util/CharUtil: add IsWhitespaceFast()

src/LogBackend.cxx

@@ -120,7 +120,7 @@ chomp_length(const char *p)
 {
 	size_t length = strlen(p);
 
-	while (length > 0 && IsWhitespaceOrNull(p[length - 1]))
+	while (length > 0 && IsWhitespaceFast(p[length - 1]))
 		--length;
 
 	return (int)length;

src/client/ClientRead.cxx

@@ -39,7 +39,7 @@ Client::OnSocketInput(void *data, size_t length)
 	BufferedSocket::ConsumeInput(newline + 1 - p);
 
 	/* skip whitespace at the end of the line */
-	while (newline > p && IsWhitespaceOrNull(newline[-1]))
+	while (newline > p && IsWhitespaceFast(newline[-1]))
 		--newline;
 
 	/* terminate the string at the end of the line */

src/input/TextInputStream.cxx

@@ -72,7 +72,7 @@ TextInputStream::ReadLine()
 
 	buffer.Consume(p - src + 1);
 
-	while (p > src && IsWhitespaceOrNull(p[-1]))
+	while (p > src && IsWhitespaceFast(p[-1]))
 		--p;
 	*p = 0;
 	return src;

src/util/CharUtil.hxx

@@ -58,6 +58,19 @@ IsWhitespaceNotNull(const char ch)
 	return ch > 0 && ch <= 0x20;
 }
 
+/**
+ * Is the given character whitespace?  This calls the faster one of
+ * IsWhitespaceOrNull() or IsWhitespaceNotNull().  Use this if you
+ * want the fastest implementation, and you don't care if a null byte
+ * matches.
+ */
+constexpr
+static inline bool
+IsWhitespaceFast(const char ch)
+{
+	return IsWhitespaceOrNull(ch);
+}
+
 constexpr
 static inline bool
 IsPrintableASCII(char ch)

src/util/Tokenizer.cxx

@@ -67,7 +67,7 @@ Tokenizer::NextWord(Error &error)
 	   whitespace or end-of-string */
 
 	while (*++input != 0) {
-		if (IsWhitespaceOrNull(*input)) {
+		if (IsWhitespaceFast(*input)) {
 			/* a whitespace: the word ends here */
 			*input = 0;
 			/* skip all following spaces, too */
@@ -112,7 +112,7 @@ Tokenizer::NextUnquoted(Error &error)
 	   whitespace or end-of-string */
 
 	while (*++input != 0) {
-		if (IsWhitespaceOrNull(*input)) {
+		if (IsWhitespaceFast(*input)) {
 			/* a whitespace: the word ends here */
 			*input = 0;
 			/* skip all following spaces, too */
@@ -176,7 +176,7 @@ Tokenizer::NextString(Error &error)
 	   line) */
 
 	++input;
-	if (!IsWhitespaceOrNull(*input)) {
+	if (!IsWhitespaceFast(*input)) {
 		error.Set(tokenizer_domain,
 			  "Space expected after closing '\"'");
 		return nullptr;