 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Java Forum / General / January 2006finite state automaton
Consider a simple finite state automaton to parse property files. They look like this: # a comment keyword=value I want to categorise each fragment of text as either comment, keyword or value. Now throw in a complication. Inside any of those three things might be literals of the form \uffff I find myself creating all kinds of rinky dink mechanisms to handle the literals. I wondered if there is a clean way to do it. There are two problems. 1) It is clumsy to invent three literal states one for in comment, one inkeyword and one invalue just so it can remember what it was doing. Yet whole idea of a finite state automaton in that the memory of the system is supposed to be encapsulated in the state. 2) you leave the literal state based on a count, not the presence of some delimiter. I could create 5 states to mark progress down the literal, but this seems a bit nuts.  SignatureCanadian Mind Products, Roedy Green. http://mindprod.com Java custom programming, consulting and coaching. > Consider a simple finite state automaton to parse property files. > [quoted text clipped - 19 lines] > some delimiter. I could create 5 states to mark progress down the > literal, but this seems a bit nuts. Roedy, Why not run the property file through a pre-processor to handle escape sequences, similar to what javac does? After all, the standard property file format supports \\ and \ followed by a line break for line continuation and who knows what else.... HTH, Ray SignatureXML is the programmer's duct tape. >Why not run the property file through a pre-processor to handle >escape sequences, similar to what javac does? You mean a preprocessor like native2ascii -reverse See http://download.java.net/jdk6/docs/tooldocs/windows/native2ascii.html Raymond DeCampo <nospam@twcny.rr.com> was quoting: >>I want to categorise each fragment of text as either comment, keyword >>or value. Now throw in a complication. Inside any of those three >>things might be literals of the form \uffff >>I find myself creating all kinds of rinky dink mechanisms to handle >>the literals. I wondered if there is a clean way to do it. The clean way is a scanner with two layers: The first layer converts each \u-Sequence to a code point. The second layer then reads code points supplied by the first layer and does not have to care about the \u-sequences anymore. > Raymond DeCampo <nospam@twcny.rr.com> was quoting: > [quoted text clipped - 11 lines] > layer and does not have to care about the \u-sequences > anymore. Gee, thanks for replying to my post, removing my contribution, removing the OP's name making it seem as if I wrote what the OP did to the casual observer, and then re-stating my idea. That was really helpful. Ray SignatureXML is the programmer's duct tape. On Sat, 31 Dec 2005 20:46:42 GMT, Raymond DeCampo <nospam@twcny.rr.com> wrote, quoted or indirectly quoted someone who said : >Why not run the property file through a pre-processor to handle escape >sequences, similar to what javac does? After all, the standard property >file format supports \\ and \ followed by a line break for line >continuation and who knows what else.... I considered that, but I wanted to display the file literally. If the file contained embedded \uxxx characters in binary, I wanted to display them differently from ones properly encoded with \uxxxx I have since solved the problem with kludge, a lookahead that handles the entire sequence as if it were a single char from the overall state machine point of view. You can see it working at http://mindprod.com/jgloss/properties.html SignatureCanadian Mind Products, Roedy Green. http://mindprod.com Java custom programming, consulting and coaching. Roedy Green <my_email_is_posted_on_my_website@munged.invalid> might have written, quoted or indirectly quoted something like: >I want to categorise each fragment of text as either comment, keyword >or value. Now throw in a complication. Inside any of those three >things might be literals of the form \uffff >I find myself creating all kinds of rinky dink mechanisms to handle >the literals. I wondered if there is a clean way to do it. The clean way is a scanner with two layers: The first layer converts each \u-Sequence to a code point. The second layer then reads code points supplied by the first layer and does not have to care about the \u-sequences anymore. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.