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# Copyright 2015 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import re
from feaTools import parser
from feaTools.writers.fdkSyntaxWriter import FDKSyntaxFeatureWriter
class FilterFeatureWriter(FDKSyntaxFeatureWriter):
"""Feature writer to detect invalid references and duplicate definitions."""
def __init__(self, refs=set(), name=None, isFeature=False):
"""Initializes the set of known references, empty by default."""
self.refs = refs
self.featureNames = set()
self.lookupNames = set()
self.tableNames = set()
self.languageSystems = set()
super(FilterFeatureWriter, self).__init__(
name=name, isFeature=isFeature)
# error to print when undefined reference is found in glyph class
self.classErr = ('Undefined reference "%s" removed from glyph class '
'definition %s.')
# error to print when undefined reference is found in sub or pos rule
subErr = ['Substitution rule with undefined reference "%s" removed']
if self._name:
subErr.append(" from ")
subErr.append("feature" if self._isFeature else "lookup")
subErr.append(' "%s"' % self._name)
subErr.append(".")
self.subErr = "".join(subErr)
self.posErr = self.subErr.replace("Substitution", "Positioning")
def _subwriter(self, name, isFeature):
"""Use this class for nested expressions e.g. in feature definitions."""
return FilterFeatureWriter(self.refs, name, isFeature)
def _flattenRefs(self, refs, flatRefs):
"""Flatten a list of references."""
for ref in refs:
if type(ref) == list:
self._flattenRefs(ref, flatRefs)
elif ref != "'": # ignore contextual class markings
flatRefs.append(ref)
def _checkRefs(self, refs, errorMsg):
"""Check a list of references found in a sub or pos rule."""
flatRefs = []
self._flattenRefs(refs, flatRefs)
for ref in flatRefs:
# trailing apostrophes should be ignored
if ref[-1] == "'":
ref = ref[:-1]
if ref not in self.refs:
print errorMsg % ref
# insert an empty instruction so that we can't end up with an
# empty block, which is illegal syntax
super(FilterFeatureWriter, self).rawText(";")
return False
return True
def classDefinition(self, name, contents):
"""Check that contents are valid, then add name to known references."""
if name in self.refs:
return
newContents = []
for ref in contents:
if ref not in self.refs and ref != "-":
print self.classErr % (ref, name)
else:
newContents.append(ref)
self.refs.add(name)
super(FilterFeatureWriter, self).classDefinition(name, newContents)
def gsubType1(self, target, replacement):
"""Check a sub rule with one-to-one replacement."""
if self._checkRefs([target, replacement], self.subErr):
super(FilterFeatureWriter, self).gsubType1(target, replacement)
def gsubType4(self, target, replacement):
"""Check a sub rule with many-to-one replacement."""
if self._checkRefs([target, replacement], self.subErr):
super(FilterFeatureWriter, self).gsubType4(target, replacement)
def gsubType6(self, precedingContext, target, trailingContext, replacement):
"""Check a sub rule with contextual replacement."""
refs = [precedingContext, target, trailingContext, replacement]
if self._checkRefs(refs, self.subErr):
super(FilterFeatureWriter, self).gsubType6(
precedingContext, target, trailingContext, replacement)
def gposType1(self, target, value):
"""Check a single positioning rule."""
if self._checkRefs([target], self.posErr):
super(FilterFeatureWriter, self).gposType1(target, value)
def gposType2(self, target, value, needEnum=False):
"""Check a pair positioning rule."""
if self._checkRefs(target, self.posErr):
super(FilterFeatureWriter, self).gposType2(target, value, needEnum)
# these rules may contain references, but they aren't present in Roboto
def gsubType3(self, target, replacement):
raise NotImplementedError
def feature(self, name):
"""Adds a feature definition only once."""
if name not in self.featureNames:
self.featureNames.add(name)
return super(FilterFeatureWriter, self).feature(name)
# we must return a new writer even if we don't add it to this one
return FDKSyntaxFeatureWriter(name, True)
def lookup(self, name):
"""Adds a lookup block only once."""
if name not in self.lookupNames:
self.lookupNames.add(name)
return super(FilterFeatureWriter, self).lookup(name)
# we must return a new writer even if we don't add it to this one
return FDKSyntaxFeatureWriter(name, False)
def languageSystem(self, langTag, scriptTag):
"""Adds a language system instruction only once."""
system = (langTag, scriptTag)
if system not in self.languageSystems:
self.languageSystems.add(system)
super(FilterFeatureWriter, self).languageSystem(langTag, scriptTag)
def table(self, name, data):
"""Adds a table only once."""
if name in self.tableNames:
return
self.tableNames.add(name)
self._instructions.append("table %s {" % name)
self._instructions.extend([" %s %s;" % line for line in data])
self._instructions.append("} %s;" % name)
def compileFeatureRE(name):
"""Compiles a feature-matching regex."""
# this is the pattern used internally by feaTools:
# https://github.com/typesupply/feaTools/blob/master/Lib/feaTools/parser.py
featureRE = list(parser.featureContentRE)
featureRE.insert(2, name)
featureRE.insert(6, name)
return re.compile("".join(featureRE))
def updateFeature(font, name, value):
"""Add a feature definition, or replace existing one."""
featureRE = compileFeatureRE(name)
if featureRE.search(font.features.text):
font.features.text = featureRE.sub(value, font.features.text)
else:
font.features.text += "\n" + value
def readFeatureFile(font, text, prepend=True):
"""Incorporate valid definitions from feature text into font."""
writer = FilterFeatureWriter(set(font.keys()))
if prepend:
text += font.features.text
else:
text = font.features.text + text
parser.parseFeatures(writer, text)
font.features.text = writer.write()
def writeFeatureFile(font, path):
"""Write the font's features to an external file."""
fout = open(path, "w")
fout.write(font.features.text)
fout.close()
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