m4sugar.m4

autoconf是一个产生可以自动配置源代码包

divert(-1)#                                                  -*- Autoconf -*-
# This file is part of Autoconf.
# Base M4 layer.
# Requires GNU M4.
#
# Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software
# Foundation, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.
#
# As a special exception, the Free Software Foundation gives unlimited
# permission to copy, distribute and modify the configure scripts that
# are the output of Autoconf.  You need not follow the terms of the GNU
# General Public License when using or distributing such scripts, even
# though portions of the text of Autoconf appear in them.  The GNU
# General Public License (GPL) does govern all other use of the material
# that constitutes the Autoconf program.
#
# Certain portions of the Autoconf source text are designed to be copied
# (in certain cases, depending on the input) into the output of
# Autoconf.  We call these the "data" portions.  The rest of the Autoconf
# source text consists of comments plus executable code that decides which
# of the data portions to output in any given case.  We call these
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# to the GPL from your modified version.
#
# Written by Akim Demaille.
#

# Set the quotes, whatever the current quoting system.
changequote()
changequote([, ])

# Some old m4's don't support m4exit.  But they provide
# equivalent functionality by core dumping because of the
# long macros we define.
ifdef([__gnu__], ,
[errprint(M4sugar requires GNU M4. Install it before installing M4sugar or
set the M4 environment variable to its absolute file name.)
m4exit(2)])


## ------------------------------- ##
## 1. Simulate --prefix-builtins.  ##
## ------------------------------- ##

# m4_define
# m4_defn
# m4_undefine
define([m4_define],   defn([define]))
define([m4_defn],     defn([defn]))
define([m4_undefine], defn([undefine]))

m4_undefine([define])
m4_undefine([defn])
m4_undefine([undefine])


# m4_copy(SRC, DST)
# -----------------
# Define DST as the definition of SRC.
# What's the difference between:
# 1. m4_copy([from], [to])
# 2. m4_define([to], [from($@)])
# Well, obviously 1 is more expensive in space.  Maybe 2 is more expensive
# in time, but because of the space cost of 1, it's not that obvious.
# Nevertheless, one huge difference is the handling of `$0'.  If `from'
# uses `$0', then with 1, `to''s `$0' is `to', while it is `from' in 2.
# The user will certainly prefer to see `to'.
m4_define([m4_copy],
[m4_define([$2], m4_defn([$1]))])


# m4_rename(SRC, DST)
# -------------------
# Rename the macro SRC as DST.
m4_define([m4_rename],
[m4_copy([$1], [$2])m4_undefine([$1])])


# m4_rename_m4(MACRO-NAME)
# ------------------------
# Rename MACRO-NAME as m4_MACRO-NAME.
m4_define([m4_rename_m4],
[m4_rename([$1], [m4_$1])])


# m4_copy_unm4(m4_MACRO-NAME)
# ---------------------------
# Copy m4_MACRO-NAME as MACRO-NAME.
m4_define([m4_copy_unm4],
[m4_copy([$1], m4_bpatsubst([$1], [^m4_\(.*\)], [[\1]]))])


# Some m4 internals have names colliding with tokens we might use.
# Rename them a` la `m4 --prefix-builtins'.
m4_rename_m4([builtin])
m4_rename_m4([changecom])
m4_rename_m4([changequote])
m4_rename_m4([debugfile])
m4_rename_m4([debugmode])
m4_rename_m4([decr])
m4_undefine([divert])
m4_rename_m4([divnum])
m4_rename_m4([dumpdef])
m4_rename_m4([errprint])
m4_rename_m4([esyscmd])
m4_rename_m4([eval])
m4_rename_m4([format])
m4_rename_m4([ifdef])
m4_rename([ifelse], [m4_if])
m4_undefine([include])
m4_rename_m4([incr])
m4_rename_m4([index])
m4_rename_m4([indir])
m4_rename_m4([len])
m4_rename([m4exit], [m4_exit])
m4_rename([m4wrap], [m4_wrap])
m4_rename_m4([maketemp])
m4_rename([patsubst], [m4_bpatsubst])
m4_undefine([popdef])
m4_rename_m4([pushdef])
m4_rename([regexp], [m4_bregexp])
m4_rename_m4([shift])
m4_undefine([sinclude])
m4_rename_m4([substr])
m4_rename_m4([symbols])
m4_rename_m4([syscmd])
m4_rename_m4([sysval])
m4_rename_m4([traceoff])
m4_rename_m4([traceon])
m4_rename_m4([translit])
m4_undefine([undivert])


## ------------------- ##
## 2. Error messages.  ##
## ------------------- ##


# m4_location
# -----------
m4_define([m4_location],
[__file__:__line__])


# m4_errprintn(MSG)
# -----------------
# Same as `errprint', but with the missing end of line.
m4_define([m4_errprintn],
[m4_errprint([$1
])])


# m4_warning(MSG)
# ---------------
# Warn the user.
m4_define([m4_warning],
[m4_errprintn(m4_location[: warning: $1])])


# m4_fatal(MSG, [EXIT-STATUS])
# ----------------------------
# Fatal the user.                                                      :)
m4_define([m4_fatal],
[m4_errprintn(m4_location[: error: $1])dnl
m4_expansion_stack_dump()dnl
m4_exit(m4_if([$2],, 1, [$2]))])


# m4_assert(EXPRESSION, [EXIT-STATUS = 1])
# ----------------------------------------
# This macro ensures that EXPRESSION evaluates to true, and exits if
# EXPRESSION evaluates to false.
m4_define([m4_assert],
[m4_if(m4_eval([$1]), 0,
       [m4_fatal([assert failed: $1], [$2])])])



## ------------- ##
## 3. Warnings.  ##
## ------------- ##


# _m4_warn(CATEGORY, MESSAGE, STACK-TRACE)
# ----------------------------------------
# Report a MESSAGE to the user if the CATEGORY of warnings is enabled.
# This is for traces only.
# The STACK-TRACE is a \n-separated list of "LOCATION: MESSAGE".
m4_define([_m4_warn], [])


# m4_warn(CATEGORY, MESSAGE)
# --------------------------
# Report a MESSAGE to the user if the CATEGORY of warnings is enabled.
m4_define([m4_warn],
[_m4_warn([$1], [$2],
m4_ifdef([m4_expansion_stack],
         [m4_defn([m4_expansion_stack])
m4_location[: the top level]]))dnl
])



## ------------------- ##
## 4. File inclusion.  ##
## ------------------- ##


# We also want to neutralize include (and sinclude for symmetry),
# but we want to extend them slightly: warn when a file is included
# several times.  This is in general a dangerous operation because
# quite nobody quotes the first argument of m4_define.
#
# For instance in the following case:
#   m4_define(foo, [bar])
# then a second reading will turn into
#   m4_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
# been included.
m4_define([m4_include_unique],
[m4_ifdef([m4_include($1)],
	  [m4_warn([syntax], [file `$1' included several times])])dnl
m4_define([m4_include($1)])])


# m4_include(FILE)
# ----------------
# As the builtin include, but warns against multiple inclusions.
m4_define([m4_include],
[m4_include_unique([$1])dnl
m4_builtin([include], [$1])])


# m4_sinclude(FILE)
# -----------------
# As the builtin sinclude, but warns against multiple inclusions.
m4_define([m4_sinclude],
[m4_include_unique([$1])dnl
m4_builtin([sinclude], [$1])])



## ------------------------------------ ##
## 5. Additional branching constructs.  ##
## ------------------------------------ ##

# Both `m4_ifval' and `m4_ifset' tests against the empty string.  The
# difference is that `m4_ifset' is specialized on macros.
#
# In case of arguments of macros, eg $[1], it makes little difference.
# In the case of a macro `FOO', you don't want to check `m4_ifval(FOO,
# TRUE)', because if `FOO' expands with commas, there is a shifting of
# the arguments.  So you want to run `m4_ifval([FOO])', but then you just
# compare the *string* `FOO' against `', which, of course fails.
#
# So you want a variation of `m4_ifset' that expects a macro name as $[1].
# If this macro is both defined and defined to a non empty value, then
# it runs TRUE etc.


# m4_ifval(COND, [IF-TRUE], [IF-FALSE])
# -------------------------------------
# If COND is not the empty string, expand IF-TRUE, otherwise IF-FALSE.
# Comparable to m4_ifdef.
m4_define([m4_ifval],
[m4_if([$1], [], [$3], [$2])])


# m4_n(TEXT)
# ----------
# If TEXT is not empty, return TEXT and a new line, otherwise nothing.
m4_define([m4_n],
[m4_if([$1],
       [], [],
	   [$1
])])


# m4_ifvaln(COND, [IF-TRUE], [IF-FALSE])
# --------------------------------------
# Same as `m4_ifval', but add an extra newline to IF-TRUE or IF-FALSE
# unless that argument is empty.
m4_define([m4_ifvaln],
[m4_if([$1],
       [],   [m4_n([$3])],
	     [m4_n([$2])])])


# m4_ifset(MACRO, [IF-TRUE], [IF-FALSE])
# --------------------------------------
# If MACRO has no definition, or of its definition is the empty string,
# expand IF-FALSE, otherwise IF-TRUE.
m4_define([m4_ifset],
[m4_ifdef([$1],
	  [m4_ifval(m4_defn([$1]), [$2], [$3])],
	  [$3])])


# m4_ifndef(NAME, [IF-NOT-DEFINED], [IF-DEFINED])
# -----------------------------------------------
m4_define([m4_ifndef],
[m4_ifdef([$1], [$3], [$2])])


# m4_case(SWITCH, VAL1, IF-VAL1, VAL2, IF-VAL2, ..., DEFAULT)
# -----------------------------------------------------------
# m4 equivalent of
# switch (SWITCH)
# {
#   case VAL1:
#     IF-VAL1;
#     break;
#   case VAL2:
#     IF-VAL2;
#     break;
#   ...
#   default:
#     DEFAULT;
#     break;
# }.
# All the values are optional, and the macro is robust to active
# symbols properly quoted.
m4_define([m4_case],
[m4_if([$#], 0, [],
       [$#], 1, [],
       [$#], 2, [$2],
       [$1], [$2], [$3],
       [$0([$1], m4_shiftn(3, $@))])])


# m4_bmatch(SWITCH, RE1, VAL1, RE2, VAL2, ..., DEFAULT)
# -----------------------------------------------------
# m4 equivalent of
#
# if (SWITCH =~ RE1)
#   VAL1;
# elif (SWITCH =~ RE2)
#   VAL2;
# elif ...
#   ...
# else
#   DEFAULT
#
# All the values are optional, and the macro is robust to active symbols
# properly quoted.
m4_define([m4_bmatch],
[m4_if([$#], 0, [m4_fatal([$0: too few arguments: $#])],
       [$#], 1, [m4_fatal([$0: too few arguments: $#: $1])],
       [$#], 2, [$2],
       [m4_if(m4_bregexp([$1], [$2]), -1, [$0([$1], m4_shiftn(3, $@))],
	      [$3])])])


# m4_car(LIST)
# m4_cdr(LIST)
# ------------
# Manipulate m4 lists.
m4_define([m4_car], [[$1]])
m4_define([m4_cdr],
[m4_if([$#], 0, [m4_fatal([$0: cannot be called without arguments])],
       [$#], 1, [],
       [m4_dquote(m4_shift($@))])])


# m4_map(MACRO, LIST)
# -------------------
# Invoke MACRO($1), MACRO($2) etc. where $1, $2... are the elements
# of LIST (which can be lists themselves, for multiple arguments MACROs).
m4_define([m4_fst], [$1])
m4_define([m4_map],
[m4_if([$2], [[]], [],
       [_m4_map([$1], [$2])])])
m4_define([_m4_map],
[m4_ifval([$2],
	  [$1(m4_fst($2))[]_m4_map([$1], m4_cdr($2))])])


# m4_map_sep(MACRO, SEPARATOR, LIST)
# ----------------------------------
# Invoke MACRO($1), SEPARATOR, MACRO($2), ..., MACRO($N) where $1, $2... $N
# are the elements of LIST (which can be lists themselves, for multiple
# arguments MACROs).
m4_define([m4_map_sep],
[m4_if([$3], [[]], [],
       [$1(m4_fst($3))[]_m4_map([$2[]$1], m4_cdr($3))])])


## ---------------------------------------- ##
## 6. Enhanced version of some primitives.  ##
## ---------------------------------------- ##

# m4_bpatsubsts(STRING, RE1, SUBST1, RE2, SUBST2, ...)
# ----------------------------------------------------
# m4 equivalent of
#
#   $_ = STRING;
#   s/RE1/SUBST1/g;
#   s/RE2/SUBST2/g;
#   ...
#
# All the values are optional, and the macro is robust to active symbols
# properly quoted.
#
# I would have liked to name this macro `m4_bpatsubst', unfortunately,
# due to quotation problems, I need to double quote $1 below, therefore
# the anchors are broken :(  I can't let users be trapped by that.
m4_define([m4_bpatsubsts],
[m4_if([$#], 0, [m4_fatal([$0: too few arguments: $#])],
       [$#], 1, [m4_fatal([$0: too few arguments: $#: $1])],
       [$#], 2, [m4_builtin([patsubst], $@)],
       [$0(m4_builtin([patsubst], [[$1]], [$2], [$3]),
	   m4_shiftn(3, $@))])])



# m4_do(STRING, ...)