From: Markus Triska <triska@metalevel.at>
Date: Sun, 27 Aug 2023 10:55:29 +0000 (+0200)
Subject: replace adjacent whitespace characters with a single SPACE character
X-Git-Tag: v0.9.2~2^2
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=75aec69de1affc63719150b9c7f28489e497877e;p=scryer-prolog.git

replace adjacent whitespace characters with a single SPACE character
---

diff --git a/src/lib/xpath.pl b/src/lib/xpath.pl
index 4ec01203..10f0fdef 100644
--- a/src/lib/xpath.pl
+++ b/src/lib/xpath.pl
@@ -642,7 +642,8 @@ normalize_space(Cs0, Cs) :-
         no_leading_whitespace(Cs0, Cs1),
         reverse(Cs1, Cs2),
         no_leading_whitespace(Cs2, Cs3),
-        reverse(Cs3, Cs).
+        reverse(Cs3, Cs4),
+        single_intermediate_space(Cs4, Cs).
 
 no_leading_whitespace([], []).
 no_leading_whitespace([C0|Cs0], Cs) :-
@@ -650,3 +651,13 @@ no_leading_whitespace([C0|Cs0], Cs) :-
             no_leading_whitespace(Cs0, Cs)
         ;   Cs = [C0|Cs0]
         ).
+
+single_intermediate_space([], []).
+single_intermediate_space([C0|Cs0], [C|Cs]) :-
+        (   char_type(C0, whitespace) ->
+            no_leading_whitespace(Cs0, Cs1),
+            C = ' ',
+            single_intermediate_space(Cs1, Cs)
+        ;   C = C0,
+            single_intermediate_space(Cs0, Cs)
+        ).