertyID(unresolvedCSSPropertyID(string));
}

} // namespace blink
"""


class CSSPropertyNamesWriter(css_properties.CSSProperties):
    class_name = "CSSPropertyNames"

    def __init__(self, in_file_path):
        super(CSSPropertyNamesWriter, self).__init__(in_file_path)
        self._outputs = {(self.class_name + ".h"): self.generate_header,
                         (self.class_name + ".cpp"): self.generate_implementation,
                        }

    def _enum_declaration(self, property):
        return "    %(property_id)s = %(enum_value)s," % property

    def generate_header(self):
        return HEADER_TEMPLATE % {
            'license': license.license_for_generated_cpp(),
            'class_name': self.class_name,
            'property_enums': "\n".join(map(self._enum_declaration, self._properties_including_aliases)),
            'first_property_id': self._first_enum_value,
            'properties_count': len(self._properties),
            'last_property_id': self._first_enum_value + len(self._properties) - 1,
            'last_unresolved_property_id': max(property["enum_value"] for property in self._properties_including_aliases),
            'max_name_length': max(map(len, self._properties)),
        }

    def generate_implementation(self):
        enum_value_to_name = {property['enum_value']: property['name'] for property in self._properties_including_aliases}
        property_offsets = []
        property_names = []
        current_offset = 0
        for enum_value in range(self._first_enum_value, max(enum_value_to_name) + 1):
            property_offsets.append(current_offset)
            if enum_value in enum_value_to_name:
                name = enum_value_to_name[enum_value]
                property_names.append(name)
                current_offset += len(name) + 1

        css_name_and_enum_pairs = [(property['name'], property['property_id']) for property in self._properties_including_aliases]

        gperf_input = GPERF_TEMPLATE % {
            'license': license.license_for_generated_cpp(),
            'class_name': self.class_name,
            'property_name_strings': '\n'.join('    "%s\\0"' % name for name in property_names),
            'property_name_offsets': '\n'.join('    %d,' % offset for offset in property_offsets),
            'property_to_enum_map': '\n'.join('%s, %s' % property for property in css_name_and_enum_pairs),
        }
        # FIXME: If we could depend on Python 2.7, we would use subprocess.check_output
        gperf_args = [self.gperf_path, '--key-positions=*', '-P', '-n']
        gperf_args.extend(['-m', '50'])  # Pick best of 50 attempts.
        gperf_args.append('-D')  # Allow duplicate hashes -> More compact code.
        gperf = subprocess.Popen(gperf_args, stdin=subprocess.PIPE, stdout=subprocess.PIPE, universal_newlines=True)
        return gperf.communicate(gperf_input)[0]


if __name__ == "__main__":
    in_generator.Maker(CSSPropertyNamesWriter).main(sys.argv)