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[REBOL] Re: REBOL Newbie tries to convert C source to REBOL (long posting)

From: antonr:iinet:au at: 21-Nov-2003 17:05

Hi, What does the application do and why does it do it? What does the data describe? Handling blocks: my-block: copy [] ; initialize the big block of data ; now within your parse rule parse-rule: [ ... ; at this point you have extracted section-name (eg. "sec1") append my-block reduce [section-name copy []] ... ; at this point you have extracted some section data ; into data1 data2 data3 etc.. so store it append last my-block reduce [data1 data2 data3] ] That should have extracted all the data into my-block, which should look like this: my-block: [ "sec1" [ "dataline1" "111.11" "N012.11.029" "E034.31.110" "dataline3" "111.11" "N015.11.099" "E034.31.110" ] "sec2" [ "datalinex" "HFD" "111.11" "N012.11.099" "E034.31.114" "dataliney" "LKA 131.41" "N011.11.049" "E031.31.116" "datalinez" "JIH 111.11" "N012.11.019" "E032.31.114" ] ] I've got all values as strings, but depending what they are you could use numbers, words and issues for easier handling later. I don't know - what do you want to do with the data? After finishing the extraction, you can get to the block of lines for each section like this: section1-data: select my-block "sec2" ;== ["dataline1" "111.11" "N012.11.029" "E034.31.110" ... To step through each line you could do this: foreach [line-title data1 data2 data3] section1-data [ print [line-title data3] ] I am assuming, for each section, that each line has the same number of elements. If not, then I recommend putting each line into a block of its own, so it looks like this: my-block: [ "sec1" [ ["dataline1" "111.11" "N012.11.029" "E034.31.110"] ["dataline3" "111.11" "N015.11.099" "E034.31.110"] ] ... ] To get that data now, you can do this: foreach line section1-data [ ?? line ; show the contents of the block print [line/1 line/4] line/3: copy "N012.11.028" ; change third item ] Read more comments interspersed below:
> Hi everybody ! > > I am currently trying to port an ANSI C application over to REBOL. > I am pretty much a newbie to REBOL - and was pretty impressed by > its capabilities. > > My problem now is, porting looked a lot easier than it actually > turns out to > be for me. > > I seem to lack some fundamental things in REBOL - maybe I just think too > "one-dimensional" > because of my ASM/C - background, indeed, in C I do parse the whole data > BYTE by BYTE - something that > doesn't seem effective with REBOL - as there seem to be more efficient > methods available, > as I understand it. > > Actually, I would think the application should be fairly easy to > be implemented with REBOL - it's bascially only 'simple' string > processing - > > not much more. That's why I thought I should give it a try - also > to be able > to compare REBOL performance with my compiled C-application. > > basically, this is what my C source does: > > 1) open a data file (approx. 1 MB data) > > filename: "test.dat" > data: read filename > > 2) parse the file for sections - every section is indicated by square > brackets > and is valid to the next (new) section > > like this: (example data) > -------------------------------------------- > [sec1] > dataline1 111.11 N012.11.029 E034.31.110 > dataline2 131.11 N012.11.099 E034.31.110 > dataline3 111.11 N015.11.099 E034.31.110 > > [sec2] > datalinex HFD 111.11 N012.11.099 E034.31.114 > dataliney LKA 131.41 N011.11.049 E031.31.116 > datalinez JIH 111.11 N012.11.019 E032.31.114 > -------------------------------------------- > So each sections contains several hundreds of lines with data, > the data syntax is different with each section. That's why I initially > separate the data only by whitespaces in C and take care of the > exact syntax > at > a later time, using parsing rules specified in another array. > > 3) In C I would now simply determine each section's offsets within the > memory > and then store (memcpy) each section into its own multi-dimensional array > using the offsets > I determined in the previous loop, where each line of data is directly > accessible > - but also every part of the data line (separated by whitespaces). > > At first I would go and compute every section's beginning like this: > ________________________________________ > sections: make block! 40 > > parse data [ > any [to "[" copy sec indx: thru "]" > (append sections index? indx) > {/* > For debugging purposes I also emit the name of > each section > that's found. > */} > (print sec) > ] > ] > ________________________________________ > > Then I got the position of each section in the data-series and compute > the offset of each section by calculating the difference between > 2 adjacent > sections. > Accordingly, in C I would then go to extract/copy the data within the two > offsets > and put it all in another array to work with. > > That's exactly where my problems start to overwhelm me. > While reading the file in, and parsing it for sections does seem to > work fairly well (and with MUCH less code !), I am having difficulties to > create the > multi-dimensional arrays for each section where all data is individually > accessible stored. > > So as an example, having parsed [sec1] I want every element in > each line to > be individually > accessible to simplify conversion. > > 4) Although the arrays don't work yet I tried to port the parsing routines > over - > In C I take the "parent" array that contains all sub-arrays and parse each > section individually. Parsing is done in C with a certain set of > rules (also > stored in an array) > - using regular expressions, I 'expect' a certain data format for > particular > sections. > If a rule is matched I parse with that rule and separate the data into > sub-arrays. > > In REBOL the latter seems fairly easy using the parse command: > > 5) when all data has been processed and separated by its > corresponding rule > I need to > convert the data for each section into a different format. > With C I am again using regular expressions to implement > conversion. That's > why I > stored the recognition-rule and the conversion-rule in the same array > > 6) Final conversion of the original data will be to CSV-format - including > most data that was > read, but occasionally not all data is needed or an abbreviated form is > sufficient. > > Maybe you guys got some thoughts on my problem - I don't want/need actual > code - rather some > hints how to accomplish my goals in REBOL. As you may be able to tell from > the way I describe > the problem, I might indeed be too heavily thinking in C. By the way: are > you aware of any > tutorials or books, particularly targeted at C-programmers. This seems > really to be a situation > where previous programming-experience limits my way of thinking. > I did read > a lot of stuff on > the REBOL webpages, but still do have problems, grasping the > inner concepts > within in REBOL.
Did you do any Java? "Everything is a pointer" is kind of more like rebol. Ask any questions here you want. We'll help you.
> Another question that just came to my mind: is there any decent REBOL code > editor available? > Simple syntax highlighting would be one thing - but I am thinking > more of a > supportive > editor that also supports syntax completion or smart tooltips, helping a > newbie like me. > > I guess, the power of REBOL is also some kind of problem for such > an editor, > as single > objects/words can mean different things and dialects can easily > be extended. > Maybe some really good REBOL-programmer should go and program an editor > for REBOL IN REBOL (view) ;-) > > I'd really love to see a REBOL-editor being implemented in REBOL > - it could > easily be > enhanced by everybody, there might even be some kind of "plugin" concept > considered - > using rebol scripts, that are executed on demand. > Using REBOL/VIEW it would also be available on pretty much all platforms.
This has often been wished for already. I think it's a bit of a waste of time at the moment. There are plenty of good text editors out there, and rebol syntax highlighting for them too. See my page on text editors:
> Thanks for any help and comments - and sorry for this rather long > eMail ;-) > P.S.: Is there any kind of REBOL-specific FORUM available on the web ? If > not: why not ? I would be willing to > create one - if there's demand. > Mike
There is - if you can read French it helps. and Vanilla and Agora-Dev Anton.