*indent.txt* For Vim version 9.0. Last change: 2022 Oct 10 VIM REFERENCE MANUAL by Bram Moolenaar This file is about indenting C programs and other files. 1. Indenting C style programs |C-indenting| 2. Indenting by expression |indent-expression| ============================================================================== 1. Indenting C style programs *C-indenting* The basics for C style indenting are explained in section |30.2| of the user manual. Vim has options for automatically indenting C style program files. Many programming languages including Java and C++ follow very closely the formatting conventions established with C. These options affect only the indent and do not perform other formatting. There are additional options that affect other kinds of formatting as well as indenting, see |format-comments|, |fo-table|, |gq| and |formatting| for the main ones. There are in fact four main methods available for indentation, each one overrides the previous if it is enabled, or non-empty for 'indentexpr': 'autoindent' uses the indent from the previous line. 'smartindent' is like 'autoindent' but also recognizes some C syntax to increase/reduce the indent where appropriate. 'cindent' Works more cleverly than the other two and is configurable to different indenting styles. 'indentexpr' The most flexible of all: Evaluates an expression to compute the indent of a line. When non-empty this method overrides the other ones. See |indent-expression|. The rest of this section describes the 'cindent' option. Note that 'cindent' indenting does not work for every code scenario. Vim is not a C compiler: it does not recognize all syntax. One requirement is that toplevel functions have a '{' in the first column. Otherwise they are easily confused with declarations. These five options control C program indenting: 'cindent' Enables Vim to perform C program indenting automatically. 'cinkeys' Specifies which keys trigger reindenting in insert mode. 'cinoptions' Sets your preferred indent style. 'cinwords' Defines keywords that start an extra indent in the next line. 'cinscopedecls' Defines strings that are recognized as a C++ scope declaration. If 'lisp' is not on and 'equalprg' is empty, the "=" operator indents using Vim's built-in algorithm rather than calling an external program. See |autocommand| for how to set the 'cindent' option automatically for C code files and reset it for others. *cinkeys-format* *indentkeys-format* The 'cinkeys' option is a string that controls Vim's indenting in response to typing certain characters or commands in certain contexts. Note that this not only triggers C-indenting. When 'indentexpr' is not empty 'indentkeys' is used instead. The format of 'cinkeys' and 'indentkeys' is equal. The default is "0{,0},0),0],:,0#,!^F,o,O,e" which specifies that indenting occurs as follows: "0{" if you type '{' as the first character in a line "0}" if you type '}' as the first character in a line "0)" if you type ')' as the first character in a line "0]" if you type ']' as the first character in a line ":" if you type ':' after a label or case statement "0#" if you type '#' as the first character in a line "!^F" if you type CTRL-F (which is not inserted) "o" if you type a anywhere or use the "o" command (not in insert mode!) "O" if you use the "O" command (not in insert mode!) "e" if you type the second 'e' for an "else" at the start of a line Characters that can precede each key: *i_CTRL-F* ! When a '!' precedes the key, Vim will not insert the key but will instead reindent the current line. This allows you to define a command key for reindenting the current line. CTRL-F is the default key for this. Be careful if you define CTRL-I for this because CTRL-I is the ASCII code for . * When a '*' precedes the key, Vim will reindent the line before inserting the key. If 'cinkeys' contains "*", Vim reindents the current line before opening a new line. 0 When a zero precedes the key (but appears after '!' or '*') Vim will reindent the line only if the key is the first character you type in the line. When used before "=" Vim will only reindent the line if there is only white space before the word. When neither '!' nor '*' precedes the key, Vim reindents the line after you type the key. So ';' sets the indentation of a line which includes the ';'. Special key names: <> Angle brackets mean spelled-out names of keys. For example: "", "" (see |key-notation|). ^ Letters preceded by a caret (^) are control characters. For example: "^F" is CTRL-F. o Reindent a line when you use the "o" command or when Vim opens a new line below the current one (e.g., when you type in insert mode). O Reindent a line when you use the "O" command. e Reindent a line that starts with "else" when you type the second 'e'. : Reindent a line when a ':' is typed which is after a label or case statement. Don't reindent for a ":" in "class::method" for C++. To Reindent for any ":", use "<:>". =word Reindent when typing the last character of "word". "word" may actually be part of another word. Thus "=end" would cause reindenting when typing the "d" in "endif" or "endwhile". But not when typing "bend". Also reindent when completion produces a word that starts with "word". "0=word" reindents when there is only white space before the word. =~word Like =word, but ignore case. If you really want to reindent when you type 'o', 'O', 'e', '0', '<', '>', '*', ':' or '!', use "", "", "", "<0>", "<<>", "<>>", "<*>", "<:>" or "", respectively, for those keys. For an emacs-style indent mode where lines aren't indented every time you press but only if you press , I suggest: :set cinkeys=0{,0},:,0#,!,!^F You might also want to switch off 'autoindent' then. Note: If you change the current line's indentation manually, Vim ignores the cindent settings for that line. This prevents vim from reindenting after you have changed the indent by typing , , or in the indent or used CTRL-T or CTRL-D. *cinoptions-values* The 'cinoptions' option sets how Vim performs indentation. The value after the option character can be one of these (N is any number): N indent N spaces -N indent N spaces to the left Ns N times 'shiftwidth' spaces -Ns N times 'shiftwidth' spaces to the left In the list below, "N" represents a number of your choice (the number can be negative). When there is an 's' after the number, Vim multiplies the number by 'shiftwidth': "1s" is 'shiftwidth', "2s" is two times 'shiftwidth', etc. You can use a decimal point, too: "-0.5s" is minus half a 'shiftwidth'. The examples below assume a 'shiftwidth' of 4. *cino->* >N Amount added for "normal" indent. Used after a line that should increase the indent (lines starting with "if", an opening brace, etc.). (default 'shiftwidth'). cino= cino=>2 cino=>2s > if (cond) if (cond) if (cond) { { { foo; foo; foo; } } } < *cino-e* eN Add N to the prevailing indent inside a set of braces if the opening brace at the End of the line (more precise: is not the first character in a line). This is useful if you want a different indent when the '{' is at the start of the line from when '{' is at the end of the line. (default 0). cino= cino=e2 cino=e-2 > if (cond) { if (cond) { if (cond) { foo; foo; foo; } } } else else else { { { bar; bar; bar; } } } < *cino-n* nN Add N to the prevailing indent for a statement after an "if", "while", etc., if it is NOT inside a set of braces. This is useful if you want a different indent when there is no '{' before the statement from when there is a '{' before it. (default 0). cino= cino=n2 cino=n-2 > if (cond) if (cond) if (cond) foo; foo; foo; else else else { { { bar; bar; bar; } } } < *cino-f* fN Place the first opening brace of a function or other block in column N. This applies only for an opening brace that is not inside other braces and is at the start of the line. What comes after the brace is put relative to this brace. (default 0). cino= cino=f.5s cino=f1s > func() func() func() { { { int foo; int foo; int foo; < *cino-{* {N Place opening braces N characters from the prevailing indent. This applies only for opening braces that are inside other braces. (default 0). cino= cino={.5s cino={1s > if (cond) if (cond) if (cond) { { { foo; foo; foo; < *cino-}* }N Place closing braces N characters from the matching opening brace. (default 0). cino= cino={2,}-0.5s cino=}2 > if (cond) if (cond) if (cond) { { { foo; foo; foo; } } } < *cino-^* ^N Add N to the prevailing indent inside a set of braces if the opening brace is in column 0. This can specify a different indent for whole of a function (some may like to set it to a negative number). (default 0). cino= cino=^-2 cino=^-s > func() func() func() { { { if (cond) if (cond) if (cond) { { { a = b; a = b; a = b; } } } } } } < *cino-L* LN Controls placement of jump labels. If N is negative, the label will be placed at column 1. If N is non-negative, the indent of the label will be the prevailing indent minus N. (default -1). cino= cino=L2 cino=Ls > func() func() func() { { { { { { stmt; stmt; stmt; LABEL: LABEL: LABEL: } } } } } } < *cino-:* :N Place case labels N characters from the indent of the switch(). (default 'shiftwidth'). cino= cino=:0 > switch (x) switch(x) { { case 1: case 1: a = b; a = b; default: default: } } < *cino-=* =N Place statements occurring after a case label N characters from the indent of the label. (default 'shiftwidth'). cino= cino==10 > case 11: case 11: a = a + 1; a = a + 1; b = b + 1; < *cino-l* lN If N != 0 Vim will align with a case label instead of the statement after it in the same line. cino= cino=l1 > switch (a) { switch (a) { case 1: { case 1: { break; break; } } < *cino-b* bN If N != 0 Vim will align a final "break" with the case label, so that case..break looks like a sort of block. (default: 0). When using 1, consider adding "0=break" to 'cinkeys'. cino= cino=b1 > switch (x) switch(x) { { case 1: case 1: a = b; a = b; break; break; default: default: a = 0; a = 0; break; break; } } < *cino-g* gN Place C++ scope declarations N characters from the indent of the block they are in. (default 'shiftwidth'). By default, a scope declaration is "public:", "protected:" or "private:". This can be adjusted with the 'cinscopedecls' option. cino= cino=g0 > { { public: public: a = b; a = b; private: private: } } < *cino-h* hN Place statements occurring after a C++ scope declaration N characters from the indent of the label. (default 'shiftwidth'). cino= cino=h10 > public: public: a = a + 1; a = a + 1; b = b + 1; < *cino-N* NN Indent inside C++ namespace N characters extra compared to a normal block. (default 0). cino= cino=N-s > namespace { namespace { void function(); void function(); } } namespace my namespace my { { void function(); void function(); } } < *cino-E* EN Indent inside C++ linkage specifications (extern "C" or extern "C++") N characters extra compared to a normal block. (default 0). cino= cino=E-s > extern "C" { extern "C" { void function(); void function(); } } extern "C" extern "C" { { void function(); void function(); } } < *cino-p* pN Parameter declarations for K&R-style function declarations will be indented N characters from the margin. (default 'shiftwidth'). cino= cino=p0 cino=p2s > func(a, b) func(a, b) func(a, b) int a; int a; int a; char b; char b; char b; < *cino-t* tN Indent a function return type declaration N characters from the margin. (default 'shiftwidth'). cino= cino=t0 cino=t7 > int int int func() func() func() < *cino-i* iN Indent C++ base class declarations and constructor initializations, if they start in a new line (otherwise they are aligned at the right side of the ':'). (default 'shiftwidth'). cino= cino=i0 > class MyClass : class MyClass : public BaseClass public BaseClass {} {} MyClass::MyClass() : MyClass::MyClass() : BaseClass(3) BaseClass(3) {} {} < *cino-+* +N Indent a continuation line (a line that spills onto the next) inside a function N additional characters. (default 'shiftwidth'). Outside of a function, when the previous line ended in a backslash, the 2 * N is used. cino= cino=+10 > a = b + 9 * a = b + 9 * c; c; < *cino-c* cN Indent comment lines after the comment opener, when there is no other text with which to align, N characters from the comment opener. (default 3). See also |format-comments|. cino= cino=c5 > /* /* text. text. */ */ < *cino-C* CN When N is non-zero, indent comment lines by the amount specified with the c flag above even if there is other text behind the comment opener. (default 0). cino=c0 cino=c0,C1 > /******** /******** text. text. ********/ ********/ < (Example uses ":set comments& comments-=s1:/* comments^=s0:/*") *cino-/* /N Indent comment lines N characters extra. (default 0). cino= cino=/4 > a = b; a = b; /* comment */ /* comment */ c = d; c = d; < *cino-(* (N When in unclosed parentheses, indent N characters from the line with the unclosed parenthesis. Add a 'shiftwidth' for every extra unclosed parentheses. When N is 0 or the unclosed parenthesis is the first non-white character in its line, line up with the next non-white character after the unclosed parenthesis. (default 'shiftwidth' * 2). cino= cino=(0 > if (c1 && (c2 || if (c1 && (c2 || c3)) c3)) foo; foo; if (c1 && if (c1 && (c2 || c3)) (c2 || c3)) { { < *cino-u* uN Same as (N, but for one nesting level deeper. (default 'shiftwidth'). cino= cino=u2 > if (c123456789 if (c123456789 && (c22345 && (c22345 || c3)) || c3)) < *cino-U* UN When N is non-zero, do not ignore the indenting specified by ( or u in case that the unclosed parenthesis is the first non-white character in its line. (default 0). cino= or cino=(s cino=(s,U1 > c = c1 && c = c1 && ( ( c2 || c2 || c3 c3 ) && c4; ) && c4; < *cino-w* wN When in unclosed parentheses and N is non-zero and either using "(0" or "u0", respectively, or using "U0" and the unclosed parenthesis is the first non-white character in its line, line up with the character immediately after the unclosed parenthesis rather than the first non-white character. (default 0). cino=(0 cino=(0,w1 > if ( c1 if ( c1 && ( c2 && ( c2 || c3)) || c3)) foo; foo; < *cino-W* WN When in unclosed parentheses and N is non-zero and either using "(0" or "u0", respectively and the unclosed parenthesis is the last non-white character in its line and it is not the closing parenthesis, indent the following line N characters relative to the outer context (i.e. start of the line or the next unclosed parenthesis). (default: 0). cino=(0 cino=(0,W4 > a_long_line( a_long_line( argument, argument, argument); argument); a_short_line(argument, a_short_line(argument, argument); argument); < *cino-k* kN When in unclosed parentheses which follow "if", "for" or "while" and N is non-zero, overrides the behaviour defined by "(N": causes the indent to be N characters relative to the outer context (i.e. the line where "if", "for" or "while" is). Has no effect on deeper levels of nesting. Affects flags like "wN" only for the "if", "for" and "while" conditions. If 0, defaults to behaviour defined by the "(N" flag. (default: 0). cino=(0 cino=(0,ks > if (condition1 if (condition1 && condition2) && condition2) action(); action(); function(argument1 function(argument1 && argument2); && argument2); < *cino-m* mN When N is non-zero, line up a line starting with a closing parenthesis with the first character of the line with the matching opening parenthesis. (default 0). cino=(s cino=(s,m1 > c = c1 && ( c = c1 && ( c2 || c2 || c3 c3 ) && c4; ) && c4; if ( if ( c1 && c2 c1 && c2 ) ) foo; foo; < *cino-M* MN When N is non-zero, line up a line starting with a closing parenthesis with the first character of the previous line. (default 0). cino= cino=M1 > if (cond1 && if (cond1 && cond2 cond2 ) ) < *java-cinoptions* *java-indenting* *cino-j* jN Indent Java anonymous classes correctly. Also works well for Javascript. The value 'N' is currently unused but must be non-zero (e.g. 'j1'). 'j1' will indent for example the following code snippet correctly: > object.add(new ChangeListener() { public void stateChanged(ChangeEvent e) { do_something(); } }); < *javascript-cinoptions* *javascript-indenting* *cino-J* JN Indent JavaScript object declarations correctly by not confusing them with labels. The value 'N' is currently unused but must be non-zero (e.g. 'J1'). If you enable this you probably also want to set |cino-j|. > var bar = { foo: { that: this, some: ok, }, "bar":{ a : 2, b: "123abc", x: 4, "y": 5 } } < *cino-)* )N Vim searches for unclosed parentheses at most N lines away. This limits the time needed to search for parentheses. (default 20 lines). *cino-star* *N Vim searches for unclosed comments at most N lines away. This limits the time needed to search for the start of a comment. If your /* */ comments stop indenting after N lines this is the value you will want to change. (default 70 lines). *cino-#* #N When N is non-zero recognize shell/Perl comments starting with '#', do not recognize preprocessor lines; allow right-shifting lines that start with "#". When N is zero (default): don't recognize '#' comments, do recognize preprocessor lines; right-shifting lines that start with "#" does not work. *cino-P* PN When N is non-zero recognize C pragmas, and indent them like any other code; does not concern other preprocessor directives. When N is zero (default): don't recognize C pragmas, treating them like every other preprocessor directive. The defaults, spelled out in full, are: cinoptions=>s,e0,n0,f0,{0,}0,^0,L-1,:s,=s,l0,b0,gs,hs,N0,E0,ps,ts,is,+s, c3,C0,/0,(2s,us,U0,w0,W0,k0,m0,j0,J0,)20,*70,#0,P0 Vim puts a line in column 1 if: - It starts with '#' (preprocessor directives), if 'cinkeys' contains '#0'. - It starts with a label (a keyword followed by ':', other than "case" and "default") and 'cinoptions' does not contain an 'L' entry with a positive value. - Any combination of indentations causes the line to have less than 0 indentation. ============================================================================== 2. Indenting by expression *indent-expression* The basics for using flexible indenting are explained in section |30.3| of the user manual. If you want to write your own indent file, it must set the 'indentexpr' option. Setting the 'indentkeys' option is often useful. See the $VIMRUNTIME/indent/README.txt file for hints. See the $VIMRUNTIME/indent directory for examples. REMARKS ABOUT SPECIFIC INDENT FILES ~ CLOJURE *ft-clojure-indent* *clojure-indent* Clojure indentation differs somewhat from traditional Lisps, due in part to the use of square and curly brackets, and otherwise by community convention. These conventions are not universally followed, so the Clojure indent script offers a few configuration options. (If the current Vim does not include |searchpairpos()|, the indent script falls back to normal 'lisp' indenting, and the following options are ignored.) *g:clojure_maxlines* Sets maximum scan distance of `searchpairpos()`. Larger values trade performance for correctness when dealing with very long forms. A value of 0 will scan without limits. The default is 300. *g:clojure_fuzzy_indent* *g:clojure_fuzzy_indent_patterns* *g:clojure_fuzzy_indent_blacklist* The 'lispwords' option is a list of comma-separated words that mark special forms whose subforms should be indented with two spaces. For example: > (defn bad [] "Incorrect indentation") (defn good [] "Correct indentation") < If you would like to specify 'lispwords' with a |pattern| instead, you can use the fuzzy indent feature: > " Default let g:clojure_fuzzy_indent = 1 let g:clojure_fuzzy_indent_patterns = ['^with', '^def', '^let'] let g:clojure_fuzzy_indent_blacklist = \ ['-fn$', '\v^with-%(meta|out-str|loading-context)$'] < |g:clojure_fuzzy_indent_patterns| and |g:clojure_fuzzy_indent_blacklist| are lists of patterns that will be matched against the unqualified symbol at the head of a list. This means that a pattern like `"^foo"` will match all these candidates: `foobar`, `my.ns/foobar`, and `#'foobar`. Each candidate word is tested for special treatment in this order: 1. Return true if word is literally in 'lispwords' 2. Return false if word matches a pattern in |g:clojure_fuzzy_indent_blacklist| 3. Return true if word matches a pattern in |g:clojure_fuzzy_indent_patterns| 4. Return false and indent normally otherwise *g:clojure_special_indent_words* Some forms in Clojure are indented such that every subform is indented by only two spaces, regardless of 'lispwords'. If you have a custom construct that should be indented in this idiosyncratic fashion, you can add your symbols to the default list below. > " Default let g:clojure_special_indent_words = \ 'deftype,defrecord,reify,proxy,extend-type,extend-protocol,letfn' < *g:clojure_align_multiline_strings* Align subsequent lines in multi-line strings to the column after the opening quote, instead of the same column. For example: > (def default "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.") (def aligned "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.") < *g:clojure_align_subforms* By default, parenthesized compound forms that look like function calls and whose head subform is on its own line have subsequent subforms indented by two spaces relative to the opening paren: > (foo bar baz) < Setting this option to `1` changes this behaviour so that all subforms are aligned to the same column, emulating the default behaviour of clojure-mode.el: > (foo bar baz) < FORTRAN *ft-fortran-indent* Block if, select case, where, and forall constructs are indented. So are type, interface, associate, block, and enum constructs. The indenting of subroutines, functions, modules, and program blocks is optional. Comments, labelled statements and continuation lines are indented if the Fortran is in free source form, whereas they are not indented if the Fortran is in fixed source form because of the left margin requirements. Hence manual indent corrections will be necessary for labelled statements and continuation lines when fixed source form is being used. For further discussion of the method used for the detection of source format see |ft-fortran-syntax|. Do loops ~ All do loops are left unindented by default. Do loops can be unstructured in Fortran with (possibly multiple) loops ending on a labelled executable statement of almost arbitrary type. Correct indentation requires compiler-quality parsing. Old code with do loops ending on labelled statements of arbitrary type can be indented with elaborate programs such as Tidy (http://www.unb.ca/chem/ajit/f_tidy.htm). Structured do/continue loops are also left unindented because continue statements are also used for purposes other than ending a do loop. Programs such as Tidy can convert structured do/continue loops to the do/enddo form. Do loops of the do/enddo variety can be indented. If you use only structured loops of the do/enddo form, you should declare this by setting the fortran_do_enddo variable in your .vimrc as follows > let fortran_do_enddo=1 in which case do loops will be indented. If all your loops are of do/enddo type only in, say, .f90 files, then you should set a buffer flag with an autocommand such as > au! BufRead,BufNewFile *.f90 let b:fortran_do_enddo=1 to get do loops indented in .f90 files and left alone in Fortran files with other extensions such as .for. Program units ~ The indenting of program units (subroutines, functions, modules, and program blocks) is enabled by default but can be suppressed if a lighter, screen-width preserving indent style is desired. To suppress the indenting of program units for all fortran files set the global fortran_indent_less variable in your .vimrc as follows > let fortran_indent_less=1 A finer level of suppression can be achieved by setting the corresponding buffer-local variable as follows > let b:fortran_indent_less=1 HTML *ft-html-indent* *html-indent* *html-indenting* This is about variables you can set in your vimrc to customize HTML indenting. You can set the indent for the first line after