Implement CONTAINS operator.

Author: RubenVerborgh

lib/util/SparqlExpressionEvaluator.js

@@ -132,6 +132,11 @@ operators = {
   'langmatches': function (a, b) {
     return a.toLowerCase() === b.toLowerCase();
   },
+  'contains': function (string, substring) {
+    substring = N3Util.getLiteralValue(substring);
+    string = N3Util.getLiteralValue(string);
+    return string.indexOf(substring) >= 0;
+  },
   'regex': function (subject, pattern) {
     if (N3Util.isLiteral(subject))
       subject = N3Util.getLiteralValue(subject);
@@ -176,7 +181,7 @@ operators = {
 
 // Tag all operators that have boolean results
 [
-  '!', '&&', '||', '=', '<', '<=', '>', '>=', 'langmatches', 'regex',
+  '!', '&&', '||', '=', '<', '<=', '>', '>=', 'langmatches', 'contains', 'regex',
 ].forEach(function (operatorName) {
   operators[operatorName].resultType = 'boolean';
 });

test/util/SparqlExpressionEvaluator-test.js

@@ -355,6 +355,29 @@ describe('SparqlExpressionEvaluator', function () {
       });
     });
 
+    describe('of the CONTAINS operator', function () {
+      var evaluator = SparqlExpressionEvaluator({
+        type: 'operation',
+        operator: 'contains',
+        args: [
+          '"defgh"',
+          '?a',
+        ],
+      });
+
+      it('should return true if the substring is part of the string', function () {
+        evaluator({ '?a': '"efg"' }).should.equal(TRUE);
+      });
+
+      it('should return true if the substring is equal to the string', function () {
+        evaluator({ '?a': '"defgh"^^<urn:type>' }).should.equal(TRUE);
+      });
+
+      it('should return false if the substring is not part of the string', function () {
+        evaluator({ '?a': '"abc"' }).should.equal(FALSE);
+      });
+    });
+
     describe('of the regex operator', function () {
       var evaluator = SparqlExpressionEvaluator({
         type: 'operation',