add lexer skeleton

parser/lexer.py

@@ -0,0 +1,38 @@
+
+import ply.lex as lex
+
+reserved = {
+        'C': 'C',
+        }
+
+tokens = [
+        'LPAREN',
+        'RPAREN',
+        'SEMICOLON',
+        'STRING',
+        'ID',
+        ] + list(reserved.values())
+
+t_LPAREN = r'\('
+t_RPAREN = r'\)'
+t_SEMICOLON = r';'
+t_STRING = r'"([^"])*"'
+
+t_ignore = ' \t\r'
+
+def t_ID(t):
+    r'[a-zA-Z_][a-zA-Z_0-9]*'
+    t.type = reserved.get(t.value, 'ID')
+    return t
+
+def t_newline(t):
+    r'\n+'
+    t.lexer.lineno += len(t.value)
+    return None
+
+def t_error(t):
+    print 'Illegal character "%s"' % t.value[0]
+    t.lexer.skip(1)
+
+def get_lexer():
+    return lex.lex()