Improve RESearch for DBCS code pages to avoid matching from trailing …

…ASCII byte. See https://sourceforge.net/p/scintilla/bugs/2405/
zufuliu · Oct 16, 2023 · e2818f5 · e2818f5
1 parent 5be563a
commit e2818f5
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Showing 2 changed files with 12 additions and 9 deletions.
diff --git a/scintilla/src/RESearch.cxx b/scintilla/src/RESearch.cxx
@@ -264,7 +264,6 @@ RESearch::RESearch(const CharClassify *charClassTable) {
 	lineStartPos = 0;
 	lineEndPos = 0;
 	sta = NOP;                  /* status of lastpat */
-	failure = 0;
 	previousFlags = FindOption::None;
 	constexpr unsigned char nul = 0;
 	std::fill(bittab, std::end(bittab), nul);
@@ -758,8 +757,6 @@ int RESearch::Execute(const CharacterIndexer &ci, Sci::Position lp, Sci::Positio
 	Sci::Position ep = NOTFOUND;
 	const char * const ap = nfa;
 
-	failure = 0;
-
 	Clear();
 
 	switch (*ap) {
@@ -787,8 +784,15 @@ int RESearch::Execute(const CharacterIndexer &ci, Sci::Position lp, Sci::Positio
 	default:			/* regular matching all the way. */
 		while (lp < endp) {
 			ep = PMatch(ci, lp, endp, ap);
-			if (ep != NOTFOUND)
-				break;
+			if (ep != NOTFOUND) {
+				// fix match started from middle of character like DBCS trailing ASCII byte
+				const Sci::Position pos = ci.MovePositionOutsideChar(lp, -1);
+				if (pos != lp) {
+					ep = NOTFOUND;
+				} else {
+					break;
+				}
+			}
 			lp++;
 		}
 		break;
@@ -809,7 +813,6 @@ int RESearch::Execute(const CharacterIndexer &ci, Sci::Position lp, Sci::Positio
 		}
 	}
 
-	lp = ci.MovePositionOutsideChar(lp, -1);
 	ep = ci.MovePositionOutsideChar(ep, 1);
 	bopat[0] = lp;
 	eopat[0] = ep;
@@ -885,7 +888,9 @@ Sci::Position RESearch::PMatch(const CharacterIndexer &ci, Sci::Position lp, Sci
 				return NOTFOUND;
 			break;
 		case BOT:
-			lp = ci.MovePositionOutsideChar(lp, -1);
+			if (lp != ci.MovePositionOutsideChar(lp, -1)) {
+				return NOTFOUND;
+			}
 			bopat[static_cast<unsigned char>(*ap++)] = lp;
 			break;
 		case EOT:
@@ -944,7 +949,6 @@ Sci::Position RESearch::PMatch(const CharacterIndexer &ci, Sci::Position lp, Sci
 				n = CCLSKIP;
 				break;
 			default:
-				failure = true;
 				//re_fail("closure: bad nfa.", *ap);
 				return NOTFOUND;
 			}

diff --git a/scintilla/src/RESearch.h b/scintilla/src/RESearch.h
@@ -51,7 +51,6 @@ class RESearch {
 	Sci::Position tagstk[MAXTAG];  /* subpat tag stack */
 	char nfa[MAXNFA];    /* automaton */
 	int sta;
-	int failure;
 
 	// cache for previous pattern to avoid recompile
 	Scintilla::FindOption previousFlags;