#32 Overlapping ranges in the raw index

[Andreas Nolda]

Consider the following raw index:

(indexentry :key ("Test") :open-range :locref "1")
(indexentry :key ("Test") :close-range :locref "3")
(indexentry :key ("Test") :open-range :locref "2")
(indexentry :key ("Test") :close-range :locref "4")

This raw index defines two overlapping ranges for the keyword
"Test": 1-3 and 2-4.

When processing this raw index with xindy, xindy drops the
second range and omits the following warning:

WARNING:
Found a :close-range in the index that wasn't opened before!
Location-reference is 4 in keyword (Test)
I'll continue and ignore this.

Accordingly, xindy outputs the Index "Test 1-3" instead of "Test
1-4" for the following simple index style:

(define-attributes (("default")))
(define-location-class
"arabic-page-numbers" ("arabic-numbers") )
(markup-locclass-list :open " ")
(markup-locref-list :sep ", ")
(markup-range :sep "-")

A problem of the same kind occurs when the first of the two
ranges is reduced to a one-page range:

(indexentry :key ("Test") :open-range :locref "2")
(indexentry :key ("Test") :close-range :locref "2")
(indexentry :key ("Test") :open-range :locref "2")
(indexentry :key ("Test") :close-range :locref "4")

Xindy issues the same warning and outputs the index "Test 2"
instead of "Test 2-4".

[Joachim Schrod]

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user_id=70318

xindy does currently not handle overlapping location ranges
-- and I don't know if it should. At least, this should be
mentioned in the documentation. The error messages are bad,
too; they should refer to the 2nd entry with the :open-range
attribute.

To support overlapping ranges, the main task is probably to
define the location sort order for overlapping ranges in
context of other entries. We should sort it according to the
start location.

In fact, the second error case should be looked at first, as
the page ranges are not overlapping. Seems to be an error
with border computation there.

[Andreas Nolda]

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user_id=950793

I agree. The second issue is clearly more annoying, as it can also arise
from non-overlapping index range commands in, e.g., a LaTeX source.

[Andreas Nolda]

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user_id=950793

I've done some further exploration of the second issue. According to
the log file (log-level = 3), xindy appears to drop the second
open-range indexentry quite early:

...
(Inital location-refrence group::
[Nor:OPEN:"2"=("2")=(2);{"arabic-page-numbers":1};`default'NIL]
[Nor:CLOSE:"2"=("2")=(2);{"arabic-page-numbers":1};`default'NIL]
[Nor:CLOSE:"4"=("4")=(4);{"arabic-page-numbers":1};`default'NIL]
)
...