/usr/share/doc/node-spdx-expression-parse/README.md is in node-spdx-expression-parse 1.0.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 | This package parses SPDX license expression strings describing license terms, like [package.json license strings](https://docs.npmjs.com/files/package.json#license), into consistently structured ECMAScript objects. The npm command-line interface depends on this package, as do many automatic license-audit tools.
In a nutshell:
```javascript
var parse = require('spdx-expression-parse')
var assert = require('assert')
assert.deepEqual(
// Licensed under the terms of the Two-Clause BSD License.
parse('BSD-2-Clause'),
{license: 'BSD-2-Clause'}
)
assert.throws(function () {
// An invalid SPDX license expression.
// Should be `Apache-2.0`.
parse('Apache 2')
})
assert.deepEqual(
// Dual licensed under LGPL 2.1 or a combination of the Three-Clause
// BSD License and the MIT License.
parse('(LGPL-2.1 OR BSD-3-Clause AND MIT)'),
{
left: {license: 'LGPL-2.1'},
conjunction: 'or',
right: {
left: {license: 'BSD-3-Clause'},
conjunction: 'and',
right: {license: 'MIT'}
}
}
)
```
The syntax comes from the [Software Package Data eXchange (SPDX)](https://spdx.org/), a standard from the [Linux Foundation](https://www.linuxfoundation.org) for shareable data about software package license terms. SPDX aims to make sharing and auditing license data easy, especially for users of open-source software.
The bulk of the SPDX standard describes syntax and semantics of XML metadata files. This package implements two lightweight, plain-text components of that larger standard:
1. The [license list](https://spdx.org/licenses), a mapping from specific string identifiers, like `Apache-2.0`, to standard form license texts and bolt-on license exceptions. The [spdx-license-ids](https://www.npmjs.com/package/spdx-exceptions) and [spdx-exceptions](https://www.npmjs.com/package/spdx-license-ids) packages implement the license list. They are development dependencies of this package.
Any license identifier from the license list is a valid license expression:
```javascript
require('spdx-license-ids').forEach(function (id) {
assert.deepEqual(parse(id), {license: id})
})
```
So is any license identifier `WITH` a standardized license exception:
```javascript
require('spdx-license-ids').forEach(function (id) {
require('spdx-exceptions').forEach(function (e) {
assert.deepEqual(
parse(id + ' WITH ' + e),
{license: id, exception: e}
)
})
})
```
2. The license expression language, for describing simple and complex license terms, like `MIT` for MIT-licensed and `(GPL-2.0 OR Apache-2.0)` for dual-licensing under GPL 2.0 and Apache 2.0. This package implements the license expression language.
```javascript
assert.deepEqual(
// Licensed under a combination of the MIT License and a combination
// of LGPL 2.1 (or a later version) and the Three-Clause BSD License.
parse('(MIT AND (LGPL-2.1+ AND BSD-3-Clause))'),
{
left: {license: 'MIT'},
conjunction: 'and',
right: {
left: {license: 'LGPL-2.1', plus: true},
conjunction: 'and',
right: {license: 'BSD-3-Clause'}
}
}
)
```
The Linux Foundation and its contributors license the SPDX standard under the terms of [the Creative Commons Attribution License 3.0 Unported (SPDX: "CC-BY-3.0")](http://spdx.org/licenses/CC-BY-3.0). "SPDX" is a United States federally registered trademark of the Linux Foundation. The authors of this package license their work under the terms of the MIT License.
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