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diff --git a/vimscript.html.markdown b/vimscript.html.markdown new file mode 100644 index 00000000..5235a149 --- /dev/null +++ b/vimscript.html.markdown @@ -0,0 +1,672 @@ +--- +language: Vimscript +filename: learnvimscript.md +contributors: + - ["HiPhish", "http://hiphish.github.io/"] +--- + +## Introduction + +Vim script (also called VimL) is the subset of Vim's ex-commands which supplies +a number of features one one would expect from a scripting language, such as +values, variables, functions or loops. Always keep in the back of your mind +that a Vim script file is just a sequence of ex-commands. It is very common for +a script to mix programming-language features and raw ex-commands. + +You can run Vim script directly by entering the commands in command-mode (press +`:` to enter command-mode), or you can write them to a file (without the +leading `:`) and source it in a running Vim instance (`:source path/to/file`). +Some files are sourced automatically as part of your configuration (see `:h +startup`). This guide assumes that you are familiar with ex-commands and will +only cover the scripting. Help topics to the relevant manual sections are +included. + +See `:h usr_41.txt` for the official introduction to Vim script. A comment is +anything following an unmatched `"` until the end of the line, and `|` +separates instructions (what `;` does in most other languages). + +```vim +" This is a comment + +" The vertical line '|' (pipe) separates commands +echo 'Hello' | echo 'world!' + +" Putting a comment after a command usually works +pwd " Displays the current working directory + +" Except for some commands it does not; use the command delemiter before the +" comment (echo assumes that the quotation mark begins a string) +echo 'Hello world!' |" Displays a message + +" Line breaks can be escaped by pacing a backslash as the first non-whitespace +" character on the *following* line. Only works in script files, not on the +" command line +echo " Hello + \ world " + +echo [1, + \ 2] + +echo { + \ 'a': 1, + \ 'b': 2 +\} +``` + + +## Types + +For an overview of types see `:h E712`. For an overview of operators see +`:h expression-syntax` + +### Numbers +See `:h expr-number` + +```vim +echo 123 |" Decimal +echo 0b1111011 |" Binary +echo 0173 |" Octal +echo 0x7B |" Hexadecimal +echo 123.0 |" Floating-point +echo 1.23e2 |" Floating-point (scientific notation) +``` + +Note that an *integer* number with a leading `0` is in octal notation. The +usual arithmetic operations are supported. + +```vim +echo 1 + 2 |" Addition +echo 1 - 2 |" Subtraction +echo - 1 |" Negation (unary minus) +echo + 1 |" Unary plus (does nothing really, but still legal) +echo 1 * 2 |" Multiplication +echo 1 / 2 |" Division +echo 1 % 2 |" Modulo (remainder) +``` + +### Booleans +See `:h Boolean` + +The number 0 is false, every other number is true. Strings are implicitly +converted to numbers (see below). There are two pre-defined semantic constants. + +```vim +echo v:true |" Evaluates to 1 or the string 'v:true' +echo v:false |" Evaluates to 0 or the string 'v:false' +``` + +Boolean values can result from comparison of two objects. + +```vim +echo x == y |" Equality by value +echo x != y |" Unequality +echo x > y |" Greater than +echo x >= y |" Greater than or equal +echo x < y |" Smaller than +echo x <= y |" Smaller than or equal +echo x is y |" Instance identity (lists and dictionaries) +echo x isnot y |" Instance non-identity (lists and dictionaries) + +" Strings are compared based on their alphanumerical ordering +" echo 'a' < 'b'. Case sensitivity depends on the setting of 'ignorecase' + +" Explicit case-sensitivity is specified by appending '#' (match case) or '?' +" (ignore case) to the operator. Prefer explicity case sensitivity when writing +" portable scripts. + +echo 'a' < 'B' | " True or false depending on 'ignorecase' +echo 'a' <? 'B' | " True +echo 'a' <# 'B' | " False + +" Regular expression matching +echo "hi" =~ "hello" |" Regular expression match, uses 'ignorecase' +echo "hi" =~# "hello" |" Regular expression match, case sensitive +echo "hi" =~? "hello" |" Regular expression match, case insensitive +echo "hi" !~ "hello" |" Regular expression unmatch, use 'ignorecase' +echo "hi" !~# "hello" |" Regular expression unmatch, case sensitive +echo "hi" !~? "hello" |" Regular expression unmatch, case insensitive +``` + +Boolean operations are possible. + +```vim +echo v:true && v:false |" Logical AND +echo v:true || v:false |" Logical OR +echo ! v:true |" Logical NOT +echo v:true ? 'yes' : 'no' |" Ternary operator +``` + + +### Strings +See `:h String` + +An ordered zero-indexed sequence of bytes. The encoding of text into bytes +depends on the option `:h 'encoding'`. + +```vim +" Literal constructors +echo "Hello world\n" |" The last two characters stand for newline +echo 'Hello world\n' |" The last two characters are literal +echo 'Let''s go!' |" Two single quotes become one quote character +``` + +Single-quote strings take all characters are literal, except two single quotes, +which are taken to be a single quote in the string itself. See `:h expr-quote` +for all possible escape sequences. + +``` +" String concatenation +" The .. operator is preferred, but only supported in since Vim 8.1.1114 +echo 'Hello ' . 'world' |" String concatenation +echo 'Hello ' .. 'world' |" String concatenation (new variant) + +" String indexing +echo 'Hello'[0] |" First byte +echo 'Hello'[1] |" Second byte +echo 'Hellö'[4] |" Returns a byte, not the character 'ö' + +" Substrings (second index is inclusive) +echo 'Hello'[:] |" Copy of entire string +echo 'Hello'[1:3] |" Substring, second to fourth byte +echo 'Hello'[1:-2] |" Substring until second to last byte +echo 'Hello'[1:] |" Substring with starting index +echo 'Hello'[:2] |" Substring with ending index +echo 'Hello'[-2:] |" Substring relative to end of string +``` + +A negative index is relative to the end of the string. See `:h +string-functions` for all string-related functions. + +### Lists +See `:h List` + +An ordered zero-indexed heterogeneous sequence of arbitrary Vim script objects. + +```vim +" Literal constructor +echo [] |" Empty list +echo [1, 2, 'Hello'] |" List with elements +echo [1, 2, 'Hello', ] |" Trailing comma permitted +echo [[1, 2], 'Hello'] |" Lists can be nested arbitrarily + +" List concatenation +echo [1, 2] + [3, 4] |" Creates a new list + +" List indexing, negative is relative to end of list (:h list-index) +echo [1, 2, 3, 4][2] |" Third element +echo [1, 2, 3, 4][-1] |" Last element + +" List slicing (:h sublist) +echo [1, 2, 3, 4][:] |" Shallow copy of entire list +echo [1, 2, 3, 4][:2] |" Sublist until third item (inclusive) +echo [1, 2, 3, 4][2:] |" Sublist from third item (inclusive) +echo [1, 2, 3, 4][:-2] |" Sublist until second-to-last item (inclusive) +``` + +All slicing operations create new lists. To modify a list in-place use list +functions (`:h list-functions`) or assign directly to an item (see below about +variables). + +### Dictionaries +See `:h Dictionary` + +An unordered sequence of key-value pairs, keys are always strings (numbers are +implicitly converted to strings). + +```vim +" Dictionary literal +echo {} |" Empty dictionary +echo {'a': 1, 'b': 2} |" Dictionary literal +echo {'a': 1, 'b': 2, } |" Trailing comma permitted +echo {'x': {'a': 1, 'b': 2}} |" Nested dictionary + +" Indexing a dictionary +echo {'a': 1, 'b': 2}['a'] |" Literal index +echo {'a': 1, 'b': 2}.a |" Syntactic sugar for simple keys +``` + +See `:h dict-functions` for dictionary manipulation functions. + +### Funcref +See `:h Funcref` + +Reference to a function, uses the function name as a string for construction. +When stored in a variable the name of the variable has the same restrictions +as a function name (see below). + +```vim +echo function('type') |" Reference to function type() +echo funcref('type') |" Reference by identity, not name +echo {x -> x * x} |" Anonymous function +echo function('substitute', ['hello']) |" Partial function +``` + +A lambda (`:h lambda`) is an anonymous function; it can only contain one +expression in its body, which is also its implicit return value. + +### Regular expression +See `:h regular-expression` + +A regular expression pattern is generally a string, but in some cases you can +also use a regular expression between a pair of delimiters (usually `/`, but +you can choose anything). + +```vim +" Substitute 'hello' for 'Hello' +substitute/hello/Hello/ +``` + +## Implicit type conversions + +Strings are converted to numbers, and numbers to strings when necessary. A +number becomes its decimal notation as a string. A string becomes its numerical +value if it can be parsed to a number, otherwise it becomes zero. + +```vim +echo "1" + 1 |" Number +echo "1" .. 1 |" String +echo "0xA" + 1 |" Number + +" Strings are treated like numbers when used as booleans +echo "true" ? 1 : 0 |" This string is parsed to 0, which is false +``` + + +## Variables + +Variables are bound within a scope; if no scope is provided a default is chosen +by Vim. Use `:let` and `:const` to bind a value and `:unlet` to unbind it. + +```vim +let b:my_var = 1 |" Local to current buffer +let w:my_var = 1 |" Local to current window +let t:my_var = 1 |" Local to current tab page +let g:my_var = 1 |" Global variable +let l:my_var = 1 |" Local to current function (see functions below) +let s:my_var = 1 |" Local to current script file +let a:my_arg = 1 |" Function argument (see functions below) + +" The Vim scope is read-only +echo v:true |" Special built-in Vim variables (:h v:var) + +" Access special Vim memory like variables +let @a = 'Hello' |" Register +let $PATH='' |" Environment variable +let &textwidth = 79 |" Option +let &l:textwidth = 79 |" Local option +let &g:textwidth = 79 |" Global option + +" Access scopes as dictionaries (can be modified like all dictionaries) +" See the :h dict-functions, especially get(), for access and manipulation +echo b: |" All buffer variables +echo w: |" All window variables +echo t: |" All tab page variables +echo g: |" All global variables +echo l: |" All local variables +echo s: |" All script variables +echo a: |" All function arguments +echo v: |" All Vim variables + +" Constant variables +const x = 10 |" See :h :const, :h :lockvar + +" Function reference variables have the same restrictions as function names +let IsString = {x -> type(x) == type('')} |" Global: capital letter +let s:isNumber = {x -> type(x) == type(0)} |" Local: any name allowed +``` + +When omitted the scope `g:` is implied, except in functions, there `l:` is +implied. + +### Multiple value binding (list unpacking) + +```vim +" Assign values of list to multiple variables (number of items must match) +let [x, y] = [1, 2] + +" Assign the remainer to a rest variable (note the semicolon) +let [mother, father; children] = ['Alice', 'Bob', 'Carol', 'Dennis', 'Emily'] +``` + +## Flow control + +### Conditional + +Conditions are set between `if` and `endif`. They can be nested. + +```vim +if condition + echo 'First condition' +elseif another_condition + echo 'Second condition' +else + echo 'Fail' +endif +``` + +### Loops + +Two types of loops: `:for` and `:while`. Use `:continue` to skip to the next +iteration, `:break` to break out of the loop. + +#### For-loop + +For-loops iterate over lists and nothing else. If you want to iterate over +another sequence you need to use a function which will create a list. + +```vim +" Iterate over a list +for person in ['Alice', 'Bob', 'Carol', 'Dennis', 'Emily'] + echo 'Hello ' .. person +endfor + +" Iterate over a nested list by unpacking it +for [x, y] in [[1, 0], [0, 1], [-1, 0], [0, -1]] + echo 'Position: x =' .. x .. ', y = ' .. y +endfor + +" Iterate over a range of numbers +for i in range(10, 0, -1) " Count down from 10 + echo 'T minus' .. i +endfor + +" Iterate over the keys of a dictionary +for symbol in keys({'π': 3.14, 'e': 2.71}) + echo 'The constant ' .. symbol .. ' is a transcendent number' +endfor + +" Iterate over the values of a dictionary +for value in values({'π': 3.14, 'e': 2.71}) + echo 'The value ' .. value .. ' approximates a transcendent number' +endfor + +" Iterate over the keys and values of a dictionary +for [symbol, value] in items({'π': 3.14, 'e': 2.71}) + echo 'The number ' .. symbol .. ' is approximately ' .. value +endfor +``` + +#### While-loops + +```vim +while !there_yet + echo 'Are we there yet?' +endwhile +``` + +### Exception handling +See `:h exception-handling` + +Throw new exceptions as strings, catch them by pattern-matching a regular +expression against the string + +```vim +" Throw new exception +throw "Wrong arguments" + +" Guard against an exception (the second catch matches any exception) +try + source path/to/file +catch /Cannot open/ + echo 'Looks like that file does not exist' +catch /.*/ + echo 'Something went wrong, but I don't know what' +finally + echo 'I'm done trying' +endtry +``` + + +## Functions + +### Defining functions + +```vim +" Unscoped function names have to start with a capital letter +function! AddNumbersLoudly(x, y) + " Use a: scope to access arguments + echo 'Adding' .. a:x .. 'and' .. a:y |" A side effect + return a:x + a:y |" A return value +endfunction + +" Scoped function names may start with a lower-case letter +function! s:addNumbersLoudly(x, y) + echo 'Adding' .. a:x .. 'and' .. a:y + return a:x + a:y +endfunction +``` + +Without the exclamation mark it would be an error to re-define a function, with +the exclamation mark the new definition can replace the old one. Since Vim +script files can be reloaded several times over the course of a session it is +best to use the exclamation mark unless you really know what you are doing. + +Function definitions can have special qualifiers following the argument list. + +```vim +" Range functions define two implicit arguments, which will be set to the range +" of the ex-command +function! FirstAndLastLine() range + echo [a:firstline, a:lastline] +endfunction + +" Prints the first and last line that match a pattern (:h cmdline-ranges) +/^#!/,/!#$/call FirstAndLastLine() + + +" Aborting functions, abort once error occurs (:h :func-abort) +function! SourceMyFile() abort + source my-file.vim |" Try sourcing non-existing file + echo 'This will never be printed' +endfunction + +" Closures, functions carrying values from outer scope (:h :func-closure) +function! MakeAdder(x) + function! Adder(n) closure + return a:n + a:x + endfunction + return funcref('Adder') +endfunction +let AddFive = MakeAdder(5) +echo AddFive(3) |" Prints 8 + +" Dictionary functions, poor man's OOP methods (:h Dictionary-function) +function! Mylen() dict + return len(self.data) |" Implicit variable self +endfunction +let mydict = {'data': [0, 1, 2, 3], 'len': function("Mylen")} +echo mydict.len() + +" Alternatively, more concise +let mydict = {'data': [0, 1, 2, 3]} +function! mydict.len() + return len(self.data) +endfunction +``` + +### Calling functions + +```vim +" Call a function for its return value, and possibly for its side effects +let animals = keys({'cow': 'moo', 'dog': 'woof', 'cat': 'meow'}) + +" Call a function for its side effects only, ignore potential result +call sign_undefine() + +" The call() function calls a function reference and passes parameters as a +" list, and returns the function's result. +echo call(function('get'), [{'a': 1, 'b': 2}, 'c', 3]) |" Prints 3 +``` + +Recall that Vim script is embedded within the ex-commands, that is why we +cannot just call a function directly, we have to use the `:call` ex-command. + +### Function namespaces + +See `:h write-library-script`, `:h autoload` + +```vim +" Must be defined in autoload/foo/bar.vim +" Namspaced function names do not have to start with a capital letter +function! foo#bar#log(value) + echomsg value +endfunction + +call foo#bar#log('Hello') +``` + + +## Frequently used ex-commands + +### Sourcing runtime files + +See `:h 'runtimepath'` + +```vim +" Source first match among runtime paths +runtime plugin/my-plugin.vim +``` + +### Defining new ex-commands +See `:h 40.2`, `:h :command` + +```vim +" First argument here is the name of the command, rest is the command body +command! SwapAdjacentLines normal! ddp +``` + +The exclamation mark works the same as with `:function`. User-defined commands +must start with a capital letter. The `:command` command can take a number of +attributes (some of which have their own parameters with `=`), such as +`-nargs`, all of them start with a dash to set them apart from the command +name. + +```vim +:command -nargs=1 Error echoerr <args> +``` + +### Defining auto-commands +See `:h 40.3`, `:h autocmd`, `:h autocommand-events` + +```vim +" The arguments are "events", "patterns", rest is "commands" +autocmd BufWritePost $MYVIMRC source $MYVIMRC +``` + +Events and patterns are separated by commas with no space between. See `:h +autocmd-events` for standard events, `:h User` for custom events. Everything +else are the ex-commands which will be executed. + +#### Auto groups + +When a file is sourced multiple times the auto-commands are defined anew, +without deleting the old ones, causing auto-commands to pile up over time. Use +auto-groups and the following ritual to guard against this. + +```vim +augroup auto-source |" The name of the group is arbitrary + autocmd! |" Deletes all auto-commands in the current group + autocmd BufWritePost $MYVIMRC source $MYVIMRC +augroup END |" Switch back to default auto-group +``` + +It is also possible to assign a group directly. This is useful if the +definition of the group is in one script and the definition of the auto-command +is in another script. + +```vim +" In one file +augroup auto-source + autocmd! +augroup END + +" In another file +autocmd auto-source BufWritePost $MYVIMRC source $MYVIMRC +``` + +### Executing (run-time macros of sorts) + +Sometimes we need to construct an ex-command where part of the command is not +known until runtime. + +```vim +let line = 3 |" Line number determined at runtime +execute line .. 'delete' |" Delete a line +``` + +### Executing normal-mode commands + +Use `:normal` to play back a sequence of normal mode commands from the +command-line. Add an exclamation mark to ignore user mappings. + +```vim +normal! ggddGp |" Transplant first line to end of buffer + +" Window commands can be used with :normal, or with :wincmd if :normal would +" not work +wincmd L |" Move current window all the way to the right +``` + + +## Frequently used functions + +```vim +" Feature check +echo has('nvim') |" Running Neovim +echo has('python3') |" Support for Python 3 plugins +echo has('unix') |" Running on a Unix system +echo has('win32') |" Running on a Windows system + + +" Test if something exists +echo exists('&mouse') |" Option (exists only) +echo exists('+mouse') |" Option (exists and works) +echo exists('$HOSTNAME') |" Environment variable +echo exists('*strftime') |" Built-in function +echo exists('**s:MyFunc') |" User-defined function +echo exists('bufcount') |" Variable (scope optional) +echo exists('my_dict["foo"]') |" Variable (dictionary entry) +echo exists('my_dict["foo"]') |" Variable (dictionary entry) +echo exists(':Make') |" Command +echo exists("#CursorHold") |" Auto-command defined for event +echo exists("#BufReadPre#*.gz") |" Event and pattern +echo exists("#filetypeindent") |" Auto-command group +echo exists("##ColorScheme") |" Auto-commnand supported for event + +" Various dynamic values (see :h expand()) +echo expand('%') |" Current file name +echo expand('<cword>') |" Current word under cursor +echo expand('%:p') |" Modifier are possible + +" Type tests +echo type(my_var) == type(0) |" Number +echo type(my_var) == type('') |" String +echo type(my_var) == type([]) |" List +echo type(my_var) == type({}) |" Dictionary +echo type(my_var) == type(function('type')) |" Funcref + +" Format strings +echo printf('%d in hexadecimal is %X', 123, 123) +``` + + +## Tricks of the trade + +### Source guard + +```vim +" Prevent a file from being source multiple times; users can set the variable +" in their configuration to prevent the plugin from loading at all. +if exists('g:loaded_my_plugin') + finish +endif +let g:loaded_my_plugin = v:true +``` + +### Default values + +```vim +" Get a default value: if the user defines a variable use it, otherwise use a +" hard-coded default. Uses the fact that a scope is also a dictionary. +let s:greeting = get(g:, 'my_plugin_greeting', 'Hello') +``` |