Elastic String Array

[Charles Pegge]

Hi Kent,

If you remove the colon on line 15 it will work. := is an assignment operator, and you cant conditionally assign to string functions.


    if left( s, 2 ) = "% " then  ...

Here is a demo using a dynamic TextArray

Code: OxygenBasic

1. include "..\..\inc\StringUtil.inc"  
2.  
3. new TextArray t  
4.  
5. t.Lines "one
6. two
7. % three
8. % four
9. five"
10.  
11.  
12. eof = t.LastLine
13.  
14. string s,ou
15.  
16. for i = 1 to eof
17.     s=t.line(i)
18.     if left(s,2)= "% " then
19.       ou+=s+cr
20.     end if
21. next
22.  
23. print ou
24.  
25. del t
26.  

This procedure in a new class:

Code: OxygenBasic

1. include "..\..\inc\StringUtil.inc"  
2.  
3. '====================
4. Class FilterTextArray
5. '====================
6. '
7. has TextArray
8. '
9. method LeftFilter(string k) as string
10. string s,u
11. sys i,e=mx
12. for i = 1 to e
13.     s=line i
14.     if left(s,2)=k then
15.       u+=s+cr
16.     end if
17. next
18. return u
19. end method
20. '
21. end class
22.  
23. '--test--
24.  
25. new FilterTextArray t
26.  
27. t.Lines "one
28. two
29. % three
30. % four
31. five"
32.  
33. print t.LeftFilter "% "
34.  
35. del t
36.  

Charles

PS: A new method for StringArray:

Code: OxygenBasic

1.  
2.   method append(string s)
3.   '======================
4.  insert mx+1,s
5.   end method
6.  
7.  

[kryton9]

Very nice, thanks.

That := is confusing me all the time. I thought in conditionals we needed to use it, like you use == in C.
I see in your examples for conditionals you use it, but not sure when?

Anyways thanks for the troubleshooting and new examples and code.

[Charles Pegge]

In Oxygen ':=' can be used to force assign in a condtional statement. C alway uses '='.

In C this is normally used to test the zero or non-zero outcome of the assignment

Oxygen also understands '==' and '!='

Code: OxygenBasic

1. function fn() as sys
2. return 42
3. end function
4.  
5. a=43
6.  
7. if a==fn
8.    print "equal"
9. end if
10.  
11. if a!=fn
12.    print "unequal"
13. end if
14.  
15. 'ASSIGN AND BOOLEAN TEST
16.  
17. if a:=fn
18.   print "fn returned non-zero value: new value for a=" a
19. end if
20.  

Charles

[kryton9]

Ohhhh, so you are assigning and checking a condition at the same time. Ok, now I get it!

[Aurel]

I just looking into this topic and thinking about interpreter.
Charles what you think...
It would be maybe good idea for interpreter to avoid constant parsing or using translate code
to bytecode - use some sort of array to store all parsed(extracted strings ) into arrays.
So what you think about that?

for example:

a[0]   a[1]   a[2]   a[3]
'print'   'x'     'y'    'string'

[Charles Pegge]

Hi Aurel,

Yes, reading a string as an array of bytes is easily done and makes parsing much more efficient.

Oops! I see a glitch
I'll get a working example

Charles

[Charles Pegge]

Code: OxygenBasic

1. string s="0123456789@abcdefghi"
2.  
3. p=strptr(s)
4. byte b at p
5.  
6. print b 'answer 48 '0'
7.  
8. indexbase 0
9.  
10. print b[1] 'answer 49 '1'
11.  
12. 'pointer p can also be moved
13.  
14. p+=10
15.  
16. print b 'answer 64 '@'
17.  

[Aurel]

Hi Charles...
Yes that is cool but i don't understand from where you get this results.
hmmm i see that 48 present 0 ,right?
maybe im not quite clear..uff
In first place i mean as i show
argument1[1024],argument2[1024],argument3[1024]
like:
lineIndex=0 : 'line index -> lndx
argument1[lndx]= "print"
argument2[lndx]= "x"
argument3[lndx]= "y"

without bycode...
how wold this work,for example?

[Charles Pegge]

I think I see what you mean now. you want to put non-token words into an array to improve parsing efficiency?

You could then encode the array indexes as tokens.

Your byte code would then be a uniform stream of tokens

Am I on the right track, Aurel?

I do something rather similar for string literals in Oxygen. All the literals are stored in the data section, and only their pointers remain in the main code.


Charles

[Aurel]

Am I on the right track, Aurel?

I do something rather similar for string literals in Oxygen. All the literals are stored in the data section, and only their pointers remain in the main code.

Yes Charles you right...

In another words:
Get Line of source like a 'print x y'
parse this line into (folowing syntax rules) agruments -> print ,  x  , y
And each argument put into arrays of arguments as i show before.
so if line index is for example 1
index=1  ' <- line number
argument1[1]="print"
argument2[1]="x"
argument3[1]="y"

So i probably must have minimum 32 arrays for arguments,right?
After all parsing is done all this elemnts are completed.
Im interested now how fast this can be executed becuse no more need for parsing again,right?
I hope that im clear now...