Page context plugin

README.md

@@ -124,6 +124,24 @@ Cactus makes it easy to relatively link to pages and static assets inside your p
 
 Just use the URL you would normally use: don't forget the leading slash.
 
+You can add extra context to your pages. Just insert it on the top of the file like this:
+
+    name: koen
+    age: 29
+    {% extends "base.html" %}
+    …
+
+which will be converted to a dict: `{'name': 'koen', 'age': '29'}` and added to the context. 
+If the first line of your document should contain a colon, 
+you can use the more explicit style of metadata [as used in Jekyll](http://jekyllrb.com/docs/frontmatter/):
+
+    ---
+    Author: Me
+    Style:  Great
+    ---
+    Todays motto: whatever
+
+Always use `---` (three dashes) to fence the metadata.
 
 ### Templates
 

cactus/page.py

@@ -75,16 +75,11 @@ def context(self, data=None, extra=None):
         """
         The page context.
         """
-        if extra is None:
-            extra = {}
-
         context = {'__CACTUS_CURRENT_PAGE__': self,}
-
-        page_context, data = self.parse_context(data or self.data())
 
         context.update(self.site.context())
-        context.update(extra)
-        context.update(page_context)
+        if extra:
+            context.update(extra)
 
         return Context(context)
 
@@ -93,15 +88,8 @@ def render(self):
         Takes the template data with context and renders it to the final output file.
         """
 
-        data = self.data()
-        context = self.context(data=data)
-
-        # This is not very nice, but we already used the header context in the
-        # page context, so we don't need it anymore.
-        page_context, data = self.parse_context(data)
-
         context, data = self.site.plugin_manager.preBuildPage(
-            self.site, self, context, data)
+            self.site, self, self.context(data=self.data()), self.data())
 
         return Template(data).render(context)
 
@@ -125,37 +113,5 @@ def build(self):
 
             self.site.plugin_manager.postBuildPage(self)
 
-    def parse_context(self, data, splitChar=':'):
-        """
-        Values like
-
-        name: koen
-        age: 29
-
-        will be converted in a dict: {'name': 'koen', 'age': '29'}
-        """
-
-        if not self.is_html():
-            return {}, data
-
-        values = {}
-        lines = data.splitlines()
-        if not lines:
-            return {}, ''
-
-        for i, line in enumerate(lines):
-
-            if not line:
-                continue
-
-            elif splitChar in line:
-                line = line.split(splitChar)
-                values[line[0].strip()] = (splitChar.join(line[1:])).strip()
-
-            else:
-                break
-
-        return values, '\n'.join(lines[i:])
-
     def __repr__(self):
         return '<Page: {0}>'.format(self.source_path)

cactus/plugin/builtin/pagecontext.py

@@ -0,0 +1,120 @@
+#coding:utf-8
+import logging
+import re
+
+
+logger = logging.getLogger(__name__)
+
+
+class PageContextPlugin(object):
+    """
+    A plugin to extract context variables from the top of the file
+
+    TODO:
+    - read style of metadata from config
+    - read splitChar from config
+    """
+
+    def preBuildPage(self, page, context, data):
+        """
+        Update the page context with the context variables from the file
+        and delete them
+        """
+        if not page.is_html() or not data:
+            return context, data
+
+        lines = data.splitlines()
+
+        # Look into the file to decide on the style of metadata
+        # TODO: make that configurable
+        if lines[0].strip() == u'---':
+            page_context, lines = self.jekyll_style(lines)
+        else:
+            page_context, lines = self.simple_style(lines)
+        context.update(page_context)
+
+        return context, '\n'.join(lines)
+
+    def jekyll_style(self, lines):
+        if not lines or lines[0].strip() != u'---':  # no metadata
+            return {}, lines
+
+        context = {}
+        splitChar = ':'
+        for i, line in enumerate(lines[1:]):
+            if line.strip() == u'---':  # end of metadata
+                i += 1
+                break
+
+            try:
+                key, value = line.split(splitChar, 1)
+            except ValueError:
+                # splitChar not in line
+                logger.warning('Page context data seem to end in line %d', i)
+                break
+
+            context[key.strip()] = value.strip()
+
+        return context, lines[i+1:]
+
+    def simple_style(self, lines):
+        """
+        Only lines at the top of the file with a colon are metadata.
+        No multiline metadata
+        """
+        context = {}
+        splitChar = ':'
+
+        for i, line in enumerate(lines):
+
+            if splitChar not in line:
+                break
+
+            key, value = line.split(splitChar, 1)
+            context[key.strip()] = value.strip()
+
+        return context, lines[i:]
+
+    def multimarkdown_style(self, lines):
+        """
+        metadata as defined in http://fletcher.github.io/MultiMarkdown-4/metadata
+        """
+        context = {}
+        splitChar = ':'
+        fenced = False
+        key = None
+
+        if splitChar not in lines[0] and lines[0].strip() != u'---':
+            return {}, lines  # no metadata
+
+        for i, line in enumerate(lines):
+            # fencing is allowed but not required in multimarkdown
+            if line.strip() == u'---':
+                if i == 0:
+                    fenced = True
+                    continue
+                elif fenced:
+                    i += 1
+                    break
+
+            # a blank line triggers the beginning of the rest of the document
+            if not line.strip():
+                # if the file starts with a blank line, nothing should be changed
+                if i != 0:
+                    i += 1
+                break
+
+            # indented lines are the continuation of the previous value
+            # but multiline values don't have to be indented
+            if key and (re.match(r'\s', line) or not splitChar in line):
+                context[key] = ' '.join(
+                    (context[key], line.lstrip()))
+                continue
+
+            key, value = line.split(splitChar, 1)
+
+            # keys are lower cased and stripped of all whitespace
+            key = re.sub(r'\s', '', key.lower())
+            context[key] = value.strip()
+
+        return context, lines[i:]

cactus/site.py

@@ -16,6 +16,7 @@
 from cactus.plugin.builtin.cache import CacheDurationPlugin
 from cactus.plugin.builtin.context import ContextPlugin
 from cactus.plugin.builtin.ignore import IgnorePatternsPlugin
+from cactus.plugin.builtin.pagecontext import PageContextPlugin
 from cactus.plugin.loader import CustomPluginsLoader, ObjectsPluginLoader
 from cactus.plugin.manager import PluginManager
 from cactus.static.external.manager import ExternalManager
@@ -75,8 +76,11 @@ def __init__(self, path, config_paths=None, ui=None,
             [
                 CustomPluginsLoader(self.plugin_path),  # User plugins
                 ObjectsPluginLoader([   # Builtin plugins
-                    ContextPlugin(), CacheDurationPlugin(),
-                    IgnorePatternsPlugin(), PageContextCompatibilityPlugin(),
+                    ContextPlugin(),
+                    PageContextPlugin(),
+                    CacheDurationPlugin(),
+                    IgnorePatternsPlugin(),
+                    PageContextCompatibilityPlugin(),
                 ])
             ]
         )

cactus/tests/test_context.py

@@ -46,21 +46,61 @@ class TestCustomPageContext(SiteTestCase):
 
     Includes the built-in site context ('CACTUS'), and custom context.
     """
-    def setUp(self):
-        super(TestCustomPageContext, self).setUp()
-
-        page = "a: 1\n\tb: Monkey\n{{ a }}\n{{ b }}"
-        with open(os.path.join(self.site.page_path, "test.html"), "w") as f:
-            f.write(page)
-
-        self.site.build()
 
     def test_custom_context(self):
         """
         Test that custom context is provided
         """
-        with open(os.path.join(self.site.build_path, "test.html")) as f:
-            a, b = f.read().split("\n")
+        test_data = [
+            ("a: 1\n"
+             "\tb: Monkey\n"
+             "{{ a }}\n"
+             "{{ b }}",
 
-        self.assertEqual(a, "1")
-        self.assertEqual(b, "Monkey")
+             "1\n"
+             "Monkey"),
+
+            ("a: 1\n"
+             "\n"      # blank line inserted
+             "\tb: Monkey\n"
+             "{{ a }}",
+
+             "\n"
+             "\tb: Monkey\n"
+             "1"),
+
+            ("---\n"    # fenced
+             " a: 1\n"
+             "b: Monkey\n"
+             "---\n"
+             "{{ a }}\n"
+             "{{ b }}",
+
+             "1\n"
+             "Monkey"),
+
+            ("---\n"    # double fenced
+             " a: 1\n"
+             "b: Monkey\n"
+             "---\n"
+             "---\n"
+             "c: 1\n"
+             "---\n"
+             "{{ a }}\n"
+             "{{ b }}",
+
+             "---\n"
+             "c: 1\n"
+             "---\n"
+             "1\n"
+             "Monkey"),
+
+        ]
+        for page, expected in test_data:
+            with open(os.path.join(self.site.page_path, "test.html"), "w") as f:
+                f.write(page)
+
+            self.site.build()
+
+            with open(os.path.join(self.site.build_path, "test.html")) as f:
+                self.assertEqual(f.read(), expected)