www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - Another short blog post/tutorial (Finding a string in a stream)

reply Alan Knowles <alan akbhome.com> writes:
Since I got such good feedback before, I though I'd post about the 
latest short tutorial...

http://www.akbkhome.com/blog.php/View/116/More_DigitalMars_D__finding_a_string_in_a_stream.html

Feel free to comment / make suggestions.

Regards
Alan
Mar 14 2006
parent reply "Regan Heath" <regan netwin.co.nz> writes:
On Wed, 15 Mar 2006 11:38:15 +0800, Alan Knowles <alan akbhome.com> wrote:
 Since I got such good feedback before, I though I'd post about the  
 latest short tutorial...

 http://www.akbkhome.com/blog.php/View/116/More_DigitalMars_D__finding_a_string_in_a_stream.html

 Feel free to comment / make suggestions.

Here is how I would write it. NOTE: - eof is (and belongs) in the MimeStream. - eof is used with property syntax i.e. no () on the method call. - there is absolutely no need to copy the characters or allocate memory - nested functions are your friends import std.stdio; void main () { MimeStream x = new MimeStream("This is a test - hello with XXX - hello world - in the middle"); uint lines = 0; bool ret = skipUntilBoundary(x,"- hello world -",lines); if (!ret) writefln("NO MATCH"); else { char c; writefln("GOT STRING! rest:"); while(x.getChar(c)) writef(c); } } class MimeStream { char[] thestring = ""; int pos = 0; this(char[] string) { thestring = string.dup; } bool getChar(inout char c) { if (eof) return false; c = thestring[pos++]; return true; } bool eof() { return (pos >= thestring.length); } } bool skipUntilBoundary(MimeStream x, char[] delim, inout uint lines) { char c; uint i; bool compareDelim() { for(i = 0; i < delim.length; i++) { if (c != delim[i]) break; if (!x.getChar(c)) return false; } return (i == delim.length); } while(x.getChar(c) && !compareDelim()) { if (c == '\n') lines++; } return !x.eof; }
Mar 15 2006
parent reply Alan Knowles <alan akbkhome.com> writes:
You missed the challenge of the task :)

looking for "- ABC - DEF -" in "test - ABC - ABC - DEF -"
as you need to backtrack as you have eaten too many characters, by the 
time you get to the real match..

the nested functions look like a good idea. -> it does make things a bit 
cleaner.

The original code returned eof, although you are right, the caller 
should really check the Stream for eof, rather than this method.

Thanks
Alan

Regan Heath wrote:
 On Wed, 15 Mar 2006 11:38:15 +0800, Alan Knowles <alan akbhome.com> wrote:
 
 Since I got such good feedback before, I though I'd post about the  
 latest short tutorial...

 http://www.akbkhome.com/blog.php/View/116/More_DigitalMars_D__finding_a_str
ng_in_a_stream.html 


 Feel free to comment / make suggestions.

Here is how I would write it. NOTE: - eof is (and belongs) in the MimeStream. - eof is used with property syntax i.e. no () on the method call. - there is absolutely no need to copy the characters or allocate memory - nested functions are your friends import std.stdio; void main () { MimeStream x = new MimeStream("This is a test - hello with XXX - hello world - in the middle"); uint lines = 0; bool ret = skipUntilBoundary(x,"- hello world -",lines); if (!ret) writefln("NO MATCH"); else { char c; writefln("GOT STRING! rest:"); while(x.getChar(c)) writef(c); } } class MimeStream { char[] thestring = ""; int pos = 0; this(char[] string) { thestring = string.dup; } bool getChar(inout char c) { if (eof) return false; c = thestring[pos++]; return true; } bool eof() { return (pos >= thestring.length); } } bool skipUntilBoundary(MimeStream x, char[] delim, inout uint lines) { char c; uint i; bool compareDelim() { for(i = 0; i < delim.length; i++) { if (c != delim[i]) break; if (!x.getChar(c)) return false; } return (i == delim.length); } while(x.getChar(c) && !compareDelim()) { if (c == '\n') lines++; } return !x.eof; }

Mar 15 2006
parent "Regan Heath" <regan netwin.co.nz> writes:
On Thu, 16 Mar 2006 09:58:55 +0800, Alan Knowles <alan akbkhome.com> wrote:
 You missed the challenge of the task :)

 looking for "- ABC - DEF -" in "test - ABC - ABC - DEF -"
 as you need to backtrack as you have eaten too many characters, by the  
 time you get to the real match..

You're right. I didn't imagine that possibility (due in part to the way the original code sidestepped the problem with it's revolving buffer and custom compare function). Regan
Mar 15 2006