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1 Changes between release 2.5.4 (11Sep96) and release 2.5.3:
3 - Fixed a bug introduced in 2.5.3 that blew it when a call
4 to input() occurred at the end of an input file.
6 - Fixed scanner skeleton so the example in the man page of
7 scanning strings using exclusive start conditions works.
9 - Minor Makefile tweaks.
12 Changes between release 2.5.3 (29May96) and release 2.5.2:
14 - Some serious bugs in yymore() have been fixed. In particular,
15 when using AT&T-lex-compatibility or %array, you can intermix
16 calls to input(), unput(), and yymore(). (This still doesn't
17 work for %pointer, and isn't likely to in the future.)
19 - A bug in handling NUL's in the input stream of scanners using
20 REJECT has been fixed.
22 - The default main() in libfl.a now repeatedly calls yylex() until
23 it returns 0, rather than just calling it once.
25 - Minor tweak for Windows NT Makefile, MISC/NT/Makefile.
28 Changes between release 2.5.2 (25Apr95) and release 2.5.1:
30 - The --prefix configuration option now works.
32 - A bug that completely broke the "-Cf" table compression
33 option has been fixed.
35 - A major headache involving "const" declarators and Solaris
36 systems has been fixed.
38 - An octal escape sequence in a flex regular expression must
39 now contain only the digits 0-7.
41 - You can now use "--" on the flex command line to mark the
42 end of flex options.
44 - You can now specify the filename '-' as a synonym for stdin.
46 - By default, the scanners generated by flex no longer
47 statically initialize yyin and yyout to stdin and stdout.
48 This change is necessary because in some ANSI environments,
49 stdin and stdout are not compile-time constant. You can
50 force the initialization using "%option stdinit" in the first
51 section of your flex input.
53 - "%option nounput" now correctly omits the unput() routine
54 from the output.
56 - "make clean" now removes config.log, config.cache, and the
57 flex binary. The fact that it removes the flex binary means
58 you should take care if making changes to scan.l, to make
59 sure you don't wind up in a bootstrap problem.
61 - In general, the Makefile has been reworked somewhat (thanks
62 to Francois Pinard) for added flexibility - more changes will
63 follow in subsequent releases.
65 - The .texi and .info files in MISC/texinfo/ have been updated,
66 thanks also to Francois Pinard.
68 - The FlexLexer::yylex(std::istream* new_in, std::ostream* new_out) method
69 now does not have a default for the first argument, to disambiguate
70 it from FlexLexer::yylex().
72 - A bug in destructing a FlexLexer object before doing any scanning
73 with it has been fixed.
75 - A problem with including FlexLexer.h multiple times has been fixed.
77 - The alloca() chud necessary to accommodate bison has grown
78 even uglier, but hopefully more correct.
80 - A portability tweak has been added to accommodate compilers that
81 use char* generic pointers.
83 - EBCDIC contact information in the file MISC/EBCDIC has been updated.
85 - An OS/2 Makefile and config.h for flex 2.5 is now available in
86 MISC/OS2/, contributed by Kai Uwe Rommel.
88 - The descrip.mms file for building flex under VMS has been updated,
89 thanks to Pat Rankin.
91 - The notes on building flex for the Amiga have been updated for
92 flex 2.5, contributed by Andreas Scherer.
95 Changes between release 2.5.1 (28Mar95) and release 2.4.7:
97 - A new concept of "start condition" scope has been introduced.
98 A start condition scope is begun with:
100 <SCs>{
102 where SCs is a list of one or more start conditions. Inside
103 the start condition scope, every rule automatically has the
104 prefix <SCs> applied to it, until a '}' which matches the
105 initial '{'. So, for example:
107 <ESC>{
108 "\\n" return '\n';
109 "\\r" return '\r';
110 "\\f" return '\f';
111 "\\0" return '\0';
112 }
114 is equivalent to:
116 <ESC>"\\n" return '\n';
117 <ESC>"\\r" return '\r';
118 <ESC>"\\f" return '\f';
119 <ESC>"\\0" return '\0';
121 As indicated in this example, rules inside start condition scopes
122 (and any rule, actually, other than the first) can be indented,
123 to better show the extent of the scope.
125 Start condition scopes may be nested.
127 - The new %option directive can be used in the first section of
128 a flex scanner to control scanner-generation options. Most
129 options are given simply as names, optionally preceded by the
130 word "no" (with no intervening whitespace) to negate their
131 meaning. Some are equivalent to flex flags, so putting them
132 in your scanner source is equivalent to always specifying
133 the flag (%option's take precedence over flags):
135 7bit -7 option
136 8bit -8 option
137 align -Ca option
138 backup -b option
139 batch -B option
140 c++ -+ option
141 caseful opposite of -i option (caseful is the default);
142 case-sensitive same as above
143 caseless -i option;
144 case-insensitive same as above
145 debug -d option
146 default opposite of -s option
147 ecs -Ce option
148 fast -F option
149 full -f option
150 interactive -I option
151 lex-compat -l option
152 meta-ecs -Cm option
153 perf-report -p option
154 read -Cr option
155 stdout -t option
156 verbose -v option
157 warn opposite of -w option (so use "%option nowarn" for -w)
159 array equivalent to "%array"
160 pointer equivalent to "%pointer" (default)
162 Some provide new features:
164 always-interactive generate a scanner which always
165 considers its input "interactive" (no call to isatty()
166 will be made when the scanner runs)
167 main supply a main program for the scanner, which
168 simply calls yylex(). Implies %option noyywrap.
169 never-interactive generate a scanner which never
170 considers its input "interactive" (no call to isatty()
171 will be made when the scanner runs)
172 stack if set, enable start condition stacks (see below)
173 stdinit if unset ("%option nostdinit"), initialize yyin
174 and yyout statically to nil FILE* pointers, instead
175 of stdin and stdout
176 yylineno if set, keep track of the current line
177 number in global yylineno (this option is expensive
178 in terms of performance). The line number is available
179 to C++ scanning objects via the new member function
180 lineno().
181 yywrap if unset ("%option noyywrap"), scanner does not
182 call yywrap() upon EOF but simply assumes there
183 are no more files to scan
185 Flex scans your rule actions to determine whether you use the
186 REJECT or yymore features (this is not new). Two %options can be
187 used to override its decision, either by setting them to indicate
188 the feature is indeed used, or unsetting them to indicate it
189 actually is not used:
191 reject
192 yymore
194 Three %option's take string-delimited values, offset with '=':
196 outfile="<name>" equivalent to -o<name>
197 prefix="<name>" equivalent to -P<name>
198 yyclass="<name>" set the name of the C++ scanning class
199 (see below)
201 A number of %option's are available for lint purists who
202 want to suppress the appearance of unneeded routines in
203 the generated scanner. Each of the following, if unset,
204 results in the corresponding routine not appearing in the
205 generated scanner:
207 input, unput
208 yy_push_state, yy_pop_state, yy_top_state
209 yy_scan_buffer, yy_scan_bytes, yy_scan_string
211 You can specify multiple options with a single %option directive,
212 and multiple directives in the first section of your flex input file.
214 - The new function:
216 YY_BUFFER_STATE yy_scan_string( const char *str )
218 returns a YY_BUFFER_STATE (which also becomes the current input
219 buffer) for scanning the given string, which occurs starting
220 with the next call to yylex(). The string must be NUL-terminated.
221 A related function:
223 YY_BUFFER_STATE yy_scan_bytes( const char *bytes, int len )
225 creates a buffer for scanning "len" bytes (including possibly NUL's)
226 starting at location "bytes".
228 Note that both of these functions create and scan a *copy* of
229 the string/bytes. (This may be desirable, since yylex() modifies
230 the contents of the buffer it is scanning.) You can avoid the
231 copy by using:
233 YY_BUFFER_STATE yy_scan_buffer( char *base, yy_size_t size )
235 which scans in place the buffer starting at "base", consisting
236 of "size" bytes, the last two bytes of which *must* be
237 YY_END_OF_BUFFER_CHAR (these bytes are not scanned; thus, scanning
238 consists of base[0] through base[size-2], inclusive). If you
239 fail to set up "base" in this manner, yy_scan_buffer returns a
240 nil pointer instead of creating a new input buffer.
242 The type yy_size_t is an integral type to which you can cast
243 an integer expression reflecting the size of the buffer.
245 - Three new routines are available for manipulating stacks of
246 start conditions:
248 void yy_push_state( int new_state )
250 pushes the current start condition onto the top of the stack
251 and BEGIN's "new_state" (recall that start condition names are
252 also integers).
254 void yy_pop_state()
256 pops the top of the stack and BEGIN's to it, and
258 int yy_top_state()
260 returns the top of the stack without altering the stack's
261 contents.
263 The start condition stack grows dynamically and so has no built-in
264 size limitation. If memory is exhausted, program execution
265 is aborted.
267 To use start condition stacks, your scanner must include
268 a "%option stack" directive.
270 - flex now supports POSIX character class expressions. These
271 are expressions enclosed inside "[:" and ":]" delimiters (which
272 themselves must appear between the '[' and ']' of a character
273 class; other elements may occur inside the character class, too).
274 The expressions flex recognizes are:
276 [:alnum:] [:alpha:] [:blank:] [:cntrl:] [:digit:] [:graph:]
277 [:lower:] [:print:] [:punct:] [:space:] [:upper:] [:xdigit:]
279 These expressions all designate a set of characters equivalent to
280 the corresponding isXXX function (for example, [:alnum:] designates
281 those characters for which isalnum() returns true - i.e., any
282 alphabetic or numeric). Some systems don't provide isblank(),
283 so flex defines [:blank:] as a blank or a tab.
285 For example, the following character classes are all equivalent:
287 [[:alnum:]]
288 [[:alpha:][:digit:]
289 [[:alpha:]0-9]
290 [a-zA-Z0-9]
292 If your scanner is case-insensitive (-i flag), then [:upper:]
293 and [:lower:] are equivalent to [:alpha:].
295 - The promised rewrite of the C++ FlexLexer class has not yet
296 been done. Support for FlexLexer is limited at the moment to
297 fixing show-stopper bugs, so, for example, the new functions
298 yy_scan_string() & friends are not available to FlexLexer
299 objects.
301 - The new macro
303 yy_set_interactive(is_interactive)
305 can be used to control whether the current buffer is considered
306 "interactive". An interactive buffer is processed more slowly,
307 but must be used when the scanner's input source is indeed
308 interactive to avoid problems due to waiting to fill buffers
309 (see the discussion of the -I flag in flex.1). A non-zero value
310 in the macro invocation marks the buffer as interactive, a zero
311 value as non-interactive. Note that use of this macro overrides
312 "%option always-interactive" or "%option never-interactive".
314 yy_set_interactive() must be invoked prior to beginning to
315 scan the buffer.
317 - The new macro
319 yy_set_bol(at_bol)
321 can be used to control whether the current buffer's scanning
322 context for the next token match is done as though at the
323 beginning of a line (non-zero macro argument; makes '^' anchored
324 rules active) or not at the beginning of a line (zero argument,
325 '^' rules inactive).
327 - Related to this change, the mechanism for determining when a scan is
328 starting at the beginning of a line has changed. It used to be
329 that '^' was active iff the character prior to that at which the
330 scan started was a newline. The mechanism now is that '^' is
331 active iff the last token ended in a newline (or the last call to
332 input() returned a newline). For most users, the difference in
333 mechanisms is negligible. Where it will make a difference,
334 however, is if unput() or yyless() is used to alter the input
335 stream. When in doubt, use yy_set_bol().
337 - The new beginning-of-line mechanism involved changing some fairly
338 twisted code, so it may have introduced bugs - beware ...
340 - The macro YY_AT_BOL() returns true if the next token scanned from
341 the current buffer will have '^' rules active, false otherwise.
343 - The new function
345 void yy_flush_buffer( struct yy_buffer_state* b )
347 flushes the contents of the current buffer (i.e., next time
348 the scanner attempts to match a token using b as the current
349 buffer, it will begin by invoking YY_INPUT to fill the buffer).
350 This routine is also available to C++ scanners (unlike some
351 of the other new routines).
353 The related macro
355 YY_FLUSH_BUFFER
357 flushes the contents of the current buffer.
359 - A new "-ooutput" option writes the generated scanner to "output".
360 If used with -t, the scanner is still written to stdout, but
361 its internal #line directives (see previous item) use "output".
363 - Flex now generates #line directives relating the code it
364 produces to the output file; this means that error messages
365 in the flex-generated code should be correctly pinpointed.
367 - When generating #line directives, filenames with embedded '\'s
368 have those characters escaped (i.e., turned into '\\'). This
369 feature helps with reporting filenames for some MS-DOS and OS/2
370 systems.
372 - The FlexLexer class includes two new public member functions:
374 virtual void switch_streams( std::istream* new_in = 0,
375 std::ostream* new_out = 0 )
377 reassigns yyin to new_in (if non-nil) and yyout to new_out
378 (ditto), deleting the previous input buffer if yyin is
379 reassigned. It is used by:
381 int yylex( std::istream* new_in = 0, std::ostream* new_out = 0 )
383 which first calls switch_streams() and then returns the value
384 of calling yylex().
386 - C++ scanners now have yy_flex_debug as a member variable of
387 FlexLexer rather than a global, and member functions for testing
388 and setting it.
390 - When generating a C++ scanning class, you can now use
392 %option yyclass="foo"
394 to inform flex that you have derived "foo" as a subclass of
395 yyFlexLexer, so flex will place your actions in the member
396 function foo::yylex() instead of yyFlexLexer::yylex(). It also
397 generates a yyFlexLexer::yylex() member function that generates a
398 run-time error if called (by invoking yyFlexLexer::LexerError()).
399 This feature is necessary if your subclass "foo" introduces some
400 additional member functions or variables that you need to access
401 from yylex().
403 - Current texinfo files in MISC/texinfo, contributed by Francois
404 Pinard.
406 - You can now change the name "flex" to something else (e.g., "lex")
407 by redefining $(FLEX) in the Makefile.
409 - Two bugs (one serious) that could cause "bigcheck" to fail have
410 been fixed.
412 - A number of portability/configuration changes have been made
413 for easier portability.
415 - You can use "YYSTATE" in your scanner as an alias for YY_START
416 (for AT&T lex compatibility).
418 - input() now maintains yylineno.
420 - input() no longer trashes yytext.
422 - interactive scanners now read characters in YY_INPUT up to a
423 newline, a large performance gain.
425 - C++ scanner objects now work with the -P option. You include
426 <FlexLexer.h> once per scanner - see comments in <FlexLexer.h>
427 (or flex.1) for details.
429 - C++ FlexLexer objects now use the "cerr" stream to report -d output
430 instead of stdio.
432 - The -c flag now has its full glorious POSIX interpretation (do
433 nothing), rather than being interpreted as an old-style -C flag.
435 - Scanners generated by flex now include two #define's giving
436 the major and minor version numbers (YY_FLEX_MAJOR_VERSION,
437 YY_FLEX_MINOR_VERSION). These can then be tested to see
438 whether certain flex features are available.
440 - Scanners generated using -l lex compatibility now have the symbol
441 YY_FLEX_LEX_COMPAT #define'd.
443 - When initializing (i.e., yy_init is non-zero on entry to yylex()),
444 generated scanners now set yy_init to zero before executing
445 YY_USER_INIT. This means that you can set yy_init back to a
446 non-zero value in YY_USER_INIT if you need the scanner to be
447 reinitialized on the next call.
449 - You can now use "#line" directives in the first section of your
450 scanner specification.
452 - When generating full-table scanners (-Cf), flex now puts braces
453 around each row of the 2-d array initialization, to silence warnings
454 on over-zealous compilers.
456 - Improved support for MS-DOS. The flex sources have been successfully
457 built, unmodified, for Borland 4.02 (all that's required is a
458 Borland Makefile and config.h file, which are supplied in
459 MISC/Borland - contributed by Terrence O Kane).
461 - Improved support for Macintosh using Think C - the sources should
462 build for this platform "out of the box". Contributed by Scott
463 Hofmann.
465 - Improved support for VMS, in MISC/VMS/, contributed by Pat Rankin.
467 - Support for the Amiga, in MISC/Amiga/, contributed by Andreas
468 Scherer. Note that the contributed files were developed for
469 flex 2.4 and have not been tested with flex 2.5.
471 - Some notes on support for the NeXT, in MISC/NeXT, contributed
472 by Raf Schietekat.
474 - The MISC/ directory now includes a preformatted version of flex.1
475 in flex.man, and pre-yacc'd versions of parse.y in parse.{c,h}.
477 - The flex.1 and flexdoc.1 manual pages have been merged. There
478 is now just one document, flex.1, which includes an overview
479 at the beginning to help you find the section you need.
481 - Documentation now clarifies that start conditions persist across
482 switches to new input files or different input buffers. If you
483 want to e.g., return to INITIAL, you must explicitly do so.
485 - The "Performance Considerations" section of the manual has been
486 updated.
488 - Documented the "yy_act" variable, which when YY_USER_ACTION is
489 invoked holds the number of the matched rule, and added an
490 example of using yy_act to profile how often each rule is matched.
492 - Added YY_NUM_RULES, a definition that gives the total number
493 of rules in the file, including the default rule (even if you
494 use -s).
496 - Documentation now clarifies that you can pass a nil FILE* pointer
497 to yy_create_buffer() or yyrestart() if you've arrange YY_INPUT
498 to not need yyin.
500 - Documentation now clarifies that YY_BUFFER_STATE is a pointer to
501 an opaque "struct yy_buffer_state".
503 - Documentation now stresses that you gain the benefits of removing
504 backing-up states only if you remove *all* of them.
506 - Documentation now points out that traditional lex allows you
507 to put the action on a separate line from the rule pattern if
508 the pattern has trailing whitespace (ugh!), but flex doesn't
509 support this.
511 - A broken example in documentation of the difference between
512 inclusive and exclusive start conditions is now fixed.
514 - Usage (-h) report now goes to stdout.
516 - Version (-V) info now goes to stdout.
518 - More #ifdef chud has been added to the parser in attempt to
519 deal with bison's use of alloca().
521 - "make clean" no longer deletes emacs backup files (*~).
523 - Some memory leaks have been fixed.
525 - A bug was fixed in which dynamically-expanded buffers were
526 reallocated a couple of bytes too small.
528 - A bug was fixed which could cause flex to read and write beyond
529 the end of the input buffer.
531 - -S will not be going away.
534 Changes between release 2.4.7 (03Aug94) and release 2.4.6:
536 - Fixed serious bug in reading multiple files.
538 - Fixed bug in scanning NUL's.
540 - Fixed bug in input() returning 8-bit characters.
542 - Fixed bug in matching text with embedded NUL's when
543 using %array or lex compatibility.
545 - Fixed multiple invocations of YY_USER_ACTION when using '|'
546 continuation action.
548 - Minor prototyping fixes.
550 Changes between release 2.4.6 (04Jan94) and release 2.4.5:
552 - Linking with -lfl no longer required if your program includes
553 its own yywrap() and main() functions. (This change will cause
554 problems if you have a non-ANSI compiler on a system for which
555 sizeof(int) != sizeof(void*) or sizeof(int) != sizeof(size_t).)
557 - The use of 'extern "C++"' in FlexLexer.h has been modified to
558 get around an incompatibility with g++'s header files.
560 Changes between release 2.4.5 (11Dec93) and release 2.4.4:
562 - Fixed bug breaking C++ scanners that use REJECT or variable
563 trailing context.
565 - Fixed serious input problem for interactive scanners on
566 systems for which char is unsigned.
568 - Fixed bug in incorrectly treating '$' operator as variable
569 trailing context.
571 - Fixed bug in -CF table representation that could lead to
572 corrupt tables.
574 - Fixed fairly benign memory leak.
576 - Added `extern "C++"' wrapper to FlexLexer.h header. This
577 should overcome the g++ 2.5.X problems mentioned in the
578 NEWS for release 2.4.3.
580 - Changed #include of FlexLexer.h to use <> instead of "".
582 - Added feature to control whether the scanner attempts to
583 refill the input buffer once it's exhausted. This feature
584 will be documented in the 2.5 release.
587 Changes between release 2.4.4 (07Dec93) and release 2.4.3:
589 - Fixed two serious bugs in scanning 8-bit characters.
591 - Fixed bug in YY_USER_ACTION that caused it to be executed
592 inappropriately (on the scanner's own internal actions, and
593 with incorrect yytext/yyleng values).
595 - Fixed bug in pointing yyin at a new file and resuming scanning.
597 - Portability fix regarding min/max/abs macros conflicting with
598 function definitions in standard header files.
600 - Added a virtual LexerError() method to the C++ yyFlexLexer class
601 for reporting error messages instead of always using cerr.
603 - Added warning in flexdoc that the C++ scanning class is presently
604 experimental and subject to considerable change between major
605 releases.
608 Changes between release 2.4.3 (03Dec93) and release 2.4.2:
610 - Fixed bug causing fatal scanner messages to fail to print.
612 - Fixed things so FlexLexer.h can be included in other C++
613 sources. One side-effect of this change is that -+ and -CF
614 are now incompatible.
616 - libfl.a now supplies private versions of the <string.h>/
617 <strings.h> string routines needed by flex and the scanners
618 it generates, to enhance portability to some BSD systems.
620 - More robust solution to 2.4.2's flexfatal() bug fix.
622 - Added ranlib of installed libfl.a.
624 - Some lint tweaks.
626 - NOTE: problems have been encountered attempting to build flex
627 C++ scanners using g++ version 2.5.X. The problem is due to an
628 unfortunate heuristic in g++ 2.5.X that attempts to discern between
629 C and C++ headers. Because FlexLexer.h is installed (by default)
630 in /usr/local/include and not /usr/local/lib/g++-include, g++ 2.5.X
631 decides that it's a C header :-(. So if you have problems, install
632 the header in /usr/local/lib/g++-include instead.
635 Changes between release 2.4.2 (01Dec93) and release 2.4.1:
637 - Fixed bug in libfl.a referring to non-existent "flexfatal" function.
639 - Modified to produce both compress'd and gzip'd tar files for
640 distributions (you probably don't care about this change!).
643 Changes between release 2.4.1 (30Nov93) and release 2.3.8:
645 - The new '-+' flag instructs flex to generate a C++ scanner class
646 (thanks to Kent Williams). flex writes an implementation of the
647 class defined in FlexLexer.h to lex.yy.cc. You may include
648 multiple scanner classes in your program using the -P flag. Note
649 that the scanner class also provides a mechanism for creating
650 reentrant scanners. The scanner class uses C++ streams for I/O
651 instead of FILE*'s (thanks to Tom Epperly). If the flex executable's
652 name ends in '+' then the '-+' flag is automatically on, so creating
653 a symlink or copy of "flex" to "flex++" results in a version of
654 flex that can be used exclusively for C++ scanners.
656 Note that without the '-+' flag, flex-generated scanners can still
657 be compiled using C++ compilers, though they use FILE*'s for I/O
658 instead of streams.
660 See the "GENERATING C++ SCANNERS" section of flexdoc for details.
662 - The new '-l' flag turns on maximum AT&T lex compatibility. In
663 particular, -l includes support for "yylineno" and makes yytext
664 be an array instead of a pointer. It does not, however, do away
665 with all incompatibilities. See the "INCOMPATIBILITIES WITH LEX
666 AND POSIX" section of flexdoc for details.
668 - The new '-P' option specifies a prefix to use other than "yy"
669 for the scanner's globally-visible variables, and for the
670 "lex.yy.c" filename. Using -P you can link together multiple
671 flex scanners in the same executable.
673 - The distribution includes a "texinfo" version of flexdoc.1,
674 contributed by Roland Pesch (thanks also to Marq Kole, who
675 contributed another version). It has not been brought up to
676 date, but reflects version 2.3. See MISC/flex.texinfo.
678 The flex distribution will soon include G.T. Nicol's flex
679 manual; he is presently bringing it up-to-date for version 2.4.
681 - yywrap() is now a function, and you now *must* link flex scanners
682 with libfl.a.
684 - Site-configuration is now done via an autoconf-generated
685 "configure" script contributed by Francois Pinard.
687 - Scanners now use fread() (or getc(), if interactive) and not
688 read() for input. A new "table compression" option, -Cr,
689 overrides this change and causes the scanner to use read()
690 (because read() is a bit faster than fread()). -f and -F
691 are now equivalent to -Cfr and -CFr; i.e., they imply the
692 -Cr option.
694 - In the blessed name of POSIX compliance, flex supports "%array"
695 and "%pointer" directives in the definitions (first) section of
696 the scanner specification. The former specifies that yytext
697 should be an array (of size YYLMAX), the latter, that it should
698 be a pointer. The array version of yytext is universally slower
699 than the pointer version, but has the advantage that its contents
700 remain unmodified across calls to input() and unput() (the pointer
701 version of yytext is, still, trashed by such calls).
703 "%array" cannot be used with the '-+' C++ scanner class option.
705 - The new '-Ca' option directs flex to trade off memory for
706 natural alignment when generating a scanner's tables. In
707 particular, table entries that would otherwise be "short"
708 become "long".
710 - The new '-h' option produces a summary of the flex flags.
712 - The new '-V' option reports the flex version number and exits.
714 - The new scanner macro YY_START returns an integer value
715 corresponding to the current start condition. You can return
716 to that start condition by passing the value to a subsequent
717 "BEGIN" action. You also can implement "start condition stacks"
718 by storing the values in an integer stack.
720 - You can now redefine macros such as YY_INPUT by just #define'ing
721 them to some other value in the first section of the flex input;
722 no need to first #undef them.
724 - flex now generates warnings for rules that can't be matched.
725 These warnings can be turned off using the new '-w' flag. If
726 your scanner uses REJECT then you will not get these warnings.
728 - If you specify the '-s' flag but the default rule can be matched,
729 flex now generates a warning.
731 - "yyleng" is now a global, and may be modified by the user (though
732 doing so and then using yymore() will yield weird results).
734 - Name definitions in the first section of a scanner specification
735 can now include a leading '^' or trailing '$' operator. In this
736 case, the definition is *not* pushed back inside of parentheses.
738 - Scanners with compressed tables are now "interactive" (-I option)
739 by default. You can suppress this attribute (which makes them
740 run slightly slower) using the new '-B' flag.
742 - Flex now generates 8-bit scanners by default, unless you use the
743 -Cf or -CF compression options (-Cfe and -CFe result in 8-bit
744 scanners). You can force it to generate a 7-bit scanner using
745 the new '-7' flag. You can build flex to generate 8-bit scanners
746 for -Cf and -CF, too, by adding -DDEFAULT_CSIZE=256 to CFLAGS
747 in the Makefile.
749 - You no longer need to call the scanner routine yyrestart() to
750 inform the scanner that you have switched to a new file after
751 having seen an EOF on the current input file. Instead, just
752 point yyin at the new file and continue scanning.
754 - You no longer need to invoke YY_NEW_FILE in an <<EOF>> action
755 to indicate you wish to continue scanning. Simply point yyin
756 at a new file.
758 - A leading '#' no longer introduces a comment in a flex input.
760 - flex no longer considers formfeed ('\f') a whitespace character.
762 - %t, I'm happy to report, has been nuked.
764 - The '-p' option may be given twice ('-pp') to instruct flex to
765 report minor performance problems as well as major ones.
767 - The '-v' verbose output no longer includes start/finish time
768 information.
770 - Newlines in flex inputs can optionally include leading or
771 trailing carriage-returns ('\r'), in support of several PC/Mac
772 run-time libraries that automatically include these.
774 - A start condition of the form "<*>" makes the following rule
775 active in every start condition, whether exclusive or inclusive.
777 - The following items have been corrected in the flex documentation:
779 - '-C' table compression options *are* cumulative.
781 - You may modify yytext but not lengthen it by appending
782 characters to the end. Modifying its final character
783 will affect '^' anchoring for the next rule matched
784 if the character is changed to or from a newline.
786 - The term "backtracking" has been renamed "backing up",
787 since it is a one-time repositioning and not a repeated
788 search. What used to be the "lex.backtrack" file is now
789 "lex.backup".
791 - Unindented "/* ... */" comments are allowed in the first
792 flex input section, but not in the second.
794 - yyless() can only be used in the flex input source, not
795 externally.
797 - You can use "yyrestart(yyin)" to throw away the
798 current contents of the input buffer.
800 - To write high-speed scanners, attempt to match as much
801 text as possible with each rule. See MISC/fastwc/README
802 for more information.
804 - Using the beginning-of-line operator ('^') is fairly
805 cheap. Using unput() is expensive. Using yyless() is
806 cheap.
808 - An example of scanning strings with embedded escape
809 sequences has been added.
811 - The example of backing-up in flexdoc was erroneous; it
812 has been corrected.
814 - A flex scanner's internal buffer now dynamically grows if needed
815 to match large tokens. Note that growing the buffer presently
816 requires rescanning the (large) token, so consuming a lot of
817 text this way is a slow process. Also note that presently the
818 buffer does *not* grow if you unput() more text than can fit
819 into the buffer.
821 - The MISC/ directory has been reorganized; see MISC/README for
822 details.
824 - yyless() can now be used in the third (user action) section
825 of a scanner specification, thanks to Ceriel Jacobs. yyless()
826 remains a macro and cannot be used outside of the scanner source.
828 - The skeleton file is no longer opened at run-time, but instead
829 compiled into a large string array (thanks to John Gilmore and
830 friends at Cygnus). You can still use the -S flag to point flex
831 at a different skeleton file.
833 - flex no longer uses a temporary file to store the scanner's
834 actions.
836 - A number of changes have been made to decrease porting headaches.
837 In particular, flex no longer uses memset() or ctime(), and
838 provides a single simple mechanism for dealing with C compilers
839 that still define malloc() as returning char* instead of void*.
841 - Flex now detects if the scanner specification requires the -8 flag
842 but the flag was not given or on by default.
844 - A number of table-expansion fencepost bugs have been fixed,
845 making flex more robust for generating large scanners.
847 - flex more consistently identifies the location of errors in
848 its input.
850 - YY_USER_ACTION is now invoked only for "real" actions, not for
851 internal actions used by the scanner for things like filling
852 the buffer or handling EOF.
854 - The rule "[^]]" now matches any character other than a ']';
855 formerly it matched any character at all followed by a ']'.
856 This change was made for compatibility with AT&T lex.
858 - A large number of miscellaneous bugs have been found and fixed
859 thanks to Gerhard Wilhelms.
861 - The source code has been heavily reformatted, making patches
862 relative to previous flex releases no longer accurate.
865 Changes between 2.3 Patch #8 (21Feb93) and 2.3 Patch #7:
867 - Fixed bugs in dynamic memory allocation leading to grievous
868 fencepost problems when generating large scanners.
869 - Fixed bug causing infinite loops on character classes with 8-bit
870 characters in them.
871 - Fixed bug in matching repetitions with a lower bound of 0.
872 - Fixed bug in scanning NUL characters using an "interactive" scanner.
873 - Fixed bug in using yymore() at the end of a file.
874 - Fixed bug in misrecognizing rules with variable trailing context.
875 - Fixed bug compiling flex on Suns using gcc 2.
876 - Fixed bug in not recognizing that input files with the character
877 ASCII 128 in them require the -8 flag.
878 - Fixed bug that could cause an infinite loop writing out
879 error messages.
880 - Fixed bug in not recognizing old-style lex % declarations if
881 followed by a tab instead of a space.
882 - Fixed potential crash when flex terminated early (usually due
883 to a bad flag) and the -v flag had been given.
884 - Added some missing declarations of void functions.
885 - Changed to only use '\a' for __STDC__ compilers.
886 - Updated mailing addresses.
889 Changes between 2.3 Patch #7 (28Mar91) and 2.3 Patch #6:
891 - Fixed out-of-bounds array access that caused bad tables
892 to be produced on machines where the bad reference happened
893 to yield a 1. This caused problems installing or running
894 flex on some Suns, in particular.
897 Changes between 2.3 Patch #6 (29Aug90) and 2.3 Patch #5:
899 - Fixed a serious bug in yymore() which basically made it
900 completely broken. Thanks goes to Jean Christophe of
901 the Nethack development team for finding the problem
902 and passing along the fix.
905 Changes between 2.3 Patch #5 (16Aug90) and 2.3 Patch #4:
907 - An up-to-date version of initscan.c so "make test" will
908 work after applying the previous patches
911 Changes between 2.3 Patch #4 (14Aug90) and 2.3 Patch #3:
913 - Fixed bug in hexadecimal escapes which allowed only digits,
914 not letters, in escapes
915 - Fixed bug in previous "Changes" file!
918 Changes between 2.3 Patch #3 (03Aug90) and 2.3 Patch #2:
920 - Correction to patch #2 for gcc compilation; thanks goes to
921 Paul Eggert for catching this.
924 Changes between 2.3 Patch #2 (02Aug90) and original 2.3 release:
926 - Fixed (hopefully) headaches involving declaring malloc()
927 and free() for gcc, which defines __STDC__ but (often) doesn't
928 come with the standard include files such as <stdlib.h>.
929 Reordered #ifdef maze in the scanner skeleton in the hope of
930 getting the declarations right for cfront and g++, too.
932 - Note that this patch supercedes patch #1 for release 2.3,
933 which was never announced but was available briefly for
934 anonymous ftp.
937 Changes between 2.3 (full) release of 28Jun90 and 2.2 (alpha) release:
939 User-visible:
941 - A lone <<EOF>> rule (that is, one which is not qualified with
942 a list of start conditions) now specifies the EOF action for
943 *all* start conditions which haven't already had <<EOF>> actions
944 given. To specify an end-of-file action for just the initial
945 state, use <INITIAL><<EOF>>.
947 - -d debug output is now contigent on the global yy_flex_debug
948 being set to a non-zero value, which it is by default.
950 - A new macro, YY_USER_INIT, is provided for the user to specify
951 initialization action to be taken on the first call to the
952 scanner. This action is done before the scanner does its
953 own initialization.
955 - yy_new_buffer() has been added as an alias for yy_create_buffer()
957 - Comments beginning with '#' and extending to the end of the line
958 now work, but have been deprecated (in anticipation of making
959 flex recognize #line directives).
961 - The funky restrictions on when semi-colons could follow the
962 YY_NEW_FILE and yyless macros have been removed. They now
963 behave identically to functions.
965 - A bug in the sample redefinition of YY_INPUT in the documentation
966 has been corrected.
968 - A bug in the sample simple tokener in the documentation has
969 been corrected.
971 - The documentation on the incompatibilities between flex and
972 lex has been reordered so that the discussion of yylineno
973 and input() come first, as it's anticipated that these will
974 be the most common source of headaches.
977 Things which didn't used to be documented but now are:
979 - flex interprets "^foo|bar" differently from lex. flex interprets
980 it as "match either a 'foo' or a 'bar', providing it comes at the
981 beginning of a line", whereas lex interprets it as "match either
982 a 'foo' at the beginning of a line, or a 'bar' anywhere".
984 - flex initializes the global "yyin" on the first call to the
985 scanner, while lex initializes it at compile-time.
987 - yy_switch_to_buffer() can be used in the yywrap() macro/routine.
989 - flex scanners do not use stdio for their input, and hence when
990 writing an interactive scanner one must explicitly call fflush()
991 after writing out a prompt.
993 - flex scanner can be made reentrant (after a fashion) by using
994 "yyrestart( yyin );". This is useful for interactive scanners
995 which have interrupt handlers that long-jump out of the scanner.
997 - a defense of why yylineno is not supported is included, along
998 with a suggestion on how to convert scanners which rely on it.
1001 Other changes:
1003 - Prototypes and proper declarations of void routines have
1004 been added to the flex source code, courtesy of Kevin B. Kenny.
1006 - Routines dealing with memory allocation now use void* pointers
1007 instead of char* - see Makefile for porting implications.
1009 - Error-checking is now done when flex closes a file.
1011 - Various lint tweaks were added to reduce the number of gripes.
1013 - Makefile has been further parameterized to aid in porting.
1015 - Support for SCO Unix added.
1017 - Flex now sports the latest & greatest UC copyright notice
1018 (which is only slightly different from the previous one).
1020 - A note has been added to flexdoc.1 mentioning work in progress
1021 on modifying flex to generate straight C code rather than a
1022 table-driven automaton, with an email address of whom to contact
1023 if you are working along similar lines.
1026 Changes between 2.2 Patch #3 (30Mar90) and 2.2 Patch #2:
1028 - fixed bug which caused -I scanners to bomb
1031 Changes between 2.2 Patch #2 (27Mar90) and 2.2 Patch #1:
1033 - fixed bug writing past end of input buffer in yyunput()
1034 - fixed bug detecting NUL's at the end of a buffer
1037 Changes between 2.2 Patch #1 (23Mar90) and 2.2 (alpha) release:
1039 - Makefile fixes: definition of MAKE variable for systems
1040 which don't have it; installation of flexdoc.1 along with
1041 flex.1; fixed two bugs which could cause "bigtest" to fail.
1043 - flex.skel fix for compiling with g++.
1045 - README and flexdoc.1 no longer list an out-of-date BITNET address
1046 for contacting me.
1048 - minor typos and formatting changes to flex.1 and flexdoc.1.
1051 Changes between 2.2 (alpha) release of March '90 and previous release:
1053 User-visible:
1055 - Full user documentation now available.
1057 - Support for 8-bit scanners.
1059 - Scanners now accept NUL's.
1061 - A facility has been added for dealing with multiple
1062 input buffers.
1064 - Two manual entries now. One which fully describes flex
1065 (rather than just its differences from lex), and the
1066 other for quick(er) reference.
1068 - A number of changes to bring flex closer into compliance
1069 with the latest POSIX lex draft:
1071 %t support
1072 flex now accepts multiple input files and concatenates
1073 them together to form its input
1074 previous -c (compress) flag renamed -C
1075 do-nothing -c and -n flags added
1076 Any indented code or code within %{}'s in section 2 is
1077 now copied to the output
1079 - yyleng is now a bona fide global integer.
1081 - -d debug information now gives the line number of the
1082 matched rule instead of which number rule it was from
1083 the beginning of the file.
1085 - -v output now includes a summary of the flags used to generate
1086 the scanner.
1088 - unput() and yyrestart() are now globally callable.
1090 - yyrestart() no longer closes the previous value of yyin.
1092 - C++ support; generated scanners can be compiled with C++ compiler.
1094 - Primitive -lfl library added, containing default main()
1095 which calls yylex(). A number of routines currently living
1096 in the scanner skeleton will probably migrate to here
1097 in the future (in particular, yywrap() will probably cease
1098 to be a macro and instead be a function in the -lfl library).
1100 - Hexadecimal (\x) escape sequences added.
1102 - Support for MS-DOS, VMS, and Turbo-C integrated.
1104 - The %used/%unused operators have been deprecated. They
1105 may go away soon.
1108 Other changes:
1110 - Makefile enhanced for easier testing and installation.
1111 - The parser has been tweaked to detect some erroneous
1112 constructions which previously were missed.
1113 - Scanner input buffer overflow is now detected.
1114 - Bugs with missing "const" declarations fixed.
1115 - Out-of-date Minix/Atari patches provided.
1116 - Scanners no longer require printf() unless FLEX_DEBUG is being used.
1117 - A subtle input() bug has been fixed.
1118 - Line numbers for "continued action" rules (those following
1119 the special '|' action) are now correct.
1120 - unput() bug fixed; had been causing problems porting flex to VMS.
1121 - yymore() handling rewritten to fix bug with interaction
1122 between yymore() and trailing context.
1123 - EOF in actions now generates an error message.
1124 - Bug involving -CFe and generating equivalence classes fixed.
1125 - Bug which made -CF be treated as -Cf fixed.
1126 - Support for SysV tmpnam() added.
1127 - Unused #define's for scanner no longer generated.
1128 - Error messages which are associated with a particular input
1129 line are now all identified with their input line in standard
1130 format.
1131 - % directives which are valid to lex but not to flex are
1132 now ignored instead of generating warnings.
1133 - -DSYS_V flag can now also be specified -DUSG for System V
1134 compilation.
1137 Changes between 2.1 beta-test release of June '89 and previous release:
1139 User-visible:
1141 - -p flag generates a performance report to stderr. The report
1142 consists of comments regarding features of the scanner rules
1143 which result in slower scanners.
1145 - -b flag generates backtracking information to lex.backtrack.
1146 This is a list of scanner states which require backtracking
1147 and the characters on which they do so. By adding rules
1148 one can remove backtracking states. If all backtracking states
1149 are eliminated, the generated scanner will run faster.
1150 Backtracking is not yet documented in the manual entry.
1152 - Variable trailing context now works, i.e., one can have
1153 rules like "(foo)*/[ \t]*bletch". Some trailing context
1154 patterns still cannot be properly matched and generate
1155 error messages. These are patterns where the ending of the
1156 first part of the rule matches the beginning of the second
1157 part, such as "zx*/xy*", where the 'x*' matches the 'x' at
1158 the beginning of the trailing context. Lex won't get these
1159 patterns right either.
1161 - Faster scanners.
1163 - End-of-file rules. The special rule "<<EOF>>" indicates
1164 actions which are to be taken when an end-of-file is
1165 encountered and yywrap() returns non-zero (i.e., indicates
1166 no further files to process). See manual entry for example.
1168 - The -r (reject used) flag is gone. flex now scans the input
1169 for occurrences of the string "REJECT" to determine if the
1170 action is needed. It tries to be intelligent about this but
1171 can be fooled. One can force the presence or absence of
1172 REJECT by adding a line in the first section of the form
1173 "%used REJECT" or "%unused REJECT".
1175 - yymore() has been implemented. Similarly to REJECT, flex
1176 detects the use of yymore(), which can be overridden using
1177 "%used" or "%unused".
1179 - Patterns like "x{0,3}" now work (i.e., with lower-limit == 0).
1181 - Removed '\^x' for ctrl-x misfeature.
1183 - Added '\a' and '\v' escape sequences.
1185 - \<digits> now works for octal escape sequences; previously
1186 \0<digits> was required.
1188 - Better error reporting; line numbers are associated with rules.
1190 - yyleng is a macro; it cannot be accessed outside of the
1191 scanner source file.
1193 - yytext and yyleng should not be modified within a flex action.
1195 - Generated scanners #define the name FLEX_SCANNER.
1197 - Rules are internally separated by YY_BREAK in lex.yy.c rather
1198 than break, to allow redefinition.
1200 - The macro YY_USER_ACTION can be redefined to provide an action
1201 which is always executed prior to the matched rule's action.
1203 - yyrestart() is a new action which can be used to restart
1204 the scanner after it has seen an end-of-file (a "real" one,
1205 that is, one for which yywrap() returned non-zero). It takes
1206 a FILE* argument indicating a new file to scan and sets
1207 things up so that a subsequent call to yylex() will start
1208 scanning that file.
1210 - Internal scanner names all preceded by "yy_"
1212 - lex.yy.c is deleted if errors are encountered during processing.
1214 - Comments may be put in the first section of the input by preceding
1215 them with '#'.
1219 Other changes:
1221 - Some portability-related bugs fixed, in particular for machines
1222 with unsigned characters or sizeof( int* ) != sizeof( int ).
1223 Also, tweaks for VMS and Microsoft C (MS-DOS), and identifiers all
1224 trimmed to be 31 or fewer characters. Shortened file names
1225 for dinosaur OS's. Checks for allocating > 64K memory
1226 on 16 bit'ers. Amiga tweaks. Compiles using gcc on a Sun-3.
1227 - Compressed and fast scanner skeletons merged.
1228 - Skeleton header files done away with.
1229 - Generated scanner uses prototypes and "const" for __STDC__.
1230 - -DSV flag is now -DSYS_V for System V compilation.
1231 - Removed all references to FTL language.
1232 - Software now covered by BSD Copyright.
1233 - flex will replace lex in subsequent BSD releases.