grbaset / hsnips

HyperSnips: a powerful snippet engine for VS Code, inspired by vim's UltiSnips

HyperSnips

HyperSnips is a snippet engine for vscode heavily inspired by vim's UltiSnips.

Usage

To use HyperSnips you create .hsnips files on a directory which depends on your platform:

• Windows: %APPDATA%\Code\User\hsnips\(language).hsnips
• Mac: $HOME/Library/Application Support/Code/User/hsnips/(language).hsnips
• Linux: $HOME/.config/Code/User/hsnips/(language).hsnips

Or alternatively, you can open this directory by running the command HyperSnips: Open snippets directory.

Additionally, you can create an all.hsnips file for snippets that should be available on all languages.

Snippets file

A snippets file is a file with the .hsnips extension, the file is composed of two types of blocks: global blocks and snippet blocks.

Global blocks are JavaScript code blocks with code that is shared between all the snippets defined in the current file. They are defined with the global keyword, as follows:

global
// JavaScript code
endglobal

Snippet blocks are snippet definitions. They are defined with the snippet keyword, as follows:

context expression
snippet trigger "description" flags
body
endsnippet

where the trigger field is required and the fields description and flags are optional.

Trigger

A trigger can be any sequence of characters which does not contain a space, or a regular expression surrounded by backticks (`).

Flags

The flags field is a sequence of characters which modify the behavior of the snippet, the available flags are the following:

• A: Automatic snippet expansion - Usually snippets are activated when the tab key is pressed, with the A flag snippets will activate as soon as their trigger matches, it is specially useful for regex snippets.

• i: In-word expansion* - By default, a snippet trigger will only match when the trigger is preceded by whitespace characters. A snippet with this option is triggered regardless of the preceding character, for example, a snippet can be triggered in the middle of a word.

• w: Word boundary* - With this option the snippet trigger will match when the trigger is a word boundary character. Use this option, for example, to permit expansion where the trigger follows punctuation without expanding suffixes of larger words.

• b: Beginning of line expansion* - A snippet with this option is expanded only if the tab trigger is the first word on the line. In other words, if only whitespace precedes the tab trigger, expand.

• M: Multi-line mode - By default, regex matches will only match content on the current line, when this option is enabled the last hsnips.multiLineContext lines will be available for matching.

*: This flag will only affect snippets which have non-regex triggers.

Snippet body

The body is the text that will replace the trigger when the snippet is expanded, as in usual snippets, the tab stops $1, $2, etc. are available.

The full power of HyperSnips comes when using JavaScript interpolation: you can have code blocks inside your snippet delimited by two backticks (``) that will run when the snippet is expanded, and every time the text in one of the tab stops is changed.

Code interpolation

Inside the code interpolation, you have access to a few special variables:

• rv: The return value of your code block, the value of this variable will replace the code block when the snippet is expanded.
• t: An array containing the text within the tab stops, in the same order as the tab stops are defined in the snippet block. You can use it to dynamically change the snippet content.
• m: An array containing the match groups of your regular expression trigger, or an empty array if the trigger is not a regular expression.
• w: A URI string of the currently opened workspace, or an empty string if no workspace is open.
• path: A URI string of the current document. (untitled documents have the scheme untitled)

Additionally, every variable defined in one code block will be available in all the subsequent code blocks in the snippet.

The require function can also be used to import NodeJS modules.

Context matching

Optionally, you can have a context line before the snippet block, it is followed by any javascript expression, and the snippet is only available if the context expression evaluates to true.

Inside the context expression you can use the context variable, which has the following type:

interface Context {
  scopes: string[];
}

Here, scopes stands for the TextMate scopes at the current cursor position, which can be viewed by running the Developer: Inspect Editor Tokens and Scopes command in vscode.

As an example, here is an automatic LaTeX snippet that only expands when inside a math block:

global
function math(context) {
    return context.scopes.some(s => s.startsWith("meta.math"));
}
endglobal

context math(context)
snippet inv "inverse" Ai
^{-1}
endsnippet

Examples

• Simple snippet which greets you with the current date and time

snippet dategreeting "Gives you the current date!"
Hello from your hsnip at ``rv = new Date().toDateString()``!
endsnippet

• Box snippet as shown in the gif above

snippet box "Box" A
``rv = '┌' + '─'.repeat(t[0].length + 2) + '┐'``
│ $1 │
``rv = '└' + '─'.repeat(t[0].length + 2) + '┘'``
endsnippet

• Snippet to insert the current filename

snippet filename "Current Filename"
``rv = require('path').basename(path)``
endsnippet