Parinfer in Emacs Lisp

A Parinfer implementation in Emacs Lisp.

About

Having a Parinfer implementation written in Emacs Lisp allows Parinfer to reach Emacs users easily.

Please note that this project is solely for the library that implements the core Parinfer algorithm; it is not an Emacs extension that can be used for editing.

This is basically a 1-to-1 port of parinfer.js.

The .json files in the tests folder are copied directly from the [main Parinfer repo].

This is my first Emacs Lisp project. There is likely lots of room for improvement in this implementation. PR's welcome :)

Usage

This library is namespaced under parinferlib.

It is expected that extension authors will use the namespace parinfer

It exposes two public functions:

• (parinferlib-indent-mode txt options)
• (parinferlib-paren-mode txt options)

txt should be a string of the text you want to process. Optional options should be a Property List (plist) with the following keys:

• :cursor-line - zero-based line number of the cursor
• :cursor-x - zero-based x-position of the cursor
• :cursor-dx - amount that the cursor moved horizontally if something was inserted or deleted (only used by Paren Mode)
• :preview-cursor-scope - t or nil, when set to t in Indent Mode, it shows the cursor's scope on an empty line by inserting close-parens after it (read more here)

The return value is a plist with keys:

• :success - t or nil, indicating if the input was properly formatted enough to create a valid result
• :text - a string, is the full text output (this is just the original text if :success is nil)
• :cursor-x - the new x-position of the cursor (since Parinfer may shift it around)
• :changed-lines - a vector of plists representing only the lines Parinfer changed, plist keys are:
  • :line-no - zero-based line number
  • :line - full text of the line
• :error - a plist if :success is nil containing keys:
  • :name - the name of the error
  • :message - a message describing the error
  • :line-no - a zero-based line number where the error occurred
  • :x - a zero-based column where the error occurred
• :tab-stops - a vector of plists representing Tab stops. Only populated in Indent Mode when a cursor position is supplied. plist keys are:
  • :x - a zero-based x-position of the tab stop
  • :line-no - a zero-based line number of the open-paren responsible for the tab stop
  • :ch - the character of the open-paren responsible for the tab stop (e.g. (, [, {)

This library closely mirrors the parinfer.js API. Please see there for more information.

Usage examples can be found in test.el and perf.el.

Development

To run tests:

emacs --script test.el

To test performance:

emacs --script perf.el

License

ISC License