Snippets-plus

This is a reimagining of the original snippets package. It introduces new features such as variables and advanced formatting.

Features

Snippets as in the snippets package, plus:

Status bar indicator for when in snippets mode
Command to leave snippets mode
Variables and named transformations
Conditional transformation replacements
Map snippets to keyboard shortcuts
Altered $0 (end tab stop) semantics

See the wiki for more in depth information.

Snippets

Syntax

Check the wiki page for snippet syntax.

Defining snippets

Snippets can be provided by packages. Any .cson or .json file in a top level snippets directory will be searched. Users can also provide snippets directly through the ~/.atom/snippets.cson file.

The structure is as follows:

source1:
  name1:
    prefix: "foo"
    body: "Hello world"
  name2:
    prefix: "bar"
    body: "second snippet"
 
source2:
  name1:
    prefix: "foo"
    body: "a snippet for a different scope"

The top level keys are scope selectors. These control what parts of a file the snippet can be expanded in. For example,

.source.js allows the snippet to be expanded in all JavaScript files
.source.js,.source.ts allows the snippet to be used in JS and TS files
.source.js .string only allows the snippet to expand in JS strings
.string allows the snippet in any string of any language

Your file may have any number of these selectors. Note that because of how CSON and JSON work, all sibling keys must be unique. If you want to add multiple snippets to the same scope, make sure to do it under the same key. E.g.,

# No good, two keys on the same object have the same value 
".source.js":
  name1:
    prefix: 'snippet1'
    body: 'my first snippet'
 
".source.js":
  name2:
    prefix: 'snippet2'
    body: 'my next snippet'
 
############### 
# Fixed 
".source.js":
  name1:
    prefix: 'snippet1'
    body: 'my first snippet'
 
  name2:
    prefix: 'snippet2'
    body: 'my next snippet'

The name is a unique identifier for the snippet.
The prefix is a string that must be directly behind the cursor for this snippet to be expanded. It must be a single line, and no longer than 50 characters.
The body is what the snippet expands into, parsed as per the above Syntax section.

You can also add autocomplete-plus attributes like description and rightLabel. They are not used by this package, but can make the autocomplete popup more descriptive.

Until now this is all the same as for the original snippets package. But this package supports a shorthand structure for when you don't care about naming snippets. If you don't declare a prefix key, then the snippet name will be used instead. And if the snippet declaration is a string, then it will be used as the body. So the following are all equivalent

".source.js":
  log:
    prefix: "log",
    body: "console.log($1)$0"
 
################ 
 
".source.js":
  log:
    body: "console.log($1)$0"
 
################ 
 
".source.js":
  log: "console.log($1)$0"

As with the original package, user snippets are watched and automatically updated when the file changes.

This package also provides a new snippet attribute key, which lets you associate a snippet with a keybinding. Doing this effectively skips using the prefix. Use prefix: null to prevent the snippet from having a prefix.

The key binding uses the same scope as the snippet to determine when it can be triggered, so you can have multiple snippets on the same key and the most specific match will be expanded.

Using

To expand a snippet, type it's prefix and run the Snippets: Expand command. This command is assigned the shortcut tab by default.

The selection of snippet to expand is follows:

Get set of snippets that can be expanded based on the cursor scope
Snippets with more specific selectors override ones that have the same prefix and are more general
User snippets override package snippets, and community package snippets override core package snippets
The snippet with the longest prefix that is completely matched by the text behind the cursor wins.

So if we had candidate prefixes log and conlog, then for the following text before the cursor:

conlogq: no snippet matches
conlog: picks the conlog snippet
onlog: picks the log snippet
og: no snippet matches

To goto the next tab stop, run Snippets: Next Tab Stop (again, tab by default) and to goto the previous run Snippets: Previous Tab Stop (shift-tab by default). The keybindings can be disabled and replaced with your own.

Technical details on how expanded snippets behave can be found on the wiki.

Legacy parsing mode

I found I have many snippets that are defined like as follows

\\\\textbf{$1}$2

Under the snippets package I never noticed a problem, but with this one you see it is still in snippets mode when you reach the $2 stop. This can cause unexpected behaviour when you next press tab, and if you have the tab stops markers visible it will look weird too.

By default, this package will try to correct snippets like these. If this option is enabled, then if

the last part of the snippet (by location) is a simple tab stop,
the tab stop is the only one of its index, and
it is also the last (by index),

then it will be converted to a $0 stop. So the above becomes

\\\\textbf{$1}$0

Which behaves much better. Disable this mode if you want full control over your snippets.

Developing

Testing

Easiest is to open the project in Atom and run Window: Run Package Specs.

Alteratively run atom test . in the command line to run the test suite. Replace atom with atom-beta and atom-nightly as appropriate.

snippets-plus