Misc cleanup

Author: lsankar4033

pycc/ll_parser.py

@@ -11,9 +11,7 @@ def __init__(self, grammar):
         # For convenience during parsing
         self.nonterminals = set([rule.sym.char for rule in grammar.rules])
 
-        first_sets = parse_table.build_first_sets(grammar)
-        follow_sets = parse_table.build_follow_sets(grammar, first_sets)
-        self.parse_table = parse_table.build_parse_table(grammar, first_sets, follow_sets)
+        self.parse_table = parse_table.build_parse_table(grammar)
 
     def parse(self, s):
         parse_stack = [END_SYMBOL, self.grammar.start_symbol.char]
@@ -32,7 +30,7 @@ def parse(self, s):
                 i += 1
 
             # predict attempt
-            elif parse_stack[-1] != s_list[i] and parse_stack[-1] in self.nonterminals:
+            elif parse_stack[-1] in self.nonterminals:
                 X = parse_stack.pop()
                 a = s_list[i]
 
@@ -45,7 +43,7 @@ def parse(self, s):
 
                 parse_stack = parse_stack + [sym for sym in syms if sym is not EPSILON_CHAR]
 
-            # mismatch
+            # terminal mismatch
             else:
                 return False
 

pycc/parse_table.py

@@ -2,7 +2,11 @@
 from pycc.grammar import NSym, TSym
 from pycc.constants import EPSILON_CHAR, END_SYMBOL
 
-def build_parse_table(grammar, first_sets, follow_sets):
+def build_parse_table(grammar, first_sets = None, follow_sets = None):
+    if first_sets is None or follow_sets is None:
+        first_sets = build_first_sets(grammar)
+        follow_sets = build_follow_sets(grammar, first_sets)
+
     parse_table = {}
 
     for rule in grammar.rules: