How to escape regexes and paths in double quote strings without going crazy?

Question

It often happens that after designing my regexp (on regex101.com) I want to paste it in my program. Consider this regexp that matches numbers and string (but keep in mind this is general question!):

^(\"(?:[^\"]|\\\")*\"|\-?[0-9]+(?:\.[0-9]+)?)$

I overlined all characters that need to be escaped before pasting them into languages that use " for strings.

Needless to say, doing this manually drives me crazy. I face this problem both at work with C++ project and at home with Java and JavaScript projects.

How can I deal with this efficiently?

score 1 · Answer 1 · answered May 20 '19 at 10:51

If you feel it to be worth make your small DSL (or maybe it already exists) so you can do (java):

// ^(\"(?:[^\"]|\\\")*\"|\-?[0-9]+(?:\.[0-9]+)?)$
// @formatter:off
Pattern pattern = Patterning.start() // ^
    .group()
    .lookahead()
        ...
        .set("0-9").plus()
        .string("E=m.c^2") // \Q ... \E
    .lookaheadEnd()
    .groupEnd();
    .end()                               // $
    .build();
// @formatter:on

class Patterning { ... }

Though most people know regex; or at least it is worth learning regex, if only to do powerfull replaces in the editor.

Useless · Answer 2 · 2021-07-09T22:23:57.270

1

In C++, use raw string literals (added in C++11). Nothing between the delimiter sequences is treated as an escape:

const char *regex = R"-regexp-(^(\"(?:[^\"]|\\\")*\"|\-?[0-9]+(?:\.[0-9]+)?)$)-regexp-";

in this case the delimiters are the literal strings -regexp-( and )-regexp-

edited Jul 09 '21 at 22:23

answered Jul 09 '21 at 13:07

Useless

12,823

score 0 · Answer 3 · edited Jun 13 '20 at 16:35

Use Unicode character escapes instead of literals. For example:

Java

boolean b = Pattern.matches("\u0022", '"');

JavaScript
```
/\u0022/.test('"');
```
Perl
```
'"' =~ /\N{U+0022}/;
```

In addition, strings that are compiled to regular expressions can use line breaks for added clarity:

Java

boolean phone_mask = Pattern.matches("^[^0-9]*"/* Optional non-numeric characters */ +
                        "\\+9{3}" /* Followed by a plus sign and three nines */ +
                        "\\s9"    /* Followed by a space and one nine */  +
                        "\\s9{3}" /* Followed by a space and three nines */ +
                        "\\s9{4}" /* Followed by a space and four nines */ +
                        "$", "Phone: +999 9 999 9999");

JavaScript

var phone_mask = RegExp("^[^0-9]*"/* Optional non-numeric characters */ +
                        "\\+9{3}" /* Followed by a plus sign and three nines */ +
                        "\\s9"    /* Followed by a space and one nine */  +
                        "\\s9{3}" /* Followed by a space and three nines */ +
                        "\\s9{4}" /* Followed by a space and four nines */ +
                        "$").test("Phone: +999 9 999 9999");

References

score -2 · Answer 4 · answered Apr 20 '19 at 07:17

Write a program that interprets and escapes your regexps for you. You can either use this to generate the code needed to paste into your source or have it work on the fly having your regexp in a separate file.

For the file version, a big downside is: not having your logic with your source.

How to escape regexes and paths in double quote strings without going crazy?

4 Answers4

References