'use strict'
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var licenses = []
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.concat(require('spdx-license-ids'))
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.concat(require('spdx-license-ids/deprecated'))
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var exceptions = require('spdx-exceptions')
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module.exports = function (source) {
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var index = 0
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function hasMore () {
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return index < source.length
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}
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// `value` can be a regexp or a string.
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// If it is recognized, the matching source string is returned and
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// the index is incremented. Otherwise `undefined` is returned.
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function read (value) {
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if (value instanceof RegExp) {
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var chars = source.slice(index)
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var match = chars.match(value)
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if (match) {
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index += match[0].length
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return match[0]
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}
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} else {
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if (source.indexOf(value, index) === index) {
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index += value.length
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return value
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}
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}
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}
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function skipWhitespace () {
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read(/[ ]*/)
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}
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function operator () {
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var string
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var possibilities = ['WITH', 'AND', 'OR', '(', ')', ':', '+']
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for (var i = 0; i < possibilities.length; i++) {
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string = read(possibilities[i])
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if (string) {
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break
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}
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}
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if (string === '+' && index > 1 && source[index - 2] === ' ') {
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throw new Error('Space before `+`')
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}
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return string && {
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type: 'OPERATOR',
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string: string
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}
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}
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function idstring () {
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return read(/[A-Za-z0-9-.]+/)
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}
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function expectIdstring () {
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var string = idstring()
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if (!string) {
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throw new Error('Expected idstring at offset ' + index)
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}
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return string
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}
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function documentRef () {
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if (read('DocumentRef-')) {
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var string = expectIdstring()
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return { type: 'DOCUMENTREF', string: string }
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}
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}
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function licenseRef () {
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if (read('LicenseRef-')) {
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var string = expectIdstring()
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return { type: 'LICENSEREF', string: string }
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}
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}
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function identifier () {
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var begin = index
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var string = idstring()
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if (licenses.indexOf(string) !== -1) {
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return {
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type: 'LICENSE',
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string: string
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}
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} else if (exceptions.indexOf(string) !== -1) {
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return {
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type: 'EXCEPTION',
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string: string
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}
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}
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index = begin
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}
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// Tries to read the next token. Returns `undefined` if no token is
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// recognized.
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function parseToken () {
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// Ordering matters
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return (
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operator() ||
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documentRef() ||
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licenseRef() ||
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identifier()
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)
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}
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var tokens = []
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while (hasMore()) {
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skipWhitespace()
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if (!hasMore()) {
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break
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}
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var token = parseToken()
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if (!token) {
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throw new Error('Unexpected `' + source[index] +
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'` at offset ' + index)
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}
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tokens.push(token)
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}
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return tokens
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}
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