data/m4sugar/m4sugar.m4

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  47 # to the GPL from your modified version.
  48 #
  49 # Written by Akim Demaille.
  50 #
  51
  52 # Set the quotes, whatever the current quoting system.
  53 changequote()
  54 changequote([, ])
  55
  56 # Some old m4's don't support m4exit.  But they provide
  57 # equivalent functionality by core dumping because of the
  58 # long macros we define.
  59 ifdef([__gnu__], ,
  60 [errprint(M4sugar requires GNU M4. Install it before installing M4sugar or
  61 set the M4 environment variable to its path name.)
  62 m4exit(2)])
  63
  64
  65 ## ------------------------------- ##
  66 ## 1. Simulate --prefix-builtins.  ##
  67 ## ------------------------------- ##
  68
  69 # m4_define
  70 # m4_defn
  71 # m4_undefine
  72 define([m4_define],   defn([define]))
  73 define([m4_defn],     defn([defn]))
  74 define([m4_undefine], defn([undefine]))
  75
  76 m4_undefine([define])
  77 m4_undefine([defn])
  78 m4_undefine([undefine])
  79
  80
  81 # m4_copy(SRC, DST)
  82 # -----------------
  83 # Define DST as the definition of SRC.
  84 # What's the difference between:
  85 # 1. m4_copy([from], [to])
  86 # 2. m4_define([from], [to($@)])
  87 # Well, obviously 1 is more expansive in space.  Maybe 2 is more expansive
  88 # in time, but because of the space cost of 1, it's not that obvious.
  89 # Nevertheless, one huge difference is the handling of `$0'.  If `from'
  90 # uses `$0', then with 1, `to''s `$0' is `to', while it is `from' in 2.
  91 # The user will certainly prefer see `from'.
  92 m4_define([m4_copy],
  93 [m4_define([$2], m4_defn([$1]))])
  94
  95
  96 # m4_rename(SRC, DST)
  97 # -------------------
  98 # Rename the macro SRC as DST.
  99 m4_define([m4_rename],
 100 [m4_copy([$1], [$2])m4_undefine([$1])])
 101
 102
 103 # m4_rename_m4(MACRO-NAME)
 104 # ------------------------
 105 # Rename MACRO-NAME as m4_MACRO-NAME.
 106 m4_define([m4_rename_m4],
 107 [m4_rename([$1], [m4_$1])])
 108
 109
 110 # m4_copy_unm4(m4_MACRO-NAME)
 111 # ---------------------------
 112 # Copy m4_MACRO-NAME as MACRO-NAME.
 113 m4_define([m4_copy_unm4],
 114 [m4_copy([$1], m4_bpatsubst([$1], [^m4_\(.*\)], [[\1]]))])
 115
 116
 117 # Some m4 internals have names colliding with tokens we might use.
 118 # Rename them a` la `m4 --prefix-builtins'.
 119 m4_rename_m4([builtin])
 120 m4_rename_m4([changecom])
 121 m4_rename_m4([changequote])
 122 m4_rename_m4([debugfile])
 123 m4_rename_m4([debugmode])
 124 m4_rename_m4([decr])
 125 m4_undefine([divert])
 126 m4_rename_m4([divnum])
 127 m4_rename_m4([dumpdef])
 128 m4_rename_m4([errprint])
 129 m4_rename_m4([esyscmd])
 130 m4_rename_m4([eval])
 131 m4_rename_m4([format])
 132 m4_rename_m4([ifdef])
 133 m4_rename([ifelse], [m4_if])
 134 m4_rename_m4([include])
 135 m4_rename_m4([incr])
 136 m4_rename_m4([index])
 137 m4_rename_m4([indir])
 138 m4_rename_m4([len])
 139 m4_rename([m4exit], [m4_exit])
 140 m4_rename([m4wrap], [m4_wrap])
 141 m4_rename_m4([maketemp])
 142 m4_rename([patsubst], [m4_bpatsubst])
 143 m4_undefine([popdef])
 144 m4_rename_m4([pushdef])
 145 m4_rename([regexp], [m4_bregexp])
 146 m4_rename_m4([shift])
 147 m4_rename_m4([sinclude])
 148 m4_rename_m4([substr])
 149 m4_rename_m4([symbols])
 150 m4_rename_m4([syscmd])
 151 m4_rename_m4([sysval])
 152 m4_rename_m4([traceoff])
 153 m4_rename_m4([traceon])
 154 m4_rename_m4([translit])
 155 m4_undefine([undivert])
 156
 157
 158 ## ------------------- ##
 159 ## 2. Error messages.  ##
 160 ## ------------------- ##
 161
 162
 163 # m4_location
 164 # -----------
 165 m4_define([m4_location],
 166 [__file__:__line__])
 167
 168
 169 # m4_errprintn(MSG)
 170 # -----------------
 171 # Same as `errprint', but with the missing end of line.
 172 m4_define([m4_errprintn],
 173 [m4_errprint([$1
 174 ])])
 175
 176
 177 # m4_warning(MSG)
 178 # ---------------
 179 # Warn the user.
 180 m4_define([m4_warning],
 181 [m4_errprintn(m4_location[: warning: $1])])
 182
 183
 184 # m4_fatal(MSG, [EXIT-STATUS])
 185 # ----------------------------
 186 # Fatal the user.                                                      :)
 187 m4_define([m4_fatal],
 188 [m4_errprintn(m4_location[: error: $1])dnl
 189 m4_expansion_stack_dump()dnl
 190 m4_exit(m4_if([$2],, 1, [$2]))])
 191
 192
 193 # m4_assert(EXPRESSION, [EXIT-STATUS = 1])
 194 # ----------------------------------------
 195 # This macro ensures that EXPRESSION evaluates to true, and exits if
 196 # EXPRESSION evaluates to false.
 197 m4_define([m4_assert],
 198 [m4_if(m4_eval([$1]), 0,
 199        [m4_fatal([assert failed: $1], [$2])])])
 200
 201
 202 ## ------------- ##
 203 ## 3. Warnings.  ##
 204 ## ------------- ##
 205
 206
 207 # m4_warning_ifelse(CATEGORY, IF-TRUE, IF-FALSE)
 208 # ----------------------------------------------
 209 # If the CATEGORY of warnings is enabled, expand IF_TRUE otherwise
 210 # IF-FALSE.
 211 #
 212 # The variable `m4_warnings' contains a comma separated list of
 213 # warnings which order is the converse from the one specified by
 214 # the user, i.e., if she specified `-W error,none,obsolete',
 215 # `m4_warnings' is `obsolete,none,error'.  We read it from left to
 216 # right, and:
 217 # - if none or noCATEGORY is met, run IF-FALSE
 218 # - if all or CATEGORY is met, run IF-TRUE
 219 # - if there is nothing left, run IF-FALSE.
 220 m4_define([m4_warning_ifelse],
 221 [_m4_warning_ifelse([$1], [$2], [$3], m4_warnings)])
 222
 223
 224 # _m4_warning_ifelse(CATEGORY, IF-TRUE, IF-FALSE, WARNING1, ...)
 225 # --------------------------------------------------------------
 226 # Implementation of the loop described above.
 227 m4_define([_m4_warning_ifelse],
 228 [m4_case([$4],
 229          [$1],    [$2],
 230          [all],   [$2],
 231          [],      [$3],
 232          [none],  [$3],
 233          [no-$1], [$3],
 234          [$0([$1], [$2], [$3], m4_shiftn(4, $@))])])
 235
 236
 237 # _m4_warning_error_ifelse(IF-TRUE, IF-FALSE)
 238 # -------------------------------------------
 239 # The same as m4_warning_ifelse, but scan for `error' only.
 240 m4_define([_m4_warning_error_ifelse],
 241 [__m4_warning_error_ifelse([$1], [$2], m4_warnings)])
 242
 243
 244 # __m4_warning_error_ifelse(IF-TRUE, IF-FALSE)
 245 # --------------------------------------------
 246 # The same as _m4_warning_ifelse, but scan for `error' only.
 247 m4_define([__m4_warning_error_ifelse],
 248 [m4_case([$3],
 249          [error],    [$1],
 250          [],         [$2],
 251          [no-error], [$2],
 252          [$0([$1], [$2], m4_shiftn(3, $@))])])
 253
 254
 255
 256 # _m4_warn(MESSAGE)
 257 # -----------------
 258 # Report MESSAGE as a warning, unless the user requested -W error,
 259 # in which case report a fatal error.
 260 m4_define([_m4_warn],
 261 [_m4_warning_error_ifelse([m4_fatal([$1])],
 262                           [m4_warning([$1])])])
 263
 264
 265 # m4_warn(CATEGORY, MESSAGE)
 266 # --------------------------
 267 # Report a MESSAGE to the autoconf user if the CATEGORY of warnings
 268 # is requested (in fact, not disabled).
 269 m4_define([m4_warn],
 270 [m4_warning_ifelse([$1], [_m4_warn([$2])])])
 271
 272
 273
 274
 275 ## ------------------- ##
 276 ## 4. File inclusion.  ##
 277 ## ------------------- ##
 278
 279
 280 # We also want to neutralize include (and sinclude for symmetry),
 281 # but we want to extend them slightly: warn when a file is included
 282 # several times.  This is in general a dangerous operation because
 283 # quite nobody quotes the first argument of m4_define.
 284 #
 285 # For instance in the following case:
 286 #   m4_define(foo, [bar])
 287 # then a second reading will turn into
 288 #   m4_define(bar, [bar])
 289 # which is certainly not what was meant.
 290
 291 # m4_include_unique(FILE)
 292 # -----------------------
 293 # Declare that the FILE was loading; and warn if it has already
 294 # been included.
 295 m4_define([m4_include_unique],
 296 [m4_ifdef([m4_include($1)],
 297           [m4_warn([syntax], [file `$1' included several times])])dnl
 298 m4_define([m4_include($1)])])
 299
 300
 301 # m4_include(FILE)
 302 # ----------------
 303 # As the builtin include, but warns against multiple inclusions.
 304 m4_define([m4_include],
 305 [m4_include_unique([$1])dnl
 306 m4_builtin([include], [$1])])
 307
 308
 309 # m4_sinclude(FILE)
 310 # -----------------
 311 # As the builtin sinclude, but warns against multiple inclusions.
 312 m4_define([m4_sinclude],
 313 [m4_include_unique([$1])dnl
 314 m4_builtin([sinclude], [$1])])
 315
 316
 317
 318 ## ------------------------------------ ##
 319 ## 5. Additional branching constructs.  ##
 320 ## ------------------------------------ ##
 321
 322 # Both `m4_ifval' and `m4_ifset' tests against the empty string.  The
 323 # difference is that `m4_ifset' is specialized on macros.
 324 #
 325 # In case of arguments of macros, eg $[1], it makes little difference.
 326 # In the case of a macro `FOO', you don't want to check `m4_ifval(FOO,
 327 # TRUE)', because if `FOO' expands with commas, there is a shifting of
 328 # the arguments.  So you want to run `m4_ifval([FOO])', but then you just
 329 # compare the *string* `FOO' against `', which, of course fails.
 330 #
 331 # So you want a variation of `m4_ifset' that expects a macro name as $[1].
 332 # If this macro is both defined and defined to a non empty value, then
 333 # it runs TRUE etc.
 334
 335
 336 # m4_ifval(COND, [IF-TRUE], [IF-FALSE])
 337 # -------------------------------------
 338 # If COND is not the empty string, expand IF-TRUE, otherwise IF-FALSE.
 339 # Comparable to m4_ifdef.
 340 m4_define([m4_ifval],
 341 [m4_if([$1], [], [$3], [$2])])
 342
 343
 344 # m4_n(TEXT)
 345 # ----------
 346 # If TEXT is not empty, return TEXT and a new line, otherwise nothing.
 347 m4_define([m4_n],
 348 [m4_if([$1],
 349        [], [],
 350            [$1
 351 ])])
 352
 353
 354 # m4_ifvaln(COND, [IF-TRUE], [IF-FALSE])
 355 # --------------------------------------
 356 # Same as `m4_ifval', but add an extra newline to IF-TRUE or IF-FALSE
 357 # unless that argument is empty.
 358 m4_define([m4_ifvaln],
 359 [m4_if([$1],
 360        [],   [m4_n([$3])],
 361              [m4_n([$2])])])
 362
 363
 364 # m4_ifset(MACRO, [IF-TRUE], [IF-FALSE])
 365 # --------------------------------------
 366 # If MACRO has no definition, or of its definition is the empty string,
 367 # expand IF-FALSE, otherwise IF-TRUE.
 368 m4_define([m4_ifset],
 369 [m4_ifdef([$1],
 370           [m4_if(m4_defn([$1]), [], [$3], [$2])],
 371           [$3])])
 372
 373
 374 # m4_ifndef(NAME, [IF-NOT-DEFINED], [IF-DEFINED])
 375 # -----------------------------------------------
 376 m4_define([m4_ifndef],
 377 [m4_ifdef([$1], [$3], [$2])])
 378
 379
 380 # m4_case(SWITCH, VAL1, IF-VAL1, VAL2, IF-VAL2, ..., DEFAULT)
 381 # -----------------------------------------------------------
 382 # m4 equivalent of
 383 # switch (SWITCH)
 384 # {
 385 #   case VAL1:
 386 #     IF-VAL1;
 387 #     break;
 388 #   case VAL2:
 389 #     IF-VAL2;
 390 #     break;
 391 #   ...
 392 #   default:
 393 #     DEFAULT;
 394 #     break;
 395 # }.
 396 # All the values are optional, and the macro is robust to active
 397 # symbols properly quoted.
 398 m4_define([m4_case],
 399 [m4_if([$#], 0, [],
 400        [$#], 1, [],
 401        [$#], 2, [$2],
 402        [$1], [$2], [$3],
 403        [$0([$1], m4_shiftn(3, $@))])])
 404
 405
 406 # m4_bmatch(SWITCH, RE1, VAL1, RE2, VAL2, ..., DEFAULT)
 407 # -----------------------------------------------------
 408 # m4 equivalent of
 409 #
 410 # if (SWITCH =~ RE1)
 411 #   VAL1;
 412 # elif (SWITCH =~ RE2)
 413 #   VAL2;
 414 # elif ...
 415 #   ...
 416 # else
 417 #   DEFAULT
 418 #
 419 # All the values are optional, and the macro is robust to active symbols
 420 # properly quoted.
 421 m4_define([m4_bmatch],
 422 [m4_if([$#], 0, [],
 423        [$#], 1, [],
 424        [$#], 2, [$2],
 425        [m4_if(m4_bregexp([$1], [$2]), -1, [$0([$1], m4_shiftn(3, $@))],
 426               [$3])])])
 427
 428
 429 # m4_map(MACRO, LIST)
 430 # -------------------
 431 # Invoke MACRO($1), MACRO($2) etc. where $1, $2... are the elements
 432 # of LIST (which can be lists themselves, for multiple arguments MACROs).
 433 m4_define([m4_fst], [$1])
 434 m4_define([m4_map],
 435 [m4_if([$2], [], [],
 436        [$2], [[]], [],
 437        [$1(m4_fst($2))[]dnl
 438 m4_map([$1], m4_cdr($2))])])
 439
 440
 441 # m4_map_sep(MACRO, SEPARATOR, LIST)
 442 # ----------------------------------
 443 # Invoke MACRO($1), SEPARATOR, MACRO($2), ..., MACRO($N) where $1, $2... $N
 444 # are the elements of LIST (which can be lists themselves, for multiple
 445 # arguments MACROs).
 446 m4_define([m4_map_sep],
 447 [m4_if([$3], [[]], [],
 448        [$1(m4_fst($3))[]dnl
 449 m4_if(m4_cdr($3),
 450       [[]], [],
 451       [$2])[]dnl
 452 m4_map_sep([$1], [$2], m4_cdr($3))])])
 453
 454
 455 ## ---------------------------------------- ##
 456 ## 6. Enhanced version of some primitives.  ##
 457 ## ---------------------------------------- ##
 458
 459 # m4_patsubsts(STRING, RE1, SUBST1, RE2, SUBST2, ...)
 460 # ---------------------------------------------------
 461 # m4 equivalent of
 462 #
 463 #   $_ = STRING;
 464 #   s/RE1/SUBST1/g;
 465 #   s/RE2/SUBST2/g;
 466 #   ...
 467 #
 468 # All the values are optional, and the macro is robust to active symbols
 469 # properly quoted.
 470 #
 471 # I would have liked to name this macro `m4_patsubst', unfortunately,
 472 # due to quotation problems, I need to double quote $1 below, therefore
 473 # the anchors are broken :(  I can't let users be trapped by that.
 474 m4_define([m4_bpatsubsts],
 475 [m4_if([$#], 0, [m4_fatal([$0: too few arguments: $#])],
 476        [$#], 1, [m4_fatal([$0: too few arguments: $#: $1])],
 477        [$#], 2, [m4_builtin([patsubst], $@)],
 478        [$0(m4_builtin([patsubst], [[$1]], [$2], [$3]),
 479            m4_shiftn(3, $@))])])
 480
 481
 482
 483 # m4_do(STRING, ...)
 484 # ------------------
 485 # This macro invokes all its arguments (in sequence, of course).  It is
 486 # useful for making your macros more structured and readable by dropping
 487 # unnecessary dnl's and have the macros indented properly.
 488 m4_define([m4_do],
 489 [m4_if($#, 0, [],
 490        $#, 1, [$1],
 491        [$1[]m4_do(m4_shift($@))])])
 492
 493
 494 # m4_define_default(MACRO, VALUE)
 495 # -------------------------------
 496 # If MACRO is undefined, set it to VALUE.
 497 m4_define([m4_define_default],
 498 [m4_ifndef([$1], [m4_define($@)])])
 499
 500
 501 # m4_default(EXP1, EXP2)
 502 # ----------------------
 503 # Returns EXP1 if non empty, otherwise EXP2.
 504 m4_define([m4_default],
 505 [m4_ifval([$1], [$1], [$2])])
 506
 507
 508 # m4_defn(NAME)
 509 # -------------
 510 # Unlike to the original, don't tolerate popping something which is
 511 # undefined.
 512 m4_define([m4_defn],
 513 [m4_ifndef([$1],
 514            [m4_fatal([$0: undefined macro: $1])])dnl
 515 m4_builtin([defn], $@)])
 516
 517
 518 # _m4_dumpdefs_up(NAME)
 519 # ---------------------
 520 m4_define([_m4_dumpdefs_up],
 521 [m4_ifdef([$1],
 522           [m4_pushdef([_m4_dumpdefs], m4_defn([$1]))dnl
 523 m4_dumpdef([$1])dnl
 524 m4_popdef([$1])dnl
 525 _m4_dumpdefs_up([$1])])])
 526
 527
 528 # _m4_dumpdefs_down(NAME)
 529 # -----------------------
 530 m4_define([_m4_dumpdefs_down],
 531 [m4_ifdef([_m4_dumpdefs],
 532           [m4_pushdef([$1], m4_defn([_m4_dumpdefs]))dnl
 533 m4_popdef([_m4_dumpdefs])dnl
 534 _m4_dumpdefs_down([$1])])])
 535
 536
 537 # m4_dumpdefs(NAME)
 538 # -----------------
 539 # Similar to `m4_dumpdef(NAME)', but if NAME was m4_pushdef'ed, display its
 540 # value stack (most recent displayed first).
 541 m4_define([m4_dumpdefs],
 542 [_m4_dumpdefs_up([$1])dnl
 543 _m4_dumpdefs_down([$1])])
 544
 545
 546 # m4_popdef(NAME)
 547 # ---------------
 548 # Unlike to the original, don't tolerate popping something which is
 549 # undefined.
 550 m4_define([m4_popdef],
 551 [m4_ifndef([$1],
 552            [m4_fatal([$0: undefined macro: $1])])dnl
 553 m4_builtin([popdef], $@)])
 554
 555
 556 # m4_quote(ARGS)
 557 # --------------
 558 # Return ARGS as a single arguments.
 559 #
 560 # It is important to realize the difference between `m4_quote(exp)' and
 561 # `[exp]': in the first case you obtain the quoted *result* of the
 562 # expansion of EXP, while in the latter you just obtain the string
 563 # `exp'.
 564 m4_define([m4_quote],  [[$*]])
 565 m4_define([m4_dquote],  [[$@]])
 566
 567
 568 # m4_noquote(STRING)
 569 # ------------------
 570 # Return the result of ignoring all quotes in STRING and invoking the
 571 # macros it contains.  Amongst other things useful for enabling macro
 572 # invocations inside strings with [] blocks (for instance regexps and
 573 # help-strings).
 574 m4_define([m4_noquote],
 575 [m4_changequote(-=<{,}>=-)$1-=<{}>=-m4_changequote([,])])
 576
 577
 578 # m4_shiftn(N, ...)
 579 # -----------------
 580 # Returns ... shifted N times.  Useful for recursive "varargs" constructs.
 581 m4_define([m4_shiftn],
 582 [m4_assert(($1 >= 0) && ($# > $1))dnl
 583 _m4_shiftn($@)])
 584
 585 m4_define([_m4_shiftn],
 586 [m4_if([$1], 0,
 587        [m4_shift($@)],
 588        [_m4_shiftn(m4_eval([$1]-1), m4_shift(m4_shift($@)))])])
 589
 590
 591 # m4_undefine(NAME)
 592 # -----------------
 593 # Unlike to the original, don't tolerate undefining something which is
 594 # undefined.
 595 m4_define([m4_undefine],
 596 [m4_ifndef([$1],
 597            [m4_fatal([$0: undefined macro: $1])])dnl
 598 m4_builtin([undefine], $@)])
 599
 600
 601 ## -------------------------- ##
 602 ## 7. Implementing m4 loops.  ##
 603 ## -------------------------- ##
 604
 605
 606 # m4_for(VARIABLE, FIRST, LAST, [STEP = +/-1], EXPRESSION)
 607 # --------------------------------------------------------
 608 # Expand EXPRESSION defining VARIABLE to FROM, FROM + 1, ..., TO.
 609 # Both limits are included, and bounds are checked for consistency.
 610 m4_define([m4_for],
 611 [m4_case(m4_sign(m4_eval($3 - $2)),
 612          1, [m4_assert(m4_sign(m4_default($4, 1)) == 1)],
 613         -1, [m4_assert(m4_sign(m4_default($4, -1)) == -1)])dnl
 614 m4_pushdef([$1], [$2])dnl
 615 m4_if(m4_eval([$3 > $2]), 1,
 616       [_m4_for([$1], [$3], m4_default([$4], 1), [$5])],
 617       [_m4_for([$1], [$3], m4_default([$4], -1), [$5])])dnl
 618 m4_popdef([$1])])
 619
 620
 621 # _m4_for(VARIABLE, FIRST, LAST, STEP, EXPRESSION)
 622 # ------------------------------------------------
 623 # Core of the loop, no consistency checks.
 624 m4_define([_m4_for],
 625 [$4[]dnl
 626 m4_if($1, [$2], [],
 627       [m4_define([$1], m4_eval($1+[$3]))_m4_for([$1], [$2], [$3], [$4])])])
 628
 629
 630 # Implementing `foreach' loops in m4 is much more tricky than it may
 631 # seem.  Actually, the example of a `foreach' loop in the m4
 632 # documentation is wrong: it does not quote the arguments properly,
 633 # which leads to undesirable expansions.
 634 #
 635 # The example in the documentation is:
 636 #
 637 # | # foreach(VAR, (LIST), STMT)
 638 # | m4_define([foreach],
 639 # |        [m4_pushdef([$1])_foreach([$1], [$2], [$3])m4_popdef([$1])])
 640 # | m4_define([_arg1], [$1])
 641 # | m4_define([_foreach],
 642 # |           [m4_if([$2], [()], ,
 643 # |                  [m4_define([$1], _arg1$2)$3[]_foreach([$1],
 644 # |                                                        (shift$2),
 645 # |                                                        [$3])])])
 646 #
 647 # But then if you run
 648 #
 649 # | m4_define(a, 1)
 650 # | m4_define(b, 2)
 651 # | m4_define(c, 3)
 652 # | foreach([f], [([a], [(b], [c)])], [echo f
 653 # | ])
 654 #
 655 # it gives
 656 #
 657 #  => echo 1
 658 #  => echo (2,3)
 659 #
 660 # which is not what is expected.
 661 #
 662 # Of course the problem is that many quotes are missing.  So you add
 663 # plenty of quotes at random places, until you reach the expected
 664 # result.  Alternatively, if you are a quoting wizard, you directly
 665 # reach the following implementation (but if you really did, then
 666 # apply to the maintenance of m4sugar!).
 667 #
 668 # | # foreach(VAR, (LIST), STMT)
 669 # | m4_define([foreach], [m4_pushdef([$1])_foreach($@)m4_popdef([$1])])
 670 # | m4_define([_arg1], [[$1]])
 671 # | m4_define([_foreach],
 672 # |  [m4_if($2, [()], ,
 673 # |         [m4_define([$1], [_arg1$2])$3[]_foreach([$1],
 674 # |                                                 [(shift$2)],
 675 # |                                                 [$3])])])
 676 #
 677 # which this time answers
 678 #
 679 #  => echo a
 680 #  => echo (b
 681 #  => echo c)
 682 #
 683 # Bingo!
 684 #
 685 # Well, not quite.
 686 #
 687 # With a better look, you realize that the parens are more a pain than
 688 # a help: since anyway you need to quote properly the list, you end up
 689 # with always using an outermost pair of parens and an outermost pair
 690 # of quotes.  Rejecting the parens both eases the implementation, and
 691 # simplifies the use:
 692 #
 693 # | # foreach(VAR, (LIST), STMT)
 694 # | m4_define([foreach], [m4_pushdef([$1])_foreach($@)m4_popdef([$1])])
 695 # | m4_define([_arg1], [$1])
 696 # | m4_define([_foreach],
 697 # |  [m4_if($2, [], ,
 698 # |         [m4_define([$1], [_arg1($2)])$3[]_foreach([$1],
 699 # |                                                   [shift($2)],
 700 # |                                                   [$3])])])
 701 #
 702 #
 703 # Now, just replace the `$2' with `m4_quote($2)' in the outer `m4_if'
 704 # to improve robustness, and you come up with a quite satisfactory
 705 # implementation.
 706
 707
 708 # m4_foreach(VARIABLE, LIST, EXPRESSION)
 709 # --------------------------------------
 710 #
 711 # Expand EXPRESSION assigning each value of the LIST to VARIABLE.
 712 # LIST should have the form `item_1, item_2, ..., item_n', i.e. the
 713 # whole list must *quoted*.  Quote members too if you don't want them
 714 # to be expanded.
 715 #
 716 # This macro is robust to active symbols:
 717 #      | m4_define(active, [ACT, IVE])
 718 #      | m4_foreach(Var, [active, active], [-Var-])
 719 #     => -ACT--IVE--ACT--IVE-
 720 #
 721 #      | m4_foreach(Var, [[active], [active]], [-Var-])
 722 #     => -ACT, IVE--ACT, IVE-
 723 #
 724 #      | m4_foreach(Var, [[[active]], [[active]]], [-Var-])
 725 #     => -active--active-
 726 m4_define([m4_foreach],
 727 [m4_pushdef([$1])_m4_foreach($@)m4_popdef([$1])])
 728
 729 # Low level macros used to define m4_foreach.
 730 m4_define([m4_car], [[$1]])
 731 m4_define([m4_cdr], [m4_dquote(m4_shift($@))])
 732 m4_define([_m4_foreach],
 733 [m4_if([$2], [[]], [],
 734        [m4_define([$1], m4_car($2))$3[]_m4_foreach([$1],
 735                                                    m4_cdr($2),
 736                                                    [$3])])])
 737
 738
 739
 740 ## --------------------------- ##
 741 ## 8. More diversion support.  ##
 742 ## --------------------------- ##
 743
 744
 745 # _m4_divert(DIVERSION-NAME or NUMBER)
 746 # ------------------------------------
 747 # If DIVERSION-NAME is the name of a diversion, return its number,
 748 # otherwise if is a NUMBER return it.
 749 m4_define([_m4_divert],
 750 [m4_ifdef([_m4_divert($1)],
 751           [m4_indir([_m4_divert($1)])],
 752           [$1])])
 753
 754 # KILL is only used to suppress output.
 755 m4_define([_m4_divert(KILL)],           -1)
 756
 757
 758 # m4_divert(DIVERSION-NAME)
 759 # -------------------------
 760 # Change the diversion stream to DIVERSION-NAME.
 761 m4_define([m4_divert],
 762 [m4_define([m4_divert_stack],
 763            m4_location[: $0: $1]m4_ifdef([m4_divert_stack], [
 764 m4_defn([m4_divert_stack])]))dnl
 765 m4_builtin([divert], _m4_divert([$1]))dnl
 766 ])
 767
 768
 769 # m4_divert_push(DIVERSION-NAME)
 770 # ------------------------------
 771 # Change the diversion stream to DIVERSION-NAME, while stacking old values.
 772 m4_define([m4_divert_push],
 773 [m4_pushdef([m4_divert_stack],
 774             m4_location[: $0: $1]m4_ifdef([m4_divert_stack], [
 775 m4_defn([m4_divert_stack])]))dnl
 776 m4_pushdef([_m4_divert_diversion], [$1])dnl
 777 m4_builtin([divert], _m4_divert(_m4_divert_diversion))dnl
 778 ])
 779
 780
 781 # m4_divert_pop([DIVERSION-NAME])
 782 # -------------------------------
 783 # Change the diversion stream to its previous value, unstacking it.
 784 # If specified, verify we left DIVERSION-NAME.
 785 m4_define([m4_divert_pop],
 786 [m4_ifval([$1],
 787      [m4_if(_m4_divert([$1]), m4_divnum, [],
 788             [m4_fatal([$0($1): diversion mismatch: ]
 789 m4_defn([m4_divert_stack]))])])dnl
 790 m4_popdef([_m4_divert_diversion])dnl
 791 dnl m4_ifndef([_m4_divert_diversion],
 792 dnl           [m4_fatal([too many m4_divert_pop])])dnl
 793 m4_builtin([divert],
 794            m4_ifdef([_m4_divert_diversion],
 795                     [_m4_divert(_m4_divert_diversion)], -1))dnl
 796 m4_popdef([m4_divert_stack])dnl
 797 ])
 798
 799
 800 # m4_divert_text(DIVERSION-NAME, CONTENT)
 801 # ---------------------------------------
 802 # Output CONTENT into DIVERSION-NAME (which may be a number actually).
 803 # An end of line is appended for free to CONTENT.
 804 m4_define([m4_divert_text],
 805 [m4_divert_push([$1])dnl
 806 $2
 807 m4_divert_pop([$1])dnl
 808 ])
 809
 810
 811 # m4_divert_once(DIVERSION-NAME, CONTENT)
 812 # ---------------------------------------
 813 # Output once CONTENT into DIVERSION-NAME (which may be a number
 814 # actually).  An end of line is appended for free to CONTENT.
 815 m4_define([m4_divert_once],
 816 [m4_expand_once([m4_divert_text([$1], [$2])])])
 817
 818
 819 # m4_undivert(DIVERSION-NAME)
 820 # ---------------------------
 821 # Undivert DIVERSION-NAME.
 822 m4_define([m4_undivert],
 823 [m4_builtin([undivert], _m4_divert([$1]))])
 824
 825
 826 ## -------------------------------------------- ##
 827 ## 8. Defining macros with bells and whistles.  ##
 828 ## -------------------------------------------- ##
 829
 830 # `m4_defun' is basically `m4_define' but it equips the macro with the
 831 # needed machinery for `m4_require'.  A macro must be m4_defun'd if
 832 # either it is m4_require'd, or it m4_require's.
 833 #
 834 # Two things deserve attention and are detailed below:
 835 #  1. Implementation of m4_require
 836 #  2. Keeping track of the expansion stack
 837 #
 838 # 1. Implementation of m4_require
 839 # ===============================
 840 #
 841 # Of course m4_defun AC_PROVIDE's the macro, so that a macro which has
 842 # been expanded is not expanded again when m4_require'd, but the
 843 # difficult part is the proper expansion of macros when they are
 844 # m4_require'd.
 845 #
 846 # The implementation is based on two ideas, (i) using diversions to
 847 # prepare the expansion of the macro and its dependencies (by Franc,ois
 848 # Pinard), and (ii) expand the most recently m4_require'd macros _after_
 849 # the previous macros (by Axel Thimm).
 850 #
 851 #
 852 # The first idea: why using diversions?
 853 # -------------------------------------
 854 #
 855 # When a macro requires another, the other macro is expanded in new
 856 # diversion, GROW.  When the outer macro is fully expanded, we first
 857 # undivert the most nested diversions (GROW - 1...), and finally
 858 # undivert GROW.  To understand why we need several diversions,
 859 # consider the following example:
 860 #
 861 # | m4_defun([TEST1], [Test...REQUIRE([TEST2])1])
 862 # | m4_defun([TEST2], [Test...REQUIRE([TEST3])2])
 863 # | m4_defun([TEST3], [Test...3])
 864 #
 865 # Because m4_require is not required to be first in the outer macros, we
 866 # must keep the expansions of the various level of m4_require separated.
 867 # Right before executing the epilogue of TEST1, we have:
 868 #
 869 #          GROW - 2: Test...3
 870 #          GROW - 1: Test...2
 871 #          GROW:     Test...1
 872 #          BODY:
 873 #
 874 # Finally the epilogue of TEST1 undiverts GROW - 2, GROW - 1, and
 875 # GROW into the regular flow, BODY.
 876 #
 877 #          GROW - 2:
 878 #          GROW - 1:
 879 #          GROW:
 880 #          BODY:        Test...3; Test...2; Test...1
 881 #
 882 # (The semicolons are here for clarification, but of course are not
 883 # emitted.)  This is what Autoconf 2.0 (I think) to 2.13 (I'm sure)
 884 # implement.
 885 #
 886 #
 887 # The second idea: first required first out
 888 # -----------------------------------------
 889 #
 890 # The natural implementation of the idea above is buggy and produces
 891 # very surprising results in some situations.  Let's consider the
 892 # following example to explain the bug:
 893 #
 894 # | m4_defun([TEST1],  [REQUIRE([TEST2a])REQUIRE([TEST2b])])
 895 # | m4_defun([TEST2a], [])
 896 # | m4_defun([TEST2b], [REQUIRE([TEST3])])
 897 # | m4_defun([TEST3],  [REQUIRE([TEST2a])])
 898 # |
 899 # | AC_INIT
 900 # | TEST1
 901 #
 902 # The dependencies between the macros are:
 903 #
 904 #                3 --- 2b
 905 #               /        \              is m4_require'd by
 906 #              /          \       left -------------------- right
 907 #           2a ------------ 1
 908 #
 909 # If you strictly apply the rules given in the previous section you get:
 910 #
 911 #          GROW - 2: TEST3
 912 #          GROW - 1: TEST2a; TEST2b
 913 #          GROW:     TEST1
 914 #          BODY:
 915 #
 916 # (TEST2a, although required by TEST3 is not expanded in GROW - 3
 917 # because is has already been expanded before in GROW - 1, so it has
 918 # been AC_PROVIDE'd, so it is not expanded again) so when you undivert
 919 # the stack of diversions, you get:
 920 #
 921 #          GROW - 2:
 922 #          GROW - 1:
 923 #          GROW:
 924 #          BODY:        TEST3; TEST2a; TEST2b; TEST1
 925 #
 926 # i.e., TEST2a is expanded after TEST3 although the latter required the
 927 # former.
 928 #
 929 # Starting from 2.50, uses an implementation provided by Axel Thimm.
 930 # The idea is simple: the order in which macros are emitted must be the
 931 # same as the one in which macro are expanded.  (The bug above can
 932 # indeed be described as: a macro has been AC_PROVIDE'd, but it is
 933 # emitted after: the lack of correlation between emission and expansion
 934 # order is guilty).
 935 #
 936 # How to do that?  You keeping the stack of diversions to elaborate the
 937 # macros, but each time a macro is fully expanded, emit it immediately.
 938 #
 939 # In the example above, when TEST2a is expanded, but it's epilogue is
 940 # not run yet, you have:
 941 #
 942 #          GROW - 2:
 943 #          GROW - 1: TEST2a
 944 #          GROW:     Elaboration of TEST1
 945 #          BODY:
 946 #
 947 # The epilogue of TEST2a emits it immediately:
 948 #
 949 #          GROW - 2:
 950 #          GROW - 1:
 951 #          GROW:     Elaboration of TEST1
 952 #          BODY:     TEST2a
 953 #
 954 # TEST2b then requires TEST3, so right before the epilogue of TEST3, you
 955 # have:
 956 #
 957 #          GROW - 2: TEST3
 958 #          GROW - 1: Elaboration of TEST2b
 959 #          GROW:     Elaboration of TEST1
 960 #          BODY:      TEST2a
 961 #
 962 # The epilogue of TEST3 emits it:
 963 #
 964 #          GROW - 2:
 965 #          GROW - 1: Elaboration of TEST2b
 966 #          GROW:     Elaboration of TEST1
 967 #          BODY:     TEST2a; TEST3
 968 #
 969 # TEST2b is now completely expanded, and emitted:
 970 #
 971 #          GROW - 2:
 972 #          GROW - 1:
 973 #          GROW:     Elaboration of TEST1
 974 #          BODY:     TEST2a; TEST3; TEST2b
 975 #
 976 # and finally, TEST1 is finished and emitted:
 977 #
 978 #          GROW - 2:
 979 #          GROW - 1:
 980 #          GROW:
 981 #          BODY:     TEST2a; TEST3; TEST2b: TEST1
 982 #
 983 # The idea, is simple, but the implementation is a bit evolved.  If you
 984 # are like me, you will want to see the actual functioning of this
 985 # implementation to be convinced.  The next section gives the full
 986 # details.
 987 #
 988 #
 989 # The Axel Thimm implementation at work
 990 # -------------------------------------
 991 #
 992 # We consider the macros above, and this configure.ac:
 993 #
 994 #           AC_INIT
 995 #           TEST1
 996 #
 997 # You should keep the definitions of _m4_defun_pro, _m4_defun_epi, and
 998 # m4_require at hand to follow the steps.
 999 #
1000 # This implements tries not to assume that of the current diversion is
1001 # BODY, so as soon as a macro (m4_defun'd) is expanded, we first
1002 # record the current diversion under the name _m4_divert_dump (denoted
1003 # DUMP below for short).  This introduces an important difference with
1004 # the previous versions of Autoconf: you cannot use m4_require if you
1005 # were not inside an m4_defun'd macro, and especially, you cannot
1006 # m4_require directly from the top level.
1007 #
1008 # We have not tried to simulate the old behavior (better yet, we
1009 # diagnose it), because it is too dangerous: a macro m4_require'd from
1010 # the top level is expanded before the body of `configure', i.e., before
1011 # any other test was run.  I let you imagine the result of requiring
1012 # AC_STDC_HEADERS for instance, before AC_PROG_CC was actually run....
1013 #
1014 # After AC_INIT was run, the current diversion is BODY.
1015 # * AC_INIT was run
1016 #   DUMP:                undefined
1017 #   diversion stack:     BODY |-
1018 #
1019 # * TEST1 is expanded
1020 # The prologue of TEST1 sets AC_DIVERSION_DUMP, which is the diversion
1021 # where the current elaboration will be dumped, to the current
1022 # diversion.  It also m4_divert_push to GROW, where the full
1023 # expansion of TEST1 and its dependencies will be elaborated.
1024 #   DUMP:       BODY
1025 #   BODY:       empty
1026 #   diversions: GROW, BODY |-
1027 #
1028 # * TEST1 requires TEST2a: prologue
1029 # m4_require m4_divert_pushes another temporary diversion GROW - 1 (in
1030 # fact, the diversion whose number is one less than the current
1031 # diversion), and expands TEST2a in there.
1032 #   DUMP:       BODY
1033 #   BODY:       empty
1034 #   diversions: GROW-1, GROW, BODY |-
1035 #
1036 # * TEST2a is expanded.
1037 # Its prologue pushes the current diversion again.
1038 #   DUMP:       BODY
1039 #   BODY:       empty
1040 #   diversions: GROW - 1, GROW - 1, GROW, BODY |-
1041 # It is expanded in GROW - 1, and GROW - 1 is popped by the epilogue
1042 # of TEST2a.
1043 #   DUMP:        BODY
1044 #   BODY:        nothing
1045 #   GROW - 1:    TEST2a
1046 #   diversions:  GROW - 1, GROW, BODY |-
1047 #
1048 # * TEST1 requires TEST2a: epilogue
1049 # The content of the current diversion is appended to DUMP (and removed
1050 # from the current diversion).  A diversion is popped.
1051 #   DUMP:       BODY
1052 #   BODY:       TEST2a
1053 #   diversions: GROW, BODY |-
1054 #
1055 # * TEST1 requires TEST2b: prologue
1056 # m4_require pushes GROW - 1 and expands TEST2b.
1057 #   DUMP:       BODY
1058 #   BODY:       TEST2a
1059 #   diversions: GROW - 1, GROW, BODY |-
1060 #
1061 # * TEST2b is expanded.
1062 # Its prologue pushes the current diversion again.
1063 #   DUMP:       BODY
1064 #   BODY:       TEST2a
1065 #   diversions: GROW - 1, GROW - 1, GROW, BODY |-
1066 # The body is expanded here.
1067 #
1068 # * TEST2b requires TEST3: prologue
1069 # m4_require pushes GROW - 2 and expands TEST3.
1070 #   DUMP:       BODY
1071 #   BODY:       TEST2a
1072 #   diversions: GROW - 2, GROW - 1, GROW - 1, GROW, BODY |-
1073 #
1074 # * TEST3 is expanded.
1075 # Its prologue pushes the current diversion again.
1076 #   DUMP:       BODY
1077 #   BODY:       TEST2a
1078 #   diversions: GROW-2, GROW-2, GROW-1, GROW-1, GROW, BODY |-
1079 # TEST3 requires TEST2a, but TEST2a has already been AC_PROVIDE'd, so
1080 # nothing happens.  It's body is expanded here, and its epilogue pops a
1081 # diversion.
1082 #   DUMP:       BODY
1083 #   BODY:       TEST2a
1084 #   GROW - 2:   TEST3
1085 #   diversions: GROW - 2, GROW - 1, GROW - 1, GROW, BODY |-
1086 #
1087 # * TEST2b requires TEST3: epilogue
1088 # The current diversion is appended to DUMP, and a diversion is popped.
1089 #   DUMP:       BODY
1090 #   BODY:       TEST2a; TEST3
1091 #   diversions: GROW - 1, GROW - 1, GROW, BODY |-
1092 # The content of TEST2b is expanded here.
1093 #   DUMP:       BODY
1094 #   BODY:       TEST2a; TEST3
1095 #   GROW - 1:   TEST2b,
1096 #   diversions: GROW - 1, GROW - 1, GROW, BODY |-
1097 # The epilogue of TEST2b pops a diversion.
1098 #   DUMP:       BODY
1099 #   BODY:       TEST2a; TEST3
1100 #   GROW - 1:   TEST2b,
1101 #   diversions: GROW - 1, GROW, BODY |-
1102 #
1103 # * TEST1 requires TEST2b: epilogue
1104 # The current diversion is appended to DUMP, and a diversion is popped.
1105 #   DUMP:       BODY
1106 #   BODY:       TEST2a; TEST3; TEST2b
1107 #   diversions: GROW, BODY |-
1108 #
1109 # * TEST1 is expanded: epilogue
1110 # TEST1's own content is in GROW, and it's epilogue pops a diversion.
1111 #   DUMP:       BODY
1112 #   BODY:       TEST2a; TEST3; TEST2b
1113 #   GROW:       TEST1
1114 #   diversions: BODY |-
1115 # Here, the epilogue of TEST1 notices the elaboration is done because
1116 # DUMP and the current diversion are the same, it then undiverts
1117 # GROW by hand, and undefines DUMP.
1118 #   DUMP:       undefined
1119 #   BODY:       TEST2a; TEST3; TEST2b; TEST1
1120 #   diversions: BODY |-
1121 #
1122 #
1123 # 2. Keeping track of the expansion stack
1124 # =======================================
1125 #
1126 # When M4 expansion goes wrong it is often extremely hard to find the
1127 # path amongst macros that drove to the failure.  What is needed is
1128 # the stack of macro `calls'. One could imagine that GNU M4 would
1129 # maintain a stack of macro expansions, unfortunately it doesn't, so
1130 # we do it by hand.  This is of course extremely costly, but the help
1131 # this stack provides is worth it.  Nevertheless to limit the
1132 # performance penalty this is implemented only for m4_defun'd macros,
1133 # not for define'd macros.
1134 #
1135 # The scheme is simplistic: each time we enter an m4_defun'd macros,
1136 # we prepend its name in m4_expansion_stack, and when we exit the
1137 # macro, we remove it (thanks to pushdef/popdef).
1138 #
1139 # In addition, we want to use the expansion stack to detect circular
1140 # m4_require dependencies.  This means we need to browse the stack to
1141 # check whether a macro being expanded is m4_require'd.  For ease of
1142 # implementation, and certainly for the benefit of performances, we
1143 # don't browse the m4_expansion_stack, rather each time we expand a
1144 # macro FOO we define _m4_expanding(FOO).  Then m4_require(BAR) simply
1145 # needs to check whether _m4_expanding(BAR) is defined to diagnose a
1146 # circular dependency.
1147 #
1148 # To improve the diagnostic, in addition to keeping track of the stack
1149 # of macro calls, m4_expansion_stack also records the m4_require
1150 # stack.  Note that therefore an m4_defun'd macro being required will
1151 # appear twice in the stack: the first time because it is required,
1152 # the second because it is expanded.  We can avoid this, but it has
1153 # two small drawbacks: (i) the implementation is slightly more
1154 # complex, and (ii) it hides the difference between define'd macros
1155 # (which don't appear in m4_expansion_stack) and m4_defun'd macros
1156 # (which do).  The more debugging information, the better.
1157
1158
1159 # m4_expansion_stack_push(TEXT)
1160 # -----------------------------
1161 m4_define([m4_expansion_stack_push],
1162 [m4_pushdef([m4_expansion_stack],
1163             [$1]m4_ifdef([m4_expansion_stack], [
1164 m4_defn([m4_expansion_stack])]))])
1165
1166
1167 # m4_expansion_stack_pop
1168 # ----------------------
1169 # Dump the expansion stack.
1170 m4_define([m4_expansion_stack_pop],
1171 [m4_popdef([m4_expansion_stack])])
1172
1173
1174 # m4_expansion_stack_dump
1175 # -----------------------
1176 # Dump the expansion stack.
1177 m4_define([m4_expansion_stack_dump],
1178 [m4_ifdef([m4_expansion_stack],
1179           [m4_errprintn(m4_defn([m4_expansion_stack]))])dnl
1180 m4_errprintn(m4_location[: the top level])])
1181
1182
1183 # _m4_divert(GROW)
1184 # ----------------
1185 # This diversion is used by the m4_defun/m4_require machinery.  It is
1186 # important to keep room before GROW because for each nested
1187 # AC_REQUIRE we use an additional diversion (i.e., two m4_require's
1188 # will use GROW - 2.  More than 3 levels has never seemed to be
1189 # needed.)
1190 #
1191 # ...
1192 # - GROW - 2
1193 #   m4_require'd code, 2 level deep
1194 # - GROW - 1
1195 #   m4_require'd code, 1 level deep
1196 # - GROW
1197 #   m4_defun'd macros are elaborated here.
1198
1199 m4_define([_m4_divert(GROW)],       10000)
1200
1201
1202 # _m4_defun_pro(MACRO-NAME)
1203 # -------------------------
1204 # The prologue for Autoconf macros.
1205 m4_define([_m4_defun_pro],
1206 [m4_expansion_stack_push(m4_defn([m4_location($1)])[: $1 is expanded from...])dnl
1207 m4_pushdef([_m4_expanding($1)])dnl
1208 m4_ifdef([_m4_divert_dump],
1209          [m4_divert_push(m4_defn([_m4_divert_diversion]))],
1210          [m4_copy([_m4_divert_diversion], [_m4_divert_dump])dnl
1211 m4_divert_push([GROW])])dnl
1212 ])
1213
1214
1215 # _m4_defun_epi(MACRO-NAME)
1216 # -------------------------
1217 # The Epilogue for Autoconf macros.  MACRO-NAME only helps tracing
1218 # the PRO/EPI pairs.
1219 m4_define([_m4_defun_epi],
1220 [m4_divert_pop()dnl
1221 m4_if(_m4_divert_dump, _m4_divert_diversion,
1222       [m4_undivert([GROW])dnl
1223 m4_undefine([_m4_divert_dump])])dnl
1224 m4_expansion_stack_pop()dnl
1225 m4_popdef([_m4_expanding($1)])dnl
1226 m4_provide([$1])dnl
1227 ])
1228
1229
1230 # m4_defun(NAME, EXPANSION)
1231 # -------------------------
1232 # Define a macro which automatically provides itself.  Add machinery
1233 # so the macro automatically switches expansion to the diversion
1234 # stack if it is not already using it.  In this case, once finished,
1235 # it will bring back all the code accumulated in the diversion stack.
1236 # This, combined with m4_require, achieves the topological ordering of
1237 # macros.  We don't use this macro to define some frequently called
1238 # macros that are not involved in ordering constraints, to save m4
1239 # processing.
1240 m4_define([m4_defun],
1241 [m4_define([m4_location($1)], m4_location)dnl
1242 m4_define([$1],
1243           [_m4_defun_pro([$1])$2[]_m4_defun_epi([$1])])])
1244
1245
1246 # m4_defun_once(NAME, EXPANSION)
1247 # ------------------------------
1248 # As m4_defun, but issues the EXPANSION only once, and warns if used
1249 # several times.
1250 m4_define([m4_defun_once],
1251 [m4_define([m4_location($1)], m4_location)dnl
1252 m4_define([$1],
1253           [m4_provide_if([$1],
1254                          [m4_warn([syntax], [$1 invoked multiple times])],
1255                          [_m4_defun_pro([$1])$2[]_m4_defun_epi([$1])])])])
1256
1257
1258 # m4_pattern_forbid(ERE, [WHY])
1259 # -----------------------------
1260 # Declare that no token matching the extended regular expression ERE
1261 # should be seen in the output but if...
1262 m4_define([m4_pattern_forbid], [])
1263
1264
1265 # m4_pattern_allow(ERE)
1266 # ---------------------
1267 # ... but if that token matches the extended regular expression ERE.
1268 # Both used via traces.
1269 m4_define([m4_pattern_allow], [])
1270
1271
1272 ## ----------------------------- ##
1273 ## Dependencies between macros.  ##
1274 ## ----------------------------- ##
1275
1276
1277 # m4_before(THIS-MACRO-NAME, CALLED-MACRO-NAME)
1278 # ---------------------------------------------
1279 m4_define([m4_before],
1280 [m4_provide_if([$2],
1281                [m4_warn([syntax], [$2 was called before $1])])])
1282
1283
1284 # m4_require(NAME-TO-CHECK, [BODY-TO-EXPAND = NAME-TO-CHECK])
1285 # -----------------------------------------------------------
1286 # If NAME-TO-CHECK has never been expanded (actually, if it is not
1287 # m4_provide'd), expand BODY-TO-EXPAND *before* the current macro
1288 # expansion.  Once expanded, emit it in _m4_divert_dump.  Keep track
1289 # of the m4_require chain in m4_expansion_stack.
1290 #
1291 # The normal cases are:
1292 #
1293 # - NAME-TO-CHECK == BODY-TO-EXPAND
1294 #   Which you can use for regular macros with or without arguments, e.g.,
1295 #     m4_require([AC_PROG_CC], [AC_PROG_CC])
1296 #     m4_require([AC_CHECK_HEADERS(limits.h)], [AC_CHECK_HEADERS(limits.h)])
1297 #   which is just the same as
1298 #     m4_require([AC_PROG_CC])
1299 #     m4_require([AC_CHECK_HEADERS(limits.h)])
1300 #
1301 # - BODY-TO-EXPAND == m4_indir([NAME-TO-CHECK])
1302 #   In the case of macros with irregular names.  For instance:
1303 #     m4_require([AC_LANG_COMPILER(C)], [indir([AC_LANG_COMPILER(C)])])
1304 #   which means `if the macro named `AC_LANG_COMPILER(C)' (the parens are
1305 #   part of the name, it is not an argument) has not been run, then
1306 #   call it.'
1307 #   Had you used
1308 #     m4_require([AC_LANG_COMPILER(C)], [AC_LANG_COMPILER(C)])
1309 #   then m4_require would have tried to expand `AC_LANG_COMPILER(C)', i.e.,
1310 #   call the macro `AC_LANG_COMPILER' with `C' as argument.
1311 #
1312 #   You could argue that `AC_LANG_COMPILER', when it receives an argument
1313 #   such as `C' should dispatch the call to `AC_LANG_COMPILER(C)'.  But this
1314 #   `extension' prevents `AC_LANG_COMPILER' from having actual arguments that
1315 #   it passes to `AC_LANG_COMPILER(C)'.
1316 m4_define([m4_require],
1317 [m4_expansion_stack_push(m4_location[: $1 is required by...])dnl
1318 m4_ifdef([_m4_expanding($1)],
1319          [m4_fatal([$0: circular dependency of $1])])dnl
1320 m4_ifndef([_m4_divert_dump],
1321           [m4_fatal([$0: cannot be used outside of an m4_defun'd macro])])dnl
1322 m4_provide_if([$1],
1323               [],
1324               [m4_divert_push(m4_eval(m4_divnum - 1))dnl
1325 m4_default([$2], [$1])
1326 m4_divert(m4_defn([_m4_divert_dump]))dnl
1327 m4_undivert(m4_defn([_m4_divert_diversion]))dnl
1328 m4_divert_pop(m4_defn([_m4_divert_dump]))])dnl
1329 m4_provide_if([$1],
1330               [],
1331               [m4_warn([syntax],
1332                        [$1 is m4_require'd but is not m4_defun'd])])dnl
1333 m4_expansion_stack_pop()dnl
1334 ])
1335
1336
1337 # m4_expand_once(TEXT, [WITNESS = TEXT])
1338 # --------------------------------------
1339 # If TEXT has never been expanded, expand it *here*.  Use WITNESS as
1340 # as a memory that TEXT has already been expanded.
1341 m4_define([m4_expand_once],
1342 [m4_provide_if(m4_ifval([$2], [[$2]], [[$1]]),
1343                [],
1344                [m4_provide(m4_ifval([$2], [[$2]], [[$1]]))[]$1])])
1345
1346
1347 # m4_provide(MACRO-NAME)
1348 # ----------------------
1349 m4_define([m4_provide],
1350 [m4_define([m4_provide($1)])])
1351
1352
1353 # m4_provide_if(MACRO-NAME, IF-PROVIDED, IF-NOT-PROVIDED)
1354 # -------------------------------------------------------
1355 # If MACRO-NAME is provided do IF-PROVIDED, else IF-NOT-PROVIDED.
1356 # The purpose of this macro is to provide the user with a means to
1357 # check macros which are provided without letting her know how the
1358 # information is coded.
1359 m4_define([m4_provide_if],
1360 [m4_ifdef([m4_provide($1)],
1361           [$2], [$3])])
1362
1363
1364 ## -------------------- ##
1365 ## 9. Text processing.  ##
1366 ## -------------------- ##
1367
1368
1369 # m4_cr_letters
1370 # m4_cr_LETTERS
1371 # m4_cr_Letters
1372 # -------------
1373 m4_define([m4_cr_letters], [abcdefghijklmnopqrstuvwxyz])
1374 m4_define([m4_cr_LETTERS], [ABCDEFGHIJKLMNOPQRSTUVWXYZ])
1375 m4_define([m4_cr_Letters],
1376 m4_defn([m4_cr_letters])dnl
1377 m4_defn([m4_cr_LETTERS])dnl
1378 )
1379
1380
1381 # m4_cr_digits
1382 # ------------
1383 m4_define([m4_cr_digits], [0123456789])
1384
1385
1386 # m4_cr_symbols1 & m4_cr_symbols2
1387 # -------------------------------
1388 m4_define([m4_cr_symbols1],
1389 m4_defn([m4_cr_Letters])dnl
1390 _)
1391
1392 m4_define([m4_cr_symbols2],
1393 m4_defn([m4_cr_symbols1])dnl
1394 m4_defn([m4_cr_digits])dnl
1395 )
1396
1397
1398 # m4_re_escape(STRING)
1399 # --------------------
1400 # Escape BRE active characters in STRING.
1401 m4_define([m4_re_escape],
1402 [m4_bpatsubst([$1],
1403               [[][+*.]], [\\\&])])
1404
1405
1406 # m4_re_string
1407 # ------------
1408 # Regexp for `[a-zA-Z_0-9]*'
1409 m4_define([m4_re_string],
1410 m4_defn([m4_cr_symbols2])dnl
1411 [*]dnl
1412 )
1413
1414
1415 # m4_re_word
1416 # ----------
1417 # Regexp for `[a-zA-Z_][a-zA-Z_0-9]*'
1418 m4_define([m4_re_word],
1419 m4_defn([m4_cr_symbols1])dnl
1420 m4_defn([m4_re_string])dnl
1421 )
1422
1423
1424 # m4_tolower(STRING)
1425 # m4_toupper(STRING)
1426 # ------------------
1427 # These macros lowercase and uppercase strings.
1428 m4_define([m4_tolower],
1429 [m4_translit([$1], m4_defn([m4_cr_LETTERS]), m4_defn([m4_cr_letters]))])
1430 m4_define([m4_toupper],
1431 [m4_translit([$1], m4_defn([m4_cr_letters]), m4_defn([m4_cr_LETTERS]))])
1432
1433
1434 # m4_split(STRING, [REGEXP])
1435 # --------------------------
1436 #
1437 # Split STRING into an m4 list of quoted elements.  The elements are
1438 # quoted with [ and ].  Beginning spaces and end spaces *are kept*.
1439 # Use m4_strip to remove them.
1440 #
1441 # REGEXP specifies where to split.  Default is [\t ]+.
1442 #
1443 # Pay attention to the m4_changequotes.  Inner m4_changequotes exist for
1444 # obvious reasons (we want to insert square brackets).  Outer
1445 # m4_changequotes are needed because otherwise the m4 parser, when it
1446 # sees the closing bracket we add to the result, believes it is the
1447 # end of the body of the macro we define.
1448 #
1449 # Also, notice that $1 is quoted twice, since we want the result to
1450 # be quoted.  Then you should understand that the argument of
1451 # patsubst is ``STRING'' (i.e., with additional `` and '').
1452 #
1453 # This macro is safe on active symbols, i.e.:
1454 #   m4_define(active, ACTIVE)
1455 #   m4_split([active active ])end
1456 #   => [active], [active], []end
1457
1458 m4_changequote(<<, >>)
1459 m4_define(<<m4_split>>,
1460 <<m4_changequote(``, '')dnl
1461 [dnl Can't use m4_default here instead of m4_if, because m4_default uses
1462 dnl [ and ] as quotes.
1463 m4_bpatsubst(````$1'''',
1464              m4_if(``$2'',, ``[         ]+'', ``$2''),
1465              ``], ['')]dnl
1466 m4_changequote([, ])>>)
1467 m4_changequote([, ])
1468
1469
1470
1471 # m4_flatten(STRING)
1472 # ------------------
1473 # If STRING contains end of lines, replace them with spaces.  If there
1474 # are backslashed end of lines, remove them.  This macro is safe with
1475 # active symbols.
1476 #    m4_define(active, ACTIVE)
1477 #    m4_flatten([active
1478 #    act\
1479 #    ive])end
1480 #    => active activeend
1481 m4_define([m4_flatten],
1482 [m4_translit(m4_bpatsubst([[[$1]]], [\\
1483 ]), [
1484 ], [ ])])
1485
1486
1487 # m4_strip(STRING)
1488 # ----------------
1489 # Expands into STRING with tabs and spaces singled out into a single
1490 # space, and removing leading and trailing spaces.
1491 #
1492 # This macro is robust to active symbols.
1493 #    m4_define(active, ACTIVE)
1494 #    m4_strip([  active                 active ])end
1495 #    => active activeend
1496 #
1497 # This macro is fun!  Because we want to preserve active symbols, STRING
1498 # must be quoted for each evaluation, which explains there are 4 levels
1499 # of brackets around $1 (don't forget that the result must be quoted
1500 # too, hence one more quoting than applications).
1501 #
1502 # Then notice the 2 last patterns: they are in charge of removing the
1503 # leading/trailing spaces.  Why not just `[^ ]'?  Because they are
1504 # applied to doubly quoted strings, i.e. more or less [[STRING]].  So
1505 # if there is a leading space in STRING, then it is the *third*
1506 # character, since there are two leading `['; equally for the last pattern.
1507 m4_define([m4_strip],
1508 [m4_bpatsubsts([[$1]],
1509                [[       ]+], [ ],
1510                [^\(..\) ],    [\1],
1511                [ \(..\)$],    [\1])])
1512
1513
1514 # m4_normalize(STRING)
1515 # --------------------
1516 # Apply m4_flatten and m4_strip to STRING.
1517 #
1518 # The argument is quoted, so that the macro is robust to active symbols:
1519 #
1520 #    m4_define(active, ACTIVE)
1521 #    m4_normalize([  act\
1522 #    ive
1523 #    active ])end
1524 #    => active activeend
1525
1526 m4_define([m4_normalize],
1527 [m4_strip(m4_flatten([$1]))])
1528
1529
1530
1531 # m4_join(SEP, ARG1, ARG2...)
1532 # ---------------------------
1533 # Produce ARG1SEPARG2...SEPARGn.
1534 m4_defun([m4_join],
1535 [m4_case([$#],
1536          [1], [],
1537          [2], [[$2]],
1538          [[$2][$1]$0([$1], m4_shiftn(2, $@))])])
1539
1540
1541
1542 # m4_append(MACRO-NAME, STRING, [SEPARATOR])
1543 # ------------------------------------------
1544 # Redefine MACRO-NAME to hold its former content plus `SEPARATOR`'STRING'
1545 # at the end.  It is valid to use this macro with MACRO-NAME undefined,
1546 # in which case no SEPARATOR is added.  Be aware that the criterion is
1547 # `not being defined', and not `not being empty'.
1548 #
1549 # This macro is robust to active symbols.  It can be used to grow
1550 # strings.
1551 #
1552 #    | m4_define(active, ACTIVE)
1553 #    | m4_append([sentence], [This is an])
1554 #    | m4_append([sentence], [ active ])
1555 #    | m4_append([sentence], [symbol.])
1556 #    | sentence
1557 #    | m4_undefine([active])dnl
1558 #    | sentence
1559 #    => This is an ACTIVE symbol.
1560 #    => This is an active symbol.
1561 #
1562 # It can be used to define hooks.
1563 #
1564 #    | m4_define(active, ACTIVE)
1565 #    | m4_append([hooks], [m4_define([act1], [act2])])
1566 #    | m4_append([hooks], [m4_define([act2], [active])])
1567 #    | m4_undefine([active])
1568 #    | act1
1569 #    | hooks
1570 #    | act1
1571 #    => act1
1572 #    =>
1573 #    => active
1574 m4_define([m4_append],
1575 [m4_define([$1],
1576            m4_ifdef([$1], [m4_defn([$1])$3])[$2])])
1577
1578
1579 # m4_append_uniq(MACRO-NAME, STRING, [SEPARATOR])
1580 # -----------------------------------------------
1581 # As `m4_append', but append only if not yet present.
1582 m4_define([m4_append_uniq],
1583 [m4_ifdef([$1],
1584           [m4_bmatch([$3]m4_defn([$1])[$3], m4_re_escape([$3$2$3]), [],
1585                      [m4_append($@)])],
1586           [m4_append($@)])])
1587
1588
1589 # m4_text_wrap(STRING, [PREFIX], [FIRST-PREFIX], [WIDTH])
1590 # -------------------------------------------------------
1591 # Expands into STRING wrapped to hold in WIDTH columns (default = 79).
1592 # If prefix is set, each line is prefixed with it.  If FIRST-PREFIX is
1593 # specified, then the first line is prefixed with it.  As a special
1594 # case, if the length of the first prefix is greater than that of
1595 # PREFIX, then FIRST-PREFIX will be left alone on the first line.
1596 #
1597 # Typical outputs are:
1598 #
1599 # m4_text_wrap([Short string */], [   ], [/* ], 20)
1600 #  => /* Short string */
1601 #
1602 # m4_text_wrap([Much longer string */], [   ], [/* ], 20)
1603 #  => /* Much longer
1604 #  =>    string */
1605 #
1606 # m4_text_wrap([Short doc.], [          ], [  --short ], 30)
1607 #  =>   --short Short doc.
1608 #
1609 # m4_text_wrap([Short doc.], [          ], [  --too-wide ], 30)
1610 #  =>   --too-wide
1611 #  =>           Short doc.
1612 #
1613 # m4_text_wrap([Super long documentation.], [          ], [  --too-wide ], 30)
1614 #  =>   --too-wide
1615 #  =>     Super long
1616 #  =>     documentation.
1617 #
1618 # FIXME: there is no checking of a longer PREFIX than WIDTH, but do
1619 # we really want to bother with people trying each single corner
1620 # of a software?
1621 #
1622 # This macro does not leave a trailing space behind the last word,
1623 # what complicates it a bit.  The algorithm is stupid simple: all the
1624 # words are preceded by m4_Separator which is defined to empty for the
1625 # first word, and then ` ' (single space) for all the others.
1626 m4_define([m4_text_wrap],
1627 [m4_pushdef([m4_Prefix], m4_default([$2], []))dnl
1628 m4_pushdef([m4_Prefix1], m4_default([$3], [m4_Prefix]))dnl
1629 m4_pushdef([m4_Width], m4_default([$4], 79))dnl
1630 m4_pushdef([m4_Cursor], m4_len(m4_Prefix1))dnl
1631 m4_pushdef([m4_Separator], [])dnl
1632 m4_Prefix1[]dnl
1633 m4_if(m4_eval(m4_Cursor > m4_len(m4_Prefix)),
1634       1, [m4_define([m4_Cursor], m4_len(m4_Prefix))
1635 m4_Prefix])[]dnl
1636 m4_foreach([m4_Word], m4_quote(m4_split(m4_normalize([$1]))),
1637 [m4_define([m4_Cursor], m4_eval(m4_Cursor + m4_len(m4_defn([m4_Word])) + 1))dnl
1638 dnl New line if too long, else insert a space unless it is the first
1639 dnl of the words.
1640 m4_if(m4_eval(m4_Cursor > m4_Width),
1641       1, [m4_define([m4_Cursor],
1642                     m4_eval(m4_len(m4_Prefix) + m4_len(m4_defn([m4_Word])) + 1))]
1643 m4_Prefix,
1644        [m4_Separator])[]dnl
1645 m4_defn([m4_Word])[]dnl
1646 m4_define([m4_Separator], [ ])])dnl
1647 m4_popdef([m4_Separator])dnl
1648 m4_popdef([m4_Cursor])dnl
1649 m4_popdef([m4_Width])dnl
1650 m4_popdef([m4_Prefix1])dnl
1651 m4_popdef([m4_Prefix])dnl
1652 ])
1653
1654
1655 # m4_text_box(MESSAGE, [FRAME-CHARACTER = `-'])
1656 # ---------------------------------------------
1657 m4_define([m4_text_box],
1658 [@%:@@%:@ m4_bpatsubst([$1], [.], m4_if([$2], [], [[-]], [[$2]])) @%:@@%:@
1659 @%:@@%:@ $1 @%:@@%:@
1660 @%:@@%:@ m4_bpatsubst([$1], [.], m4_if([$2], [], [[-]], [[$2]])) @%:@@%:@[]dnl
1661 ])
1662
1663
1664
1665 ## ----------------------- ##
1666 ## 10. Number processing.  ##
1667 ## ----------------------- ##
1668
1669 # m4_sign(A)
1670 # ----------
1671 #
1672 # The sign of the integer A.
1673 m4_define([m4_sign],
1674 [m4_bmatch([$1],
1675            [^-], -1,
1676            [^0+], 0,
1677                   1)])
1678
1679 # m4_cmp(A, B)
1680 # ------------
1681 #
1682 # Compare two integers.
1683 # A < B -> -1
1684 # A = B ->  0
1685 # A > B ->  1
1686 m4_define([m4_cmp],
1687 [m4_sign(m4_eval([$1 - $2]))])
1688
1689
1690 # m4_list_cmp(A, B)
1691 # -----------------
1692 #
1693 # Compare the two lists of integers A and B.  For instance:
1694 #   m4_list_cmp((1, 0),     (1))    ->  0
1695 #   m4_list_cmp((1, 0),     (1, 0)) ->  0
1696 #   m4_list_cmp((1, 2),     (1, 0)) ->  1
1697 #   m4_list_cmp((1, 2, 3),  (1, 2)) ->  1
1698 #   m4_list_cmp((1, 2, -3), (1, 2)) -> -1
1699 #   m4_list_cmp((1, 0),     (1, 2)) -> -1
1700 #   m4_list_cmp((1),        (1, 2)) -> -1
1701 m4_define([m4_list_cmp],
1702 [m4_if([$1$2], [()()], 0,
1703        [$1], [()], [$0((0), [$2])],
1704        [$2], [()], [$0([$1], (0))],
1705        [m4_case(m4_cmp(m4_car$1, m4_car$2),
1706                 -1, -1,
1707                  1, 1,
1708                  0, [$0((m4_shift$1), (m4_shift$2))])])])
1709
1710
1711
1712 ## ------------------------ ##
1713 ## 11. Version processing.  ##
1714 ## ------------------------ ##
1715
1716
1717 # m4_version_unletter(VERSION)
1718 # ----------------------------
1719 # Normalize beta version numbers with letters to numbers only for comparison.
1720 #
1721 #   Nl -> (N+1).-1.(l#)
1722 #
1723 #i.e., 2.14a -> 2.15.-1.1, 2.14b -> 2.15.-1.2, etc.
1724 # This macro is absolutely not robust to active macro, it expects
1725 # reasonable version numbers and is valid up to `z', no double letters.
1726 m4_define([m4_version_unletter],
1727 [m4_translit(m4_bpatsubsts([$1],
1728                            [\([0-9]+\)\([abcdefghi]\)],
1729                              [m4_eval(\1 + 1).-1.\2],
1730                            [\([0-9]+\)\([jklmnopqrs]\)],
1731                              [m4_eval(\1 + 1).-1.1\2],
1732                            [\([0-9]+\)\([tuvwxyz]\)],
1733                              [m4_eval(\1 + 1).-1.2\2]),
1734              [abcdefghijklmnopqrstuvwxyz],
1735              [12345678901234567890123456])])
1736
1737
1738 # m4_version_compare(VERSION-1, VERSION-2)
1739 # ----------------------------------------
1740 # Compare the two version numbers and expand into
1741 #  -1 if VERSION-1 < VERSION-2
1742 #   0 if           =
1743 #   1 if           >
1744 m4_define([m4_version_compare],
1745 [m4_list_cmp((m4_split(m4_version_unletter([$1]), [\.])),
1746              (m4_split(m4_version_unletter([$2]), [\.])))])
1747
1748
1749 # m4_version_prereq(VERSION, [IF-OK], [IF-NOT = FAIL])
1750 # ----------------------------------------------------
1751 # Check this Autoconf version against VERSION.
1752 m4_define([m4_version_prereq],
1753 [m4_if(m4_version_compare(m4_defn([m4_PACKAGE_VERSION]), [$1]), -1,
1754        [m4_default([$3],
1755                    [m4_fatal([Autoconf version $1 or higher is required])])],
1756        [$2])[]dnl
1757 ])
1758
1759
1760
1761 ## ------------------- ##
1762 ## 12. File handling.  ##
1763 ## ------------------- ##
1764
1765
1766 # It is a real pity that M4 comes with no macros to bind a diversion
1767 # to a file.  So we have to deal without, which makes us a lot more
1768 # fragile that we should.
1769
1770
1771 # m4_file_append(FILE-NAME, CONTENT)
1772 # ----------------------------------
1773 m4_define([m4_file_append],
1774 [m4_syscmd([cat >>$1 <<_m4eof
1775 $2
1776 _m4eof
1777 ])
1778 m4_if(m4_sysval, [0], [],
1779       [m4_fatal([$0: cannot write: $1])])])
1780
1781
1782
1783 ## ------------------------ ##
1784 ## 13. Setting M4sugar up.  ##
1785 ## ------------------------ ##
1786
1787
1788 # m4_init
1789 # -------
1790 m4_define([m4_init],
1791 [# All the M4sugar macros start with `m4_', except `dnl' kept as is
1792 # for sake of simplicity.
1793 m4_pattern_forbid([^_?m4_])
1794 m4_pattern_forbid([^dnl$])
1795
1796 # Check the divert push/pop perfect balance.
1797 m4_wrap([m4_ifdef([_m4_divert_diversion],
1798                   [m4_fatal([$0: unbalanced m4_divert_push:]
1799 m4_defn([m4_divert_stack]))])[]])
1800
1801 m4_divert_push([KILL])
1802 m4_wrap([m4_divert_pop([KILL])[]])
1803 ])