Added to Renderer class support for missing_tags (not finished yet).

Support for partial loading added.  Still need to support missing tags.

4 files changed, 79 insertions, 31 deletions

diff --git a/pystache/common.py b/pystache/common.py
index c1fd7a1..0d0ab01 100644
--- a/pystache/common.py
+++ b/pystache/common.py
@@ -26,6 +26,14 @@ def read(path):
         f.close()
 
 
+class MissingTags(object):
+
+    """Contains the valid values for Renderer.missing_tags."""
+
+    ignore = 'ignore'
+    strict = 'strict'
+
+
 class PystacheError(Exception):
     """Base class for Pystache exceptions."""
     pass
diff --git a/pystache/defaults.py b/pystache/defaults.py
index fcd04c3..a510cfe 100644
--- a/pystache/defaults.py
+++ b/pystache/defaults.py
@@ -17,6 +17,8 @@ except ImportError:
 import os
 import sys
 
+from pystache.common import MissingTags
+
 
 # How to handle encoding errors when decoding strings from str to unicode.
 #
@@ -36,6 +38,9 @@ STRING_ENCODING = sys.getdefaultencoding()
 # strings that arise from files.
 FILE_ENCODING = sys.getdefaultencoding()
 
+# How to handle missing tags when rendering a template.
+MISSING_TAGS = MissingTags.ignore
+
 # The starting list of directories in which to search for templates when
 # loading a template by file name.
 SEARCH_DIRS = [os.curdir]  # i.e. ['.']
diff --git a/pystache/renderer.py b/pystache/renderer.py
index 05c5e07..0c50577 100644
--- a/pystache/renderer.py
+++ b/pystache/renderer.py
@@ -8,7 +8,7 @@ This module provides a Renderer class to render templates.
 import sys
 
 from pystache import defaults
-from pystache.common import TemplateNotFoundError
+from pystache.common import TemplateNotFoundError, MissingTags
 from pystache.context import ContextStack
 from pystache.loader import Loader
 from pystache.renderengine import RenderEngine
@@ -27,6 +27,7 @@ else:
     _STRING_TYPES = (unicode, type(u"a".encode('utf-8')))
 
 
+
 class Renderer(object):
 
     """
@@ -49,7 +50,7 @@ class Renderer(object):
 
     def __init__(self, file_encoding=None, string_encoding=None,
                  decode_errors=None, search_dirs=None, file_extension=None,
-                 escape=None, partials=None):
+                 escape=None, partials=None, missing_tags=None):
         """
         Construct an instance.
 
@@ -104,6 +105,11 @@ class Renderer(object):
             argument to the built-in function unicode().  Defaults to the
             package default.
 
+          missing_tags: a string specifying how to handle missing tags.
+            If 'strict', an error is raised on a missing tag.  If 'ignore',
+            the value of the tag is the empty string.  Defaults to the
+            package default.
+
         """
         if decode_errors is None:
             decode_errors = defaults.DECODE_ERRORS
@@ -117,6 +123,9 @@ class Renderer(object):
         if file_extension is None:
             file_extension = defaults.TEMPLATE_EXTENSION
 
+        if missing_tags is None:
+            missing_tags = defaults.MISSING_TAGS
+
         if search_dirs is None:
             search_dirs = defaults.SEARCH_DIRS
 
@@ -131,6 +140,7 @@ class Renderer(object):
         self.escape = escape
         self.file_encoding = file_encoding
         self.file_extension = file_extension
+        self.missing_tags = missing_tags
         self.partials = partials
         self.search_dirs = search_dirs
         self.string_encoding = string_encoding
@@ -222,7 +232,7 @@ class Renderer(object):
 
         return load_template
 
-    # TODO: rename this to _make_resolve_partial().
+    # TODO: simplify this method.
     def _make_resolve_partial(self):
         """
         Return the resolve_partial function to pass to RenderEngine.__init__().
@@ -230,6 +240,11 @@ class Renderer(object):
         """
         if self.partials is None:
             load_template = self._make_load_template()
+
+            if self.missing_tags == MissingTags.strict:
+                return load_template
+            # Otherwise, ignore missing tags.
+
             def resolve_partial(name):
                 try:
                     return load_template(name)
@@ -243,14 +258,18 @@ class Renderer(object):
         # a nicer exception, etc).
         partials = self.partials
 
+        if self.missing_tags == MissingTags.strict:
+            def on_template_none(name, partials):
+                raise TemplateNotFoundError("Name %s not found in partials: %s" %
+                                            (repr(name), type(partials)))
+        else:
+            # Otherwise, ignore missing tags.
+            on_template_none = lambda name, partials: u''
+
         def resolve_partial(name):
             template = partials.get(name)
             if template is None:
-                return u''
-
-#            if template is None:
-#                raise TemplateNotFoundError("Name %s not found in partials: %s" %
-#                                            (repr(name), type(partials)))
+                return on_template_none(name, partials)
 
             # RenderEngine requires that the return value be unicode.
             return self._to_unicode_hard(template)
diff --git a/pystache/tests/test_renderer.py b/pystache/tests/test_renderer.py
index 04e9691..9c40d2a 100644
--- a/pystache/tests/test_renderer.py
+++ b/pystache/tests/test_renderer.py
@@ -124,6 +124,22 @@ class RendererInitTestCase(unittest.TestCase):
         renderer = Renderer(file_extension='foo')
         self.assertEqual(renderer.file_extension, 'foo')
 
+    def test_missing_tags(self):
+        """
+        Check that the missing_tags attribute is set correctly.
+
+        """
+        renderer = Renderer(missing_tags='foo')
+        self.assertEqual(renderer.missing_tags, 'foo')
+
+    def test_missing_tags__default(self):
+        """
+        Check the missing_tags default.
+
+        """
+        renderer = Renderer()
+        self.assertEqual(renderer.missing_tags, 'ignore')
+
     def test_search_dirs__default(self):
         """
         Check the search_dirs default.
@@ -457,19 +473,19 @@ class Renderer_MakeRenderEngineTests(unittest.TestCase, AssertStringMixin, Asser
 
         self.assertString(resolve_partial('foo'), u'')
 
-# TODO: add this test case back when we add support to Renderer for strict mode.
-#    def test__resolve_partial__not_found__default(self):
-#        """
-#        Check that resolve_partial provides a nice message when a template is not found.
+    def test__resolve_partial__not_found__strict__default(self):
+        """
+        Check that resolve_partial provides a nice message when a template is not found.
 
-#        """
-#        renderer = Renderer()
+        """
+        renderer = Renderer()
+        renderer.missing_tags = 'strict'
 
-#        engine = renderer._make_render_engine()
-#        resolve_partial = engine.resolve_partial
+        engine = renderer._make_render_engine()
+        resolve_partial = engine.resolve_partial
 
-#        self.assertException(TemplateNotFoundError, "File 'foo.mustache' not found in dirs: ['.']",
-#                             resolve_partial, "foo")
+        self.assertException(TemplateNotFoundError, "File 'foo.mustache' not found in dirs: ['.']",
+                             resolve_partial, "foo")
 
     def test__resolve_partial__not_found__dict(self):
         """
@@ -484,22 +500,22 @@ class Renderer_MakeRenderEngineTests(unittest.TestCase, AssertStringMixin, Asser
 
         self.assertString(resolve_partial('foo'), u'')
 
-# TODO: add this test case back when we add support to Renderer for strict mode.
-#    def test__resolve_partial__not_found__dict(self):
-#        """
-#        Check that resolve_partial provides a nice message when a template is not found.
+    def test__resolve_partial__not_found__strict__dict(self):
+        """
+        Check that resolve_partial provides a nice message when a template is not found.
 
-#        """
-#        renderer = Renderer()
-#        renderer.partials = {}
+        """
+        renderer = Renderer()
+        renderer.missing_tags = 'strict'
+        renderer.partials = {}
 
-#        engine = renderer._make_render_engine()
-#        resolve_partial = engine.resolve_partial
+        engine = renderer._make_render_engine()
+        resolve_partial = engine.resolve_partial
 
-        # Include dict directly since str(dict) is different in Python 2 and 3:
-        #   <type 'dict'> versus <class 'dict'>, respectively.
-#        self.assertException(TemplateNotFoundError, "Name 'foo' not found in partials: %s" % dict,
-#                             resolve_partial, "foo")
+       # Include dict directly since str(dict) is different in Python 2 and 3:
+       #   <type 'dict'> versus <class 'dict'>, respectively.
+        self.assertException(TemplateNotFoundError, "Name 'foo' not found in partials: %s" % dict,
+                             resolve_partial, "foo")
 
     ## Test the engine's literal attribute.