Add first version of the c parser

Add:
    c.py
        - CTreeCutter class is very similar to PyTreeCutter. It utilizes
          self.cache as opposed to PyTreeCutter which doesn't yet.
        - CTreeCutter visit functions simply add start and end lines of
          the node to the cache, and visit_Decl pushes the cache onto
          accum.
        - parse_c performs a task identical to parse_py.  However, many
          c files need to be pre-processed before they are parsed.

bitshift/parser/c.py

@@ -1,3 +1,106 @@
+from pycparser import c_parser, c_ast
 
-def parse_c():
-    pass
+class CTreeCutter(c_ast.NodeVisitor):
+    """
+    Local node visitor for c abstract syntax trees.
+
+    :ivar accum: (dict) Information on variables, functions, and structs
+        accumulated from an abstract syntax tree.
+
+    :ivar cache: (dict or None) Information stored about parent nodes. Added
+        to accum when node reaches the lowest possible level.
+
+    .. todo::
+        Add visit function for c_ast.ID to record all uses of a variable.
+
+        Use self.cache to store extra information about variables.
+    """
+
+    def __init__(self):
+        """
+        Create a CTreeCutter instance.
+        """
+
+        self.accum = {'vars': {}, 'functions': {}, 'structs': {}}
+        self.cache = None
+
+    def start_n_end(self, node):
+        pass
+
+    def visit_FuncDecl(self, node):
+        """
+        Visits FuncDecl nodes in a tree.  Adds relevant data about them to accum
+            after visiting all of its children as well.
+
+        :param node: The current node.
+
+        :type node: c_ast.FuncDecl
+
+        .. todo::
+            Add other relevant information about functions like parameters and
+                return type.
+        """
+
+        self.cache['group'] = 'functions'
+        self.cache['meta']['end_ln'] = node.coord.line
+        self.cache['meta']['end_col'] = node.coord.column
+
+        self.generic_visit(node)
+
+    def visit_Struct(self, node):
+        """
+        Visits Struct nodes in a tree.  Adds relevant data about them to accum
+            after visiting all of its children as well.
+
+        :param node: The current node.
+
+        :type node: c_ast.Struct
+
+        .. todo::
+            Find other relevant information to add about structs.
+        """
+
+        self.cache['group'] = 'structs'
+        self.cache['meta']['end_ln'] = node.coord.line
+        self.cache['meta']['end_col'] = node.coord.column
+
+        self.generic_visit(node)
+
+    def visit_Decl(self, node):
+        """
+        Visits Decl nodes in a tree.  Adds relevant data about them to accum
+            after visiting all of its children as well.
+
+        :param node: The current node.
+
+        :type node: c_ast.Decl
+        """
+
+        self.cache = {'group': 'vars', 'meta': {}}
+
+        self.cache['meta']['start_ln'] = node.coord.line
+        self.cache['meta']['start_col'] = node.coord.column
+        self.cache['meta']['end_ln'] = node.coord.line
+        self.cache['meta']['end_col'] = node.coord.column
+
+        self.generic_visit(node)
+
+        self.accum[self.cache['group']][node.name] = self.cache['meta']
+        self.cache = None
+
+def parse_c(codelet):
+    """
+    Adds 'symbols' field to the codelet after parsing the c code.
+
+    :param codelet: The codelet object to parsed.
+
+    :type code: Codelet
+
+    .. todo::
+        Preprocess c code so that no ParseErrors are thrown.
+    """
+
+    tree = c_parser.CParser().parse(codelet.code)
+    cutter = CTreeCutter()
+    cutter.visit(tree)
+    codelet.symbols = cutter.accum