python-style-slicing

PythonStyleListSlice

Python like list slicing in javascript. Transpiles JavaScript to allow for arr[1:2], arr[::2], arr[-1], arr[-1] = 5, etc...

Installation

npm -g install python-style-slicing

Node API

PSS::transpile(code, filename='dummy.js', sourceMap=false)

• code: the code to transpile
• filename: original file code came from. Used in creation of sourcemaps. Defaults to 'dummy.js'
• sourceMap: boolean indicating whether or not to generate source maps. Defaults to false

Example usage

import PSS from 'python-style-slicing';

const code = ['var x = [1, 2, 3, 4, 5];', 'console.log(x[::2]);'].join('\n');

const output = PSS.transpile(code, 'test.js', true);

CLI

pss [file] [--s] [-o output_location]

If no file given, pss will read from stdin. If no output location given, pss will output to stdout. The --s flag option indicates whether or not to generate source maps along with output.

How It Works

Uses a modified version of the acorn parser to generate an AST with the following new nodes:

ComputedMemberRangeExpression: {
    startExpression: Expression,
    endExpression: Expression,
    skipExpression: Expression
},
ComputedMemberAssignmentExpression: <The same as an AssignmentExpression>

A modified version of the escodegen code generator then generates code.

ComputedMemberRangeExpression ->
    __$$__computedMemberRangeGet__$$__(array, startExpression, endExpression, skipExpression)
ComputedMemberAssignmentExpression ->
    __$$__computedMemberSet__$$__(array, property, value, operator)
ComputedMember ->
    __$$__ComputedMemberGet__$$__(array, property)

License

MIT