diff piecrust/processing/sass.py @ 196:154b8df04829

processing: Add Compass and Sass processors. The Sass processor is similar to the Less processor, i.e. it tries to be part of the structured pipeline processing by using the mapfile produced by the Sass compiler in order to provide a list of dependencies. The Compass processor is completely acting outside of the pipeline, so the server won't know what's up to date and what's not. It's expected that the user will run `compass watch` to keep things up to date. However, it will require to pass the server's cache directory to put things in, so we'll need to add some easy way to get that path for the user.
author Ludovic Chabant <ludovic@chabant.com>
date Sun, 11 Jan 2015 23:08:49 -0800
parents
children c2ca72fb7f0b
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/piecrust/processing/sass.py	Sun Jan 11 23:08:49 2015 -0800
@@ -0,0 +1,151 @@
+import os
+import os.path
+import json
+import hashlib
+import logging
+import platform
+import subprocess
+from piecrust.processing.base import SimpleFileProcessor
+from piecrust.processing.tree import FORCE_BUILD
+
+
+logger = logging.getLogger(__name__)
+
+
+class SassProcessor(SimpleFileProcessor):
+    PROCESSOR_NAME = 'sass'
+
+    def __init__(self):
+        super(SassProcessor, self).__init__(
+                extensions={'scss': 'css', 'sass': 'css'})
+        self._conf = None
+        self._map_dir = None
+
+    def initialize(self, app):
+        super(SassProcessor, self).initialize(app)
+
+    def onPipelineStart(self, pipeline):
+        super(SassProcessor, self).onPipelineStart(pipeline)
+        self._map_dir = os.path.join(pipeline.tmp_dir, 'sass')
+        if not os.path.isdir(self._map_dir):
+            os.makedirs(self._map_dir)
+
+        # Ignore include-only Sass files.
+        pipeline.addSkipPatterns(['_*.scss', '_*.sass'])
+
+    def getDependencies(self, path):
+        if _is_include_only(path):
+            raise Exception("Include only Sass files should be ignored!")
+
+        map_path = self._getMapPath(path)
+        try:
+            with open(map_path, 'r') as f:
+                dep_map = json.load(f)
+        except IOError:
+            # Map file not found... rebuild.
+            logger.debug("No map file found for Sass file '%s' at '%s'. "
+                         "Rebuilding." % (path, map_path))
+            return FORCE_BUILD
+
+        if dep_map.get('version') != 3:
+            logger.warning("Unknown Sass map version. Rebuilding.")
+            return FORCE_BUILD
+
+        sources = dep_map.get('sources', [])
+        deps = list(map(_clean_scheme, sources))
+        return deps
+
+    def _doProcess(self, in_path, out_path):
+        self._ensureInitialized()
+
+        if _is_include_only(in_path):
+            raise Exception("Include only Sass files should be ignored!")
+
+        sourcemap = 'none'
+        if self.app.cache.enabled:
+            sourcemap = 'file'
+
+        args = [self._conf['bin'],
+                '--sourcemap=%s' % sourcemap,
+                '--style', self._conf['style']]
+
+        cache_dir = self._conf['cache_dir']
+        if cache_dir:
+            args += ['--cache-location', cache_dir]
+        else:
+            args += ['--no-cache']
+
+        for lp in self._conf['load_paths']:
+            args += ['-I', lp]
+
+        args += self._conf['options']
+        args += [in_path, out_path]
+        logger.debug("Processing Sass file: %s" % args)
+
+        # On Windows, we need to run the process in a shell environment
+        # otherwise it looks like `PATH` isn't taken into account.
+        shell = (platform.system() == 'Windows')
+        try:
+            retcode = subprocess.call(args, shell=shell)
+        except FileNotFoundError as ex:
+            logger.error("Tried running Sass processor with command: %s" %
+                         args)
+            raise Exception("Error running Sass processor. "
+                            "Did you install it?") from ex
+
+        # The sourcemap is generated next to the CSS file... there doesn't
+        # seem to be any option to override that, sadly... so we need to move
+        # it to the cache directory.
+        if self.app.cache.enabled:
+            src_map_file = out_path + '.map'
+            dst_map_file = self._getMapPath(in_path)
+            try:
+                os.rename(src_map_file, dst_map_file)
+            except OSError:
+                pass
+
+        if retcode != 0:
+            raise Exception("Error occured in Sass compiler. Please check "
+                            "log messages above for more information.")
+
+        return True
+
+    def _ensureInitialized(self):
+        if self._conf is not None:
+            return
+
+        self._conf = self.app.config.get('sass') or {}
+        self._conf.setdefault('bin', 'scss')
+        self._conf.setdefault('style', 'nested')
+        self._conf.setdefault('load_paths', [])
+        if not isinstance(self._conf['load_paths'], list):
+            raise Exception("The `sass/load_paths` configuration setting "
+                            "must be an array of paths.")
+        self._conf.setdefault('options', [])
+        if not isinstance(self._conf['options'], list):
+            raise Exception("The `sass/options` configuration setting "
+                            "must be an array of arguments.")
+
+        cache_dir = None
+        if self.app.cache.enabled:
+            cache_dir = os.path.join(self.app.cache_dir, 'sass')
+        self._conf.setdefault('cache_dir', cache_dir)
+
+    def _getMapPath(self, path):
+        map_name = "%s_%s.map" % (
+                os.path.basename(path),
+                hashlib.md5(path.encode('utf8')).hexdigest())
+        map_path = os.path.join(self._map_dir, map_name)
+        return map_path
+
+
+def _clean_scheme(p):
+    if p.startswith('file://'):
+        return p[7:]
+    return p
+
+
+def _is_include_only(path):
+    name = os.path.basename(path)
+    return len(name) > 0 and name[0] == '_'
+