diff options
Diffstat (limited to 'usr.bin/lex/NEWS')
| -rw-r--r-- | usr.bin/lex/NEWS | 527 |
1 files changed, 523 insertions, 4 deletions
diff --git a/usr.bin/lex/NEWS b/usr.bin/lex/NEWS index aff90a3..e4ba93f 100644 --- a/usr.bin/lex/NEWS +++ b/usr.bin/lex/NEWS @@ -1,3 +1,525 @@ +Changes between release 2.5.3 (29May96) and release 2.5.2: + + - Some serious bugs in yymore() have been fixed. In particular, + when using AT&T-lex-compatibility or %array, you can intermix + calls to input(), unput(), and yymore(). (This still doesn't + work for %pointer, and isn't likely to in the future.) + + - A bug in handling NUL's in the input stream of scanners using + REJECT has been fixed. + + - The default main() in libfl.a now repeatedly calls yylex() until + it returns 0, rather than just calling it once. + + - Minor tweak for Windows NT Makefile, MISC/NT/Makefile. + + +Changes between release 2.5.2 (25Apr95) and release 2.5.1: + + - The --prefix configuration option now works. + + - A bug that completely broke the "-Cf" table compression + option has been fixed. + + - A major headache involving "const" declarators and Solaris + systems has been fixed. + + - An octal escape sequence in a flex regular expression must + now contain only the digits 0-7. + + - You can now use "--" on the flex command line to mark the + end of flex options. + + - You can now specify the filename '-' as a synonym for stdin. + + - By default, the scanners generated by flex no longer + statically initialize yyin and yyout to stdin and stdout. + This change is necessary because in some ANSI environments, + stdin and stdout are not compile-time constant. You can + force the initialization using "%option stdinit" in the first + section of your flex input. + + - "%option nounput" now correctly omits the unput() routine + from the output. + + - "make clean" now removes config.log, config.cache, and the + flex binary. The fact that it removes the flex binary means + you should take care if making changes to scan.l, to make + sure you don't wind up in a bootstrap problem. + + - In general, the Makefile has been reworked somewhat (thanks + to Francois Pinard) for added flexibility - more changes will + follow in subsequent releases. + + - The .texi and .info files in MISC/texinfo/ have been updated, + thanks also to Francois Pinard. + + - The FlexLexer::yylex(istream* new_in, ostream* new_out) method + now does not have a default for the first argument, to disambiguate + it from FlexLexer::yylex(). + + - A bug in destructing a FlexLexer object before doing any scanning + with it has been fixed. + + - A problem with including FlexLexer.h multiple times has been fixed. + + - The alloca() chud necessary to accommodate bison has grown + even uglier, but hopefully more correct. + + - A portability tweak has been added to accommodate compilers that + use char* generic pointers. + + - EBCDIC contact information in the file MISC/EBCDIC has been updated. + + - An OS/2 Makefile and config.h for flex 2.5 is now available in + MISC/OS2/, contributed by Kai Uwe Rommel. + + - The descrip.mms file for building flex under VMS has been updated, + thanks to Pat Rankin. + + - The notes on building flex for the Amiga have been updated for + flex 2.5, contributed by Andreas Scherer. + + +Changes between release 2.5.1 (28Mar95) and release 2.4.7: + + - A new concept of "start condition" scope has been introduced. + A start condition scope is begun with: + + <SCs>{ + + where SCs is a list of one or more start conditions. Inside + the start condition scope, every rule automatically has the + prefix <SCs> applied to it, until a '}' which matches the + initial '{'. So, for example: + + <ESC>{ + "\\n" return '\n'; + "\\r" return '\r'; + "\\f" return '\f'; + "\\0" return '\0'; + } + + is equivalent to: + + <ESC>"\\n" return '\n'; + <ESC>"\\r" return '\r'; + <ESC>"\\f" return '\f'; + <ESC>"\\0" return '\0'; + + As indicated in this example, rules inside start condition scopes + (and any rule, actually, other than the first) can be indented, + to better show the extent of the scope. + + Start condition scopes may be nested. + + - The new %option directive can be used in the first section of + a flex scanner to control scanner-generation options. Most + options are given simply as names, optionally preceded by the + word "no" (with no intervening whitespace) to negate their + meaning. Some are equivalent to flex flags, so putting them + in your scanner source is equivalent to always specifying + the flag (%option's take precedence over flags): + + 7bit -7 option + 8bit -8 option + align -Ca option + backup -b option + batch -B option + c++ -+ option + caseful opposite of -i option (caseful is the default); + case-sensitive same as above + caseless -i option; + case-insensitive same as above + debug -d option + default opposite of -s option + ecs -Ce option + fast -F option + full -f option + interactive -I option + lex-compat -l option + meta-ecs -Cm option + perf-report -p option + read -Cr option + stdout -t option + verbose -v option + warn opposite of -w option (so use "%option nowarn" for -w) + + array equivalent to "%array" + pointer equivalent to "%pointer" (default) + + Some provide new features: + + always-interactive generate a scanner which always + considers its input "interactive" (no call to isatty() + will be made when the scanner runs) + main supply a main program for the scanner, which + simply calls yylex(). Implies %option noyywrap. + never-interactive generate a scanner which never + considers its input "interactive" (no call to isatty() + will be made when the scanner runs) + stack if set, enable start condition stacks (see below) + stdinit if unset ("%option nostdinit"), initialize yyin + and yyout statically to nil FILE* pointers, instead + of stdin and stdout + yylineno if set, keep track of the current line + number in global yylineno (this option is expensive + in terms of performance). The line number is available + to C++ scanning objects via the new member function + lineno(). + yywrap if unset ("%option noyywrap"), scanner does not + call yywrap() upon EOF but simply assumes there + are no more files to scan + + Flex scans your rule actions to determine whether you use the + REJECT or yymore features (this is not new). Two %options can be + used to override its decision, either by setting them to indicate + the feature is indeed used, or unsetting them to indicate it + actually is not used: + + reject + yymore + + Three %option's take string-delimited values, offset with '=': + + outfile="<name>" equivalent to -o<name> + prefix="<name>" equivalent to -P<name> + yyclass="<name>" set the name of the C++ scanning class + (see below) + + A number of %option's are available for lint purists who + want to suppress the appearance of unneeded routines in + the generated scanner. Each of the following, if unset, + results in the corresponding routine not appearing in the + generated scanner: + + input, unput + yy_push_state, yy_pop_state, yy_top_state + yy_scan_buffer, yy_scan_bytes, yy_scan_string + + You can specify multiple options with a single %option directive, + and multiple directives in the first section of your flex input file. + + - The new function: + + YY_BUFFER_STATE yy_scan_string( const char *str ) + + returns a YY_BUFFER_STATE (which also becomes the current input + buffer) for scanning the given string, which occurs starting + with the next call to yylex(). The string must be NUL-terminated. + A related function: + + YY_BUFFER_STATE yy_scan_bytes( const char *bytes, int len ) + + creates a buffer for scanning "len" bytes (including possibly NUL's) + starting at location "bytes". + + Note that both of these functions create and scan a *copy* of + the string/bytes. (This may be desirable, since yylex() modifies + the contents of the buffer it is scanning.) You can avoid the + copy by using: + + YY_BUFFER_STATE yy_scan_buffer( char *base, yy_size_t size ) + + which scans in place the buffer starting at "base", consisting + of "size" bytes, the last two bytes of which *must* be + YY_END_OF_BUFFER_CHAR (these bytes are not scanned; thus, scanning + consists of base[0] through base[size-2], inclusive). If you + fail to set up "base" in this manner, yy_scan_buffer returns a + nil pointer instead of creating a new input buffer. + + The type yy_size_t is an integral type to which you can cast + an integer expression reflecting the size of the buffer. + + - Three new routines are available for manipulating stacks of + start conditions: + + void yy_push_state( int new_state ) + + pushes the current start condition onto the top of the stack + and BEGIN's "new_state" (recall that start condition names are + also integers). + + void yy_pop_state() + + pops the top of the stack and BEGIN's to it, and + + int yy_top_state() + + returns the top of the stack without altering the stack's + contents. + + The start condition stack grows dynamically and so has no built-in + size limitation. If memory is exhausted, program execution + is aborted. + + To use start condition stacks, your scanner must include + a "%option stack" directive. + + - flex now supports POSIX character class expressions. These + are expressions enclosed inside "[:" and ":]" delimiters (which + themselves must appear between the '[' and ']' of a character + class; other elements may occur inside the character class, too). + The expressions flex recognizes are: + + [:alnum:] [:alpha:] [:blank:] [:cntrl:] [:digit:] [:graph:] + [:lower:] [:print:] [:punct:] [:space:] [:upper:] [:xdigit:] + + These expressions all designate a set of characters equivalent to + the corresponding isXXX function (for example, [:alnum:] designates + those characters for which isalnum() returns true - i.e., any + alphabetic or numeric). Some systems don't provide isblank(), + so flex defines [:blank:] as a blank or a tab. + + For example, the following character classes are all equivalent: + + [[:alnum:]] + [[:alpha:][:digit:] + [[:alpha:]0-9] + [a-zA-Z0-9] + + If your scanner is case-insensitive (-i flag), then [:upper:] + and [:lower:] are equivalent to [:alpha:]. + + - The promised rewrite of the C++ FlexLexer class has not yet + been done. Support for FlexLexer is limited at the moment to + fixing show-stopper bugs, so, for example, the new functions + yy_scan_string() & friends are not available to FlexLexer + objects. + + - The new macro + + yy_set_interactive(is_interactive) + + can be used to control whether the current buffer is considered + "interactive". An interactive buffer is processed more slowly, + but must be used when the scanner's input source is indeed + interactive to avoid problems due to waiting to fill buffers + (see the discussion of the -I flag in flex.1). A non-zero value + in the macro invocation marks the buffer as interactive, a zero + value as non-interactive. Note that use of this macro overrides + "%option always-interactive" or "%option never-interactive". + + yy_set_interactive() must be invoked prior to beginning to + scan the buffer. + + - The new macro + + yy_set_bol(at_bol) + + can be used to control whether the current buffer's scanning + context for the next token match is done as though at the + beginning of a line (non-zero macro argument; makes '^' anchored + rules active) or not at the beginning of a line (zero argument, + '^' rules inactive). + + - Related to this change, the mechanism for determining when a scan is + starting at the beginning of a line has changed. It used to be + that '^' was active iff the character prior to that at which the + scan started was a newline. The mechanism now is that '^' is + active iff the last token ended in a newline (or the last call to + input() returned a newline). For most users, the difference in + mechanisms is negligible. Where it will make a difference, + however, is if unput() or yyless() is used to alter the input + stream. When in doubt, use yy_set_bol(). + + - The new beginning-of-line mechanism involved changing some fairly + twisted code, so it may have introduced bugs - beware ... + + - The macro YY_AT_BOL() returns true if the next token scanned from + the current buffer will have '^' rules active, false otherwise. + + - The new function + + void yy_flush_buffer( struct yy_buffer_state* b ) + + flushes the contents of the current buffer (i.e., next time + the scanner attempts to match a token using b as the current + buffer, it will begin by invoking YY_INPUT to fill the buffer). + This routine is also available to C++ scanners (unlike some + of the other new routines). + + The related macro + + YY_FLUSH_BUFFER + + flushes the contents of the current buffer. + + - A new "-ooutput" option writes the generated scanner to "output". + If used with -t, the scanner is still written to stdout, but + its internal #line directives (see previous item) use "output". + + - Flex now generates #line directives relating the code it + produces to the output file; this means that error messages + in the flex-generated code should be correctly pinpointed. + + - When generating #line directives, filenames with embedded '\'s + have those characters escaped (i.e., turned into '\\'). This + feature helps with reporting filenames for some MS-DOS and OS/2 + systems. + + - The FlexLexer class includes two new public member functions: + + virtual void switch_streams( istream* new_in = 0, + ostream* new_out = 0 ) + + reassigns yyin to new_in (if non-nil) and yyout to new_out + (ditto), deleting the previous input buffer if yyin is + reassigned. It is used by: + + int yylex( istream* new_in = 0, ostream* new_out = 0 ) + + which first calls switch_streams() and then returns the value + of calling yylex(). + + - C++ scanners now have yy_flex_debug as a member variable of + FlexLexer rather than a global, and member functions for testing + and setting it. + + - When generating a C++ scanning class, you can now use + + %option yyclass="foo" + + to inform flex that you have derived "foo" as a subclass of + yyFlexLexer, so flex will place your actions in the member + function foo::yylex() instead of yyFlexLexer::yylex(). It also + generates a yyFlexLexer::yylex() member function that generates a + run-time error if called (by invoking yyFlexLexer::LexerError()). + This feature is necessary if your subclass "foo" introduces some + additional member functions or variables that you need to access + from yylex(). + + - Current texinfo files in MISC/texinfo, contributed by Francois + Pinard. + + - You can now change the name "flex" to something else (e.g., "lex") + by redefining $(FLEX) in the Makefile. + + - Two bugs (one serious) that could cause "bigcheck" to fail have + been fixed. + + - A number of portability/configuration changes have been made + for easier portability. + + - You can use "YYSTATE" in your scanner as an alias for YY_START + (for AT&T lex compatibility). + + - input() now maintains yylineno. + + - input() no longer trashes yytext. + + - interactive scanners now read characters in YY_INPUT up to a + newline, a large performance gain. + + - C++ scanner objects now work with the -P option. You include + <FlexLexer.h> once per scanner - see comments in <FlexLexer.h> + (or flex.1) for details. + + - C++ FlexLexer objects now use the "cerr" stream to report -d output + instead of stdio. + + - The -c flag now has its full glorious POSIX interpretation (do + nothing), rather than being interpreted as an old-style -C flag. + + - Scanners generated by flex now include two #define's giving + the major and minor version numbers (YY_FLEX_MAJOR_VERSION, + YY_FLEX_MINOR_VERSION). These can then be tested to see + whether certain flex features are available. + + - Scanners generated using -l lex compatibility now have the symbol + YY_FLEX_LEX_COMPAT #define'd. + + - When initializing (i.e., yy_init is non-zero on entry to yylex()), + generated scanners now set yy_init to zero before executing + YY_USER_INIT. This means that you can set yy_init back to a + non-zero value in YY_USER_INIT if you need the scanner to be + reinitialized on the next call. + + - You can now use "#line" directives in the first section of your + scanner specification. + + - When generating full-table scanners (-Cf), flex now puts braces + around each row of the 2-d array initialization, to silence warnings + on over-zealous compilers. + + - Improved support for MS-DOS. The flex sources have been successfully + built, unmodified, for Borland 4.02 (all that's required is a + Borland Makefile and config.h file, which are supplied in + MISC/Borland - contributed by Terrence O Kane). + + - Improved support for Macintosh using Think C - the sources should + build for this platform "out of the box". Contributed by Scott + Hofmann. + + - Improved support for VMS, in MISC/VMS/, contributed by Pat Rankin. + + - Support for the Amiga, in MISC/Amiga/, contributed by Andreas + Scherer. Note that the contributed files were developed for + flex 2.4 and have not been tested with flex 2.5. + + - Some notes on support for the NeXT, in MISC/NeXT, contributed + by Raf Schietekat. + + - The MISC/ directory now includes a preformatted version of flex.1 + in flex.man, and pre-yacc'd versions of parse.y in parse.{c,h}. + + - The flex.1 and flexdoc.1 manual pages have been merged. There + is now just one document, flex.1, which includes an overview + at the beginning to help you find the section you need. + + - Documentation now clarifies that start conditions persist across + switches to new input files or different input buffers. If you + want to e.g., return to INITIAL, you must explicitly do so. + + - The "Performance Considerations" section of the manual has been + updated. + + - Documented the "yy_act" variable, which when YY_USER_ACTION is + invoked holds the number of the matched rule, and added an + example of using yy_act to profile how often each rule is matched. + + - Added YY_NUM_RULES, a definition that gives the total number + of rules in the file, including the default rule (even if you + use -s). + + - Documentation now clarifies that you can pass a nil FILE* pointer + to yy_create_buffer() or yyrestart() if you've arrange YY_INPUT + to not need yyin. + + - Documentation now clarifies that YY_BUFFER_STATE is a pointer to + an opaque "struct yy_buffer_state". + + - Documentation now stresses that you gain the benefits of removing + backing-up states only if you remove *all* of them. + + - Documentation now points out that traditional lex allows you + to put the action on a separate line from the rule pattern if + the pattern has trailing whitespace (ugh!), but flex doesn't + support this. + + - A broken example in documentation of the difference between + inclusive and exclusive start conditions is now fixed. + + - Usage (-h) report now goes to stdout. + + - Version (-V) info now goes to stdout. + + - More #ifdef chud has been added to the parser in attempt to + deal with bison's use of alloca(). + + - "make clean" no longer deletes emacs backup files (*~). + + - Some memory leaks have been fixed. + + - A bug was fixed in which dynamically-expanded buffers were + reallocated a couple of bytes too small. + + - A bug was fixed which could cause flex to read and write beyond + the end of the input buffer. + + - -S will not be going away. + + Changes between release 2.4.7 (03Aug94) and release 2.4.6: - Fixed serious bug in reading multiple files. @@ -24,7 +546,6 @@ Changes between release 2.4.6 (04Jan94) and release 2.4.5: - The use of 'extern "C++"' in FlexLexer.h has been modified to get around an incompatibility with g++'s header files. - Changes between release 2.4.5 (11Dec93) and release 2.4.4: - Fixed bug breaking C++ scanners that use REJECT or variable @@ -296,9 +817,7 @@ Changes between release 2.4.1 (30Nov93) and release 2.3.8: - 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. + at a different skeleton file. - flex no longer uses a temporary file to store the scanner's actions. |
