1 files changed, 90 insertions, 0 deletions
diff --git a/common/checks.js b/common/checks.js
new file mode 100644
index 0000000..f3c27bc
--- /dev/null
+++ b/common/checks.js
@@ -0,0 +1,90 @@
+/**
+* GNU LibreJS - A browser add-on to block nonfree nontrivial JavaScript.
+* *
+* Copyright (C) 2018 Nathan Nichols
+* Copyright (C) 2022 Yuchen Pei
+*
+* This file is part of GNU LibreJS.
+*
+* GNU LibreJS is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+*
+* GNU LibreJS is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with GNU LibreJS.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+const { licenses } = require('./license_definitions.js');
+const { patternUtils } = require('./pattern_utils.js');
+
+const LIC_RE = /@licstartThefollowingistheentirelicensenoticefortheJavaScriptcodeinthis(?:page|file)(.*)?@licendTheaboveistheentirelicensenoticefortheJavaScriptcodeinthis(?:page|file)/mi;
+
+
+/**
+ * stripLicenseToRegexp
+ *
+ * Removes all non-alphanumeric characters except for the 
+ * special tokens, and replace the text values that are 
+ * hardcoded in license_definitions.js
+ *
+ */
+const stripLicenseToRegexp = function(license) {
+  for (const frag of license.licenseFragments) {
+    frag.regex = patternUtils.removeNonalpha(frag.text);
+    frag.regex = new RegExp(
+      patternUtils.replaceTokens(frag.regex), '');
+  }
+};
+
+const init = function() {
+  console.log('initializing regexes');
+  for (const key in licenses) {
+    stripLicenseToRegexp(licenses[key]);
+  }
+}
+
+module.exports.init = init;
+
+/**
+*
+*	Takes in the declaration that has been preprocessed and 
+*	tests it against regexes in our table.
+*/
+const searchTable = function(strippedComment) {
+  const stripped = patternUtils.removeNonalpha(strippedComment);
+  // looking up license
+  for (const key in licenses) {
+    const license = licenses[key];
+    for (const frag of license.licenseFragments) {
+      if (frag.regex.test(stripped)) {
+        return license.licenseName;
+      }
+    }
+  }
+  console.log('No global license found.');
+  return null;
+}
+
+/**
+ * Checks whether licenseText, modulo whitespace, starts with
+ * a @licstart / @licend with a free license, returns the license name
+ * if so, and null otherwise.
+ */
+const check = function(licenseText) {
+  if (licenseText === undefined || licenseText === null) {
+    return null;
+  }
+  // remove whitespace
+  const stripped = patternUtils.removeWhitespace(licenseText);
+  // Search for @licstart/@licend
+  const matches = stripped.match(LIC_RE);
+  return matches && searchTable(matches[0]);
+};
+
+module.exports.check = check;