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Forum Index : Microcontroller and PC projects : Regular Expressions
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| damos Regular Member  Joined: 15/04/2016 Location: AustraliaPosts: 63 |
Am I the only twisted person here who uses regular expressions? For the sort of low level parsing stuff I tend to do, they are very handy. I am not sure how big the C regular expression libraries are, but if they aren't too big, could this functionality be added to Webmites as they have a fair amount of space? I don't just use them for pattern matching but also for extracting the values, so for a sequence like this: Test string: relay1State=1&relay2State=0 Regular expression: relay(\d+)State=(\d+) Matches: 1 values 1,1 2 values 2,0 |
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LeoNicolas Guru  Joined: 07/10/2020 Location: CanadaPosts: 479 |
I use regex all the time. They are pretty handy for dealing with string matching and replacing. I'm not sure if the library can be incorported to the webmite. |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
Every time I come across them I have to dive for a reference book or Google. Not something I've ever used and certainly never come across in any versions of BASIC. As far as I'm concerned they belong in C land and can stay there. :) BASIC has its own methods of comparison and searching. Edited 2023-06-16 16:34 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3804 |
Maybe best in a CSUB? Some info from duckduckgo site:https://www.thebackshed.com csub pico John Edited 2023-06-16 17:12 by JohnS |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2076 |
not a complete implementation http://www.fruitoftheshed.com/MMBasic.Regular-Expression-Function.ashx |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 9129 |
Have a play with this (PicoMite) PicoMite (2).zip function REGEX(string$, regularexpression$) gives error if the regular expression won't compile or the match fails gives 1 for a match gives 0 for no match Let me know if it works at all/nearly/well etc. |
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| hhtg1968 Senior Member  Joined: 25/05/2023 Location: GermanyPosts: 123 |
does exist a list of used "special" chars for regex? i know from unix and cp/m *.com, test???.tx? and so on... |
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| hhtg1968 Senior Member Joined: 25/05/2023 Location: GermanyPosts: 123 |
perhaps here?: http://www.fruitoftheshed.com/MMBasic.Regular-Expression-Function.ashx (i hope the url is correct). the "add hyperlink" function is to complicated for me... |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
As that link shows, regular expressions are already available to anyone who wants them if they cut & paste. No need to add anything to the MMBasic interpreter. ;) [/Mr Grumpy] (To add a hyperlink first copy the url from the page to be inked into the clipboard. I right click on the url, Select All, right click on it again, Copy. Now, in the Edit box click the hyperlink button (Earth with a chain link). You get a popup. Type into that the words that you want the viewer to see on the screen e.g. "This Link" and press OK. You get a second popup. Simply paste the clipboard contents into this. Don't delete the http at the beginning, it will all be sorted out. Press OK. A block of text will appear in your Edit window. That's the link. Just carry on typing after it as usual.) . Edited 2023-06-17 18:00 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| damos Regular Member Joined: 15/04/2016 Location: AustraliaPosts: 63 |
Thanks for the quick turn around Peter. The BASIC example looks like it only does half the job - tells if there is a match. The other half of the job is to extract all the values. When you use () in a regular expressions it specifies a return value is required. Normally you return an array of matches which in turn contain the return values. This is a little bit complex for BASIC as it really doesn't handle objects, but it could just return an array of values. As per my example above, the results are: Matches: [ ["1","1"], ["2","0"] ] This could be done as a 2-dimensional array [Matches][Value], or as single dimension array: [ number of matches, match 1 value 1, match 1 value 2, match 2 value 1, match 2 value 2] This gives the number of matches as return value which is indeterminate from the 2 dimensional array. |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 9129 |
This was deliberate. You can emulate the same thing by looping while incrementing the start point of the search. |
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| damos Regular Member Joined: 15/04/2016 Location: AustraliaPosts: 63 |
Hi Peter, I finally got a chance to test the REGEX expression in your experimental code. I am not sure what library you were using but the regex capabilities are very limited. With a test string like: "Extract value from v122 in test string" I can use regular expressions like: "value" "v123" "v.23" "v[1234567890][1234567890]" But I could not use other escapes like: "v\d\d" which is basically the same as "v[1234567890][1234567890]". It also does not support quantifiers like +. At this stage it is useful as a search with wildcards but a long way from regex handling. I did what you suggested and tried operating it inside a loop to find the position. This works but is a bit slow and so it doesn't realize the performance advantages of a native function. If it returned 0 or a value greater than 0 which indicates position found, it would greatly enhance the capability. The other suggestion if you are thinking of tinkering with this is to make the string being searched a longstring as a big use of the function will be to parse responses from web api calls. My idea is to use the Webmite to provide RESTful APIs to hardware rather than normal web pages. Not a lot of equipment seems to go this and people seem to be using GET. With RESTful APIs the verbs are used as follows: GET - get data from a resource POST - add new data to a resource PUT - update data DELETE - remove data PATCH - small modifications I noticed references to a new JSON$ (not documented in the functions section of the version of the manual I have) which will greatly assist in this implementation. |
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disco4now Guru Joined: 18/12/2014 Location: AustraliaPosts: 897 |
@damos, This regex functionality is integrated into the INSTR and LINSTR commands in V5.07.08 beta6. It does return the position if the string is matched, otherwise 0. LINSTR works on longstrings. I have played with it, the main thing with the syntax is that various operators need to be escaped. These expressions can be used to pull the version from your example. "v[0-9]\+" matches 1 or more (escape the +) "v[0-9]\{1,3\}" match 1 to 3 (escape { and } "v[[:digit:]]\{1,\} match 1 or more [:class:] PicoMite V5.07.08 betas Gerry Latest F4 Latest H7 |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
At what point did MMBasic stop being BASIC? <confused by this lot> ') . Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3150 |
With the introduction of DO ... LOOP? ;-} PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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IanRogers Senior Member Joined: 09/12/2022 Location: United KingdomPosts: 151 |
I was pondering this myself!! Imagine asking Clive Sinclair to include all these item into his basic..LOL He would have run for the hills. Whilst Peter is up to the challenge, I'll just watch. How much can be crammed into this lil device.. I'd give my left arm to be ambidextrous |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
Clive got one thing very right IMHO: "abcdef"(2 TO 5 )= "bcde" "abcdef"( TO 5) = "abcdef"(1 TO 5) = "abcde" "abcdef"(2 TO ) = "abcdef"(2 TO 6) = "bcdef" "abcdef"( TO ) = "abcdef"(1 TO 6) = "abcdef" "abcdef"(3) = "abcdef"(3 TO 3) = "c" Unusually powerful and elegant with none of that left$, right$, mid$ stuff. It saved on keywords but it was decidedly (and typically) non-standard. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
True at the time. The ULA idea, also used on amstrad 464 and acorn electron really slowed things down but kept costs low. A game I wrote in asm for bbc micro was too slow to play on the acorn electron. |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
RAM access on the electron was only half the speed of the BBC machines. It wasn't a bad machine though. The ULA chips weren't particularly slow. In fact they had a lot in common with today's FPGAs. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| damos Regular Member Joined: 15/04/2016 Location: AustraliaPosts: 63 |
When we stopped using line numbers. MMBASIC is a long way ahead of BASIC but has not gone down the path of VB. I have mixed feeling about this. I would really love to have objects and proper collections but need to remember that the intent is more of a scripting language for simple tasks. The real power is the massive amount of work done by Peter and Geoff poring over endless datasheets (and sometimes just reverse engineering) to figure out all the nuances of specific bits of hardware and condense it into a single line BASIC command. This has made the hardware side trivially easy. On the Micromite I could easily limit myself to simple applications, but with the Webmite there is so much more potential that I am trying more challenging projects and then wishing for more powerful tools. The biggest limitation is data processing. There is no database, SQL, LINQ or even collections apart from arrays. JSON is just at the early stages but not at the point of navigating complex trees, but even simple capabilities are really appreciated. This means that Webmite will still be just an endpoint that controls hardware and the business logic needs to be elsewhere, but that is perfectly fine. So I am looking at REST endpoints which can be accessed using React applications. This is a huge step forward from HTML applications controlling Micromites through serial ports. |
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