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django_libsass.py
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django_libsass.py
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import base64
import json
import os
import re
import sass
from compressor.filters.base import FilterBase
from django.conf import settings
from django.contrib.staticfiles.finders import get_finders
from django.templatetags.static import static as django_static
def static(path):
"""
Use the Django builtin static file resolver to return an absolute path
usable as CSS url() argument. Sass equivalent of the 'static' template
tag.
"""
return django_static(path)
OUTPUT_STYLE = getattr(settings, 'LIBSASS_OUTPUT_STYLE', 'nested')
SOURCE_COMMENTS = getattr(settings, 'LIBSASS_SOURCE_COMMENTS', settings.DEBUG)
CUSTOM_FUNCTIONS = getattr(settings, 'LIBSASS_CUSTOM_FUNCTIONS', {'static': static})
SOURCEMAPS = getattr(settings, 'LIBSASS_SOURCEMAPS', False)
PRECISION = getattr(settings, 'LIBSASS_PRECISION', None) # None use libsass default
ADDITIONAL_INCLUDE_PATHS = getattr(settings, 'LIBSASS_ADDITIONAL_INCLUDE_PATHS', None)
INCLUDE_PATHS = None # populate this on first call to 'get_include_paths'
def get_include_paths():
"""
Generate a list of include paths that libsass should use to find files
mentioned in @import lines.
"""
global INCLUDE_PATHS
if INCLUDE_PATHS is not None:
return INCLUDE_PATHS
include_paths = []
# Look for staticfile finders that define 'storages'
for finder in get_finders():
try:
storages = finder.storages
except AttributeError:
continue
for storage in storages.values():
try:
include_paths.append(storage.path('.'))
except NotImplementedError:
# storages that do not implement 'path' do not store files locally,
# and thus cannot provide an include path
pass
global ADDITIONAL_INCLUDE_PATHS
if ADDITIONAL_INCLUDE_PATHS:
include_paths.extend(ADDITIONAL_INCLUDE_PATHS)
INCLUDE_PATHS = include_paths
return include_paths
def prefix_sourcemap(sourcemap, base_path):
decoded_sourcemap = json.loads(sourcemap)
source_urls = []
include_paths = get_include_paths()
for source_filename in decoded_sourcemap['sources']:
# expand source_filename into an absolute file path
full_source_path = os.path.normpath(os.path.join(base_path, source_filename))
# look for a path in include_paths that is a prefix of full_source_path
for path in include_paths:
if full_source_path.startswith(path):
# A matching path has been found; take the remainder as a relative path.
# include_paths entries do not include a trailing slash;
# [len(path) + 1:] ensures that we trim the path plus trailing slash
remainder = full_source_path[len(path) + 1:]
# Invoke the 'static' template tag to turn the relative path into a URL
source_urls.append(django_static(remainder))
break
else:
# no matching path was found in include_paths; return the original source filename
# as a fallback
source_urls.append(source_filename)
decoded_sourcemap['sources'] = source_urls
return json.dumps(decoded_sourcemap)
def embed_sourcemap(output, sourcemap):
encoded_sourcemap = base64.standard_b64encode(
sourcemap.encode('utf-8')
)
sourcemap_fragment = 'sourceMappingURL=data:application/json;base64,{} '\
.format(encoded_sourcemap.decode('utf-8'))
url_re = re.compile(r'sourceMappingURL=[^\s]+', re.M)
output = url_re.sub(sourcemap_fragment, output)
return output
def compile(**kwargs):
"""Perform sass.compile, but with the appropriate include_paths for Django added"""
kwargs = kwargs.copy()
if PRECISION is not None:
kwargs['precision'] = PRECISION
kwargs['include_paths'] = (kwargs.get('include_paths') or []) + get_include_paths()
custom_functions = CUSTOM_FUNCTIONS.copy()
custom_functions.update(kwargs.get('custom_functions', {}))
kwargs['custom_functions'] = custom_functions
if SOURCEMAPS and kwargs.get('filename', None):
# We need to pass source_map_file to libsass so it generates
# correct paths to source files.
base_path = os.path.dirname(kwargs['filename'])
sourcemap_filename = os.path.join(base_path, 'sourcemap.map')
kwargs['source_map_filename'] = sourcemap_filename
libsass_output, sourcemap = sass.compile(**kwargs)
sourcemap = prefix_sourcemap(sourcemap, base_path)
output = embed_sourcemap(libsass_output, sourcemap)
else:
output = sass.compile(**kwargs)
return output
class SassCompiler(FilterBase):
def __init__(self, content, attrs=None, filter_type=None, charset=None, filename=None):
# FilterBase doesn't handle being passed attrs, so fiddle the signature
super(SassCompiler, self).__init__(content=content,
filter_type=filter_type,
filename=filename)
def input(self, **kwargs):
if self.filename:
return compile(filename=self.filename,
output_style=OUTPUT_STYLE,
source_comments=SOURCE_COMMENTS)
else:
return compile(string=self.content,
output_style=OUTPUT_STYLE)