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Avoid _m4_shiftn for m4 1.6 speedup.

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* lib/m4sugar/m4sugar.m4 (m4_foreach, _m4_foreach, m4_map)
(_m4_map, m4_map_sep): Rewrite recursion to use one less m4_if.
* lib/m4sugar/foreach.m4 (_m4_map): Accomodate changed signature.

Signed-off-by: Eric Blake <ebb9@byu.net>
This commit is contained in:
Eric Blake 2008-07-28 11:24:03 -06:00
parent 3f1a601013
commit 64474728e7
3 changed files with 19 additions and 12 deletions
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5
ChangeLog
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@ -1,5 +1,10 @@
2008-07-28 Eric Blake <ebb9@byu.net>
Avoid _m4_shiftn for m4 1.6 speedup.
* lib/m4sugar/m4sugar.m4 (m4_foreach, _m4_foreach, m4_map)
(_m4_map, m4_map_sep): Rewrite recursion to use one less m4_if.
* lib/m4sugar/foreach.m4 (_m4_map): Accomodate changed signature.
Implement O(n) unique element set creation.
* lib/m4sugar/m4sugar.m4 (m4_set_add, m4_set_add_all)
(m4_set_contains, m4_set_contents, m4_set_delete)

4
lib/m4sugar/foreach.m4
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@ -162,8 +162,8 @@ m4_define([m4_dquote_elt],
# m4_map/m4_map_sep only execute once; the speedup comes in fixing
# _m4_map. m4_foreach to the rescue.
m4_define([_m4_map],
[m4_if([$#], [1], [],
[m4_foreach([_m4_elt], [m4_shift($@)],
[m4_if([$#], [2], [],
[m4_foreach([_m4_elt], [m4_shift2($@)],
[m4_apply([$1], m4_defn([_m4_elt]))])])])
# m4_join(SEP, ARG1, ARG2...)

22
lib/m4sugar/m4sugar.m4
View File

@ -958,14 +958,15 @@ m4_if(m4_defn([$1]), [$2], [],
# as little as possible in _m4_foreach; each extra use requires that much
# more memory for expansion. So, rather than directly compare $2 against
# [] and use m4_car/m4_cdr for recursion, we instead unbox the list (which
# requires swapping the argument order in the helper) and use _m4_shift3
# to detect when recursion is complete.
# requires swapping the argument order in the helper), insert an ignored
# third argument, and use m4_shift3 to detect when recursion is complete.
m4_define([m4_foreach],
[m4_pushdef([$1])_$0([$1], [$3]m4_if([$2], [], [], [, $2]))m4_popdef([$1])])
[m4_if([$2], [], [],
[m4_pushdef([$1])_$0([$1], [$3], [], $2)m4_popdef([$1])])])
m4_define([_m4_foreach],
[m4_if([$#], [2], [],
[m4_define([$1], [$3])$2[]$0([$1], [$2]_m4_shift3($@))])])
[m4_if([$#], [3], [],
[m4_define([$1], [$4])$2[]$0([$1], [$2], m4_shift3($@))])])
# m4_foreach_w(VARIABLE, LIST, EXPRESSION)
@ -990,13 +991,14 @@ m4_define([m4_foreach_w],
#
# Since LIST may be quite large, we want to minimize how often it appears
# in the expansion. Rather than use m4_car/m4_cdr iteration, we unbox the
# list, and use _m4_shift2 to detect the end of recursion.
# list, ignore the second argument, and use m4_shift2 to detect the end of
# recursion.
m4_define([m4_map],
[m4_if([$2], [], [],
[_$0([$1], $2)])])
[_$0([$1], [], $2)])])
m4_define([_m4_map],
[m4_if([$#], [1], [],
[m4_apply([$1], [$2])$0([$1]_m4_shift2($@))])])
[m4_if([$#], [2], [],
[m4_apply([$1], [$3])$0([$1], m4_shift2($@))])])
# m4_map_sep(MACRO, SEPARATOR, LIST)
@ -1006,7 +1008,7 @@ m4_define([_m4_map],
# SEPARATOR is not further expanded.
m4_define([m4_map_sep],
[m4_if([$3], [], [],
[m4_apply([$1], m4_car($3))_m4_map([[$2]$1]_m4_shift2(,$3))])])
[m4_apply([$1], m4_car($3))_m4_map([[$2]$1], $3)])])
## --------------------------- ##