Liner

Want to customize your favorite languages without having to set up and tab through snippets? Liner lets you define regular expressions and replacement patterns that are automatically applied when you hit Enter in VS Code.

Features

Liner lets you import as many pattern libraries as you like, and checks the current line against all imported patterns until it finds a match. If a match is found, the pattern defines how to manipulate the line, using both regex capture groups and custom Javascript. Patterns are defined per language, allowing for a standardized set of enhancements across languages.

Patterns can be single or multiline. A single line pattern will do the replacement and then move to the next line like a normal Enter press.

A multiline pattern will place the cursor on the last line that only contains whitespace.

Usage

To trigger Liner:

• Hit Enter on a line.
  • If a match is found, Liner behaves the same regardless of where the cursor is.
  • If no match is found, normal text input occurs.
  • VS Code multiple cursors and selections are supported.
• Make a selection and hit Enter.

Liner can be toggled through the Liner: Toggle command, or by clicking on the status bar at the bottom.

Commands

• Liner: Toggle - Toggle Liner for the current file.
• Liner: Reload Patterns - Reload all pattern libraries, useful when developing new patterns.
• Liner: Set Pattern Library Location - Display the pattern library location prompt.

Sample Pattern Library

The sample pattern library defiant00/alpha-code contains the following patterns for the Javascript and Typescript languages, meant to reduce the number of symbols you have to type:

• for [var] in [start] to [finish] -> for (let [var] = [start]; [var] < [finish]; var++) { }
• if [condition] -> if ([condition]) { }
• while [condition] -> while ([condition]) { }
• [code] / -> [code] { }

As well, the following are replaced inline:

• and -> &&
• or -> ||
• eq -> ===
• neq -> !==

Extension Settings

This extension contributes the following settings:

• liner.enabledByDefault - Enable/disable whether Liner is active when first opening a file.
• liner.libraryLocation - Pattern library location, or 'none' to only use the built-in libraries.
• liner.patterns - List of pattern libraries to load (comma or semicolon-delimited).

Creating Pattern Libraries

Example

This is a simple example that demonstrates a minimal pattern that turns "g [name]" into "Hello [name]!".

exports.patterns = [
    {
        match: /^g (.*)$/,
        replacement: {
            plaintext: { value: (...m) => `Hello ${m[1]}!`, moveCursor: false }
        }
    }
];

Syntax

A pattern library should export an array of patterns named patterns containing the following:

• match - the regex used to match the line.
• replacement - an object containing properties named for the supported language. For example, if you want a replacement behavior for Typescript and C#, your replacement object should have properties named typescript and csharp.
  • _ can be used as a wildcard to match any name that is not explicitly defined.
  • Languages are objects with two properties:
    • value - A function that is used as the second argument for string.replace when processing the line with a regex.
    • moveCursor - Whether the cursor position should be moved after the text update.
      • false - the cursor will stay at the end of the input.
      • true - the cursor will be moved to the end of the last line in the output that only contains whitespace.

Cursor Example

If you entered "for x in 1 to 3" using defiant00/alpha-code, the output would be (with | indicating the cursor):

moveCursor false

for (let x = 1; x < 3; x++) {

}
| <- (at the end)

moveCursor true

for (let x = 1; x < 3; x++) {
    | <- (moved up)
}

Contributing

Bug fixes and new pattern libraries are both welcome, please send a pull request!

Known Issues

Liner may conflict with other extensions that intercept individual type events.

Release Notes

1.1.0

• Added Liner: Reload Patterns and Liner: Set Pattern Library Location commands

1.0.1

• Documentation cleanup and added images

1.0.0

• Initial version