-Changes between release 2.4 (04Oct93) and release 2.3:
-
-skeleton file: John Gilmore
- flex.skel -> flex.skl
- -S to go away unless hear it's useful
-yywrap() a function
-must link with libfl.a
-C++: Kent Williams
- use for reentrant scanners
- C++ streams: Tom Epperly
- lex.yy.cc
- FlexLexer.h
- flex++
-no temp file
-manual/
-detects if -8 flag needed
--h for help
-buffer dynamically enlarges; but *slow* to match big tokens
- and doesn't do so on unput()
-fewer porting headaches; memset(), malloc() type in particular
-MISC/
--P prefix
--V
-<*>
-%array/%pointer
- use %array to avoid input()/unput() trashing yytext
- YYLMAX
- not with -+
-flex -V
--8 by default (except -C{f,F}?); -7 supported
--A align option, promotes short -> long
-number of fencepost table expansion bugs fixed
-YY_START: integer value, can do stacks
-yyrestart() no longer needed; just point yyin at a new file
-fencepost bug fixes
-'#' no longer a comment character
-\n in flex input can optionally include leading or trailing \r
-warnings for rules that can't be matched; REJECT obviates
-more consistent identification of error locations
-yyleng a global
-definitions can now include leading '^' or trailing '$'
-scanners are -I interactive if compressed, by default; -B
-warnings for unmatchable rules; if -s given but default rule can be matched
-YY_USER_ACTION only called for real actions
-many misc bug fixes thanks to Gerhard Wilhelms
-\n\r stuff
-yyless() usable in section 3 (Ceriel Jacobs)
-formfeed no longer a whitespace character
-run-time detection of out-of-range characters (8 bit when built for 7 bit)
-%t nuked
-yyleng may be modified
--w: suppress warnings
--p -p: report minor performance problems, too
-no more time information in -v output
-MISC/fastwc
-MISC/debflex.awk (Francois)
-MISC/testxxLexerl.l
-YY_NEW_FILE no longer needed
-definitions with ^, $ allowed; not expanded inside parens
-version.h
-
-corrected doc: -C options are cumulative
- may modify yytext but not lengthen it (append chars)
- modifying last char may affect anchoring
- backtracking -> backing up
- unindented comments allowed in first section, but not in second
- yyless() only usable in scanner source, not externally
- yyrestart(yyin) throws away current buffer
- high-speed scanners: match as much text as possible w/ each rule
- beginning-of-line operator is fairly cheap
- unput() expensive, yyless() cheap
- corrected backing-up example
-
-code reformatted
+Changes between release 2.4 (09Nov93) and release 2.3:
+
+ - The new '-+' flag instructs flex to generate a C++ scanner class
+ (thanks to Kent Williams). flex writes an implementation of the
+ class defined in FlexLexer.h to lex.yy.cc. You may include
+ multiple scanner classes in your program using the -P flag. Note
+ that the scanner class also provides a mechanism for creating
+ reentrant scanners. The scanner class uses C++ streams for I/O
+ instead of FILE*'s (thanks to Tom Epperly). If the flex executable's
+ name ends in '+' then the '-+' flag is automatically on, so creating
+ a symlink or copy of "flex" to "flex++" results in a version of
+ flex that can be used exclusively for C++ scanners.
+
+ Note that without the '-+' flag, flex-generated scanners can still
+ be compiled using C++ compilers, though they use FILE*'s for I/O
+ instead of streams.
+
+ See the "GENERATING C++ SCANNERS" section of flexdoc for details.
+
+ - The new '-P' option specifies a prefix to use other than "yy"
+ for the scanner's globally-visible variables, and for the
+ "lex.yy.c" filename. Using -P you can link together multiple
+ flex scanners in the same executable.
+
+ - The distribution includes G.T. Nicol's flex manual (note
+ that the manual has not yet been brought up to date; it
+ presently reflects flex version 2.3). See the manual/
+ subdirectory. Note that the PostScript for the manual
+ presently lacks an index; this will be fixed soon.
+
+ The distribution also includes a "texinfo" version of flexdoc.1,
+ contributed by Roland Pesch (thanks also to Marq Kole, who
+ contributed another version). It also has not been brought
+ up to date, but reflects version 2.3. See MISC/flex.texinfo.
+
+ - yywrap() is now a function, and you now *must* link flex scanners
+ with libfl.a.
+
+ - In the blessed name of POSIX compliance, flex supports "%array"
+ and "%pointer" directives in the definitions (first) section of
+ the scanner specification. The former specifies that yytext
+ should be an array (of size YYLMAX), the latter, that it should
+ be a pointer. The array version of yytext is universally slower
+ than the pointer version, but has the advantage that its contents
+ remain unmodified across calls to input() and unput() (the pointer
+ version of yytext is, still, trashed by such calls).
+
+ "%array" cannot be used with the '-+' C++ scanner class option.
+
+ - The new '-a' option directs flex to trade off memory for
+ natural alignment when generating a scanner's tables. In
+ particular, table entries that would otherwise be "short"
+ become "long".
+
+ - The new '-h' option produces a summary of the flex flags.
+
+ - The new '-V' option reports the flex version number and exits.
+
+ - The new scanner macro YY_START returns an integer value
+ corresponding to the current start condition. You can return
+ to that start condition by passing the value to a subsequent
+ "BEGIN" action. You also can implement "start condition stacks"
+ by storing the values in an integer stack.
+
+ - flex now generates warnings for rules that can't be matched.
+ These warnings can be turned off using the new '-w' flag. If
+ your scanner uses REJECT then you will not get these warnings.
+
+ - If you specify the '-s' flag but the default rule can be matched,
+ flex now generates a warning.
+
+ - "yyleng" is now a global, and may be modified by the user (though
+ doing so and then using yymore() will yield weird results).
+
+ - Name definitions in the first section of a scanner specification
+ can now include a leading '^' or trailing '$' operator. In this
+ case, the definition is *not* pushed back inside of parentheses.
+
+ - Scanners with compressed tables are now "interactive" (-I option)
+ by default. You can suppress this attribute (which makes them
+ run slighly slower) using the new '-B' flag.
+
+ - Flex now generates 8-bit scanners by default, unless you use the
+ -Cf or -CF compression options (-Cfe and -CFe result in 8-bit
+ scanners). You can force it to generate a 7-bit scanner using
+ the new '-7' flag. You can build flex to generate 8-bit scanners
+ for -Cf and -CF, too, by adding -DDEFAULT_CSIZE=256 to CFLAGS
+ in the Makefile.
+
+ - You no longer need to call the scanner routine yyrestart() to
+ inform the scanner that you have switched to a new file after
+ having seen an EOF on the current input file. Instead, just
+ point yyin at the new file and continue scanning.
+
+ - You no longer need to invoke YY_NEW_FILE in an <<EOF>> action
+ to indicate you wish to continue scanning. Simply point yyin
+ at a new file.
+
+ - A leading '#' no longer introduces a comment in a flex input.
+
+ - flex no longer considers formfeed ('\f') a whitespace character.
+
+ - %t, I'm happy to report, has been nuked.
+
+ - The '-p' option may be given twice ('-pp') to instruct flex to
+ report minor performance problems as well as major ones.
+
+ - The '-v' verbose output no longer includes start/finish time
+ information.
+
+ - Newlines in flex inputs can optionally include leading or
+ trailing carriage-returns ('\r'), in support of several PC/Mac
+ run-time libraries that automatically include these.
+
+ - A start condition of the form "<*>" makes the following rule
+ active in every start condition, whether exclusive or inclusive.
+
+ - The following items have been corrected in the flex documentation:
+
+ - '-C' table compression options *are* cumulative.
+
+ - You may modify yytext but not lengthen it by appending
+ characters to the end. Modifying its final character
+ will affect '^' anchoring for the next rule matched
+ if the character is changed to or from a newline.
+
+ - The term "backtracking" has been renamed "backing up",
+ since it is a one-time repositioning and not a repeated
+ search. What used to be the "lex.backtrack" file is now
+ "lex.backup".
+
+ - Unindented "/* ... */" comments are allowed in the first
+ flex input section, but not in the second.
+
+ - yyless() can only be used in the flex input source, not
+ externally.
+
+ - You can use "yyrestart(yyin)" to throw away the
+ current contents of the input buffer.
+
+ - To write high-speed scanners, attempt to match as much
+ text as possible with each rule. See MISC/fastwc/README
+ for more information.
+
+ - Using the beginning-of-line operator ('^') is fairly
+ cheap. Using unput() is expensive. Using yyless() is
+ cheap.
+
+ - An example of scanning strings with embedded escape
+ sequences has been added.
+
+ - The example of backing-up in flexdoc was erroneous; it
+ has been corrected.
+
+ - A flex scanner's internal buffer now dynamically grows if needed
+ to match large tokens. Note that growing the buffer presently
+ requires rescanning the (large) token, so consuming a lot of
+ text this way is a slow process. Also note that presently the
+ buffer does *not* grow if you unput() more text than can fit
+ into the buffer.
+
+ - The MISC/ directory has been reorganized; see MISC/README for
+ details.
+
+ - yyless() can now be used in the third (user action) section
+ of a scanner specification, thanks to Ceriel Jacobs. yyless()
+ remains a macro and cannot be used outside of the scanner source.
+
+ - The skeleton file is no longer opened at run-time, but instead
+ compiled into a large string array (thanks to John Gilmore and
+ friends at Cygnus). You can still use the -S flag to point flex
+ at a different skeleton file, though if you use this option let
+ me know, as I plan to otherwise do away with -S in the near
+ future.
+
+ - flex no longer uses a temporary file to store the scanner's
+ actions.
+
+ - A number of changes have been made to decrease porting headaches.
+ In particular, flex no longer uses memset() or ctime(), and
+ provides a single simple mechanism for dealing with C compilers
+ that still define malloc() as returning char* instead of void*.
+
+ - Flex now detects if the scanner specification requires the -8 flag
+ but the flag was not given or on by default.
+
+ - A number of table-expansion fencepost bugs have been fixed,
+ making flex more robust for generating large scanners.
+
+ - flex more consistently identifies the location of errors in
+ its input.
+
+ - YY_USER_ACTION is now invoked only for "real" actions, not for
+ internal actions used by the scanner for things like filling
+ the buffer or handling EOF.
+
+ - A large number of miscellaneous bugs have been found and fixed
+ thanks to Gerhard Wilhelms.
+
+ - The source code has been heavily reformatted, making patches
+ relative to previous flex releases no longer accurate.
+
Changes between 2.3 Patch #8 (21Feb93) and 2.3 Patch #7:
projects / flex / commitdiff