Experimental parser: add back code generator

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
+#       with the distribution.
+#     * Neither the name of Google Inc. nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# 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:
+
+  @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:
+        code += ' || '
+      if r[0] == r[1]:
+        code += 'yych == %s' % r[0]
+      elif r[0] == 0:
+        code += 'yych <= %s' % r[1]
+      elif r[1] == 255: # FIXME: this should depend on the char type maybe??
+        code += 'yych >= %s' % r[0]
+      else:
+        code += '(yych >= %s && yych <= %s)' % (r[0], r[1])
+      first = False
+    code += ')'
+    return code
+
+  @staticmethod
+  def dfa_state_to_code(state, start_node_number):
+    # FIXME: add different check types (if, switch, lookup table)
+    # FIXME: add action + break / continue
+    # FIXME: add default action
+    code = '''
+code_%s:
+    fprintf(stderr, "state %s\\n");''' % (state.node_number(),
+                                          state.node_number())
+
+    action = state.action()
+    if action:
+      if action[1] == 'terminate':
+        code += 'return 0;'
+        return code
+      elif action[1] == 'terminate_illegal':
+        code += 'return 1;'
+        return code
+
+    code += '''
+    yych = *(++cursor_);
+    fprintf(stderr, "char at hand is %c (%d)\\n", yych, yych);\n'''
+
+    for key, s in state.transitions().items():
+      code += CodeGenerator.key_to_code(key)
+      code += ''' {
+        goto code_%s;
+    }
+''' % s.node_number()
+
+    if action:
+      code += '%s\nyych = *(--cursor_);\ngoto code_%s;\n' % (state.action()[1],
+                                                             start_node_number)
+    return code
+
+  @staticmethod
+  def dfa_to_code(dfa):
+    code = '''
+YYCTYPE yych = *cursor_;
+goto code_%s;
+''' % (dfa.start_state().node_number())
+    for n in dfa.all_states_iter():
+      code += CodeGenerator.dfa_state_to_code(n,
+                                              dfa.start_state().node_number())
+    return code