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Support possessive quantifiers, which cannot backtrack.

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They are approximated by limiting them to up to one repetition (effectively making *+ like ? and ++ like a no-op).
This commit is contained in:
Joe Farebrother
2022-03-08 16:47:39 +00:00
parent 49374b877a
commit bb562643c6
4 changed files with 32 additions and 6 deletions
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13
java/ql/lib/semmle/code/java/regex/RegexTreeView.qll
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@@ -253,7 +253,12 @@ class RegExpQuantifier extends RegExpTerm, TRegExpQuantifier {
predicate mayRepeatForever() { may_repeat_forever = true }
/** Gets the quantifier for this term. That is e.g "?" for "a?". */
string getquantifier() { result = re.getText().substring(part_end, end) }
string getQuantifier() { result = re.getText().substring(part_end, end) }
/** Holds if this is a possessive quantifier, e.g. a*+. */
predicate isPossessive() {
exists(string q | q = this.getQuantifier() | q.length() > 1 and q.charAt(q.length() - 1) = "+")
}
override string getPrimaryQLClass() { result = "RegExpQuantifier" }
}
@@ -275,7 +280,7 @@ class InfiniteRepetitionQuantifier extends RegExpQuantifier {
* ```
*/
class RegExpStar extends InfiniteRepetitionQuantifier {
RegExpStar() { this.getquantifier().charAt(0) = "*" }
RegExpStar() { this.getQuantifier().charAt(0) = "*" }
override string getPrimaryQLClass() { result = "RegExpStar" }
}
@@ -290,7 +295,7 @@ class RegExpStar extends InfiniteRepetitionQuantifier {
* ```
*/
class RegExpPlus extends InfiniteRepetitionQuantifier {
RegExpPlus() { this.getquantifier().charAt(0) = "+" }
RegExpPlus() { this.getQuantifier().charAt(0) = "+" }
override string getPrimaryQLClass() { result = "RegExpPlus" }
}
@@ -305,7 +310,7 @@ class RegExpPlus extends InfiniteRepetitionQuantifier {
* ```
*/
class RegExpOpt extends RegExpQuantifier {
RegExpOpt() { this.getquantifier().charAt(0) = "?" }
RegExpOpt() { this.getQuantifier().charAt(0) = "?" }
override string getPrimaryQLClass() { result = "RegExpOpt" }
}