- osc.cli: added render module.

It provides a class to render templates.

osc/cli/render.py

@@ -0,0 +1,79 @@
+"""Provides methods and classes to render templates."""
+
+import sys
+
+from jinja2 import Environment, FileSystemLoader
+
+
+class Renderer(object):
+    """Renders a template."""
+
+    def __init__(self, path=None, loader=None):
+        """Constructs a new Renderer object.
+
+        Either path or loader has to be specified.
+
+        Keyword arguments:
+        loader -- a jinja2 template loader instance (default: None)
+        path -- list or str which represents template locations
+
+        """
+        if (path is None and loader is None
+            or path is not None and loader is not None):
+            raise ValueError('Either specify path oder loader')
+        if path is not None:
+            loader = FileSystemLoader(path)
+        self._env = Environment(loader=loader)
+        self._env.add_extension('jinja2.ext.do')
+
+    def _custom_template_names(self, template):
+        """Returns a list of custom template names.
+
+        template is the name of the original template.
+
+        """
+        splitted = template.rsplit('/', 1)
+        name = 'custom_' + splitted[-1]
+        ret = [name]
+        if len(splitted) == 2:
+            ret.append(splitted[0] + '/' + name)
+        return ret
+
+    def _render(self, template, out, *args, **kwargs):
+        """Renders template template.
+
+        out is a file or file-like object to which the rendered
+        template should be written to.
+        *args and **kwargs are passed to jinja2 Template's render
+        method.
+
+        """
+        names = self._custom_template_names(template)
+        names.append(template)
+        tmpl = self._env.select_template(names)
+        text = tmpl.render(*args, **kwargs)
+        try:
+            out.write(text)
+        except UnicodeEncodeError:
+            text = text.encode('utf-8')
+            out.write(text)
+
+    def render(self, template, *args, **kwargs):
+        """Renders template template.
+
+        Writes the rendered template to sys.stdout.
+        *args and **kwargs are passed to jinja2 Template's render
+        method.
+
+        """
+        self._render(template, sys.stdout, *args, **kwargs)
+
+    def render_error(self, template, *args, **kwargs):
+        """Renders template template.
+
+        Writes the rendered template to sys.stderr.
+        *args and **kwargs are passed to jinja2 Template's render
+        method.
+
+        """
+        self._render(template, sys.stderr, *args, **kwargs)