JavaScript: Distinguish {lo} and {lo,} in the regular expression parser.

javascript/extractor/src/com/semmle/js/extractor/Main.java

@@ -37,7 +37,7 @@ public class Main {
    * A version identifier that should be updated every time the extractor changes in such a way that
    * it may produce different tuples for the same file under the same {@link ExtractorConfig}.
    */
-  public static final String EXTRACTOR_VERSION = "2020-02-05";
+  public static final String EXTRACTOR_VERSION = "2020-02-14";
 
   public static final Pattern NEWLINE = Pattern.compile("\n");
 

javascript/extractor/src/com/semmle/js/parser/RegExpParser.java

@@ -281,8 +281,19 @@ public class RegExpParser {
     if (this.match("+")) return this.finishTerm(new Plus(loc, atom, !this.match("?")));
     if (this.match("?")) return this.finishTerm(new Opt(loc, atom, !this.match("?")));
     if (this.match("{")) {
-      Double lo = toNumber(this.readDigits(false)), hi = null;
-      if (this.match(",") && !this.lookahead("}")) hi = toNumber(this.readDigits(false));
+      Double lo = toNumber(this.readDigits(false)), hi;
+      if (this.match(",")) {
+        if (!this.lookahead("}")) {
+          // atom{lo, hi}
+          hi = toNumber(this.readDigits(false));
+        } else {
+          // atom{lo,}
+          hi = null;
+        }
+      } else {
+        // atom{lo}
+        hi = lo;
+      }
       this.expectRBrace();
       return this.finishTerm(new Range(loc, atom, !this.match("?"), lo, hi));
     }

javascript/extractor/tests/exprs/output/trap/regexp.js.trap

@@ -1088,6 +1088,7 @@ locations_default(#20376,#10000,15,2,15,5)
 hasLocation(#20375,#20376)
 isGreedy(#20375)
 rangeQuantifierLowerBound(#20375,1)
+rangeQuantifierUpperBound(#20375,1)
 #20377=*
 regexpterm(#20377,14,#20375,0,"a")
 #20378=@"loc,{#10000},15,2,15,2"
@@ -1157,6 +1158,7 @@ regexpterm(#20393,11,#20392,0,"a{1}?")
 locations_default(#20394,#10000,18,2,18,6)
 hasLocation(#20393,#20394)
 rangeQuantifierLowerBound(#20393,1)
+rangeQuantifierUpperBound(#20393,1)
 #20395=*
 regexpterm(#20395,14,#20393,0,"a")
 #20396=@"loc,{#10000},18,2,18,2"
@@ -1670,6 +1672,7 @@ locations_default(#20543,#10000,37,2,37,3)
 locations_default(#20543,#10000,37,2,37,3)
 hasLocation(#20542,#20543)
 isGreedy(#20542)
+rangeQuantifierLowerBound(#20542,0)
 rangeQuantifierUpperBound(#20542,0)
 #20544=*
 regexpterm(#20544,14,#20542,0,"a")
@@ -1708,6 +1711,7 @@ locations_default(#20555,#10000,38,2,38,3)
 locations_default(#20555,#10000,38,2,38,3)
 hasLocation(#20554,#20555)
 isGreedy(#20554)
+rangeQuantifierLowerBound(#20554,0)
 rangeQuantifierUpperBound(#20554,0)
 #20556=*
 regexpterm(#20556,14,#20554,0,"a")
@@ -1754,6 +1758,7 @@ locations_default(#20569,#10000,39,2,39,4)
 locations_default(#20569,#10000,39,2,39,4)
 hasLocation(#20568,#20569)
 isGreedy(#20568)
+rangeQuantifierLowerBound(#20568,2)
 rangeQuantifierUpperBound(#20568,2)
 #20570=*
 regexpterm(#20570,14,#20568,0,"a")

javascript/ql/src/semmle/javascript/Regexp.qll

@@ -506,17 +506,25 @@ class RegExpOpt extends RegExpQuantifier, @regexp_opt {
 /**
  * A range-quantified term
  *
- * Example:
+ * Examples:
  *
  * ```
  * \w{2,4}
+ * \w{2,}
+ * \w{2}
  * ```
  */
 class RegExpRange extends RegExpQuantifier, @regexp_range {
-  /** Gets the lower bound of the range, if any. */
+  /** Gets the lower bound of the range. */
   int getLowerBound() { rangeQuantifierLowerBound(this, result) }
 
-  /** Gets the upper bound of the range, if any. */
+  /**
+   * Gets the upper bound of the range, if any.
+   *
+   * If there is no upper bound, any number of repetitions is allowed.
+   * For a term of the form `r{lo}`, both the lower and the upper bound
+   * are `lo`.
+   */
   int getUpperBound() { rangeQuantifierUpperBound(this, result) }
 
   override predicate isNullable() {

javascript/ql/test/library-tests/RegExp/Bounds/Bounds.expected

@@ -0,0 +1,4 @@
+| tst.js:1:2:1:5 | a{1} | 1 | 1 |
+| tst.js:2:2:2:6 | a{1,} | 1 | <none> |
+| tst.js:3:2:3:7 | a{1,5} | 1 | 5 |
+| tst.js:4:2:4:6 | a{,5} | 0 | 5 |

javascript/ql/test/library-tests/RegExp/Bounds/Bounds.ql

@@ -0,0 +1,7 @@
+import javascript
+
+from RegExpRange rr, string lb, string ub
+where
+  lb = rr.getLowerBound().toString() and
+  if exists(rr.getUpperBound()) then ub = rr.getUpperBound().toString() else ub = "<none>"
+select rr, lb, ub

javascript/ql/test/library-tests/RegExp/Bounds/tst.js

@@ -0,0 +1,4 @@
+/a{1}/;
+/a{1,}/;
+/a{1,5}/;
+/a{,5}/;