Remove useless character-length checks in contrib/ltree.

The t_iseq() macro does not need to be guarded by a character
length check (at least when the comparison value is an ASCII
character, as its documentation requires).  Some portions of
contrib/ltree hadn't read that memo, so simplify them.

The last change in gettoken_query,

-                else if (charlen == 1 && !t_iseq(state->buf, ' '))
+                else if (!t_iseq(state->buf, ' '))

looks like it's actually a bug fix: I doubt that the intention
was to silently ignore multibyte characters as if they were
whitespace.  I'm not tempted to back-patch though, because this
will have the effect of tightening what is allowed in ltxtquery
strings.

Discussion: https://postgr.es/m/2548310.1664999615@sss.pgh.pa.us

contrib/ltree/lquery_op.c

@@ -25,17 +25,16 @@ static char *
 getlexeme(char *start, char *end, int *len)
 {
 	char	   *ptr;
-	int			charlen;
 
-	while (start < end && (charlen = pg_mblen(start)) == 1 && t_iseq(start, '_'))
-		start += charlen;
+	while (start < end && t_iseq(start, '_'))
+		start += pg_mblen(start);
 
 	ptr = start;
 	if (ptr >= end)
 		return NULL;
 
-	while (ptr < end && !((charlen = pg_mblen(ptr)) == 1 && t_iseq(ptr, '_')))
-		ptr += charlen;
+	while (ptr < end && !t_iseq(ptr, '_'))
+		ptr += pg_mblen(ptr);
 
 	*len = ptr - start;
 	return start;

contrib/ltree/ltree.h

@@ -126,7 +126,7 @@ typedef struct
 
 #define LQUERY_HASNOT		0x01
 
-#define ISALNUM(x)	( t_isalnum(x) || ( pg_mblen(x) == 1 && t_iseq((x), '_') ) )
+#define ISALNUM(x)	( t_isalnum(x) || t_iseq(x, '_') )
 
 /* full text query */
 

contrib/ltree/ltxtquery_io.c

@@ -64,13 +64,13 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 		switch (state->state)
 		{
 			case WAITOPERAND:
-				if (charlen == 1 && t_iseq(state->buf, '!'))
+				if (t_iseq(state->buf, '!'))
 				{
 					(state->buf)++;
 					*val = (int32) '!';
 					return OPR;
 				}
-				else if (charlen == 1 && t_iseq(state->buf, '('))
+				else if (t_iseq(state->buf, '('))
 				{
 					state->count++;
 					(state->buf)++;
@@ -97,11 +97,11 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 								 errmsg("modifiers syntax error")));
 					*lenval += charlen;
 				}
-				else if (charlen == 1 && t_iseq(state->buf, '%'))
+				else if (t_iseq(state->buf, '%'))
 					*flag |= LVAR_SUBLEXEME;
-				else if (charlen == 1 && t_iseq(state->buf, '@'))
+				else if (t_iseq(state->buf, '@'))
 					*flag |= LVAR_INCASE;
-				else if (charlen == 1 && t_iseq(state->buf, '*'))
+				else if (t_iseq(state->buf, '*'))
 					*flag |= LVAR_ANYEND;
 				else
 				{
@@ -110,14 +110,14 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 				}
 				break;
 			case WAITOPERATOR:
-				if (charlen == 1 && (t_iseq(state->buf, '&') || t_iseq(state->buf, '|')))
+				if (t_iseq(state->buf, '&') || t_iseq(state->buf, '|'))
 				{
 					state->state = WAITOPERAND;
 					*val = (int32) *(state->buf);
 					(state->buf)++;
 					return OPR;
 				}
-				else if (charlen == 1 && t_iseq(state->buf, ')'))
+				else if (t_iseq(state->buf, ')'))
 				{
 					(state->buf)++;
 					state->count--;
@@ -125,7 +125,7 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 				}
 				else if (*(state->buf) == '\0')
 					return (state->count) ? ERR : END;
-				else if (charlen == 1 && !t_iseq(state->buf, ' '))
+				else if (!t_iseq(state->buf, ' '))
 					return ERR;
 				break;
 			default: