When adding a divider in code I can easily repeat a '=' N times using
C-<N> =
where N is the number of equal signs to insert.
Is there a similarly quick command that would insert a character repeatedly up to a given column number? So I could execute
<magic command>-<N> =
and get a line of equal signs from the present cursor position to column N?
I don't know of anything built in that can do that, but you could bind the function below to a key sequence of your choice:
(defun repeat-char-to-column (column character)
"Insert copies of CHARACTER on the current line until column COLUMN.
Interactively, prompt for COLUMN and CHARACTER. If the current column is
equal to or greater than COLUMN, do nothing."
(interactive "nRepeat to column: \ncCharacter to repeat: \n")
(let ((cur (current-column)))
(if (< cur column)
(insert (make-string (- column cur) character)))))
Related
I need to extract a substring from a string; the substring is enclosed by ":" and ";". E.g.
:substring;
But with Lisp (SBCL), I'm having trouble extracting the substring. When I run:
(subseq "8.I:123;" : ;)
I get:
#<THREAD "main thread" RUNNING {1000510083}>:
illegal terminating character after a colon: #\
Stream: #<SYNONYM-STREAM :SYMBOL SB-SYS:*STDIN* {1000025923}>
Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.
restarts (invokable by number or by possibly-abbreviated name):
0: [ABORT] Exit debugger, returning to top level.
(SB-IMPL::READ-TOKEN #<SYNONYM-STREAM :SYMBOL SB-SYS:*STDIN* {1000025923}> #\:)
I've tried preceding the colon and semicolon with \ but that throws a different error. Can anyone advise? Thanks in advance for the help!
As you can see in docs for subseq, start and end are bounding index designators and they can be either integer or nil.
#\: and #\; are characters, so you can't use them, but you can use the function position to find the first index of each character and use these indices as arguments for subseq. You have to check that both indices exist and the second one is bigger than the first one:
(let* ((string "8.I:123;")
(pos1 (position #\: string))
(pos2 (position #\; string)))
(when (and pos1 pos2 (> pos2 pos1))
(subseq string
(1+ pos1)
pos2)))
=> "123"
This is a little bit cumbersome, so I suggest you to use some regex library. The following example was created with CL-PPCRE:
(load "~/quicklisp/setup.lisp")
(ql:quickload :cl-ppcre)
> (cl-ppcre:all-matches-as-strings "(?<=:)([^;]*)(?=;)" "8.I:123;:aa;")
("123" "aa")
I am getting an input from a user for a tex-field% in racket which would look something like this:
open button a = fwd; button b = xxx; button s = xxx; close
I have verified that it does contain open and close at beginning and end respectively. But now i need to store each of the substrings based on the semicolons to check them for semicolons at the end, among other things. For example, in the example above it should store 3 substrings in a vector/list (whichever is easier). It would be stored as:
button a = fwd;
button b = xxx;
button s = xxx;
;input is the name of the string the user enters
(define vec (apply vector (string-split input)))
(define vecaslist(vector->list vec))
(define removedopen (cdr vecaslist))
(define withoutopenandclose (reverse(cdr(reverse removedopen))))
(define stringwithoutopen (string-replace input "open " ""))
(define stringtoderivate (string-replace stringwithoutopen " close" ""))
(define tempvec (apply vector (string-split stringtoderivate ";" #:trim? #f #:repeat? #t)))
Attempted to split it by semicolons and place in a vector, but it removes the semicolons. When i do print the length of the vector it correctly shows 3 though, but i would like to keep the semicolons for now.
You can use string-split with a regular expression separator, as follows:
(string-split input #rx"(open | close)|(?<=;).")
which will output the list:
'("button a = fwd;" "button b = xxx;" "button s = xxx;")
To break down the regular expression:
(exp) matches any sub-expression "exp". Hence, (open ) matches the sub-expression "open " in input. Similarly with ( close), matching " close".
(?<=exp) does a positive look-behind, matching if "exp" matches preceding.
. matches anything, such as whitespace, characters etc.
| matches either the expression that comes before it, or after it, trying left first.
Currently, I have my global TODO list shown as follows thanks to erikstokes:
(org-agenda-prefix-format " %i %?-12(concat \"[ \"(org-format-outline-path (list (nth 1 (org-get-outline-path)))) \" ]\") ")))
which outputs:
for org layout:
However, as you can see, for Task A, even though there is nothing in the project, it still shows up on the list.
describe-variable for org-agenda-prefix-format says :
If the first character after `%' is a question mark, the entire field
will only be included if the corresponding value applies to the current
entry. This is useful for fields which should have fixed width when
present, but zero width when absent.
So I feel like by using %?, [ ] shouldn't be there for Task A, yet it still shows up.
The problem is that the field is never empty: it will always contain at least the left and right square brackets plus the white space to bring it to a width of 12.
The solution is to write a function that returns either an empty string or the bracketed project and use that in the format:
(defun foo ()
(let ((x (nth 1 (org-get-outline-path))))
(if x
(concat "[ " (org-format-outline-path (list x)) " ]")
"")))
(setq org-agenda-prefix-format " %i %?-12(foo) "
I'm trying to write a skeleton-function to output expressions in a loop. Out of a loop I can do,
(define-skeleton test
""
> "a")
When I evaluate this function it outputs "a" into the working buffer as desired. However, I'm having issues when inserting this into a loop. I now have,
(define-skeleton test
"A test skeleton"
(let ((i 1))
(while (< i 5)
>"a"
(setq i (1+ i)))))
I would expect this to output "aaaaa". However, instead nothing is outputted into the working buffer in this case. What is happening when I insert the loop?
The > somestring skeleton dsl does not work inside lisp forms.
You can however concatenate the string inside a loop:
(define-skeleton barbaz
""
""
(let ((s ""))
(dotimes (i 5)
(setq s (concat s "a")))
s)
)
My understanding is that code such as
> "a"
only works at the first nesting level inside a skeleton.
[EDIT] Regarding your question
What is happening when I insert the loop?
The return value of the let form (that is, the return value of the while form)is inserted. I do not know why it does not raise an error when evaluating > "a", but the return value of a while form is nil, so nothing is inserted.
I do agree that there's not much point using define-skeleton if you're going to need an (insert function within the skeleton.
This is also a rather trivial example to be using define-skeleton.
That said, they are often easier to read than a defun and useful when you want to create a function that inserts text (and optionally, takes input).
For example you may wish to have a different character repeated a set no. of times... Below, str refers to the argument supplied with the function (usually a string) and v1, v2 are the default names for local variables in a skeleton. Thus:
(define-skeleton s2 ""
nil ; don't prompt for value of 'str'
'(set 'v1 (make-string 5 (string-to-char str)))
\n v1 \n \n)
Below, calling the function leads to a newline, the string, then leaves the cursor at the position indicated by the square brackets [].
(s2 "a")
aaaaa
[]
Emacs 24.3.1, Windows 2003
I found the 'byte-to-position' function is a little strange.
According to the document:
-- Function: byte-to-position byte-position
Return the buffer position, in character units, corresponding to
given BYTE-POSITION in the current buffer. If BYTE-POSITION is
out of range, the value is `nil'. **In a multibyte buffer, an
arbitrary value of BYTE-POSITION can be not at character boundary,
but inside a multibyte sequence representing a single character;
in this case, this function returns the buffer position of the
character whose multibyte sequence includes BYTE-POSITION.** In
other words, the value does not change for all byte positions that
belong to the same character.
We can make a simple experiment:
Create a buffer, eval this expression: (insert "a" (- (max-char) 128) "b")
Since the max bytes number in Emacs' internal coding system is 5, the character between 'a' and 'b' is 5 bytes. (Note that the last 128 characters is used for 8 bits raw bytes, their size is only 2 bytes.)
Then define and eval this test function:
(defun test ()
(interactive)
(let ((max-bytes (1- (position-bytes (point-max)))))
(message "%s"
(loop for i from 1 to max-bytes collect (byte-to-position i)))))
What I get is "(1 2 3 2 2 2 3)".
The number in the list represents the character position in the buffer. Because there is a 5 bytes big character, there should be five '2' between '1' and '3', but how to explain the magic '3' in the '2's ?
This was a bug. I no longer see this behavior in 26.x. You can read more about it here (which actually references this SO question).
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=20783