m4sugar.m4

autoconf是一个产生可以自动配置源代码包

m4_define([m4_cr_symbols2],
m4_defn([m4_cr_symbols1])dnl
m4_defn([m4_cr_digits])dnl
)


# m4_re_escape(STRING)
# --------------------
# Escape RE active characters in STRING.
m4_define([m4_re_escape],
[m4_bpatsubst([$1],
	      [[][*+.?\^$]], [\\\&])])


# m4_re_string
# ------------
# Regexp for `[a-zA-Z_0-9]*'
# m4_dquote provides literal [] for the character class.
m4_define([m4_re_string],
m4_dquote(m4_defn([m4_cr_symbols2]))dnl
[*]dnl
)


# m4_re_word
# ----------
# Regexp for `[a-zA-Z_][a-zA-Z_0-9]*'
m4_define([m4_re_word],
m4_dquote(m4_defn([m4_cr_symbols1]))dnl
m4_defn([m4_re_string])dnl
)


# m4_tolower(STRING)
# m4_toupper(STRING)
# ------------------
# These macros lowercase and uppercase strings.
m4_define([m4_tolower],
[m4_translit([$1], m4_defn([m4_cr_LETTERS]), m4_defn([m4_cr_letters]))])
m4_define([m4_toupper],
[m4_translit([$1], m4_defn([m4_cr_letters]), m4_defn([m4_cr_LETTERS]))])


# m4_split(STRING, [REGEXP])
# --------------------------
#
# Split STRING into an m4 list of quoted elements.  The elements are
# quoted with [ and ].  Beginning spaces and end spaces *are kept*.
# Use m4_strip to remove them.
#
# REGEXP specifies where to split.  Default is [\t ]+.
#
# If STRING is empty, the result is an empty list.
#
# Pay attention to the m4_changequotes.  When m4 reads the definition of
# m4_split, it still has quotes set to [ and ].  Luckily, these are matched
# in the macro body, so the definition is stored correctly.
#
# Also, notice that $1 is quoted twice, since we want the result to
# be quoted.  Then you should understand that the argument of
# patsubst is ``STRING'' (i.e., with additional `` and '').
#
# This macro is safe on active symbols, i.e.:
#   m4_define(active, ACTIVE)
#   m4_split([active active ])end
#   => [active], [active], []end

m4_define([m4_split],
[m4_ifval([$1], [_m4_split($@)])])

m4_define([_m4_split],
[m4_changequote(``, '')dnl
[dnl Can't use m4_default here instead of m4_if, because m4_default uses
dnl [ and ] as quotes.
m4_bpatsubst(````$1'''',
	     m4_if(``$2'',, ``[	 ]+'', ``$2''),
	     ``], ['')]dnl
m4_changequote([, ])])



# m4_flatten(STRING)
# ------------------
# If STRING contains end of lines, replace them with spaces.  If there
# are backslashed end of lines, remove them.  This macro is safe with
# active symbols.
#    m4_define(active, ACTIVE)
#    m4_flatten([active
#    act\
#    ive])end
#    => active activeend
m4_define([m4_flatten],
[m4_translit(m4_bpatsubst([[[$1]]], [\\
]), [
], [ ])])


# m4_strip(STRING)
# ----------------
# Expands into STRING with tabs and spaces singled out into a single
# space, and removing leading and trailing spaces.
#
# This macro is robust to active symbols.
#    m4_define(active, ACTIVE)
#    m4_strip([  active <tab> <tab>active ])end
#    => active activeend
#
# Because we want to preserve active symbols, STRING must be double-quoted.
#
# Then notice the 2 last patterns: they are in charge of removing the
# leading/trailing spaces.  Why not just `[^ ]'?  Because they are
# applied to doubly quoted strings, i.e. more or less [[STRING]].  So
# if there is a leading space in STRING, then it is the *third*
# character, since there are two leading `['; equally for the last pattern.
m4_define([m4_strip],
[m4_bpatsubsts([[$1]],
	       [[	 ]+], [ ],
	       [^\(..\) ],    [\1],
	       [ \(..\)$],    [\1])])


# m4_normalize(STRING)
# --------------------
# Apply m4_flatten and m4_strip to STRING.
#
# The argument is quoted, so that the macro is robust to active symbols:
#
#    m4_define(active, ACTIVE)
#    m4_normalize([  act\
#    ive
#    active ])end
#    => active activeend

m4_define([m4_normalize],
[m4_strip(m4_flatten([$1]))])



# m4_join(SEP, ARG1, ARG2...)
# ---------------------------
# Produce ARG1SEPARG2...SEPARGn.
m4_defun([m4_join],
[m4_case([$#],
	 [1], [],
	 [2], [[$2]],
	 [[$2][$1]$0([$1], m4_shiftn(2, $@))])])



# m4_append(MACRO-NAME, STRING, [SEPARATOR])
# ------------------------------------------
# Redefine MACRO-NAME to hold its former content plus `SEPARATOR`'STRING'
# at the end.  It is valid to use this macro with MACRO-NAME undefined,
# in which case no SEPARATOR is added.  Be aware that the criterion is
# `not being defined', and not `not being empty'.
#
# This macro is robust to active symbols.  It can be used to grow
# strings.
#
#    | m4_define(active, ACTIVE)
#    | m4_append([sentence], [This is an])
#    | m4_append([sentence], [ active ])
#    | m4_append([sentence], [symbol.])
#    | sentence
#    | m4_undefine([active])dnl
#    | sentence
#    => This is an ACTIVE symbol.
#    => This is an active symbol.
#
# It can be used to define hooks.
#
#    | m4_define(active, ACTIVE)
#    | m4_append([hooks], [m4_define([act1], [act2])])
#    | m4_append([hooks], [m4_define([act2], [active])])
#    | m4_undefine([active])
#    | act1
#    | hooks
#    | act1
#    => act1
#    =>
#    => active
m4_define([m4_append],
[m4_define([$1],
	   m4_ifdef([$1], [m4_defn([$1])$3])[$2])])


# m4_append_uniq(MACRO-NAME, STRING, [SEPARATOR])
# -----------------------------------------------
# As `m4_append', but append only if not yet present.
m4_define([m4_append_uniq],
[m4_ifdef([$1],
	  [m4_bmatch([$3]m4_defn([$1])[$3], m4_re_escape([$3$2$3]), [],
		     [m4_append($@)])],
	  [m4_append($@)])])


# m4_text_wrap(STRING, [PREFIX], [FIRST-PREFIX], [WIDTH])
# -------------------------------------------------------
# Expands into STRING wrapped to hold in WIDTH columns (default = 79).
# If PREFIX is given, each line is prefixed with it.  If FIRST-PREFIX is
# specified, then the first line is prefixed with it.  As a special case,
# if the length of FIRST-PREFIX is greater than that of PREFIX, then
# FIRST-PREFIX will be left alone on the first line.
#
# Typical outputs are:
#
# m4_text_wrap([Short string */], [   ], [/* ], 20)
#  => /* Short string */
#
# m4_text_wrap([Much longer string */], [   ], [/* ], 20)
#  => /* Much longer
#  =>    string */
#
# m4_text_wrap([Short doc.], [          ], [  --short ], 30)
#  =>   --short Short doc.
#
# m4_text_wrap([Short doc.], [          ], [  --too-wide ], 30)
#  =>   --too-wide
#  =>           Short doc.
#
# m4_text_wrap([Super long documentation.], [          ], [  --too-wide ], 30)
#  =>   --too-wide
#  =>      Super long
#  =>      documentation.
#
# FIXME: there is no checking of a longer PREFIX than WIDTH, but do
# we really want to bother with people trying each single corner
# of a software?
#
# This macro does not leave a trailing space behind the last word,
# what complicates it a bit.  The algorithm is stupid simple: all the
# words are preceded by m4_Separator which is defined to empty for the
# first word, and then ` ' (single space) for all the others.
m4_define([m4_text_wrap],
[m4_pushdef([m4_Prefix], [$2])dnl
m4_pushdef([m4_Prefix1], m4_default([$3], [m4_Prefix]))dnl
m4_pushdef([m4_Width], m4_default([$4], 79))dnl
m4_pushdef([m4_Cursor], m4_qlen(m4_Prefix1))dnl
m4_pushdef([m4_Separator], [])dnl
m4_Prefix1[]dnl
m4_if(m4_eval(m4_qlen(m4_Prefix1) > m4_len(m4_Prefix)),
      1, [m4_define([m4_Cursor], m4_len(m4_Prefix))
m4_Prefix],
      m4_if(m4_eval(m4_qlen(m4_Prefix1) < m4_len(m4_Prefix)),
	    [0], [],
	    [m4_define([m4_Cursor], m4_len(m4_Prefix))[]dnl
m4_for(m4_Space, m4_qlen(m4_Prefix1), m4_eval(m4_len(m4_Prefix) - 1),
		    [], [ ])])[]dnl
)[]dnl
m4_foreach_w([m4_Word], [$1],
[m4_define([m4_Cursor], m4_eval(m4_Cursor + m4_qlen(m4_defn([m4_Word])) + 1))dnl
dnl New line if too long, else insert a space unless it is the first
dnl of the words.
m4_if(m4_eval(m4_Cursor > m4_Width),
      1, [m4_define([m4_Cursor],
		    m4_eval(m4_len(m4_Prefix) + m4_qlen(m4_defn([m4_Word])) + 1))]
m4_Prefix,
       [m4_Separator])[]dnl
m4_defn([m4_Word])[]dnl
m4_define([m4_Separator], [ ])])dnl
m4_popdef([m4_Separator])dnl
m4_popdef([m4_Cursor])dnl
m4_popdef([m4_Width])dnl
m4_popdef([m4_Prefix1])dnl
m4_popdef([m4_Prefix])dnl
])


# m4_text_box(MESSAGE, [FRAME-CHARACTER = `-'])
# ---------------------------------------------
m4_define([m4_text_box],
[@%:@@%:@ m4_bpatsubst([$1], [.], m4_if([$2], [], [[-]], [[$2]])) @%:@@%:@
@%:@@%:@ $1 @%:@@%:@
@%:@@%:@ m4_bpatsubst([$1], [.], m4_if([$2], [], [[-]], [[$2]])) @%:@@%:@[]dnl
])


# m4_qlen(STRING)
# ---------------
# Expands to the length of STRING after autom4te converts all quadrigraphs.
m4_define([m4_qlen],
[m4_len(m4_bpatsubsts([[$1]], [@\(<:\|:>\|S|\|%:\)@], [P], [@&t@]))])


# m4_qdelta(STRING)
# -----------------
# Expands to the net change in the length of STRING from autom4te converting the
# quadrigraphs in STRING.  This number is always negative or zero.
m4_define([m4_qdelta],
[m4_eval(m4_qlen([$1]) - m4_len([$1]))])



## ----------------------- ##
## 10. Number processing.  ##
## ----------------------- ##

# m4_sign(A)
# ----------
#
# The sign of the integer A.
m4_define([m4_sign],
[m4_bmatch([$1],
	   [^-], -1,
	   [^0+], 0,
		  1)])

# m4_cmp(A, B)
# ------------
#
# Compare two integers.
# A < B -> -1
# A = B ->  0
# A > B ->  1
m4_define([m4_cmp],
[m4_sign(m4_eval([$1 - $2]))])


# m4_list_cmp(A, B)
# -----------------
#
# Compare the two lists of integers A and B.  For instance:
#   m4_list_cmp((1, 0),     (1))    ->  0
#   m4_list_cmp((1, 0),     (1, 0)) ->  0
#   m4_list_cmp((1, 2),     (1, 0)) ->  1
#   m4_list_cmp((1, 2, 3),  (1, 2)) ->  1
#   m4_list_cmp((1, 2, -3), (1, 2)) -> -1
#   m4_list_cmp((1, 0),     (1, 2)) -> -1
#   m4_list_cmp((1),        (1, 2)) -> -1
m4_define([m4_list_cmp],
[m4_if([$1$2], [()()], 0,
       [$1], [()], [$0((0), [$2])],
       [$2], [()], [$0([$1], (0))],
       [m4_case(m4_cmp(m4_car$1, m4_car$2),
		-1, -1,
		 1, 1,
		 0, [$0((m4_shift$1), (m4_shift$2))])])])



## ------------------------ ##
## 11. Version processing.  ##
## ------------------------ ##


# m4_version_unletter(VERSION)
# ----------------------------
# Normalize beta version numbers with letters to numbers only for comparison.
#
#   Nl -> (N+1).-1.(l#)
#
#i.e., 2.14a -> 2.15.-1.1, 2.14b -> 2.15.-1.2, etc.
# This macro is absolutely not robust to active macro, it expects
# reasonable version numbers and is valid up to `z', no double letters.
m4_define([m4_version_unletter],
[m4_translit(m4_bpatsubsts([$1],
			   [\([0-9]+\)\([abcdefghi]\)],
			     [m4_eval(\1 + 1).-1.\2],
			   [\([0-9]+\)\([jklmnopqrs]\)],
			     [m4_eval(\1 + 1).-1.1\2],
			   [\([0-9]+\)\([tuvwxyz]\)],
			     [m4_eval(\1 + 1).-1.2\2]),
	     [abcdefghijklmnopqrstuvwxyz],
	     [12345678901234567890123456])])


# m4_version_compare(VERSION-1, VERSION-2)
# ----------------------------------------
# Compare the two version numbers and expand into
#  -1 if VERSION-1 < VERSION-2
#   0 if           =
#   1 if           >
m4_define([m4_version_compare],
[m4_list_cmp((m4_split(m4_version_unletter([$1]), [\.])),
	     (m4_split(m4_version_unletter([$2]), [\.])))])


# m4_PACKAGE_NAME
# m4_PACKAGE_TARNAME
# m4_PACKAGE_VERSION
# m4_PACKAGE_STRING
# m4_PACKAGE_BUGREPORT
# --------------------
m4_include([m4sugar/version.m4])


# m4_version_prereq(VERSION, [IF-OK], [IF-NOT = FAIL])
# ----------------------------------------------------
# Check this Autoconf version against VERSION.
m4_define([m4_version_prereq],
[m4_if(m4_version_compare(m4_defn([m4_PACKAGE_VERSION]), [$1]), -1,
       [m4_default([$3],
		   [m4_fatal([Autoconf version $1 or higher is required],
			     63)])],
       [$2])[]dnl
])



## ------------------- ##
## 12. File handling.  ##
## ------------------- ##


# It is a real pity that M4 comes with no macros to bind a diversion
# to a file.  So we have to deal without, which makes us a lot more
# fragile that we should.


# m4_file_append(FILE-NAME, CONTENT)
# ----------------------------------
m4_define([m4_file_append],
[m4_syscmd([cat >>$1 <<_m4eof
$2
_m4eof
])
m4_if(m4_sysval, [0], [],
      [m4_fatal([$0: cannot write: $1])])])



## ------------------------ ##
## 13. Setting M4sugar up.  ##
## ------------------------ ##


# m4_init
# -------
m4_define([m4_init],
[# All the M4sugar macros start with `m4_', except `dnl' kept as is
# for sake of simplicity.
m4_pattern_forbid([^_?m4_])
m4_pattern_forbid([^dnl$])

# _m4_divert_diversion should be defined:
m4_divert_push([KILL])

# Check the divert push/pop perfect balance.
m4_wrap([m4_divert_pop([])
	 m4_ifdef([_m4_divert_diversion],
	   [m4_fatal([$0: unbalanced m4_divert_push:]_m4_divert_n_stack)])[]])
])