Translated YACC and LEX to a single PLY file.

src/parser.py

+#!/usr/bin/python
+import ply.lex as lex
+import ply.yacc as yacc
+
+tokens = ('NEWLINE', 'WORD', 'COMMENT', 'DIRECTIVE', 'COMMA', 'COLON')
+
+# Tokens
+def t_NEWLINE(t):
+    r'\n+'
+    t.lexer.lineno += t.value.count('\n')
+    return t
+
+def t_COLON(t):
+    r':'
+    return t
+
+def t_COMMA(t):
+    r','
+    return t
+
+def t_COMMENT(t):
+    r'\#.*'
+    return t
+
+def t_DIRECTIVE(t):
+    r'\..*'
+    return t
+
+def t_offset_address(t):
+    r'[0-9]+(\([a-zA-Z0-9$_.]+\))?'
+    t.type = 'WORD'
+    return t
+
+def t_WORD(t):
+    r'[a-zA-Z0-9$_.]+'
+    return t
+
+# Ignore whitespaces
+t_ignore = ' \t'
+
+def t_error(t):
+    print('Illegal character "%s"' % t.value[0])
+    t.lexer.skip(1)
+
+# Build the lexer
+lexer = lex.lex()
+
+# Parsing rules
+precedence = (
+    ('nonassoc', 'COLON', 'COMMA'),
+    ('nonassoc', 'COMMENT', 'DIRECTIVE'),
+    ('nonassoc', 'WORD'),
+    )
+
+def p_input(p):
+    '''input :
+             | input line'''
+    pass
+
+def p_line_instruction(p):
+    'line : instruction NEWLINE'
+    pass
+
+def p_line_comment(p):
+    'line : COMMENT NEWLINE'
+    print 'comment line', list(p)[1:]
+
+def p_line_inline_comment(p):
+    'line : instruction COMMENT NEWLINE'
+    print 'inline comment', list(p)[1:]
+
+def p_instruction_command(p):
+    'instruction : command'
+    pass
+
+def p_instruction_directive(p):
+    'instruction : DIRECTIVE'
+    print 'directive', list(p)[1:]
+
+def p_instruction_label(p):
+    'instruction : WORD COLON'
+    print 'label', list(p)[1:]
+
+def p_command_3(p):
+    'command : WORD WORD COMMA WORD COMMA WORD'
+    print 'command with 3 args', list(p)[1:]
+
+def p_command_2(p):
+    'command : WORD WORD COMMA WORD'
+    print 'command with 2 args', list(p)[1:]
+
+def p_command_1(p):
+    'command : WORD WORD'
+    print 'command with 1 args', list(p)[1:]
+
+def p_error(p):
+    print 'Syntax error at "%s"' % p.value
+
+yacc.yacc()
+yacc.parse(open('hello.s').read())
+
+#lexer.input(open('hello.s').read())
+#
+#while True:
+#    tok = lexer.token()
+#
+#    if not tok:
+#        break
+#
+#    print tok
+
+#while 1:
+    #try:
+    #    s = input('calc > ')  # Use raw_input on Python 2
+    #except EOFError:
+    #    break
+    #yacc.parse(s)