parser_bug_fix (#10)

* Add tests that fail

* Added default snippet to be retried when stack is empty

* Added docs for implicit snippet

* Added tests for implicit snippet

docs/contributing.rst

@@ -111,6 +111,19 @@ This should be translated to:
 Character :code:`>` is used to donate the inside of a snippet in snippet definitions.
 This is why all occurrences of :code:`<` and :code:`&` are translated to :code:`>`.
 
+Implicit snippet
+""""""""""""""""
+
+Consider following example:
+
+.. code-block:: text
+
+    for>if<while
+
+The :code:`while` is not a part of :code:`for` snippet.
+Parser creates an implicit :code:`block` snippet at the beginning.
+:code:`block` snippet is implemented as a list of sub-snippets in new lines.
+
 
 Syntax tree
 ^^^^^^^^^^^

homotopy/parser.py

@@ -61,7 +61,7 @@ def merge_stack(stack):
         """
         last_tree = stack.pop()
         if last_tree != SimpleSnippet(''):
-            next_tree = stack.pop()
+            next_tree = stack.pop() if stack else SimpleSnippet("block")
             stack.append(CompositeSnippet(next_tree, Parser.in_operator, last_tree))
 
 

homotopy/stdlib/cpp.json

@@ -15,5 +15,7 @@
   {"name": "prot_extend","language": "C++","snippet": ": protected %%%"},
   {"name": "func","language": "C++","snippet": "### $$$({{params}}){\n{{inside_block}}\n}"},
   {"name": "params","language": "C++","snippet": "### $$${{opt_params}}"},
-  {"name": "opt_params","language": "C++","snippet": ", ### $$${{opt_params}}"}
+  {"name": "opt_params","language": "C++","snippet": ", ### $$${{opt_params}}"},
+  {"name": "block","language": "C++","snippet": ">>>{{opt_block}}"},
+  {"name": "opt_block","language": "C++","snippet": "\n>>>{{opt_block}}"}
 ]

test/testParser.py

@@ -68,3 +68,28 @@ def test_into(self):
                                                   SimpleSnippet('if'))), '>',
                              SimpleSnippet('if'))
                          )
+
+        self.assertEqual(parser.parse('for&for'),
+                         CompositeSnippet(
+                             CompositeSnippet(
+                                 SimpleSnippet('block'),
+                                 '>',
+                                 SimpleSnippet('for')),
+                             '>',
+                             SimpleSnippet('for')
+                         ))
+
+        self.assertEqual(parser.parse('for>if<if'),
+                         CompositeSnippet(
+                             CompositeSnippet(
+                                 SimpleSnippet('block'),
+                                 '>',
+                                 CompositeSnippet(
+                                     SimpleSnippet('for'),
+                                     '>',
+                                     SimpleSnippet('if')
+                                 )
+                             ),
+                             '>',
+                             SimpleSnippet('if')
+                         ))