set the M4 environment variable to its path name.)
m4exit(2)])
+
+
+## ---------------------------------------------- ##
+## Defining macros and disabling/enabling libm4. ##
+## ---------------------------------------------- ##
+
+# Private copies of the macros we used in disabling/enabling libm4.
+# It is much more convenient than fighting with the renamed version
+# of define etc.
+
+define([m4_dnl], defn([dnl]))
+define([m4_define], defn([define]))
+define([m4_undefine], defn([undefine]))
+define([m4_defn], defn([defn]))
+
+# Name spaces.
+
+# Sometimes we want to disable some *set* of macros, and restore them
+# later. We provide support for this via name spaces.
+
+# There are basically three characters playing this scene: defining a
+# macro in a namespace, disabling a namespace, and restoring a namespace
+# (i.e., all the definitions it holds).
+
+# Technically, to define a MACRO in NAMESPACE means to define the
+# macro named `m4_defn(NAMESPACE, MACRO)' to the VALUE. At the same
+# time, we append `undefine(NAME)' in the macro named
+# `m4_disable(NAMESPACE)', and similarly a binding of NAME to the
+# value of `m4_defn(NAMESPACE, MACRO)' in `m4_enable(NAMESPACE)'.
+# These mechanisms allow to bind the macro of NAMESPACE and to unbind
+# them at will.
+
+# Of course this implementation is not really efficient: m4 has to
+# grow strings which can become quickly huge, which slows it
+# significantly. A better implementation should be a list of the
+# symbols associated to the name space, and m4_enable?m4_disable
+# would just loop over this list. Unfortunately loops of active
+# symbols are extremely delicate in m4, and I'm still unsure of the
+# implementation I want. So, until we reach a perfect agreement on
+# foreach loops implementation, I prefer to use the brute force.
+
+# It should be noted that one should avoid as much as possible to use
+# `define' for temporaries. Now that `define' as quite a complex
+# meaning, it is an expensive operations that should be limited to
+# macros. Use `m4_define' for temporaries.
+
+m4_define([m4_namespace_push], [pushdef([m4_namespace], [$1])])
+m4_define([m4_namespace_pop], [popdef([m4_namespace])])
+
+m4_namespace_push([libm4])
+
+
+# m4_namespace_define(NAMESPACE, NAME, VALUE)
+# -------------------------------------------
+#
+# Assign VALUE to NAME in NAMESPACE, and append the binding/unbinding
+# in `m4_disable(NAMESPACE)'/`m4_enable(NAMESPACE)'.
+m4_define([m4_namespace_define],
+[m4_define([m4_defn([$1], [$2])], [$3])dnl
+m4_define([m4_disable($1)],
+defn([m4_disable($1)])dnl
+[m4_undefine([$2])])dnl
+m4_define([m4_enable($1)],
+defn([m4_enable(]m4_namespace[)])dnl
+[m4_define([$2], defn([m4_defn([$1], [$2])]))])dnl
+])
+
+
+# define(NAME, VALUE)
+# -------------------
+#
+# Assign VALUE to NAME in the current name space, and bind it at top level.
+m4_define([define],
+[m4_namespace_define(m4_namespace, [$1], [$2])dnl
+m4_define([$1], [$2])dnl
+])
+
+
+# m4_disable(NAMESPACE)
+# ---------------------
+#
+# Undefine all the macros of NAMESPACE.
+m4_define([m4_disable], [indir([m4_disable($1)])])
+
+
+# m4_enable(NAMESPACE)
+# --------------------
+#
+# Restore all the macros of NAMESPACE.
+m4_define([m4_enable], [indir([m4_enable($1)])])
+
+
+# m4_rename(SRC, DST)
+# -------------------
+#
+# Rename the macro SRC as DST.
+define([m4_rename],
+[m4_define([$2], m4_defn([$1]))m4_undefine([$1])])
+
+
+
## --------------------------------------------- ##
## Move some m4 builtins to a safer name space. ##
## --------------------------------------------- ##
m4exit(ifelse([$2],, 1, [$2]))])
-# Some m4 internals have names colliding with tokens we might use.
-# Rename them a` la `m4 --prefix-builtins'.
-define([m4_prefix],
-[define([m4_$1], defn([$1]))
-undefine([$1])])
-
-m4_prefix([eval])
-m4_prefix([shift])
-m4_prefix([format])
-
# We also want to neutralize include (and sinclude for symmetry),
# but we want to extend them slightly: warn when a file is included
# define(bar, [bar])
# which is certainly not what was meant.
-
# m4_include_unique(FILE)
# -----------------------
# Declare that the FILE was loading; and warn if it has already
define([m4_for],
[pushdef([$1], [$2])_m4_for([$1], [$2], [$3], [$4])popdef([$1])])
+# Low level macros used to define m4_for.
+# Use m4_define for temporaries.
define([_m4_for],
[$4[]ifelse($1, [$3], [],
- [define([$1], incr($1))_m4_for([$1], [$2], [$3], [$4])])])
+ [m4_define([$1], incr($1))_m4_for([$1], [$2], [$3], [$4])])])
define(m4_foreach,
[pushdef([$1], [])_m4_foreach($@)popdef([$1])])
-# Low level macros used to define m4_foreach
+# Low level macros used to define m4_foreach.
+# Use m4_define for temporaries.
define(m4_car, [[$1]])
define(_m4_foreach,
[ifelse($2, [()], ,
- [define([$1], [m4_car$2])$3[]_m4_foreach([$1],
- [(m4_shift$2)],
- [$3])])])
+ [m4_define([$1], [m4_car$2])$3[]_m4_foreach([$1],
+ [(m4_shift$2)],
+ [$3])])])
## ----------------------- ##
# Use m4_strip to remove them.
#
# REGEXP specifies where to split. Default is [\t ]+.
-#
# Pay attention to the changequotes. Inner changequotes exist for
# obvious reasons (we want to insert square brackets). Outer
# changequotes are needed because otherwise the m4 parser, when it
# define(active, ACTIVE)
# m4_split([active active ])end
# => [active], [active], []end
-changequote(<<, >>)
-define(<<m4_split>>,
-<<changequote(``, '')dnl
-[dnl Can't use m4_default here instead of ifelse, because m4_default uses
-dnl [ and ] as quotes.
-patsubst(````$1'''',
- ifelse(``$2'',, ``[ ]+'', ``$2''),
- ``], ['')]dnl
-changequote([, ])>>)
-changequote([, ])
+#changequote(<<, >>)
+#define(m4_split,
+#<<changequote(``, '')dnl
+#[dnl Can't use m4_default here instead of ifelse, because m4_default uses
+#dnl [ and ] as quotes.
+#patsubst(````$1'''',
+# ifelse(``$2'',, ``[ ]+'', ``$2''),
+# ``], ['')]dnl
+#changequote([, ])>>)
+#changequote([, ])
+#changequote(<<, >>)
+
+define(m4_split,
+[patsubst([[$1]],
+ ifelse([$2],, [[[ ]+]], [[$2]]),
+ [,])])
# m4_join(STRING)
-## --------------------------------- ##
-## Helping macros to display strings ##
-## --------------------------------- ##
+## ----------------------------------- ##
+## Helping macros to display strings. ##
+## ----------------------------------- ##
# m4_wrap(STRING, [PREFIX], [FIRST-PREFIX], [WIDTH])
1, [define([m4_Cursor], len(m4_Prefix))
m4_Prefix])[]dnl
m4_foreach([m4_Word], (m4_split(m4_strip(m4_join([$1])))),
-[define([m4_Cursor], m4_eval(m4_Cursor + len(m4_Word) + 1))dnl
+[m4_define([m4_Cursor], m4_eval(m4_Cursor + len(m4_Word) + 1))dnl
dnl New line if too long, else insert a space unless it is the first
dnl of the words.
ifelse(m4_eval(m4_Cursor > m4_Width),
m4_Prefix,
[m4_Separator])[]dnl
m4_Word[]dnl
-define([m4_Separator], [ ])])dnl
+m4_define([m4_Separator], [ ])])dnl
popdef([m4_Separator])dnl
popdef([m4_Cursor])dnl
popdef([m4_Width])dnl
popdef([m4_Prefix1])dnl
popdef([m4_Prefix])dnl
])
+
+# Some m4 internals have names colliding with tokens we might use.
+# Rename them a` la `m4 --prefix-builtins'.
+m4_rename([eval], [m4_eval])
+m4_rename([shift], [m4_shift])
+m4_rename([format], [m4_format])
projects / thirdparty / autoconf.git / commitdiff
