From f2173ceeaf86e55dc4dd00a46fcc6547c3d7a5de Mon Sep 17 00:00:00 2001 From: Vern Paxson Date: Tue, 6 Dec 1994 21:59:34 +0000 Subject: 2.5.0.1 --- NEWS | 308 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 298 insertions(+), 10 deletions(-) (limited to 'NEWS') diff --git a/NEWS b/NEWS index 68e466c..462c40b 100644 --- a/NEWS +++ b/NEWS @@ -1,12 +1,214 @@ -Changes between release 2.5.0 (xxDec93) and release 2.4.5: +Changes between release 2.5.0.1 (05Dec94) and release 2.4.7: + + - A new concept of "start condition" scope has been introduced. + A start condition scope is begun with: + + { + + where SCs is a list of one or more start conditions. Inside + the start condition scope, every rule automatically has the + prefix applied to it, until a '}' which matches the + initial '{'. So, for example: + + { + "\\n" return '\n'; + "\\r" return '\r'; + "\\f" return '\f'; + "\\0" return '\0'; + } + + is equivalent to: + + "\\n" return '\n'; + "\\r" return '\r'; + "\\f" return '\f'; + "\\0" return '\0'; + + 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 yywrap. + 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 + 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 + + Two %option's take string-delimited values, offset with '=': + + outfile="" equivalent to -o + prefix="" equivalent to -P + + 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() - - Snapshot for installation on ell. + pops the top of the stack and BEGIN's to it, and - - Self-contained scanners (modulo yywrap()). + int yy_top_state() - - Three new routines are available for manipulating stacks - of start conditions: yy_push_state( int new_state ), - void yy_pop_state(), 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. + + - 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 flexdoc). 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 determing 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. - Flex now generates #line directives relating the code it produces to the output file; this means that error messages @@ -14,8 +216,96 @@ Changes between release 2.5.0 (xxDec93) and release 2.4.5: - 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 use "output". + its internal #line directives (see previous item) use "output". + + - 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. + + - 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. + + - 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 using -l lex compatiblity now have the symbol + YY_FLEX_LEX_COMPAT #define'd. + + - 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. + + - 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. + + - 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. + + - -S will not be going away. + + - With the 2.6 release, I am considering dropping support for non-ANSI + C compilers (in particular, non-prototyping C compilers). If this + puts you in a panic, drop me a line at flex-ansi@ee.lbl.gov. If + your mail bounces with "no such user", then enough people have + already complained that I've rescinded my decision. + + +Changes between release 2.4.7 (03Aug94) and release 2.4.6: + + - Fixed serious bug in reading multiple files. + + - Fixed bug in scanning NUL's. + + - Fixed bug in input() returning 8-bit characters. + + - Fixed bug in matching text with embedded NUL's when + using %array or lex compatibility. + + - Fixed multiple invocations of YY_USER_ACTION when using '|' + continuation action. + + - Minor prototyping fixes. + +Changes between release 2.4.6 (04Jan94) and release 2.4.5: + + - Linking with -lfl no longer required if your program includes + its own yywrap() and main() functions. (This change will cause + problems if you have a non-ANSI compiler on a system for which + sizeof(int) != sizeof(void*) or sizeof(int) != sizeof(size_t).) + - 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: @@ -288,9 +578,7 @@ 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. -- cgit v1.2.3