Use more pythonic type checking

Use isinstance() and abstract base classes for checking available
functionality instead of strictly checking for base types. Among other
things, this allows for rendering any non-string sequences, iterators or
generators as lists (resolves #33) and for passing in any callable
instead of just plain functions.

diff --git a/chevron/renderer.py b/chevron/renderer.py
index 3c284d116aa8ce69ebf207c50fbd5ca21dc683d8..c66471d04d8a1a112b23a1342f06051fccee39f3 100644 (file)
--- a/chevron/renderer.py
+++ b/chevron/renderer.py
@@ -1,5 +1,9 @@
 # -*- coding: utf-8 -*-
 
+try:
+    from collections.abc import Sequence, Iterator, Callable
+except ImportError:  # python 2
+    from collections import Sequence, Iterator, Callable
 try:
     from .tokenizer import tokenize
 except (ValueError, SystemError):  # python 2
@@ -9,12 +13,16 @@ except (ValueError, SystemError):  # python 2
 import sys
 if sys.version_info[0] == 3:
     python3 = True
+    unicode_type = str
+    string_type = str
 
     def unicode(x, y):
         return x
 
 else:  # python 2
     python3 = False
+    unicode_type = unicode
+    string_type = basestring
 
 
 #
@@ -155,10 +163,9 @@ def render(template='', data={}, partials_path='.', partials_ext='mustache',
     A string containing the rendered template.
     """
 
-    function = type(render)
-
-    # If the template is a list
-    if type(template) is list:
+    # If the template is a seqeuence but not derived from a string
+    if isinstance(template, Sequence) and \
+            not isinstance(template, string_type):
         # Then we don't need to tokenize it
         # But it does need to be a generator
         tokens = (token for token in template)
@@ -194,7 +201,7 @@ def render(template='', data={}, partials_path='.', partials_ext='mustache',
         # If we're a literal tag
         elif tag == 'literal':
             # Add padding to the key and add it to the output
-            if type(key) != unicode:
+            if not isinstance(key, unicode_type):
                 key = unicode(key, 'utf-8')
             output += key.replace('\n', '\n' + (' ' * padding))
 
@@ -207,7 +214,7 @@ def render(template='', data={}, partials_path='.', partials_ext='mustache',
                 # (inverted tags do this)
                 # then get the un-coerced object (next in the stack)
                 thing = scopes[1]
-            if type(thing) != unicode:
+            if not isinstance(thing, unicode_type):
                 thing = unicode(str(thing), 'utf-8')
             output += _html_escape(thing)
 
@@ -215,7 +222,7 @@ def render(template='', data={}, partials_path='.', partials_ext='mustache',
         elif tag == 'no escape':
             # Just lookup the key and add it
             thing = _get_key(key, scopes)
-            if type(thing) != unicode:
+            if not isinstance(thing, unicode_type):
                 thing = unicode(str(thing), 'utf-8')
             output += thing
 
@@ -226,7 +233,7 @@ def render(template='', data={}, partials_path='.', partials_ext='mustache',
 
             # If the scope is a callable (as described in
             # https://mustache.github.io/mustache.5.html)
-            if type(scope) is function:
+            if isinstance(scope, Callable):
 
                 # Generate template text from tags
                 text = unicode('', 'utf-8')
@@ -268,8 +275,10 @@ def render(template='', data={}, partials_path='.', partials_ext='mustache',
                 else:  # python 2
                     output += rend.decode('utf-8')
 
-            # If the scope is a list
-            elif type(scope) is list:
+            # If the scope is a sequence, an iterator or generator but not
+            # derived from a string
+            elif isinstance(scope, (Sequence, Iterator)) and \
+                    not isinstance(scope, string_type):
                 # Then we need to do some looping
 
                 # Gather up all the tags inside the section