ability to strip all leading whitespaces from text

[bobi6666]

I have loaded the lines of text from file and I would like to know what is the best way to use regex to replace all starting whitespaces I tried the code that allowed me to strip all trailing whitespaces from textlet RE_SPACES: Regex = Regex::new(r"<\s+?>").unwrap(); let text: String = RE_SPACES.replace_all(&s, "><").to_string();

[BurntSushi]

Your regex matches neither leading nor trailing whitespace though. It matches things like < >. If you want to match leading whitespace, then use ^\s*. To match trailing whitespace, use \s*$. You're also not "stripping" whitespace. You're replacing things like < > with ><.

If my answer is unhelpful, then the next step here would be to share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output.

[bobi6666]

the point is that I have an indented rust code with spaces and I would like to replace them with nothing so that my lines of code start with the code but no longer with spaces 2021-12-09 18:41 GMT+01:00, Andrew Gallant ***@***.***>:

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Your regex matches neither leading nor trailing whitespace though. It matches things like `< >`. If you want to match leading whitespace, then use `^\s*`. To match trailing whitespace, use `\s*$`. You're also not "stripping" whitespace. You're replacing things like `< >` with `><`. If my answer is unhelpful, then the next step here would be to share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (comment)

[BurntSushi]

Apologies, but I don't understand what the problem is. Which is why I said this:

then the next step here would be to share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output

Let's start there please.

[bobi6666]

the tip you suggested removed the starting whitespaces from the first line but the other lines were left with spaces at the beginning 2021-12-09 18:51 GMT+01:00, Andrew Gallant ***@***.***>:

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Apologies, but I don't understand what the problem is. Which is why I said this: > then the next step here would be to share a small Rust program that I'm > able to compile and run, the input to that program, the actual output > you're seeing and your desired output Let's start there please. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)

[BurntSushi]

Please share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output.

I can't keep making the same request in different ways. This is my last attempt.

[bobi6666]

here is the code from playground which can remove whitespace from the first line of text but omits the other lines https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=7d14d90f881c1ffc9b390f78c917e1a3 2021-12-09 19:04 GMT+01:00, Andrew Gallant ***@***.***>:

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Please share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output. I can't keep asking the same question in different ways. This is my last attempt. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)

[BurntSushi]

^ only matches at the beginning of text. You need to enable multi-line mode so that it matches both at the beginning of text and at the start of a line. So, (?m)^\s* should do the trick: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=36b37294850c99adc515d03c2ac6fa23

[bobi6666]

thanks your tip solved my problem but i have a question if this indentation is good in terms of performance? or could there be something better to improve? here is final code that including your tip with regex: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=b075a44a6ecb66a535b543bd1c64f367 2021-12-09 19:45 GMT+01:00, Andrew Gallant ***@***.***>:

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`^` only matches at the beginning of text. You need to enable multi-line mode so that it matches both at the beginning of text and at the start of a line. So, `(?m)^\s*` should do the trick: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=36b37294850c99adc515d03c2ac6fa23 -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (comment)

[BurntSushi]

Seems fine to me, but it's just a guess. If you're concerned about performance, you should come up with multiple strategies and benchmark each of them. Once you have benchmarks, you can profile the code to find the hot spots.

[bobi6666]

I think it's fast enough but regex causes me that if I had 1 line with code 1 empty line and another 1 line with code then empty line will be deleted and I would like to solve it if possible 2021-12-09 20:49 GMT+01:00, Andrew Gallant ***@***.***>:

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Seems fine to me, but it's just a guess. If you're concerned about performance, you should come up with multiple strategies and benchmark each of them. Once you have benchmarks, you can profile the code to find the hot spots. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)

[BurntSushi]

Please share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output.

I am personally finding it very difficult to help you. Your comments are short and difficult for me to comprehend. I cannot keep going back-and-forth like this. You might have better luck with something more structured like StackOverflow.

[bobi6666]

this code that is on the playground works in such a way that it removes spaces but also does that in removing empty lines and it would be better if he left those empty lines there because they are useful, for example, when I'm unindenting main.rs where there will be free lines to separate functions https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=361e8c1b2abaae4189bb85717464b1e4 2021-12-09 21:01 GMT+01:00, Andrew Gallant ***@***.***>:

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Please share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output. I am personally finding it very difficult to help you. Your comments are short and difficult for me to comprehend. I cannot keep going back-and-forth like this. You might have better luck with something more structured like StackOverflow. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)

[BurntSushi]

Sure. Just don't match newline characters then: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=0f1b3a129aaaea738692137d5ae390e8

[bobi6666]

you just solved all the problems I had in this code thank you and in the end I just want to ask where can I learn regex sintax better? and what will regex do if in the text will be non utf 8 character? 2021-12-10 18:48 GMT+01:00, Andrew Gallant ***@***.***>:

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Sure. Just don't match newline characters then: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=0f1b3a129aaaea738692137d5ae390e8 -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (comment)

[BurntSushi]

You're using strings, which are guaranteed to be valid UTF-8. If you need to deal with non-UTF-8, you can use the bytes sub-module. But everything should just work.

As for learning regex, I'd recommend just checking out the syntax docs for this crate: https://docs.rs/regex/latest/regex/#syntax

There's also this for more general stuff: https://www.regular-expressions.info/

Otherwise, maybe search around for regex tutorials.

[bobi6666]

could you tell me that how could the following be done? if regex finds somewhere {then it puts it on a new line with the fact that --\r\n as we talked before and with the fact that if it finds the combination {} together then it will ignore it for example code like use crate::{Test1, Test2}; should look like use crate:: { test1, test2 }; the same can be applied for playground link i sent before 2021-12-10 19:51 GMT+01:00, Andrew Gallant ***@***.***>:

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You're using strings, which are guaranteed to be valid UTF-8. If you need to deal with non-UTF-8, you can use the `bytes` sub-module. But everything should just work. As for learning regex, I'd recommend just checking out the syntax docs for this crate: https://docs.rs/regex/latest/regex/#syntax There's also this for more general stuff: https://www.regular-expressions.info/ Otherwise, maybe search around for regex tutorials. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)

[BurntSushi]

As with before: please share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output.

[bobi6666]

i didn't post code because i have no idea how to do this but i would like if code that will be at the end of this message can do: if regexfinds somewhere {then it puts it on a new line with the fact that --\r\n as we talked before and with the fact that if it finds the combination {} together then it will ignore it for example code like use crate::{Test1, Test2}; should look like use crate:: { test1, test2 }; https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=2d323d8c10db4df1ce18898a3f6ffb56 2021-12-14 19:31 GMT+01:00, Andrew Gallant ***@***.***>:

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As with before: please share a small Rust program that I'm able to compile and run, the input to that program, the actual output you're seeing and your desired output. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)

[BurntSushi]

I'm asking for code because I can't understand your English. If you can't give me code, give me inputs and outputs.

[bobi6666]

here is for example code like: use dotenv::var; pub fn get_env(val: &str) -> String { match var(val) { Ok(v) => v, _ => String::from(""), } } and i would like if regex can reformat this code to be like: use dotenv::var; pub fn get_env(val: &str) -> String { match var(val) { Ok(v) => v, _ => String::from(""), } } or code like: use std::ffi::{CStr,CString}; should look like: use std::ffi:: { CStr,CString }; 2021-12-14 19:53 GMT+01:00, Andrew Gallant ***@***.***>:

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I'm asking for code because I can't understand your English. If you can't give me code, give me inputs and outputs. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)

[BurntSushi]

I don't know, sorry. I don't have the time to build regexes for you like this. It kind of looks like regex is the wrong tool for this job. You might do better with a Rust parser and a pretty printer. Maybe look at rustfmt. Otherwise, for general regex help, I'd recommend other forums.

[bobi6666]

I think my problem can be solved when there is a closed issue in which someone requested to be able to create multiple matches and was told to wait for the automata 2021-12-14 20:24 GMT+01:00, Andrew Gallant ***@***.***>:

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I don't know, sorry. I don't have the time to build regexes for you like this. It kind of looks like regex is the wrong tool for this job. You might do better with a Rust parser and a pretty printer. Maybe look at rustfmt. Otherwise, for general regex help, I'd recommend other forums. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #823 (reply in thread)