From 16eb62608bbec4781621b67550d3c2ebf9c00ff8 Mon Sep 17 00:00:00 2001
From: Peter Wu <lekensteyn@gmail.com>
Date: Wed, 30 Nov 2011 19:09:16 +0000
Subject: Support for evil goto and labels (debugging aid!!!)

---
 pp2cc.py | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/pp2cc.py b/pp2cc.py
index ca50191..78ce05d 100755
--- a/pp2cc.py
+++ b/pp2cc.py
@@ -289,10 +289,15 @@ class LinkedNode(object):
             if defined_names is None:
                 raise RuntimeError("No object found for storing variables")
             self.variables = Variables(defined_names, parent_variables)
+        # Identifiers which are in use (think of variables and labels)
+        self.defined_names = defined_names
         if not self.variables:
             raise RuntimeError("No variables object found")
         if level_increment:
             self.incrementLevel()
+        # labels are limited to function contexts
+        if self.type == "FuncDef":
+            self.goto_labels = {}
     def handle_post_lines(self, lines):
         """Add post-increment lines to the lines list and clear the queue"""
         lines += self.post_lines
@@ -372,6 +377,32 @@ class LinkedNode(object):
         if self.parent:
             return self.parent.getContinueNode()
         return None
+    def setLabel(self, label_name):
+        """Sets the label for this node"""
+        if self.parent:
+            function = self.parent.getFunctionNode()
+        if not self.parent or not function:
+            raise RuntimeError("Labels are only allowed in functions")
+        if label_name in function.goto_labels:
+            raise RuntimeError("Duplicate label '{}'".format(label_name))
+
+        label_asm = "lbl_" + label_name
+        i = 0
+        while label_asm in self.defined_names:
+            label_asm = "lbl_" + label_name + str(i)
+            i += 1
+
+        function.goto_labels[label_name] = label_asm
+    def lookupLabel(self, label_name):
+        """Returns the label name as it appears in assembly for label_name"""
+        # get the nearest function for this node
+        if self.parent:
+            function = self.parent.getFunctionNode()
+        if not self.parent or not function:
+            raise RuntimeError("Labels are only allowed in functions")
+        if label_name in function.goto_labels:
+            return function.goto_labels[label_name]
+        raise RuntimeError("Label '{}' used but not defined".format(name))
 
 class Function(object):
     def __init__(self, node):
@@ -1301,6 +1332,19 @@ class Parse(object):
         lines.append(self.asm.binary_op("LOAD", name_reg,
                                         "[" + name_reg + "+" + index_reg + "]"))
         return lines
+    def parseLabel(self, linked_node):
+        lines = []
+        label_name = linked_node.node.name
+        linked_node.setLabel(label_name)
+        lines.append(self.asm.noop(label_name))
+        lines += self.parseStatement(linked_node.node.stmt, linked_node)
+        return lines
+    def parseGoto(self, linked_node):
+        """Provides support for the infinitely abused goto statement. Use it
+        for debugging only!
+        """
+        label_name = linked_node.lookupLabel(linked_node.node.name)
+        return [self.asm.branch_op("BRA", label_name)]
     def parseStatement(self, node, parent_linked_node, level_increment=False):
         linked_node = LinkedNode(node, parent_linked_node, level_increment=level_increment)
         self.asm.level = linked_node.level
-- 
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