catdad/line-merge

:construction: merge strings line by line, to result in a string of unique lines

line merge

This kind of weird lib was created for a kind of weird reason. I needed to merge what are essentially list files -- files that have one list item per line. Namely, files like .gitignore. This module will merge the contents of such files, resulting in a unique list of item (duplicated will be removed), and it will do its best to preserve comments and new lines.

Install

npm install line-merge

Use

The main function you will care about is the merge function.

merge({String} str, ...) → {String}

Takes any number of strings, and merges all the unique lines in each, resulting in a single string containing all lines from the input strings. It will merge all strings passed into the method in order.

var fs = require('fs');
var lines = require('line-merge');

var file1 = fs.readFileSync('location/to/one/.gitignore', 'utf8');
var file2 = fs.readFileSync('location/to/two/.gitignore', 'utf8');
var file3 = fs.readFileSync('location/to/three/.gitignore', 'utf8');

var merged = lines.merge(file1, file2, file3);

fs.writeFileSync('location/to/merged/.gitingore', merged);

You can also access the internals:

tokenize({String} str) → {Array}

Tokenize a single list string into an array.

var tokens = lines.tokenize('pineapples\ncherries');
// [{ line: 'pineapples' }, { line: 'cherries' }]

Comments are determined as lines that start with #.

var tokens = lines.tokenize('# fruits\npineapples\ncherries');
// [{ line: 'pineapples', comments: ['# fruits'] }, { line: 'cherries' }]

serialize({Array} arr) → {String}

Serialize a tokenized array into a list string.

var output = lines.serialize([
    { line: 'pineapples' },
    { line: 'cherries' }
]);
// 'pineapples\ncherries\n'

Note that the output will always end in a new line.

mergeRaw({Array} arr, ...) → {Array}

Merges the underlying tokenized array representation of the list files. It will merge all arrays passed into the method in order.

var tokens = lines.mergeRaw(
    [{ line: 'pineapples' }, { line: 'apples' }],
    [{ line: 'cherries' }, { line: 'apples', comments: ['# not the company'] }]
);

// [{ line: 'pineapples' }, { line: 'apples', comments: ['# not the company'] }, { line: 'cherries' }]