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* libm4.m4 (m4_assert, m4_shiftn): New macros.

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(m4_case,m4_match): Rewrite to use m4_shiftn (for readability reasons).
(m4_for): Add the STEP argument and some argument-verifying asserts.
(m4_split): Correct spaces to tabulator in regexp.
This commit is contained in:
Akim Demaille 2000-03-16 15:17:26 +00:00
parent cbccb222a2
commit 7da2f6d008
2 changed files with 44 additions and 13 deletions
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7
ChangeLog
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@ -1,3 +1,10 @@
2000-3-16 Lars J. Aas <larsa@sim.no>
* libm4.m4 (m4_assert, m4_shiftn): New macros.
(m4_case,m4_match): Rewrite to use m4_shiftn (for readability reasons).
(m4_for): Add the STEP argument and some argument-verifying asserts.
(m4_split): Correct spaces to tabulator in regexp.
2000-03-15 Akim Demaille <akim@epita.fr>
Revamp AC_FUNC_SELECT_ARGTYPES.

50
libm4.m4
View File

@ -231,7 +231,14 @@ define(m4_fatal,
[m4_errprint([error: $1])dnl
m4exit(ifelse([$2],, 1, [$2]))])
# m4_assert( EXPRESSION [, EXIT-STATUS = 1 ])
# ------------------------------------------
# This macro ensures that EXPRESSION evaluates to true, and exits if
# EXPRESSION evaluates to false.
define([m4_assert],
[ifelse(m4_eval([$1]), 0,
[m4_fatal([assert failed: $1], [$2])],
[])])
# We also want to neutralize include (and sinclude for symmetry),
# but we want to extend them slightly: warn when a file is included
@ -321,6 +328,19 @@ define([ifndef],
define([m4_default], [ifval([$1], [$1], [$2])])
# m4_shiftn( N, ... )
# -------------------
# Returns ... shifted N times. Useful for recursive "varargs" constructs.
define([m4_shiftn],
[m4_assert(($1 >= 0) && ($# > $1))dnl
_m4_shiftn($@)])
define([_m4_shiftn],
[ifelse([$1], 0,
[m4_shift($@)],
[_m4_shiftn(m4_eval([$1]-1), m4_shift(m4_shift($@)))])])
# m4_case(SWITCH, VAL1, IF-VAL1, VAL2, IF-VAL2, ..., DEFAULT)
# -----------------------------------------------------------
# m4 equivalent of
@ -344,7 +364,7 @@ define(m4_case,
[$#], 1, [],
[$#], 2, [$2],
[$1], [$2], [$3],
[m4_case([$1], m4_shift(m4_shift(m4_shift($@))))])])
[m4_case([$1], m4_shiftn(3, $@))])])
# m4_match(SWITCH, RE1, VAL1, RE2, VAL2, ..., DEFAULT)
@ -366,29 +386,33 @@ define(m4_match,
[ifelse([$#], 0, [],
[$#], 1, [],
[$#], 2, [$2],
regexp([$1], [$2]), -1, [m4_match([$1],
m4_shift(m4_shift(m4_shift($@))))],
regexp([$1], [$2]), -1, [m4_match([$1], m4_shiftn(3, $@))],
[$3])])
## --------------------- ##
## Implementing m4 loops ##
## --------------------- ##
# m4_for(VARIABLE, FROM, TO, EXPRESSION)
# m4_for(VARIABLE, FIRST, LAST, [STEP = +/-1], EXPRESSION)
# --------------------------------------
# Expand EXPRESSION defining VARIABLE to FROM, FROM + 1, ..., TO.
# Both limits are included.
define([m4_for],
[pushdef([$1], [$2])_m4_for([$1], [$2], [$3], [$4])popdef([$1])])
[m4_case(m4_sign(m4_eval($3 - $2)),
1, [m4_assert(m4_sign(m4_default($4, 1)) == 1)],
-1, [m4_assert(m4_sign(m4_default($4, -1)) == -1)])dnl
pushdef([$1], [$2])dnl
ifelse(m4_eval([$3 > $2]), 1,
[_m4_for([$1], [$3], m4_default([$4], 1), [$5])],
[_m4_for([$1], [$3], m4_default([$4], -1), [$5])])dnl
popdef([$1])])
# Low level macros used to define m4_for.
# Use m4_define for temporaries.
define([_m4_for],
[$4[]ifelse($1, [$3], [],
[m4_define([$1], incr($1))_m4_for([$1], [$2], [$3], [$4])])])
[$4[]dnl
ifelse($1, [$2], [],
[m4_define([$1], m4_eval($1+[$3]))_m4_for([$1], [$2], [$3], [$4])])])
# Implementing `foreach' loops in m4 is much more tricky than it may
@ -525,7 +549,7 @@ m4_define(m4_split,
[dnl Can't use m4_default here instead of ifelse, because m4_default uses
dnl [ and ] as quotes.
patsubst(````$1'''',
ifelse(``$2'',, ``[ ]+'', ``$2''),
ifelse(``$2'',, ``[ ]+'', ``$2''),
``], ['')]dnl
changequote([, ])>>)
changequote([, ])