C++11 mode or settings for emacs? - c++

I'm running Emacs 23.3.1 (Ubuntu, Oneiric package) and emacs doesn't appear to understand any of the new C++11 keywords, constexpr, thread_local, etc. Also it doesn't understand that '>>' is now permitted in template parameters, or the new 'enum class' syntax. Is there an updated or alternative module somewhere? Or failing that, some settings to make emacs more C++11 friendly in the mean time?

Well, I'm using 24.1. Some C++98 keywords are missing, and all new C++11 keywords. It does not even fontify number constants. It seems as if c++-mode hasn't been updated for a decade.
I'm using the following code for a long time now, and recently added C++11 keywords. Try putting it in your .emacs; it should fill some holes.
(require 'font-lock)
(defun --copy-face (new-face face)
"Define NEW-FACE from existing FACE."
(copy-face face new-face)
(eval `(defvar ,new-face nil))
(set new-face new-face))
(--copy-face 'font-lock-label-face ; labels, case, public, private, proteced, namespace-tags
'font-lock-keyword-face)
(--copy-face 'font-lock-doc-markup-face ; comment markups such as Javadoc-tags
'font-lock-doc-face)
(--copy-face 'font-lock-doc-string-face ; comment markups
'font-lock-comment-face)
(global-font-lock-mode t)
(setq font-lock-maximum-decoration t)
(add-hook 'c++-mode-hook
'(lambda()
(font-lock-add-keywords
nil '(;; complete some fundamental keywords
("\\<\\(void\\|unsigned\\|signed\\|char\\|short\\|bool\\|int\\|long\\|float\\|double\\)\\>" . font-lock-keyword-face)
;; add the new C++11 keywords
("\\<\\(alignof\\|alignas\\|constexpr\\|decltype\\|noexcept\\|nullptr\\|static_assert\\|thread_local\\|override\\|final\\)\\>" . font-lock-keyword-face)
("\\<\\(char[0-9]+_t\\)\\>" . font-lock-keyword-face)
;; PREPROCESSOR_CONSTANT
("\\<[A-Z]+[A-Z_]+\\>" . font-lock-constant-face)
;; hexadecimal numbers
("\\<0[xX][0-9A-Fa-f]+\\>" . font-lock-constant-face)
;; integer/float/scientific numbers
("\\<[\\-+]*[0-9]*\\.?[0-9]+\\([ulUL]+\\|[eE][\\-+]?[0-9]+\\)?\\>" . font-lock-constant-face)
;; user-types (customize!)
("\\<[A-Za-z_]+[A-Za-z_0-9]*_\\(t\\|type\\|ptr\\)\\>" . font-lock-type-face)
("\\<\\(xstring\\|xchar\\)\\>" . font-lock-type-face)
))
) t)
Hope this helps.

According to a request by Mike Weller here an updated version for C++11 strings literals (incl. user-defined literals).
(add-hook
'c++-mode-hook
'(lambda()
;; We could place some regexes into `c-mode-common-hook', but note that their evaluation order
;; matters.
(font-lock-add-keywords
nil '(;; complete some fundamental keywords
("\\<\\(void\\|unsigned\\|signed\\|char\\|short\\|bool\\|int\\|long\\|float\\|double\\)\\>" . font-lock-keyword-face)
;; namespace names and tags - these are rendered as constants by cc-mode
("\\<\\(\\w+::\\)" . font-lock-function-name-face)
;; new C++11 keywords
("\\<\\(alignof\\|alignas\\|constexpr\\|decltype\\|noexcept\\|nullptr\\|static_assert\\|thread_local\\|override\\|final\\)\\>" . font-lock-keyword-face)
("\\<\\(char16_t\\|char32_t\\)\\>" . font-lock-keyword-face)
;; PREPROCESSOR_CONSTANT, PREPROCESSORCONSTANT
("\\<[A-Z]*_[A-Z_]+\\>" . font-lock-constant-face)
("\\<[A-Z]\\{3,\\}\\>" . font-lock-constant-face)
;; hexadecimal numbers
("\\<0[xX][0-9A-Fa-f]+\\>" . font-lock-constant-face)
;; integer/float/scientific numbers
("\\<[\\-+]*[0-9]*\\.?[0-9]+\\([ulUL]+\\|[eE][\\-+]?[0-9]+\\)?\\>" . font-lock-constant-face)
;; c++11 string literals
;; L"wide string"
;; L"wide string with UNICODE codepoint: \u2018"
;; u8"UTF-8 string", u"UTF-16 string", U"UTF-32 string"
("\\<\\([LuU8]+\\)\".*?\"" 1 font-lock-keyword-face)
;; R"(user-defined literal)"
;; R"( a "quot'd" string )"
;; R"delimiter(The String Data" )delimiter"
;; R"delimiter((a-z))delimiter" is equivalent to "(a-z)"
("\\(\\<[uU8]*R\"[^\\s-\\\\()]\\{0,16\\}(\\)" 1 font-lock-keyword-face t) ; start delimiter
( "\\<[uU8]*R\"[^\\s-\\\\()]\\{0,16\\}(\\(.*?\\))[^\\s-\\\\()]\\{0,16\\}\"" 1 font-lock-string-face t) ; actual string
( "\\<[uU8]*R\"[^\\s-\\\\()]\\{0,16\\}(.*?\\()[^\\s-\\\\()]\\{0,16\\}\"\\)" 1 font-lock-keyword-face t) ; end delimiter
;; user-defined types (rather project-specific)
("\\<[A-Za-z_]+[A-Za-z_0-9]*_\\(type\\|ptr\\)\\>" . font-lock-type-face)
("\\<\\(xstring\\|xchar\\)\\>" . font-lock-type-face)
))
) t)
In the above implementation of user-defined strings literals, the delimiter tags are marked up separately as font-lock-keyword-face; another option would be font-lock-constant-face. This implementation is not as efficient as it could be; but it works and does not slow down Emacs. Note that the regexps for user-defined strings literals have not been "stolen" from somehere; so I hope they work. Any comments are welcome.
If you like to fontify the whole literal string as font-lock-string-face - including the delimiters - replace the three regexps by just one. Like this one:
.
.
("\\<\\([uU8]*R\"[^\\s-\\\\()]\\{0,16\\}(.*?)[^\\s-\\\\()]\\{0,16\\}\"\\)\\>" 1 font-lock-string-face t)
Have fun.

Have a look at the package : "Modern C++" font-lock for Emacs. It is also available on Melpa.
Syntax highlighting support for "Modern C++" - until C++17 and
Technical Specification. This package aims to provide a simple
highlight of the C++ language without dependency.
It is recommended to use it in addition with the c++-mode major mode
for extra highlighting (user defined types, functions, etc.) and
indentation.
I am the maintainer of this minor mode. Any feedback is appreciated.

Replacing Andreas' floating point regexp with this will improve hilighting of floats.
integer/float/scientific literals
("\\<[-+]?[0-9]*\\.?[0-9]+\\([uUlL]+\\|[eE][-+]?[0-9]+\\)?[fFlL]?\\>" . font-lock-constant-face)
Hope that helps someone.

I've checked trunk version, cc-mode hasn't been updated yet, and AFAIK there's no alternative. If you really want it, but don't want to get your hands dirty, you should pay someone to implement it for you...

For me, the two most pressing pain points with font-locking of modern C++ code have been
the fact that auto is highlighted as a keyword (and not a type) and thus the following identifier would normally not higlight as a variable declaration, and
that highlighting simply goes crazy when presented with some code (for an example, try rtags' src/ClangIndexer.cpp) and then e.g fails to highlight top-level constructs such as function definitions.
After a bit of experimentation, I arrived at a solution that works well for me and addresses both points.
The first one is achieved by modifying lisp/progmodes/cc-langs.el (copying to one's load-path and then modifying also works) to remove "auto" from
(c-lang-defconst c-modifier-kwds
"Keywords that can prefix normal declarations of identifiers
and add it to c++-font-lock-extra-types (e.g. via Customize).
For the second one, emptying c++-font-lock-extra-types (except for keeping "auto") helps.

Related

Custom character classes in Emacs' regexp

Is it possible to add own character classes to emacs in order to use them in regular expressions?
Let's say, i want to add a class [[:consonant:]] which matches all letters that are not vowels in order to avoid writing [b-df-hj-np-tv-z] all the time (and yes, i am aware that my shortcut is almost as long as the term i want to avoid, take it as a simplification of my problem).
Is this possible at all or do i have to use format or concat, respectively? If it is possible, how do i do that?
An MWE could be like this:
(defun myfun ()
"Finds clusters of three or more consonants"
(interactive)
(if (search-forward-regexp "[b-df-hj-np-tv-z]\\{3,\\}")
(message "Yepp, here is a consonant cluster.")
))
(defun myfun-1 ()
"Should also find clusters of three or more consonants."
(interactive)
(if (search-forward-regexp "[[:consonant:]]\\{3,\\}")
(message "Yepp, here is a consonant cluster.")
))
Both functions myfun and myfun-1 should do the very same thing.
One step further i'd like to know if it is possible to put whole expressions in such "shortcuts", like
[[:ending:]] ==> "\\(?:en\\|st\\|t\\|e\\)"
Jordon-Biondo is correct, you cannot extend Emacs' character classes for regexp search. If you peek into Emacs' source code, you can see these defined in the routine re_wctype_parse on line 1510(ish) of regex-emacs.c. So adding to these natively would require modifying the .c file and rebuilding.
I do not believe you can do this. But there is something similar that was recently released in the ample-regexp package found HERE. This was taken from the readme as an example:
(define-arx h-w-rx
'((h "Hello, ")
(w "world"))) ;; -> hello-world-rx
(h-w-rx h w) ;; -> "Hello, world"
(h-w-rx (* h w)) ;; -> "\\(?:Hello, world\\)*"
You could use this to define a wide range of aliases in one big define-arx.

How do I beautify lisp source code?

My code is a mess many long lines in this language like the following
(defn check-if-installed[x] (:exit(sh "sh" "-c" (str "command -v " x " >/dev/null 2>&1 || { echo >&2 \"\"; exit 1; }"))))
or
(def Open-Action (action :handler (fn [e] (choose-file :type :open :selection-mode :files-only :dir ListDir :success-fn (fn [fc file](setup-list file)))) :name "Open" :key "menu O" :tip "Open spelling list"))
which is terrible. I would like to format it like so
(if (= a something)
(if (= b otherthing)
(foo)))
How can I beautify the source code in a better way?
The real answer hinges on whether you're willing to insert the newlines yourself. Many systems
can indent the lines for you in an idiomatic way, once you've broken it up into lines.
If you don't want to insert them manually, Racket provides a "pretty-print" that does some of what you want:
#lang racket
(require racket/pretty)
(parameterize ([pretty-print-columns 20])
(pretty-print '(b aosentuh onethunoteh (nte huna) oehnatoe unathoe)))
==>
'(b
aosentuh
onethunoteh
(nte huna)
oehnatoe
unathoe)
... but I'd be the first to admit that inserting newlines in the right places is hard, because
the choice of line breaks has a lot to do with how you want people to read your code.
I use Clojure.pprint often for making generated code more palatable to humans.
it works well for reporting thought it is targeted at producing text. The formatting built into the clojure-mode emacs package produces very nicely formatted Clojure if you put the newlines in your self.
Now you can do it with Srefactor package.
Some demos:
Formatting whole buffer demo in Emacs Lisp (applicable in Common Lisp as well).
Transform between one line <--> Multiline demo
Available Commands:
srefactor-lisp-format-buffer: format whole buffer
srefactor-lisp-format-defun: format current defun cursor is in
srefactor-lisp-format-sexp: format the current sexp cursor is in.
srefactor-lisp-one-line: turn the current sexp of the same level into one line; with prefix argument, recursively turn all inner sexps into one line.
Scheme variants are not as polished as Emacs Lisp and Common Lisp yet but work for simple and small sexp. If there is any problem, please submit an issue report and I will be happy to fix it.

Emacs Brace and Bracket Highlighting?

When entering code Emacs transiently highlights the matching brace or bracket. With existing code however is there a way to ask it to highlight a matching brace or bracket if I highlight its twin?
I am often trying to do a sanity check when dealing with compiler errors and warnings. I do enter both braces usually when coding before inserting the code in between, but have on occasion unintentionally commented out one brace when commenting out code while debugging.
Any advice with dealing with brace and bracket matching with Emacs?
OS is mostly Linux/Unix, but I do use it also on OS X and Windows.
If you're dealing with a language that supports it, give ParEdit a serious look. If you're not using with a Lisp dialect, it's not nearly as useful though.
For general brace/bracket/paren highlighting, look into highlight-parentheses mode (which color codes multiple levels of braces whenever point is inside them). You can also turn on show-paren-mode through customizations (that is M-x customize-variable show-paren-mode); that one strongly highlights the brace/bracket/paren matching one at point (if the one at point doesn't match anything, you get a different color).
my .emacs currently contains (among other things)
(require 'highlight-parentheses)
(define-globalized-minor-mode global-highlight-parentheses-mode highlight-parentheses-mode
(lambda nil (highlight-parentheses-mode t)))
(global-highlight-parentheses-mode t)
as well as that show-paren-mode customization, which serves me well (of course, I also use paredit when lisping, but these are still marginally useful).
Apart from the answer straight from the manual or wiki, also have a look at autopair.
tried on emacs 26
(show-paren-mode 1)
(setq show-paren-style 'mixed)
enable showing parentheses
set the showing in such as highlit the braces char., or if either one invisible higlight what they enclose
for toggling the cursor position / point between both, put this script in .emacs
(defun swcbrace ()(interactive)
(if (looking-at "(")(forward-list)
(backward-char)
(cond
((looking-at ")")(forward-char)(backward-list))
((looking-at ".)")(forward-char 2)(backward-list))
)))
(global-set-key (kbd "<C-next>") 'swcbrace)
it works toggling by press Control-Pgdn
BTW, for the immediate question: M-x blink-matching-open will "re-blink" for an existing close paren, as if you had just inserted it. Another way to see the matching paren is to use M-C-b and M-C-f (which jump over matched pairs of parens), which are also very useful navigation commands.
I second ParEdit. it is very good atleast for lisp development.
FWIW I use this function often to go to matching paren (back and forth).
;; goto-matching-paren
;; -------------------
;; If point is sitting on a parenthetic character, jump to its match.
;; This matches the standard parenthesis highlighting for determining which
;; one it is sitting on.
;;
(defun goto-matching-paren ()
"If point is sitting on a parenthetic character, jump to its match."
(interactive)
(cond ((looking-at "\\s\(") (forward-list 1))
((progn
(backward-char 1)
(looking-at "\\s\)")) (forward-char 1) (backward-list 1))))
(define-key global-map [(control ?c) ?p] 'goto-matching-paren) ; Bind to C-c p
Declaimer: I am NOT the author of this function, copied from internet.
If you just want to check the balanced delimiters, be them parentheses, square brackets or curly braces, you can use backward-sexp (bound to CtrlAltB) and forward-sexp (bound to CtrlAltF) to skip backward and forward to the corresponding delimiter. These commands are very handy to navigate through source files, skipping structures and function definitions, without any buffer modifications.
You can set the below in your init.el:
(setq show-paren-delay 0)
(show-paren-mode 1)
to ensure matching parenthesis are highlighted.
Note that (setq show-paren-delay 0) needs to be set before (show-paren-mode 1) so that there's no delay in highlighting, as per the wiki.
If you want to do a quick check to see whether brackets in the current file are balanced:
M-x check-parens
Both options tested on Emacs 27.1

What is the difference between ; and ;; in Clojure code comments?

What is the difference between ; and ;; when starting a comment in Clojure? I see that my text editor colours them differently, so I'm assuming there is notionally some difference.
I also see that Marginalia treats them differently:
; Stripped entirely
;; Appears in text section of marginalia
(defn foobar []
; Appears in code section of marginalia output
;; Again, appears in code section of marginalia output
6)
There is no difference as far as the interpreter is concerned. Think of ; ;; ;;; and ;;;; as different heading levels.
Here is my personal use convention:
;;;; Top-of-file level comments, such as a description of the whole file/module/namespace
;;; Documentation for major code sections (i.e. groups of functions) within the file.
;; Documentation for single functions that extends beyond the doc string (e.g. an explanation of the algorithm within the function)
; In-line comments possibly on a single line, and possibly tailing a line of code
Check out the official description of the meaning of ; vs ;; in elisp: since the Clojure indenter is basically the same, it will treat them similarly. Basically, use ; if you are writing a long sentence/description "in the margins" that will span multiple lines but should be considered a single entity. Their example is:
(setq base-version-list ; there was a base
(assoc (substring fn 0 start-vn) ; version to which
file-version-assoc-list)) ; this looks like
; a subversion
The indenter will make sure those stay lined up next to each other. If, instead, you want to make several unrelated single-line comments next to each other, use ;;.
(let [x 99 ;; as per ticket #425
y "test"] ;; remember to test this
(str x y)) ;; TODO actually write this function
Emacs ; to be used for end-of-line comments and will indent in surprising ways if that is not your intent. ;; does not so I usually use ;;.
Clojure doesn't care - any line is ignored from the ; to EOL.
I believe there is a tradition in CL of using increasing numbers of ; to indicate more important comments/sections.
no meaning for the language. ; is a reader macro for comment
perhaps other tools parse them but "within clojure" they are the same.
There is no difference from a Clojure-perspective. I find that ;; stands out a little better than ;, but that's only my opinion.
Marginalia on the other hand treats them differently because there are times when a comment should remain in the code section (e.g. license) and those are flagged with ;. This is an arbitrary decision and may change in the future.
In emacs lisp modes including clojure-mode, ;; is formatted with the convention of being at the beginning of a line, and indented as as any other line, based on the context. ; is expected to be used at the end of a line, so emacs will not do what you want it to if you put a single-semicolon comment at the beginning of a line expecting it to tab to the indentation for the present context.
Example:
(let [foo 1]
;; a comment
foo) ; a comment
I'm not sure (not used Clojure and never heard of this before), but this thread might help.

in emacs-lisp, how do I correctly use replace-regexp-in-string?

Given a string, I want to replace all links within it with the link's description. For example, given
this is a [[http://link][description]]
I would like to return
this is a description
I used re-builder to construct this regexp for a link:
\\[\\[[^\\[]+\\]\\[[^\\[]+\\]\\]
This is my function:
(defun flatten-string-with-links (string)
(replace-regexp-in-string "\\[\\[[^\\[]+\\]\\[[^\\[]+\\]\\]"
(lambda(s) (nth 2 (split-string s "[\]\[]+"))) string))
Instead of replacing the entire regexp sequence, it only replaces the trailing "]]". This is what it produces:
this is a [[http://link][descriptiondescription
I don't understand what's going wrong. Any help would be much appreciated.
UPDATE: I've improved the regex for the link. It's irrelevant to the question but if someone's gonna copy it they may as well get the better version.
Your problem is that split-string is clobbering the match data, which
replace-regexp-in-string is relying on being unchanged, since it is going to
go use that match data to decide which sections of the string to cut out. This
is arguably a doc bug in that replace-regexp-in-string does not mention that
your replacement function must preserve the match data.
You can work around by using save-match-data, which is a macro provided for
exactly this purpose:
(defun flatten-string-with-links (string)
(replace-regexp-in-string "\\[\\[[a-zA-Z:%#/\.]+\\]\\[[a-zA-Z:%#/\.]+\\]\\]"
(lambda (s) (save-match-data
(nth 2 (split-string s "[\]\[]+")))) string))