34
votes
Accepted
how do I quickly remove lines from emacs buffer
You can go to beginning of buffer with M-<, then M-x flush-lines, type your word and hit RET.
(flush-lines REGEXP &optional RSTART REND INTERACTIVE)
Delete lines containing matches for ...
- 1,390
22
votes
Accepted
Incrementally replace a given string
General technique
Your replacement string can contain arbitrary lisp code. From the documentation for replace-regexp:
In interactive calls, the replacement text may contain ‘\,’ followed by a Lisp ...
- 9,142
20
votes
support for regex look behind and ahead?
No, Emacs regular expressions do not support arbitrary zero-width look-ahead/behind assertions.
n.b. Evil and Spacemacs (like all elisp libraries) are irrelevant when it comes to questions about the ...
- 52.4k
17
votes
Accepted
Search through the values of all variables in Emacs
Does apropos-value do what you're looking for?
(apropos-value PATTERN &optional DO-ALL)
Show all symbols whose value’s printed representation matches PATTERN.
PATTERN can be a word, a list of ...
- 481
17
votes
What's the idiomatic (or best) way to trim surrounding whitespace from a string?
What's the idiomatic (or best) way to trim surrounding whitespace from a string?
The built-in library subr-x.el has included the inline functions string-trim-left, string-trim-right, and string-trim ...
- 12.5k
13
votes
Accepted
Is there any principal difference between "A-Z" and upper?
The macro rx returns regexp strings that can be passed to other Emacs functions.
ELISP> (rx (one-or-more (any upper lower)))
"[[:lower:][:upper:]]+"
ELISP> (rx (one-or-more (any "A-Z" "a-z")))
"...
- 9,142
12
votes
Accepted
How to apply arithmetic operators to query-replace-regex
\2 in your replacement is a string, and it needs to be a number in order to perform the division.
You could convert it to a number using string-to-number, but there's in-built shorthand for treating ...
- 5,385
11
votes
Accepted
What does a backslash followed by a single quote mean in a regular expression?
It's a special construct in emacs regexp that matches the end of a string (not just the end of a line). Quoting the the manual
\'
matches the empty string, but only at the end of the string or ...
- 1,510
11
votes
Accepted
How does Emacs compile the regular expressions?
Emacs' regexp implementation caches previously used patterns in
compiled form (20 of them, last time I looked). This is not a detail
you should rely on too much.
(while (re-search-forward rx nil t) ......
- 5,385
9
votes
Accepted
Most performant matching of "any char"
In Emacs's regexps, . does not match all characters. It is a synonym of [^\n]. So the reason for using [\0-\377[:nonascii:]] is when you want to match "any char, even a newline".
W.r.t overflowing ...
- 26.6k
9
votes
Accepted
Multiple URL formats for bug-reference-mode
Update
Starting with Emacs 28, bug-reference is able to automatically detect and configure itself for Git forges including GitHub and GitLab. Quoth (info "(emacs) Bug Reference"):
[...]
...
- 12.5k
9
votes
Whitespace and newlines in regexps?
You could always use one of the character classes. I would say use [:blank:] when the usage context is textual, and use [:space:] when it is programmatic, i.e. plain text vs source code.
When ...
- 1,648
9
votes
Accepted
Regexp replace to match a string, but not match a superstring
Try \_<Vector\_>. The \_< construct matches the empty string, but only at the beginning of a symbol. \_> is the same, but at the end of a symbol. What is a "symbol" depends on the buffer's ...
- 32.5k
9
votes
What's the idiomatic (or best) way to trim surrounding whitespace from a string?
There is the string manipulation library s.el where trimming whitespace and newlines at the beginning and the end of a string is implemented as function s-trim. I cite that function here with its ...
- 33.5k
8
votes
Accepted
Evil mode and regular expressions
evil uses the Emacs regexp facilities under the hood. Unfortunately, Emacs does not appear to have a separate syntax
class for digits, and does not recognize the \d regexp class.
So, to match your ...
Dan♦
- 33.3k
8
votes
Accepted
Enable mode if file content contains a matching string
I would like to enable [some mode] whenever a file I open contains a specific string, or a regex
This is exactly what magic-mode-alist is for (there is also magic-fallback-mode-alist if you want the ...
- 9,233
8
votes
Accepted
Find and remove consecutive duplicated words while ignoring case
You can query-replace-regexp as follows:
\(\b\w+\b\)\W+\1\b → \1
This means, match a whole word (\b\w+\b), followed by non word characters (\W+), followed by the first word (\1) and a word ending (\...
- 5,475
8
votes
Accepted
Emacs replace-regexp reference the match in the replace argument
replace-regexp is perfect for the job. You could also use query-replace-regexp, which is more visual.
You want to replace XYZ\(...\) with 'XYZ\1'.
Explanation:
. stands for a single character, you ...
- 4,666
8
votes
Accepted
Regex for the last line of a string
$ matches at the end of a line, not the end of a string. If you want to match at the end of a string you need to use the \' operator:
(string-match "\n.*\\'" "\n \n \n ")
=> 4
...
- 5,385
7
votes
Accepted
How do I match a closing bracket in Emacs lisp
Put the ] as the first character after the [ which starts the character class, e.g.
[])}]
This is the manual page
- 1,934
7
votes
Accepted
How can I use more than 9 regex capture groups in Emacs Lisp?
Going by the Emacs source code, it is absolutely possible to use more than 9 regex capture groups:
/* Since we have one byte reserved for the register number argument to
{start,stop}_memory, the ...
- 22.3k
7
votes
emacs regex with multiple match for text, in multi line buffer
You can use the following regexp
This is test\(.*\n\)+?shoes>\nshoes/\n
.*\n matches a line
+? matches multiple lines in non-greedy way
Using the regexp in C-M-s (isearch-forward-regexp):
Note: ...
- 14.7k
7
votes
Regexp replace to match a string, but not match a superstring
Another simple trick you can use is to match both Vector and VectorBase, and replace them both with VectorBase.
Vector\(Base\)? → VectorBase
More complicated cases can be handled by using elisp in ...
- 52.4k
7
votes
Accepted
Why is this regex [[:upper:]] matching with lowercase string?
C-hf string-match-p:
string-match-p is a byte-compiled Lisp function in ‘subr.el’.
(string-match-p REGEXP STRING &optional START)
Same as ‘string-match’ except this function does not change the ...
- 52.4k
6
votes
Accepted
regexp to find two consecutive and identical words not necessarily in the same line
\s- matches a whitespace character. A newline character can have whitespace syntax in some modes, but often it does not. Many programming modes change the syntax of newlines to that of a comment end, ...
- 78.5k
6
votes
How to grep marked files in the dired mode of emacs?
If you use library Dired+ (dired+.el) then you can use command dired-do-grep (bound by default to M-g in Dired mode) to do what you request.
diredp-do-grep is an interactive compiled Lisp function ...
- 78.5k
6
votes
support for regex look behind and ahead?
https://github.com/benma/visual-regexp-steroids.el/
Visual regexp steroids allows you to replace, search, etc. using python regex. Python regex has support for look ahead and look behind.
It even ...
- 357
Only top scored, non community-wiki answers of a minimum length are eligible