A source extractor for lightweight literate programming

The processFile() function handles all the processing for one DocBook source file.

# - - -   p r o c e s s F i l e   - - -

def processFile ( inFileName ):
    """Process one input file.

      [ inFileName is a string ->
          if inFileName names a readable, valid DocBook XML file ->
            output files named in that file  :=  code fragments
              designated for those files
            sys.stderr  +:=  error messages from processing that file,
                             if any
          else ->
            sys.stderr  +:=  error message ]
    """

The first step is to open the input file, and report errors if that fails.

    #-- 1 --
    # [ if inFileName names a readable file ->
    #     inFile  :=  that file opened for reading
    #   else ->
    #     sys.stderr  +:=  error message
    #     return ]
    try:
        inFile  =  open ( inFileName )
    except IOError, detail:
        sys.stderr.write ( "*** Can't open file '%s' for reading: %s\n" %
            (inFileName, detail) )
        return

The next step is to create a SAX parser. We first create a content handler object, an ArticleHandler object. This object contains the three handlers that observe start tags, text content, and end tags. See Section 4.7, “class ArticleHandler: The customized content handler”.

    #-- 2 --
    # [ ch  :=  an ArticleHandler instance ]
    ch  =  ArticleHandler()

The remaining steps obey the usual SAX protocol. We create a new SAX parser with the make_parser() function, associate our content handler with it using its .setContentHandler() method, and then use its .parse() method to read inFile.

This process is fairly well-described on page 53 of the O'Reilly Python and XML book. (However, the example on this page does not run unless you first import the ContentHandler class.)

    #-- 3 --
    # [ ch is an ArticleHandler object ->
    #     if inFile contains a readable, well-formed XML file ->
    #       output files named in inFile  :=  code fragments
    #           designated for those files
    #       sys.stderr  +:=  error message(s), if any ]
    saxparser  =  make_parser()
    saxparser.setContentHandler ( ch )
    saxparser.parse ( inFile )