Why does XQuery add an extra space? - xquery

Question

XQuery adds a space and I don't understand why. I have the following simple query :
declare option saxon:output "method=text";
for $i in 1 to 10
return concat(".", $i, " ", 100, "
", ".")
I ran it with Saxon (SaxonEE9-5-1-8J and SaxonHE9-5-1-8J):
java net.sf.saxon.Query -q:query.xq -o:result.txt
The result is the following:
.1 100
. .2 100
. .3 100
. .4 100
. .5 100
. .6 100
. .7 100
. .8 100
. .9 100
. .10 100
.
My question comes from the presence of an extra space between dots. The first line is OK but the folllowing lines (2 to 10) have that space and I don't understand why. What we see as spaces between digits is in fact a tabulation inserted by the character reference.
Could you enlighten me about that behavior ?
PS: I have added saxon as a tag for the question even if the question is not specific to Saxon.

Answer 1

I think your query returns a sequence of string values which are then by default concatenated with a space (see http://www.w3.org/TR/xslt-xquery-serialization/#sequence-normalization where it says "For each subsequence of adjacent strings in S2, copy a single string to the new sequence equal to the values of the strings in the subsequence concatenated in order, each separated by a single space"). If you don't want that then you can use
string-join(for $i in 1 to 10
return concat(".", $i, " ", 100, "
", "."), '')

Answer 2

The space between the dots is basically a separator introduced between the items in the sequence that you are constructing. It would seem that Saxon's text serializer where it outputs to the console inserts that space character to allow you to make sense of the output items.
Considering your code:
declare option saxon:output "method=text";
for $i in 1 to 10
return
concat(".", $i, " ", 100, "
", ".")
The result of for $i in 1 to 10 return is a sequence of 10 xs:string items. From your output you can determine that the space is interspersed between each evaluation of concat(".", $i, " ", 100, "
", ".").
If you want to check that you can rewrite your query as:
for $i in 1 to 10
return
<x>{concat(".", $i, " ", 100, "
", ".")}</x>
And you will see your 10 distinct items with no spaces between.
If you are trying to create a single text string, as you are already controlling the line-breaks, then you could also join all of the 10 xs:string items together yourself, which would have the effect of eliminating the spaces you are seeing between the sequence items. For example:
declare option saxon:output "method=text";
string-join(
for $i in 1 to 10
return
(".", string($i), " ", "100", "
", ".")
, "")