From cb66f1ff4eea101f3219c1e6f3f363463c21c3ca Mon Sep 17 00:00:00 2001
From: Sei Lisa <sei-lisa@email.fake>
Date: Thu, 31 Jul 2014 05:41:15 +0200
Subject: [PATCH] Make if ... else if ... chains iterative, rather than
 recursive.

Should save some stack if the chain is long.
---
 lslopt/lslparse.py | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/lslopt/lslparse.py b/lslopt/lslparse.py
index 9522446..7b54187 100644
--- a/lslopt/lslparse.py
+++ b/lslopt/lslparse.py
@@ -1198,21 +1198,25 @@ class parser(object):
             if value is None:
                 return {'nt':'RETURN', 't':None}
             return {'nt':'RETURN', 't':None, 'ch':[self.autocastcheck(value, ReturnType)]}
-        if tok0 == 'IF': # TODO: Convert this into a loop for ELSE IF's, saving recursion
-            self.NextToken()
-            self.expect('(')
-            self.NextToken()
-            condition = self.Parse_expression()
-            self.expect(')')
-            self.NextToken()
-            then_branch = self.Parse_statement(ReturnType)
-            else_branch = None
-            if self.tok[0] == 'ELSE':
+        if tok0 == 'IF':
+            ret = {'nt':'IF', 't':None, 'ch':[]}
+            cur = ret
+            while True:
                 self.NextToken()
-                else_branch = self.Parse_statement(ReturnType)
-            if else_branch is not None:
-                return {'nt':'IF', 't':None, 'ch':[condition, then_branch, else_branch]}
-            return {'nt':'IF', 't':None, 'ch':[condition, then_branch]}
+                self.expect('(')
+                self.NextToken()
+                cur['ch'].append(self.Parse_expression())
+                self.expect(')')
+                self.NextToken()
+                cur['ch'].append(self.Parse_statement(ReturnType))
+                if self.tok[0] == 'ELSE':
+                    self.NextToken()
+                    if self.tok[0] == 'IF':
+                        cur['ch'].append({'nt':'IF', 't':None, 'ch':[]})
+                        cur = cur['ch'][2]
+                        continue
+                    cur['ch'].append(self.Parse_statement(ReturnType))
+                return ret
 
         if tok0 == 'WHILE':
             self.NextToken()