From 95ddeb4012c4e6a9a136ef2785116a7ba66985ab Mon Sep 17 00:00:00 2001
From: Dave Halter <davidhalter88@gmail.com>
Date: Wed, 13 Jun 2018 00:54:18 +0200
Subject: [PATCH] Factor out start_symbol into a better position

---
 parso/pgen2/grammar.py |  8 ++++++--
 parso/pgen2/pgen.py    | 11 +++--------
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/parso/pgen2/grammar.py b/parso/pgen2/grammar.py
index bb51530..b2aa96d 100644
--- a/parso/pgen2/grammar.py
+++ b/parso/pgen2/grammar.py
@@ -70,7 +70,7 @@ class Grammar(object):
 
     """
 
-    def __init__(self, bnf_text):
+    def __init__(self, bnf_text, start_symbol):
         self.symbol2number = {}
         self.number2symbol = {}
         self.states = []
@@ -80,7 +80,11 @@ class Grammar(object):
         self.tokens = {}
         self.symbol2label = {}
         self.label2symbol = {}
-        self.start = 256
+        self.start_symbol = start_symbol
+
+    @property
+    def start_symbol(self):
+        return self.symbol2number[self.start_symbol]
 
     def report(self):
         """Dump the grammar tables to standard output, for debugging."""
diff --git a/parso/pgen2/pgen.py b/parso/pgen2/pgen.py
index 1637c3d..0965416 100644
--- a/parso/pgen2/pgen.py
+++ b/parso/pgen2/pgen.py
@@ -25,10 +25,9 @@ from parso.utils import parse_version_string
 
 
 class ParserGenerator(object):
-    def __init__(self, dfas, start_symbol, token_namespace):
+    def __init__(self, dfas, token_namespace):
         self._token_namespace = token_namespace
         self.dfas = dfas
-        self.start_symbol = start_symbol
 
     def make_grammar(self, grammar):
         self._first = {}  # map from symbol name to set of tokens
@@ -36,9 +35,6 @@ class ParserGenerator(object):
 
         names = list(self.dfas.keys())
         names.sort()
-        # TODO do we still need this?
-        names.remove(self.start_symbol)
-        names.insert(0, self.start_symbol)
         for name in names:
             i = 256 + len(grammar.symbol2number)
             grammar.symbol2number[name] = i
@@ -55,7 +51,6 @@ class ParserGenerator(object):
                 states.append(arcs)
             grammar.states.append(states)
             grammar.dfas[grammar.symbol2number[name]] = (states, self._make_first(grammar, name))
-        grammar.start = grammar.symbol2number[self.start_symbol]
         return grammar
 
     def _make_first(self, grammar, name):
@@ -419,5 +414,5 @@ def generate_grammar(bnf_grammar, token_namespace):
     own parser.
     """
     dfas, start_symbol = _GrammarParser(bnf_grammar)._parse()
-    p = ParserGenerator(dfas, start_symbol, token_namespace)
-    return p.make_grammar(Grammar(bnf_grammar))
+    p = ParserGenerator(dfas, token_namespace)
+    return p.make_grammar(Grammar(bnf_grammar, start_symbol))