awk.shar

c programming pearls answer

-	then unchanged it -- it really does run slower in too many cases.
-	left the code in place, commented out.
-
-Feb 10, 1991:
-	check error status on all writes, to avoid banging on full disks.
-
-Jan 28, 1991:
-	awk -f - reads the program from stdin.
-
-Jan 11, 1991:
-	failed to set numeric state on $0 in cmd|getline context in run.c.
-
-Nov 2, 1990:
-	fixed sleazy test for integrality in getsval;  use modf.
-
-Oct 29, 1990:
-	fixed sleazy buggy code in lib.c that looked (incorrectly) for
-	too long input lines.
-
-Oct 14, 1990:
-	fixed the bug on p. 198 in which it couldn't deduce that an
-	argument was an array in some contexts.  replaced the error
-	message in intest() by code that damn well makes it an array.
-
-Oct 8, 1990:
-	fixed horrible bug:  types and values were not preserved in
-	some kinds of self-assignment. (in assign().)
-
-Aug 24, 1990:
-	changed NCHARS to 256 to handle 8-bit characters in strings
-	presented to match(), etc.
-
-Jun 26, 1990:
-	changed struct rrow (awk.h) to use long instead of int for lval,
-	since cfoll() stores a pointer in it.  now works better when int's
-	are smaller than pointers!
-
-May 6, 1990:
-	AVA fixed the grammar so that ! is uniformly of the same precedence as
-	unary + and -.  This renders illegal some constructs like !x=y, which
-	now has to be parenthesized as !(x=y), and makes others work properly:
-	!x+y is (!x)+y, and x!y is x !y, not two pattern-action statements.
-	(These problems were pointed out by Bob Lenk of Posix.)
-
-	Added \x to regular expressions (already in strings).
-	Limited octal to octal digits; \8 and \9 are not octal.
-	Centralized the code for parsing escapes in regular expressions.
-	Added a bunch of tests to T.re and T.sub to verify some of this.
-
-Feb 9, 1990:
-	fixed null pointer dereference bug in main.c:  -F[nothing].  sigh.
-
-	restored srand behavior:  it returns the current seed.
-
-Jan 18, 1990:
-	srand now returns previous seed value (0 to start).
-
-Jan 5, 1990:
-	fix potential problem in tran.c -- something was freed,
-	then used in freesymtab.
-
-Oct 18, 1989:
-	another try to get the max number of open files set with
-	relatively machine-independent code.
-
-	small fix to input() in case of multiple reads after EOF.
-
-Oct 11, 1989:
-	FILENAME is now defined in the BEGIN block -- too many old
-	programs broke.
-
-	"-" means stdin in getline as well as on the commandline.
-
-	added a bunch of casts to the code to tell the truth about
-	char * vs. unsigned char *, a right royal pain.  added a
-	setlocale call to the front of main, though probably no one
-	has it usefully implemented yet.
-
-Aug 24, 1989:
-	removed redundant relational tests against nullnode if parse
-	tree already had a relational at that point.
-
-Aug 11, 1989:
-	fixed bug:  commandline variable assignment has to look like
-	var=something.  (consider the man page for =, in file =.1)
-
-	changed number of arguments to functions to static arrays
-	to avoid repeated malloc calls.
-
-Aug 2, 1989:
-	restored -F (space) separator
-
-Jul 30, 1989:
-	added -v x=1 y=2 ... for immediate commandline variable assignment;
-	done before the BEGIN block for sure.  they have to precede the
-	program if the program is on the commandline.
-	Modified Aug 2 to require a separate -v for each assignment.
-
-Jul 10, 1989:
-	fixed ref-thru-zero bug in environment code in tran.c
-
-Jun 23, 1989:
-	add newline to usage message.
-
-Jun 14, 1989:
-	added some missing ansi printf conversion letters: %i %X %E %G.
-	no sensible meaning for h or L, so they may not do what one expects.
-
-	made %* conversions work.
-
-	changed x^y so that if n is a positive integer, it's done
-	by explicit multiplication, thus achieving maximum accuracy.
-	(this should be done by pow() but it seems not to be locally.)
-	done to x ^= y as well.
-
-Jun 4, 1989:
-	ENVIRON array contains environment: if shell variable V=thing,
-		ENVIRON["V"] is "thing"
-
-	multiple -f arguments permitted.  error reporting is naive.
-	(they were permitted before, but only the last was used.)
-
-	fixed a really stupid botch in the debugging macro dprintf
-
-	fixed order of evaluation of commandline assignments to match
-	what the book claims:  an argument of the form x=e is evaluated
-	at the time it would have been opened if it were a filename (p 63).
-	this invalidates the suggested answer to ex 4-1 (p 195).
-
-	removed some code that permitted -F (space) fieldseparator,
-	since it didn't quite work right anyway.  (restored aug 2)
-
-Apr 27, 1989:
-	Line number now accumulated correctly for comment lines.
-
-Apr 26, 1989:
-	Debugging output now includes a version date,
-	if one compiles it into the source each time.
-
-Apr 9, 1989:
-	Changed grammar to prohibit constants as 3rd arg of sub and gsub;
-	prevents class of overwriting-a-constant errors.  (Last one?)
-	This invalidates the "banana" example on page 43 of the book.
-
-	Added \a ("alert"), \v (vertical tab), \xhhh (hexadecimal),
-	as in ANSI, for strings.  Rescinded the sloppiness that permitted
-	non-octal digits in \ooo.  Warning:  not all compilers and libraries
-	will be able to deal with \x correctly.
-
-Jan 9, 1989:
-	Fixed bug that caused tempcell list to contain a duplicate.
-	The fix is kludgy.
-
-Dec 17, 1988:
-	Catches some more commandline errors in main.
-	Removed redundant decl of modf in run.c (confuses some compilers).
-	Warning:  there's no single declaration of malloc, etc., in awk.h
-	that seems to satisfy all compilers.
-
-Dec 7, 1988:
-	Added a bit of code to error printing to avoid printing nulls.
-	(Not clear that it actually would.)
-
-Nov 27, 1988:
-	With fear and trembling, modified the grammar to permit
-	multiple pattern-action statements on one line without
-	an explicit separator.  By definition, this capitulation
-	to the ghost of ancient implementations remains undefined
-	and thus subject to change without notice or apology.
-	DO NOT COUNT ON IT.
-
-Oct 30, 1988:
-	Fixed bug in call() that failed to recover storage.
-
-	A warning is now generated if there are more arguments
-	in the call than in the definition (in lieu of fixing
-	another storage leak).
-
-Oct 20, 1988:
-	Fixed %c:  if expr is numeric, use numeric value;
-	otherwise print 1st char of string value.  still
-	doesn't work if the value is 0 -- won't print \0.
-
-	Added a few more checks for running out of malloc.
-
-Oct 12, 1988:
-	Fixed bug in call() that freed local arrays twice.
-
-	Fixed to handle deletion of non-existent array right;
-	complains about attempt to delete non-array element.
-
-Sep 30, 1988:
-	Now guarantees to evaluate all arguments of built-in
-	functions, as in C;  the appearance is that arguments
-	are evaluated before the function is called.  Places
-	affected are sub (gsub was ok), substr, printf, and
-	all the built-in arithmetic functions in bltin().
-	A warning is generated if a bltin() is called with
-	the wrong number of arguments.
-
-	This requires changing makeprof on p167 of the book.
-
-Aug 23, 1988:
-	setting FILENAME in BEGIN caused core dump, apparently
-	because it was freeing space not allocated by malloc.
-
-July 24, 1988:
-	fixed egregious error in toupper/tolower functions.
-	still subject to rescinding, however.
-
-July 2, 1988:
-	flush stdout before opening file or pipe
-
-July 2, 1988:
-	performance bug in b.c/cgoto(): not freeing some sets of states.
-	partial fix only right now, and the number of states increased
-	to make it less obvious.
-
-June 1, 1988:
-	check error status on close
-
-May 28, 1988:
-	srand returns seed value it's using.
-	see 1/18/90
-
-May 22, 1988:
-	Removed limit on depth of function calls.
-
-May 10, 1988:
-	Fixed lib.c to permit _ in commandline variable names.
-
-Mar 25, 1988:
-	main.c fixed to recognize -- as terminator of command-
-	line options.  Illegal options flagged.
-	Error reporting slightly cleaned up.
-
-Dec 2, 1987:
-	Newer C compilers apply a strict scope rule to extern
-	declarations within functions.  Two extern declarations in
-	lib.c and tran.c have been moved to obviate this problem.
-
-Oct xx, 1987:
-	Reluctantly added toupper and tolower functions.
-	Subject to rescinding without notice.
-
-Sep 17, 1987:
-	Error-message printer had printf(s) instead of
-	printf("%s",s);  got core dumps when the message
-	included a %.
-
-Sep 12, 1987:
-	Very long printf strings caused core dump;
-	fixed aprintf, asprintf, format to catch them.
-	Can still get a core dump in printf itself.
-
-
//GO.SYSIN DD FIXES
echo awk.h 1>&2
sed 's/.//' >awk.h <<'//GO.SYSIN DD awk.h'
-/****************************************************************
-Copyright (C) Lucent Technologies 1997
-All Rights Reserved
-
-Permission to use, copy, modify, and distribute this software and
-its documentation for any purpose and without fee is hereby
-granted, provided that the above copyright notice appear in all
-copies and that both that the copyright notice and this
-permission notice and warranty disclaimer appear in supporting
-documentation, and that the name Lucent Technologies or any of
-its entities not be used in advertising or publicity pertaining
-to distribution of the software without specific, written prior
-permission.
-
-LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
-INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
-IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
-SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
-IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
-ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
-THIS SOFTWARE.
-****************************************************************/
-
-#include <assert.h>
-
-typedef double	Awkfloat;
-
-/* unsigned char is more trouble than it's worth */
-
-typedef	unsigned char uschar;
-
-#define	xfree(a)	{ if ((a) != NULL) { free((char *) a); a = NULL; } }
-
-#define	NN(p)	((p) ? (p) : "(null)")	/* guaranteed non-null for dprintf 
-*/
-#define	DEBUG
-#ifdef	DEBUG
-			/* uses have to be doubly parenthesized */
-#	define	dprintf(x)	if (dbg) printf x
-#else
-#	define	dprintf(x)
-#endif
-
-extern int	compile_time;	/* 1 if compiling, 0 if running */
-extern int	safe;		/* 0 => unsafe, 1 => safe */
-
-#define	RECSIZE	(8 * 1024)	/* sets limit on records, fields, etc., etc. */
-extern int	recsize;	/* size of current record, orig RECSIZE */
-
-extern char	**FS;
-extern char	**RS;
-extern char	**ORS;
-extern char	**OFS;
-extern char	**OFMT;
-extern Awkfloat *NR;
-extern Awkfloat *FNR;
-extern Awkfloat *NF;
-extern char	**FILENAME;
-extern char	**SUBSEP;
-extern Awkfloat *RSTART;
-extern Awkfloat *RLENGTH;
-
-extern char	*record;	/* points to $0 */
-extern int	lineno;		/* line number in awk program */
-extern int	errorflag;	/* 1 if error has occurred */
-extern int	donefld;	/* 1 if record broken into fields */
-extern int	donerec;	/* 1 if record is valid (no fld has changed */
-extern char	inputFS[];	/* FS at time of input, for field splitting */
-
-extern int	dbg;
-
-extern	char	*patbeg;	/* beginning of pattern matched */
-extern	int	patlen;		/* length of pattern matched.  set in b.c */
-
-/* Cell:  all information about a variable or constant */
-
-typedef struct Cell {
-	uschar	ctype;		/* OCELL, OBOOL, OJUMP, etc. */
-	uschar	csub;		/* CCON, CTEMP, CFLD, etc. */
-	char	*nval;		/* name, for variables only */
-	char	*sval;		/* string value */
-	Awkfloat fval;		/* value as number */
-	int	 tval;		/* type info: STR|NUM|ARR|FCN|FLD|CON|DONTFREE */
-	struct Cell *cnext;	/* ptr to next if chained */
-} Cell;
-
-typedef struct Array {		/* symbol table array */
-	int	nelem;		/* elements in table right now */
-	int	size;		/* size of tab */
-	Cell	**tab;		/* hash table pointers */
-} Array;
-
-#define	NSYMTAB	50	/* initial size of a symbol table */
-extern Array	*symtab;
-
-extern Cell	*nrloc;		/* NR */
-extern Cell	*fnrloc;	/* FNR */
-extern Cell	*nfloc;		/* NF */
-extern Cell	*rstartloc;	/* RSTART */
-extern Cell	*rlengthloc;	/* RLENGTH */
-
-/* Cell.tval values: */
-#define	NUM	01	/* number value is valid */
-#define	STR	02	/* string value is valid */
-#define DONTFREE 04	/* string space is not freeable */
-#define	CON	010	/* this is a constant */