Experimental lexer generator: Add an option to add debug prints.

tools/lexer_generator/code_generator.py

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 10 matching lines @@
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 from dfa import Dfa
 
 class CodeGenerator:
+  debug = False
 
   @staticmethod
   def key_to_code(key):
     code = 'if ('
     first = True
     for (kind, r) in key.range_iter():
       if kind == 'CLASS': # FIXME: add class checks
         continue
       assert kind == 'LATIN_1'
       if not first:
@@ skipping 61 matching lines @@
 
   def __dfa_state_to_code(self, state):
     # FIXME: add different check types (if, switch, lookup table)
     # FIXME: add action + break / continue
     # FIXME: add default action
     code = ''
     if self.__start_node_number == state.node_number():
       code += '''
 code_start:
 '''
+
     code += '''
 code_%s:
-    //fprintf(stderr, "state %s\\n");
-''' % (state.node_number(),
-       state.node_number())
+''' % state.node_number()
+
+    if CodeGenerator.debug:
+      code += '''
+  fprintf(stderr, "state %s\\n");
+''' % state.node_number()
 
     entry_action = state.action().entry_action() if state.action() else None
     match_action = state.action().match_action() if state.action() else None
 
     if entry_action:
       code += self.__action_code_map[entry_action[0]](entry_action[1])
 
-    code += '''
-    //fprintf(stderr, "char at hand is %c (%d)\\n", yych, yych);\n'''
+    if CodeGenerator.debug:
+      code += '''
+  fprintf(stderr, "char at hand is %c (%d)\\n", yych, yych);
+'''
 
     for key, s in state.transitions().items():
       code += CodeGenerator.key_to_code(key)
       code += ''' {
         FORWARD();
         goto code_%s;
     }
 ''' % s.node_number()
 
     if match_action:
@@ skipping 19 matching lines @@
       code += self.__dfa_state_to_code(state)
       return code
     code = dfa.visit_all_states(f, code)
 
     default_action_code = ''
     assert(default_action and default_action.match_action())
     action = default_action.match_action()
     default_action_code = self.__action_code_map[action[0]](action[1])
     code += '''
   CHECK(false); goto code_start;
-default_action:
-  //fprintf(stderr, "default action\\n");
+default_action:'''
+    if CodeGenerator.debug:
+      code += '''
+fprintf(stderr, "default action\\n");
+'''
+    code += '''
   %s
   FORWARD();
   goto code_%s;
   return 0;
 }
 }
 }
 ''' % (default_action_code, self.__start_node_number)
     return code
 
   @staticmethod
   def rule_processor_to_code(rule_processor, use_mdfa):
     if use_mdfa:
       dfa = rule_processor.default_automata().minimal_dfa()
     else:
       dfa = rule_processor.default_automata().dfa()
     return CodeGenerator(dfa, rule_processor.default_action).__process()