WebKit/Source/JavaScriptCore/KeywordLookupGenerator.py at main · WebKit/WebKit · GitHub

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# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions

# are met:

# 1. Redistributions of source code must retain the above copyright

# notice, this list of conditions and the following disclaimer.

# 2. Redistributions in binary form must reproduce the above copyright

# notice, this list of conditions and the following disclaimer in the

# documentation and/or other materials provided with the distribution.

# THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY

# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR

# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import sys

import string

import operator

keywordsText = open(sys.argv[1]).read()

# A second argument signifies that the output

# should be redirected to a file

redirect_to_file = len(sys.argv) > 2

# Change stdout to point to the file if requested

if redirect_to_file:

file_output = open(sys.argv[-1], "w")

sys.stdout = file_output

# Observed weights of the most common keywords, rounded to 2.s.d

keyWordWeights = {

"catch": 0.01,

"try": 0.01,

"while": 0.01,

"case": 0.01,

"break": 0.01,

"new": 0.01,

"in": 0.01,

"typeof": 0.02,

"true": 0.02,

"false": 0.02,

"for": 0.03,

"null": 0.03,

"else": 0.03,

"return": 0.13,

"var": 0.13,

"if": 0.16,

"function": 0.18,

"this": 0.18,

}

def allWhitespace(str):

for c in str:

if not(c in string.whitespace):

return False

return True

def parseKeywords(keywordsText):

if sys.platform == "cygwin":

keywordsText = keywordsText.replace("\r\n", "\n")

lines = keywordsText.split("\n")

lines = [line.split("#")[0] for line in lines]

lines = [line for line in lines if (not allWhitespace(line))]

name = lines[0].split()

terminator = lines[-1]

if not name[0] == "@begin":

raise Exception("expected description beginning with @begin")

if not terminator == "@end":

raise Exception("expected description ending with @end")

lines = lines[1:-1] # trim off the old heading

return [line.split() for line in lines]

def makePadding(size):

str = ""

for i in range(size):

str = str + " "

return str

class Trie:

def __init__(self, prefix):

self.prefix = prefix

self.keys = {}

self.value = None

def insert(self, key, value):

if len(key) == 0:

self.value = value

return

if not (key[0] in self.keys):

self.keys[key[0]] = Trie(key[0])

self.keys[key[0]].insert(key[1:], value)

def coalesce(self):

keys = {}

for k, v in self.keys.items():

t = v.coalesce()

keys[t.prefix] = t

self.keys = keys

if self.value != None:

return self

if len(self.keys) != 1:

return self

prefix, suffix = next(iter(self.keys.items()))

res = Trie(self.prefix + prefix)

res.value = suffix.value

res.keys = suffix.keys

return res

def fillOut(self, prefix=""):

self.fullPrefix = prefix + self.prefix

weight = 0

if self.fullPrefix in keyWordWeights:

weight = weight + keyWordWeights[self.fullPrefix]

self.selfWeight = weight

for trie in self.keys.values():

trie.fillOut(self.fullPrefix)

weight = weight + trie.weight

self.keys = [(trie.prefix, trie) for trie in sorted(self.keys.values(), key=operator.attrgetter('weight'), reverse=True)]

self.weight = weight

def printSubTreeAsC(self, typeName, indent):

str = makePadding(indent)

if self.value != None:

print(str + "if (cannotBeIdentPartOrEscapeStart(code[%d])) [[likely]] {" % (len(self.fullPrefix)))

print(str + " internalShift<%d>();" % len(self.fullPrefix))

print(str + " if (shouldCreateIdentifier)")

print(str + (" data->ident = &m_vm.propertyNames->%sKeyword;" % self.fullPrefix))

print(str + " return " + self.value + ";")

print(str + "}")

rootIndex = len(self.fullPrefix)

itemCount = 0

for k, trie in self.keys:

baseIndex = rootIndex

if (baseIndex > 0) and (len(k) == 3):

baseIndex = baseIndex - 1

k = trie.fullPrefix[baseIndex] + k

test = [("'%s'" % c) for c in k]

if len(test) == 1:

comparison = "code[%d] == %s" % (baseIndex, test[0])

else:

base = "code"

if baseIndex > 0:

base = "code + %d" % baseIndex

comparison = ("compareCharacters(%s, " % (base,)) + ", ".join(test) + ")"

if itemCount == 0:

print(str + "if (" + comparison + ") {")

else:

print(str + "} else if (" + comparison + ") {")

trie.printSubTreeAsC(typeName, indent + 4)

itemCount = itemCount + 1

if itemCount == len(self.keys):

print(str + "}")

def maxLength(self):

max = len(self.fullPrefix)

for (_, trie) in self.keys:

l = trie.maxLength()

if l > max:

max = l

return max

def printAsC(self):

print("WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN")

print("")

print("namespace JSC {")

print("")

print("static ALWAYS_INLINE bool cannotBeIdentPartOrEscapeStart(Latin1Character);")

print("static ALWAYS_INLINE bool cannotBeIdentPartOrEscapeStart(char16_t);")

# max length + 1 so we don't need to do any bounds checking at all

print("static constexpr int maxTokenLength = %d;" % (self.maxLength() + 1))

print("")

print("template <>")

print("template <bool shouldCreateIdentifier> ALWAYS_INLINE JSTokenType Lexer<char16_t>::parseKeyword(JSTokenData* data)")

print("{")

print(" ASSERT(m_codeEnd - m_code >= maxTokenLength);")

print("")

print(" const char16_t* code = m_code;")

self.printSubTreeAsC("UCHAR", 4)

print(" return IDENT;")

print("}")

print("")

print("template <>")

print("template <bool shouldCreateIdentifier> ALWAYS_INLINE JSTokenType Lexer<Latin1Character>::parseKeyword(JSTokenData* data)")

WebKit/Source/JavaScriptCore/KeywordLookupGenerator.py at main · WebKit/WebKit · GitHub

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