Add relaxed option to allow invalid licenses and exception names

Fix #11.

index.js

@@ -1,6 +1,6 @@
 var scan = require('./scan')
 var parse = require('./parse')
 
-module.exports = function (source) {
-  return parse(scan(source))
+module.exports = function (source, options) {
+  return parse(scan(source), options)
 }

parse.js

@@ -1,11 +1,16 @@
+var licenses = require('spdx-license-ids')
+var exceptions = require('spdx-exceptions')
 var util = require('./util')
 
 // The ABNF grammar in the spec is totally ambiguous.
 //
 // This parser follows the operator precedence defined in the
 // `Order of Precedence and Parentheses` section.
-
-module.exports = function (tokens) {
+//
+// options:
+//  - Set `relaxed` to `true` to accept invalid license or exception IDs.
+module.exports = function (tokens, options) {
+  options = options || {}
   var index = 0
 
   function hasMore () {
@@ -34,7 +39,10 @@ module.exports = function (tokens) {
   function parseWith () {
     if (parseOperator('WITH')) {
       var t = token()
-      if (t && t.type === 'EXCEPTION') {
+      if (t && t.type === 'IDENTIFIER') {
+        if (!options.relaxed && exceptions.indexOf(t.string) === -1) {
+          throw new Error('`' + t.string + '` is not a valid exception name')
+        }
         next()
         return t.string
       }
@@ -67,7 +75,10 @@ module.exports = function (tokens) {
 
   function parseLicense () {
     var t = token()
-    if (t && t.type === 'LICENSE') {
+    if (t && t.type === 'IDENTIFIER') {
+      if (!options.relaxed && licenses.indexOf(t.string) === -1) {
+        throw new Error('`' + t.string + '` is not a valid license name')
+      }
       next()
       var node = {license: t.string}
       if (parseOperator('+')) {

scan.js

@@ -1,5 +1,3 @@
-var licenses = require('spdx-license-ids')
-var exceptions = require('spdx-exceptions')
 var util = require('./util')
 
 module.exports = function (source) {
@@ -77,22 +75,11 @@ module.exports = function (source) {
   }
 
   function identifier () {
-    var begin = index
     var string = idstring()
-
-    if (licenses.indexOf(string) !== -1) {
-      return {
-        type: 'LICENSE',
-        string
-      }
-    } else if (exceptions.indexOf(string) !== -1) {
-      return {
-        type: 'EXCEPTION',
-        string
-      }
+    return string && {
+      type: 'IDENTIFIER',
+      string
     }
-
-    index = begin
   }
 
   // Tries to read the next token. Returns `undefined` if no token is

test/index.js

@@ -81,3 +81,27 @@ it('parses `AND`, `OR` and `WITH` with the correct precedence', () => {
     }
   )
 })
+
+it('rejects invalid license and exception names by default', () => {
+  assert.throws(
+    () => p('unknownLicense'),
+    /`unknownLicense` is not a valid license name/
+  )
+
+  assert.throws(
+    () => p('MIT WITH unknownException'),
+    /`unknownException` is not a valid exception name/
+  )
+})
+
+it('accepts invalid license and exception names in relaxed mode', () => {
+  assert.deepStrictEqual(
+    p('unknownLicense', {relaxed: true}),
+    {license: 'unknownLicense'}
+  )
+
+  assert.deepStrictEqual(
+    p('MIT WITH unknownException', {relaxed: true}),
+    {license: 'MIT', exception: 'unknownException'}
+  )
+})