Sketch for #50 - branch mangler

This is only slightly better. The insert point needs to walk
    with the for loop.

hy/core/__init__.py

@@ -20,15 +20,22 @@
 
 from hy.macros import process as mprocess
 
+import hy.mangle
+
 
 MACROS = [
-    "hy.core.bootstrap",  # defn, cond
+    "hy.core.bootstrap",
+    "hy.core.mangles",
 ]
 
 
 def process(tree):
     load_macros()
-    return mprocess(tree)
+    tree = mprocess(tree)
+    for m in hy.mangle.MANGLES:
+        m().mangle(tree)
+    print tree
+    return tree
 
 
 def load_macros():

hy/core/mangles.py

@@ -0,0 +1,52 @@
+# Copyright (c) 2013 Paul Tagliamonte <paultag@debian.org>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the "Software"),
+# to deal in the Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,
+# and/or sell copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+# DEALINGS IN THE SOFTWARE.
+
+from hy.models.expression import HyExpression
+from hy.models.symbol import HySymbol
+
+import hy.mangle
+
+
+class FunctionMangle(hy.mangle.Mangle):
+    hoistable = ["fn"]
+
+    def __init__(self):
+        self.series = 0
+
+    def unique_name(self):
+        self.series += 1
+        return "_hy_hoisted_fn_%s" % (self.series)
+
+    def visit(self, tree):
+        if isinstance(tree, HyExpression):
+            call = tree[0]
+            if isinstance(call, HyExpression) and len(call) != 0:
+                what = call[0]
+                if what in self.hoistable:
+                    name = self.unique_name()
+                    call = HyExpression([HySymbol("def"), name, call])
+                    self.hoist(call)
+                    tree.pop(0)
+                    entry = HySymbol(name)
+                    entry.replace(tree)
+                    tree.insert(0, entry)
+                    raise self.TreeChanged()
+
+hy.mangle.MANGLES.append(FunctionMangle)

hy/mangle.py

@@ -0,0 +1,99 @@
+# Copyright (c) 2013 Paul Tagliamonte <paultag@debian.org>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the "Software"),
+# to deal in the Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,
+# and/or sell copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+# DEALINGS IN THE SOFTWARE.
+
+from hy.models.expression import HyExpression
+# from hy.models.list import HyList
+
+MANGLES = []
+
+
+class Mangle(object):
+    """
+    Mangle (n.)
+
+        1. To mutilate or disfigure by battering, hacking, cutting,
+           or tearing. See Synonyms at batter1.
+
+        (but mostly hacking)
+    """
+
+    class TreeChanged(Exception):
+        pass
+
+    def _mangle(self, tree):
+        # Things that force a scope push to go into:
+        #
+        #  - Functions
+        #  - If
+        scopable = ["fn", "if"]
+        scoped = False
+
+        if isinstance(tree, HyExpression):
+            what = tree[0]
+            if what in scopable:
+                self.push_scope(tree)
+                scoped = True
+
+        if isinstance(tree, list):
+            for element in tree:
+                self.visit(element)
+                self._mangle(element)
+
+        if scoped:
+            self.pop_scope()
+
+    def hoist(self, what):
+        #print "HOIST: "
+        #print " --> (fro) ", what
+        #print " --> (to)  ", self.scope
+        scope = self.scope
+        point = 0
+
+        if isinstance(scope, HyExpression) and len(scope):
+            if scope[0] == 'fn':
+                point = 3
+
+        self.scope.insert(point, what)
+        #print " --> (aft) ", self.scope
+
+    def get_scope(self):
+        return self.scopes[0]
+
+    @property
+    def scope(self):
+        return self.get_scope()
+
+    def push_scope(self, tree):
+        self.scopes.insert(0, tree)
+
+    def pop_scope(self):
+        return self.scopes.pop(0)
+
+    def mangle(self, tree):
+        unfinished = True
+        while unfinished:
+            self.root = tree
+            self.scopes = []
+            self.push_scope(tree)
+            try:
+                self._mangle(tree)
+                unfinished = False
+            except self.TreeChanged:
+                pass