VIM Completion Configuration

Built-in

Vim has built-in support for completions in insert or replace modes.See :help ins-completion.

By default, Vim uses separate Emacs style key bindings (<C-x C-key>)for different kinds of completions.

There are two plugins to use a single Tab key for completions:

There is also AutoComplPop to automatically pop up completions.

VimCompletesMe

Why

Count source lines of code (VimScript comments start with "):

; cat supertab.vim | egrep -v '^("|([[:blank:]]*$))' | wc -l
923
; cat VimCompletesMe.vim | egrep -v '^("|([[:blank:]]*$))' | wc -l
82

Period.

Configuration

Without any configuration, the Tab key will, depending on the context, offer:

Vim’s local keyword completion (Ctrl-X_Ctrl-N)
File path completion when typing a path (Ctrl-X_Ctrl-F)
Omni-completion after typing a period or an arrow operator (Ctrl-X_Ctrl-O)

With a b:vcm_tab_complete variable,you can set the Tab key to use the following type of completions:

Dictionary words (Ctrl-X_Ctrl-K)
User-defined completion (Ctrl-X_Ctrl-U)
Tags (Ctrl-X_Ctrl-])
Vim command line (Ctrl-X_Ctrl-V)
Omni completion (Ctrl-X_Ctrl-O)

If any of above types of completions fails to return any results,hitting Tab again will switch back to Vim’s local keyword completion.

You can set the b:vcm_tab_complete variable interactively, or in ~/.vimrc:

autocmd FileType text,markdown let b:vcm_tab_complete = 'dict'

AutoComplPop

Use Enter to commit completion.Use arrow keys (Up|Down) to select completions.

It works well for certain file types,while distracting on other types such as text.

External engine

YouCompleteMe

YouCompleteMe is a fast, as-you-type, fuzzy-search code completion engine.It has several completion engines:

an identifier based engine that works with every programming language,
a Clang based engine that provides native semantic completion for C-family languages,
a Jedi-based completion engine for Python 2 and 3,
an OmniSharp-based completion engine for C#,
a combination of Gocode and Godef semantic engines for Go,
a TSServer-based completion engine for TypeScript,
a Tern-based completion engine for JavaScript,
a racer-based completion engine for Rust,
and an omnifunc-based completer for many other languages

YCM also provides semantic IDE-like features in a number of languages:

finding declarations, definitions, usages, etc. of identifiers,
displaying type information for classes, variables, functions etc.,
displaying documentation for methods, members, etc. in the preview window,
fixing common coding errors, like missing semi-colons, typos, etc.,
semantic renaming of variables across files (JavaScript only).

Tho downside is it consumes a lot of RAM.

neocomplete

neocomplete maintains a cache of keywords in the current buffer.It requires Vim 7.3.885+ with Lua enabled.It sometimes be slower than YCM, but requires much less RAM.

You can configure it to use Tab key to complete,and/or automatically pops up completion menu.