factor out some common code for sub(), suball() and extract() in the

C++ implementation

src/vre2/vre2.cpp

@@ -182,6 +182,23 @@ vre2_get_group(vre2 *vre2, const char * const name, int * const refnum)
 	CATCHALL
 }
 
+static inline const char *
+copy_on_match(const string& result, const int match, char * const dest,
+    const size_t bytes, size_t * const len)
+{
+	try {
+		if (!match)
+			return NULL;
+		if (result.size() + 1 > bytes)
+			throw runtime_error("insufficient workspace");
+		*len = result.size() + 1;
+		result.copy(dest, *len);
+		dest[*len] = '\0';
+		return NULL;
+	}
+	CATCHALL
+}
+
 const char *
 vre2_replace(vre2 *vre2, const int all, const char * const text,
     const char * const rewrite, char * const dest, const size_t bytes,
@@ -193,14 +210,7 @@ vre2_replace(vre2 *vre2, const int all, const char * const text,
 			*match = vre2->global_replace(&t, rewrite);
 		else
 			*match = vre2->replace(&t, rewrite);
-		if (!*match)
-			return NULL;
-		if (t.size() + 1 > bytes)
-			throw runtime_error("insufficient workspace");
-		*len = t.size() + 1;
-		t.copy(dest, *len);
-		dest[*len] = '\0';
-		return NULL;
+		return copy_on_match(t, *match, dest, bytes, len);
 	}
 	CATCHALL
 }
@@ -213,14 +223,7 @@ vre2_extract(vre2 *vre2, const char * const text, const char * const rewrite,
 	try {
 		string out;
 		*match = vre2->extract(&out, text, rewrite);
-		if (!*match)
-			return NULL;
-		if (out.size() + 1 > bytes)
-			throw runtime_error("insufficient workspace");
-		*len = out.size() + 1;
-		out.copy(dest, *len);
-		dest[*len] = '\0';
-		return NULL;
+		return copy_on_match(out, *match, dest, bytes, len);
 	}
 	CATCHALL
 }