From df54de37b0a372a49bed0130406a5b75b85cd119 Mon Sep 17 00:00:00 2001
From: Zufu Liu <unknown>
Date: Tue, 21 Nov 2023 11:29:30 +1100
Subject: Bug [#2413]. Fix regular expression search failure.

---
 src/RESearch.cxx | 23 ++++++++++++++---------
 src/RESearch.h   |  3 +--
 2 files changed, 15 insertions(+), 11 deletions(-)

(limited to 'src')

diff --git a/src/RESearch.cxx b/src/RESearch.cxx
index ca0f1b552..ac41138c8 100644
--- a/src/RESearch.cxx
+++ b/src/RESearch.cxx
@@ -256,8 +256,7 @@ RESearch::RESearch(CharClassify *charClassTable) {
 	bol = 0;
 	constexpr unsigned char nul = 0;
 	std::fill(bittab, std::end(bittab), nul);
-	std::fill(tagstk, std::end(tagstk), 0);
-	std::fill(nfa, std::end(nfa), '\0');
+	nfa[0] = END;
 	Clear();
 }
 
@@ -419,12 +418,24 @@ int RESearch::GetBackslashExpression(
 	return result;
 }
 
-const char *RESearch::Compile(const char *pattern, Sci::Position length, bool caseSensitive, bool posix) noexcept {
+const char *RESearch::Compile(const char *pattern, Sci::Position length, bool caseSensitive, bool posix) {
+	if (!pattern || !length) {
+		if (sta)
+			return nullptr;
+		else
+			return badpat("No previous regular expression");
+	}
+
+	constexpr unsigned char nul = 0;
+	std::fill(bittab, std::end(bittab), nul);
+	nfa[0] = END;
+
 	char *mp=nfa;          /* nfa pointer       */
 	char *lp=nullptr;      /* saved pointer     */
 	char *sp=nfa;          /* another one       */
 	const char * mpMax = mp + MAXNFA - BITBLK - 10;
 
+	int tagstk[MAXTAG]{};  /* subpat tag stack */
 	int tagi = 0;          /* tag stack index   */
 	int tagc = 1;          /* actual tag count  */
 
@@ -434,12 +445,6 @@ const char *RESearch::Compile(const char *pattern, Sci::Position length, bool ca
 	int c2 = 0;
 	int prevChar = 0;
 
-	if (!pattern || !length) {
-		if (sta)
-			return nullptr;
-		else
-			return badpat("No previous regular expression");
-	}
 	sta = NOP;
 
 	const char *p=pattern;     /* pattern pointer   */
diff --git a/src/RESearch.h b/src/RESearch.h
index 05bc0e093..5ac3f00dc 100644
--- a/src/RESearch.h
+++ b/src/RESearch.h
@@ -22,7 +22,7 @@ public:
 	explicit RESearch(CharClassify *charClassTable);
 	// No dynamic allocation so default copy constructor and assignment operator are OK.
 	void Clear();
-	const char *Compile(const char *pattern, Sci::Position length, bool caseSensitive, bool posix) noexcept;
+	const char *Compile(const char *pattern, Sci::Position length, bool caseSensitive, bool posix);
 	int Execute(const CharacterIndexer &ci, Sci::Position lp, Sci::Position endp);
 
 	static constexpr int MAXTAG = 10;
@@ -48,7 +48,6 @@ private:
 	Sci::Position PMatch(const CharacterIndexer &ci, Sci::Position lp, Sci::Position endp, const char *ap);
 
 	Sci::Position bol;
-	Sci::Position tagstk[MAXTAG];  /* subpat tag stack */
 	char nfa[MAXNFA];    /* automaton */
 	int sta;
 	unsigned char bittab[BITBLK]; /* bit table for CCL pre-set bits */
-- 
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