Emacs highlighting: how to deal with highlighting messed up by unusual usage of special characters? - emacs

Problem:
In Emacs configuration modes (e.g. conf-xdefaults-mode or conf-space-mode), some special characters are used in unusual ways, for instance when they define keybindings. This messes up the highlighting for the rest of the buffer.
Example:
The ranger rc.conf file uses conf-space-mode which greatly helps its readability. But lines such as:
map # console shell -p%space
map "<any> tag_toggle tag=%any
mess up the highlighting since # usually defines a comment and is followed by font-lock-comment-face until the end of the line and " defines the beginning of a string and is followed by font-lock-string-face until it encounters a closing quote.
Escaping those characters is not an option because it would prevent them from defining the keybindings.
Possible solution:
The best solution I can think of is to fiddle with font lock settings for those configuration modes to remove the highlighting after those special characters. But I will then loose the proper highlighting after those characters when it is suitable.
A compromise could be to keep highlighting after # since this only messes up one line and there are a lot of comments in those configuration files, while removing the highlighting after single and double quotes since those mess up the entire rest of the buffer and strings are not so common in configuration files.
Question:
What is the proper way to deal with these situations?
Is there a way to reset the highlighting at a point in the buffer? or to insert a character which would affect the highlighting (to fix it) without affecting the code? or is there a way to "escape" some characters for the highlighting only without affecting the code?

The easy way
It's probably easiest to just live with it but keep things constrained. Here, I took ranger's default rc.conf and re-arranged some of the font-lock errors.
Let's ignore the blue "map" for now. We have two visible font-lock errors. The map #... is font-locking as a comment, and the map "... font-locking as a string to the end of the buffer. The first error is self-constrained. Comments end at the end of the line. The second error we constrain by adding a comment. (I don't know if ranger would accept comments in the middle of the line, so I'm only using beginning-of-line comments here.)
The second error is now constrained to one line, but a couple more errors have popped up. Quickly adjusting these we get.
This is something that I could live with, as I'm not in conf files all day long (as opposed to say, source code.) It would be even neater if our new "comments" could be included on the same line.
The hard way
You'll want to use Emacs font-lock-add-keywords. Let's get back to that blue map in the first image. It's rendering blue because conf-space-mode thinks that a string, followed by any amount of whitespace, followed by an opening brace should be rendered in font-lock-type-face (the actually regexp that triggers this is ^[_space__tab_]*\\(.+?\\)[_space__tab_\n]*{[^{}]*?$ where _space_ and _tab_ are actual space and tab characters.)
We can override this in a simple fashion by evaluating
(font-lock-remove-keywords
'conf-space-mode
'(("^\\<\\(map\\)\\>" 1 font-lock-variable-name-face)))
and reloading the buffer with C-x C-v RET. Now, every time that the word "map" appears at the beginning of a line it's rendered as font-lock-variable-name-face (yellow in our example.)
You can make this change permanent by adding a hook to your init file.
(add-hook 'conf-space-mode-hook (lambda ()
(font-lock-remove-keywords
nil
'(("^\\<\\(map\\)\\>" 1 font-lock-variable-name-face)))))
This method doesn't appear to work for your comment (#) and string (' ") delimiters as they're defined in the syntax table. Modifying the syntax table to provide special cases is probably more effort than it's worth.

Related

How do I auto-fill lines in brackets in emacs (markdown-mode)?

I'm relatively new to Emacs, but have been experimenting with it to see if it would be worth switching. I write in Markdown and use pandoc to convert to whatever I need. In case it matters, I'm running Emacs 23.3.1 on Ubuntu 12.04.
I'm a graduate student in the humanities, so my writing is heavy on the footnotes. Footnotes, in pandoc, are formatted within square brackets. The problem I'm having is that auto-fill mode seems to ignore text within brackets, so my footnotes end up snaking their way across the page--and the only fix I've been able to find is to manually break the lines myself, every time I edit the paragraph. That's obviously less than ideal. (I could also give up on inline footnotes, and leave them all separate references, but I'd prefer not to, and it doesn't seem like that should be necessary.)
So my question is, is there a way to make auto-fill mode operate on text within brackets, too? Is there a reason it doesn't by default?
Many thanks,
-- Brian
It turns out that markdown-mode, as of v. 1.7, deliberately avoids breaking lines in square brackets in order to avoid breaking links--which is the most common use of brackets for Markdown. See http://jblevins.org/projects/markdown-mode/rev-1-7.
Brian,
Add the following to your init file† to allow auto-fill in markdown-mode to break lines inside square brackets:
(require 'markdown-mode)
(defun markdown-nobreak-p () nil)
What we did is redefine the function "markdown-nobreak-p" (originally defined here: http://jblevins.org/git/markdown-mode.git/commit/?id=66566a55 ) to always return "nil" which means "yes you are allowed to break at this point". The original version of this function would return non-nil for points inside square brackets.
† http://www.gnu.org/software/emacs/manual/html_node/emacs/Find-Init.html
Auto-fill by itself does not prevent filling inside brackets. It can be told to do so by the major-mode, tho, so I guess the problem depends on your major mode. If you're using mardown-mode, then please report this problem to its maintainer. In any case, you may want to try and use M-q to explicitly fill the paragraph, since it does not always follow the same conventions as auto-filling: it's more explicit than auto-fill, but still more automatic than placing the newlines by hand.

Problem writing a snippet containing Emacs Lisp code

I've been trying to make use of a cool feature of YASnippet: write snippets containing embedded Emacs Lisp code. There is a snippet for rst-mode that surrounds the entered text with "=" that is as long as the text such as in
====
Text
====
Based on this snippet, I decided to slightly modify it (with Elisp) so that it comments out these three lines depending on the major mode you are in (I thought that such a snippet would be useful to organize the source code). So I wrote this:
${1:`(insert comment-start)`} ${2:$(make-string (string-width text) ?\-)}
$1 ${2:Text}
$1 ${2:$(make-string (string-width text) ?\-)}
$0
This code works relatively well except for one problem: the indentation of these three lines gets mixed up, depending on the major mode I'm in (e.g., in emacs-lisp-mode, the second and the third lines move more to the right than the first line).
I think the source of the problem might have something to do with what comes after the string ${1: on the first line. If I add a character, I have no problem (i.e., all three lines are correctly aligned at the end of the snippet expansion). If I add a single space after this string, the misalignment problem still continues though.
So my question is: do you know of any way of rewriting this snippet so that this misalignment does not arise? Do you know what's the source of this behaviour?
Cheers,
From Writing snippets:
yas/indent-line
The variable yas/indent-line controls the indenting. It is bound to 'auto by default, which causes your snippet to be indented according to the mode of the buffer it was inserted in.
Another variable yas/also-auto-indent-first-line, when non-nil does exactly that :-).
To use the hard-coded indentation in your snippet template, set this variable to fixed.
To control indentation on a per-snippet basis, see also the directive # expand-env: in Writing Snippets.
For backward compatibility with earlier versions of YASnippet, you can also place a $> in your snippet, an (indent-according-to-mode) will be executed there to indent the line. This only takes effect when yas/indent-line is set to something other than 'auto.
for (${int i = 0}; ${i < 10}; ${++i})
{$>
$0$>
}$>

Show trailing whitespace on emacs only on non-empty lines

Right now I'm using:
(setq show-trailing-whitespace t)
In my .emacs to show trailing whitespace for my CC mode. I can't seem to figure out how to have it not show the whitespace font for whitespace only lines.
Empty lines separating indenting code are sometimes indented at the code level and sometimes not indented at all, and I don't want to draw my attention to a line I don't care to change.
I'd like to stick to built-in emacs modules, but I'm willing to use whitespace.el but it's not clear how to configure it to do this.
Since you want to use built-in modules, I'd advise using the whitespace.el link you specified - as it is shipped with Emacs 23. This answer works when using that whitespace.
As long as you have 'trailing in your 'whitespace-style variable (which it is by default), the following change to the regular expression for what indicates "trailing" whitespace should give you what you want:
(setq whitespace-trailing-regexp
"\\b\\(\\(\t\\| \\|\xA0\\|\x8A0\\|\x920\\|\xE20\\|\xF20\\)+\\)$")
Note: It is just the default value, with the \b prepended, indicating that the whitespace should follow a word.
With
"\\b.*\\(\\(\t\\| \\|\xA0\\|\x8A0\\|\x920\\|\xE20\\|\xF20\\)+\\)$"
the word does not need to be directly in front of the trailing whitespaces but there can be e.g. punctuation characters between them (i.e. this also highlights trailing whitespaces behind non-word characters).
Edit:
Using
"\\b.*?\\(\\(\t\\| \\|\xA0\\|\x8A0\\|\x920\\|\xE20\\|\xF20\\)+\\)$")
highlights all the trailing whitespaces and thus eliminates the drawback mentioned in comment #1.

How to make part of a word bold in org-mode

How can I make org-mode markup work for a part of a word? For example, I'd like it to work for cases like this:
=Class=es
and this:
/Method/s
Based on my tests it seems like org-mode markup syntax works on complete words only.
These days, there is a way to do this (without using quoted HTML tags):
(setcar org-emphasis-regexp-components " \t('\"{[:alpha:]")
(setcar (nthcdr 1 org-emphasis-regexp-components) "[:alpha:]- \t.,:!?;'\")}\\")
(org-set-emph-re 'org-emphasis-regexp-components org-emphasis-regexp-components)
Explanation
The manual says that org-emphasis-regexp-components can be used to
fine tune what characters are allowed before and after the markup characters [...].
It is a list containing five entries. The first entry lists characters that are allowed to immediately precede markup characters, and the second entry lists characters that are allowed to follow markup characters. By default, letters are not included in either one of these entries. So in order to successfully apply formatting to strings immediately preceded or followed by a letter, we have to add [:alpha:] (which matches any letter) to both entries.
This is what the calls to setcar do. The purpose of the third line is to rebuild the regular expression for emphasis based on the modified version of org-emphasis-regexp-components.
I don't think you can do it so that it shows up in the buffer as bold. If you just need it so that it appears bold when you export it to html, you can use:
th#<b>is is ha#</b>lf bold
See Quoting HTML tags
No, you can't do that. I searched for the same solution before and found nothing. A (very) bad hack is to do something like *Class* es (with a whitespace).
Perhaps you can write a short message to the creator, Carsten Dominik (Homepage), and ask him for a solution. He seems to be a nice guy.
A solution that has not been mentioned is to use a unicode zero width space (U+200B) in between the desired bolded and unbolded parts of a word.
To get the desired bolding of the word "Classes":
Type 'Class*es' in the buffer (without quotes).
Move the cursor between the '*' and 'e' characters.
Press C-x 8 RET (to execute the insert-char command).
Type 'zero width space' (without quotes) and press RET.
Move the cursor to the beginning of the word and insert a '*' character.
The word "Classes" should now have the desired appearance.
Note that there is the possibility that this will cause problems when exporting.
src_latex{\textbf{Class}es and \textit{Method}s}
Building up on the previous excellent answer
I had to modify it a bit in order to make it work with spacemacs. Indeed, from the spacamacs org-layer documentation, available here, we can read
Because of autoloading, calling to org functions will trigger the
loading up of the org shipped with emacs which will induce conflicts.
One way to avoid conflict is to wrap your org config code in a
with-eval-after-load block [...]
So, I put the following lines inside my dotspacemacs/user-config ()
(eval-after-load "org"
'(progn
(setcar org-emphasis-regexp-components " \t('\"{[:alpha:]")
(setcar (nthcdr 1 org-emphasis-regexp-components) "[:alpha:]- \t.,:!?;'\")}\\")
(org-set-emph-re 'org-emphasis-regexp-components org-emphasis-regexp-components)
))

Getting Emacs fill-paragraph to play nice with javadoc-like comments

I'm writing an Emacs major mode for an APL dialect I use at work. I've gotten
basic font locking to work, and after setting comment-start and
comment-start-skip, comment/uncomment region and fill paragraph also
work.
However, comment blocks often contain javadoc style comments and i
would like fill-paragraph to avoid glueing together lines starting
with such commands.
If I have this (\ instead of javadoc #):
# This is a comment that is long and should be wrapped.
# \arg Description of argument
# \ret Description of return value
M-q gives me:
# This is a comment that is long and
# should be wrapped. \arg Description
# of argument \ret Description of
# return value
But I want:
# This is a comment that is long and
# should be wrapped.
# \arg Description of argument
# \ret Description of return value
I've tried setting up paragraph-start and paragraph-separate to
appropriate values, but fill-paragraph still doesn't work inside a
comment block. If I remove the comment markers, M-q works as I want
to, so the regexp I use for paragraph-start seems to work.
Do I have to write a custom fill-paragraph for my major
mode? cc-mode has one that handles cases like this, but it's really
complex, I'd like to avoid it if possible.
The problem was that the paragraph-start regexp has to match the entire line to work, including the actual comment character. The following elisp works for the example I gave:
(setq paragraph-start "^\\s-*\\#\\s-*\\\\\\(arg\\|ret\\).*$")
Here a page that has an example regexp for php-mode that does this:
http://barelyenough.org/blog/2006/10/nicer-phpdoc-comments/
There's other modes that have less complex functions used for fill-paragraph-function. Browsing through my install, it looks like the ones in ada-mode and make-mode are good examples.
What I do in these cases is open a blank line between the paragraph lines and the argument lines, then use M-q to wrap the paragraph lines, then kill the blank line between them. Not ideal, but it works and is easy enough to record in a macro if you need to repeat it.