Repository: getnikola/nikola

Issue:
Add support for SASS and other preprocessors.



Discussion:

Resolving patch:
diff --git a/nikola/plugins/task/build_sass.py b/nikola/plugins/task/build_sass.py
new file mode 100644
--- /dev/null
+++ b/nikola/plugins/task/build_sass.py
@@ -0,0 +1,118 @@
+# -*- coding: utf-8 -*-
+
+# Copyright © 2012-2013 Roberto Alsina and others.
+
+# Permission is hereby granted, free of charge, to any
+# person obtaining a copy of this software and associated
+# documentation files (the "Software"), to deal in the
+# Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the
+# Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice
+# shall be included in all copies or substantial portions of
+# the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
+# OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+from __future__ import unicode_literals
+
+import codecs
+import glob
+import os
+import subprocess
+
+from nikola.plugin_categories import Task
+from nikola import utils
+
+LOGGER = utils.get_logger('build_sass')
+
+
+class BuildSass(Task):
+    """Generate CSS out of Sass sources."""
+
+    name = "build_sass"
+    sources_folder = "sass"
+    sources_ext = (".sass", ".scss")
+    compiler_name = "sass"
+
+    def gen_tasks(self):
+        """Generate CSS out of Sass sources."""
+
+        kw = {
+            'cache_folder': self.site.config['CACHE_FOLDER'],
+            'themes': self.site.THEMES,
+        }
+
+        # Find where in the theme chain we define the Sass targets
+        # There can be many *.sass/*.scss in the folder, but we only
+        # will build the ones listed in sass/targets
+        targets_path = utils.get_asset_path(os.path.join(self.sources_folder, "targets"), self.site.THEMES)
+        try:
+            with codecs.open(targets_path, "rb", "utf-8") as inf:
+                targets = [x.strip() for x in inf.readlines()]
+        except Exception:
+            targets = []
+
+        for theme_name in kw['themes']:
+            src = os.path.join(utils.get_theme_path(theme_name), self.sources_folder)
+            for task in utils.copy_tree(src, os.path.join(kw['cache_folder'], self.sources_folder)):
+                task['basename'] = 'prepare_sass_sources'
+                yield task
+
+        # Build targets and write CSS files
+        base_path = utils.get_theme_path(self.site.THEMES[0])
+        dst_dir = os.path.join(self.site.config['OUTPUT_FOLDER'], 'assets', 'css')
+        # Make everything depend on all sources, rough but enough
+        deps = glob.glob(os.path.join(
+            base_path,
+            self.sources_folder,
+            *("*{0}".format(ext) for ext in self.sources_ext)))
+
+        def compile_target(target, dst):
+            utils.makedirs(dst_dir)
+            src = os.path.join(kw['cache_folder'], self.sources_folder, target)
+            compiled = subprocess.check_output([self.compiler_name, src])
+            with open(dst, "wb+") as outf:
+                outf.write(compiled)
+
+        yield self.group_task()
+
+        # We can have file conflicts.  This is a way to prevent them.
+        # I orignally wanted to use sets and their cannot-have-duplicates
+        # magic, but I decided not to do this so we can show the user
+        # what files were problematic.
+        # If we didn’t do this, there would be a cryptic message from doit
+        # instead.
+        seennames = {}
+        for target in targets:
+            base = os.path.splitext(target)[0]
+            dst = os.path.join(dst_dir, base + ".css")
+
+            if base in seennames:
+                LOGGER.error(
+                    'Duplicate filenames for SASS compiled files: {0} and '
+                    '{1} (both compile to {2})'.format(
+                        seennames[base], target, base + ".css"))
+            else:
+                seennames.update({base: target})
+
+            yield {
+                'basename': self.name,
+                'name': dst,
+                'targets': [dst],
+                'file_dep': deps,
+                'task_dep': ['prepare_sass_sources'],
+                'actions': ((compile_target, [target, dst]), ),
+                'uptodate': [utils.config_changed(kw)],
+                'clean': True
+            }


Test patch: