将C语言源程序文件中的C89的32个关键字转换为大写，但不包括在注释里面的。 可以批处理文件，也可以通过管道输入，或者进入交互模式。 这是《编译原理及实践》的2.21习题的一个实践。

upper_keyword.py

#!/usr/bin/env python
#-*- coding:utf-8 -*-


"""
upper-keyword.py   ------- Change C source keyword which not in comment to  UPPER.

Author: Leslie Zhu
Email: [email protected]
Version: 1.0


upper_keyword:   read source and output with upper keyword(not in comment)
file_stream:     check and read a file line by line
parse_line:      parse each line based on status
status:          a list with each flag

"""

Usage="""

     Usage:  python upper_keyword.py infile.c

       e.g:

          $ python upper_keyword.py [?|-?|-h|--help]

          $ python upper_keyword.py FILE1.c FILE2.c FILE3.c [..]

          $ cat FILE1.c FILE2.c [..] | python upper_keyword.py

          $ python upper_keyword.py

          /* test: int a=3;*/
          // test: float b=3.0;*/

         int
         main()
         {
            int c=1;
         
            return c;
         }

         ^D

         /* test: int a=3;*/
         // test: float b=3.0;*/

         INT
         main()
         {
             INT c=1;
 
             RETURN c;
         }
            
"""

import os,sys

# init status list
# '/' :           status_0 = False          
# '*' :           status_1 = False          
# '//':           status_2 = False         
# '/*':           status_3 = False         
# '*/':           status_4 = False         
# not in comment: status_5 = True
status=[False,False,False,False,False,True]

# C89 32 keywords
keywords=['auto','enum','unsigned','break','extern',
          'return','void','case','float','short',
          'volatile','char','for','signed','while',
          'const','goto','sizeof','continue','if',
          'static','default','struct','do','int',
          'switch','double','long','typedef',
          'else','register','union']

# a keyword endswith token
tokens = [" ",";",",","(",")","{","}","\t",'\n']


def parse_line(line=""):
    "parse line and determine its status in C source comments,then upper the comments."

    outline = ""
    global status,keywords,tokens

    if status[2]: status[5] = True
    status[2] = False

    word_flag = False          # a flag for mark word in source file
    prev_word = ""         # init prev word split by blackspace     


    line = line
    length = len(line) - 1
    for i,c in enumerate(line):
        # update status 
        if status[5]:
            if c == '/':
                status=[True,False,False,False,False,False]
        elif status[0]:
            if c == '*' and not status[2]: status=[False,False,False,True,False,False]
            if c == '/' and not status[3]: status=[False,False,True,False,False,False]
        elif status[3]:
            if status[1] and c != '/': status[2] = False
            if c == '*': status=[False,True,False,True,False,False]
            if c == '/' and status[1]: status=[False,False,False,False,False,True]

        # depends on status
        if status[2] or status[3]:
            outline += str(c)
        elif c in ['/','*']:
            outline += str(c)
        else:
            if c != " " and not word_flag:
                word_flag = True
            if (c not in tokens and i != length) and word_flag:
                prev_word += str(c)
            if (c in tokens or i == length) and word_flag:
                word_flag = False
                if prev_word in keywords: 
                    prev_word = prev_word.upper()
                outline += prev_word
                prev_word = ""
            if (c in tokens or i == length) and not word_flag:
                outline += str(c)


    return outline


def file_stream(filename=None):
    if not os.path.exists(filename):
        print "File %s not exists!" % filename
        sys.exit(1)
    else:
        return open(filename).readlines()

def upper_keyword(data=sys.stdin):
    "read infile line by line and parse it."

    for line in data:
        print parse_line(line),

if __name__ == "__main__":
    if len(sys.argv) == 2 and sys.argv[1] in ["?","-?","-h","--help"]:
        print Usage
        sys.exit(0)
    if len(sys.argv) >= 2:
        for i in range(1,len(sys.argv)):
            upper_keyword(file_stream(sys.argv[i]))
    else:
        try:
            upper_keyword(sys.stdin.readlines())
        except (KeyboardInterrupt,EOFError,IOError):
            print Usage