Checking Parts of Strings

code review
1

I've converted a Python script into Rust, and it is working the same, but wonder if this is a proper way to splice and check strings?

The 2 "if" statements is the code in question.

Python Code:

            if k[:3] == "'''" and doc_switch == False or k[:3] == '"""' and doc_switch == False:
                if "'''" in k[3:] or '"""' in k[3:]:
                    not_code_lines += 1
                    only_comments += 1
                    continue
                else:
                    doc_switch = True

Converted to Rust code:

if k.get(..3) == Some("'''") && doc_switch == false || k.get(..3) == Some("\"\"\"") &&
                doc_switch == false {

                if k.get(3..).unwrap().to_string().contains("'''") ||
                    k.get(3..).unwrap().to_string().contains("\"\"\"") {
                    not_code_lines += 1;
                    only_comments += 1;
                    continue;
                }
                else {
                    doc_switch = true;
                }
            }

If you would like to see the full scripts their on my repository: https://github.com/Bren3232/Count-Lines

2
  1. You don't need to to_string() in order to .contains().
  2. The Python code raises an exception when the string is too short, so the Rust code is not completely equivalent.
1 Like
3

Instead of slicing and specifying lengths manually, you are probably looking for more evocative helper methods such as starts_with() and ends_with().

1 Like
4

I don't think so, if the string is too short it will gives you the whole string

5

The above suggestions are true and useful, except the python code does work on short strings.
Thanks.

6

So if the string is '''""", then not_code_lines += 1 and only_comments += 1? I'm not sure this is intended behaviour.

If it's not, you should consider matching against a regexp '''.*?''' and """.*?""".

1 Like
7

:+1: to this. The regex crate is incredibly fast, so if you're doing string processing, you should probably just default to using it unless you have strong reasons to do something else. As a bonus, you're more likely to handle Unicode properly that way too.

1 Like
8

Without going into the algorithm or anything like that...

You can uses matches! to remove some redundancy.

if doc_switch == false && matches!(k.get(..3), Some("'''") | Some("\"\"\""))

get followed by unwrap is pretty much just indexing.

    let rest = &k[3..];
    if rest.contains("'''") || rest.contains("\"\"\"") {
2 Likes
9

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