[aldo_14]

Trying to get a character / String output from java (read in from file), except I can;t get the character to output properly;

Code: [Select]



   public TokenIterator ParseThroughFile() throws Exception
    {
  //takes the file and returns the tokens as an iterator (see implementation)
//create StreamTokeniser
Reader r = new BufferedReader(new FileReader(sourceData));
StreamTokenizer st = new StreamTokenizer(r);


st.ordinaryChar('(');
 //set the following characters as ordinary, to be read as token
st.ordinaryChar(')');
st.ordinaryChar(',');
st.ordinaryChar('.');
st.ordinaryChar('\'');
st.eolIsSignificant(false);
//do not store end of lines' as tokens
st.commentChar(':');
//ignore all file lines starting with ':' when parsing


//now parse and read into iterator
tokens = new TokenIterator();


while(st.nextToken()!=st.TT_EOF)
 {
 tokens.add(st.toString());
 }
tokens.add("EOF");

return tokens;
}  


Single characters read as null (printing st.sval) or

Token[tree], line 3
Token['('], line 3
Token[tree], line 3
Token['('], line 3
Token[nil], line 3
Token[','], line 3
Token, line 3
Token[','], line 3
Token[nil], line 3
Token[')'], line 3
Token[','], line 3
Token[a], line 3
Token[','], line 3
Token[nil], line 3
Token[')'], line 3
Token['.'], line 3


with toString.

(source file contents- tree(tree(nil,b,nil),a,nil). [i/] )

I'm a bit stumped with this.... so I'm hoping someone knows a bit of java

[Styxx]

Bah, use a LineNumberReader and a StringTokenizer. You're trying to do it the hard way...

[Odyssey]

Hmm... I can do basic Java, but this little bit of code looks a tad too complicated for me, so I'll pick up the simplest 'error' I can think of:

st.ordinaryChar(''');

That line, I assume, would not be liked too much by the Java. First it opens with a quote mark, and follows it by two more quote marks. Surely that would confuse it? Which one would it take as the end?

I'm probably way off, but I might as well try, no?

[Styxx]

Yeah, that line should have an escape charachter, or use double quotes... but that would be a compile problem, not a runtime one. What exactly is it that you're trying to do anyway...?

[aldo_14]

Originally posted by Styxx
Yeah, that line should have an escape charachter, or use double quotes... but that would be a compile problem, not a runtime one. What exactly is it that you're trying to do anyway...?

That's a miss-type, BTW - I missed the \ in the post

prolog tree parser... see Question 5; http://www.cs.strath.ac.uk/teaching/ug/classes/52.222/222_P_2.html

Basically, to break a prolog tree definition ala tree(nil,a,nil).
(left, middle, right)
into tokens, and then to feed the tokens into a Binary Tree and display it.

(inc. nested trees, eg tree(tree(nil,b,nil),a,nil)  )

I'm trying to split it into tokens, either strings (eg nil, node data)  or single characters, like left and right brackets.....  i have a StringTokenizer method written earlier, but this was a lot simpler.  Plus my method removed all the punctuation - just kept letters -  which I want to keep here, so I replaced it.


Edit

Stringtokenizer won't work b- or it'll be a ***** - and I can't use linereader cos it runs over mutliple lines and I don't want to do the workaround code just yet (I need to code in a line seperator later on, because of Unix string buffer restrictions).  It seperates the tokens fine, it's just getting out the damn character ones that's the problem.