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Python: Move constraints into pranch charpreds

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For sequences and alternations, we require at least one child.
Otherwise, we wish to represent the term differently.
This avoids multiple representations.
This commit is contained in:
Rasmus Lerchedahl Petersen
2021-08-23 11:44:00 +02:00
parent c4554836ca
commit 34d7772a0d
1 changed files with 18 additions and 13 deletions
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31
python/ql/src/semmle/python/RegexTreeView.qll
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@@ -7,6 +7,10 @@ private import semmle.python.regex
* An element containing a regular expression term, that is, either
* a string literal (parsed as a regular expression)
* or another regular expression term.
*
* For sequences and alternations, we require at least one child.
* Otherwise, we wish to represent the term differently.
* This avoids multiple representations of the same term.
*/
newtype TRegExpParent =
/** A string literal used as a regular expression */
@@ -14,9 +18,18 @@ newtype TRegExpParent =
/** A quantified term */
TRegExpQuantifier(Regex re, int start, int end) { re.qualifiedItem(start, end, _, _) } or
/** A sequence term */
TRegExpSequence(Regex re, int start, int end) { re.sequence(start, end) } or
TRegExpSequence(Regex re, int start, int end) {
re.sequence(start, end) and
exists(seqChild(re, start, end, 1)) // if a sequence does not have more than one element, it should be treated as that element instead.
} or
/** An alternatio term */
TRegExpAlt(Regex re, int start, int end) { re.alternation(start, end) } or
TRegExpAlt(Regex re, int start, int end) {
re.alternation(start, end) and
exists(int part_end |
re.alternationOption(start, end, start, part_end) and
part_end < end
) // if an alternation does not have more than one element, it should be treated as that element instead.
} or
/** A character class term */
TRegExpCharacterClass(Regex re, int start, int end) { re.charSet(start, end) } or
/** A character range term */
@@ -75,11 +88,7 @@ class RegExpTerm extends RegExpParent {
int end;
RegExpTerm() {
this = TRegExpAlt(re, start, end) and
exists(int part_end |
re.alternationOption(start, end, start, part_end) and
part_end < end
) // if an alternation does not have more than one element, it should be treated as that element instead.
this = TRegExpAlt(re, start, end)
or
this = TRegExpBackRef(re, start, end)
or
@@ -93,8 +102,7 @@ class RegExpTerm extends RegExpParent {
or
this = TRegExpQuantifier(re, start, end)
or
this = TRegExpSequence(re, start, end) and
exists(seqChild(re, start, end, 1)) // if a sequence does not have more than one element, it should be treated as that element instead.
this = TRegExpSequence(re, start, end)
or
this = TRegExpSpecialChar(re, start, end)
}
@@ -341,10 +349,7 @@ class RegExpRange extends RegExpQuantifier {
* This is a sequence with the elements `(ECMA|Java)` and `Script`.
*/
class RegExpSequence extends RegExpTerm, TRegExpSequence {
RegExpSequence() {
this = TRegExpSequence(re, start, end) and
exists(seqChild(re, start, end, 1)) // if a sequence does not have more than one element, it should be treated as that element instead.
}
RegExpSequence() { this = TRegExpSequence(re, start, end) }
override RegExpTerm getChild(int i) { result = seqChild(re, start, end, i) }