field.c

早期freebsd实现

/*
 * field.c - routines for dealing with fields and record parsing
 */

/* 
 * Copyright (C) 1986, 1988, 1989, 1991, 1992 the Free Software Foundation, Inc.
 * 
 * This file is part of GAWK, the GNU implementation of the
 * AWK Progamming Language.
 * 
 * GAWK is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * GAWK is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with GAWK; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "awk.h"

static int (*parse_field) P((int, char **, int, NODE *,
			     Regexp *, void (*)(), NODE *));
static void rebuild_record P((void));
static int re_parse_field P((int, char **, int, NODE *,
			     Regexp *, void (*)(), NODE *));
static int def_parse_field P((int, char **, int, NODE *,
			      Regexp *, void (*)(), NODE *));
static int sc_parse_field P((int, char **, int, NODE *,
			     Regexp *, void (*)(), NODE *));
static int fw_parse_field P((int, char **, int, NODE *,
			     Regexp *, void (*)(), NODE *));
static void set_element P((int, char *, int, NODE *));
static void grow_fields_arr P((int num));
static void set_field P((int num, char *str, int len, NODE *dummy));


static Regexp *FS_regexp = NULL;
static char *parse_extent;	/* marks where to restart parse of record */
static int parse_high_water=0;	/* field number that we have parsed so far */
static int nf_high_water = 0;	/* size of fields_arr */
static int resave_fs;
static NODE *save_FS;		/* save current value of FS when line is read,
				 * to be used in deferred parsing
				 */

NODE **fields_arr;		/* array of pointers to the field nodes */
int field0_valid;		/* $(>0) has not been changed yet */
int default_FS;
static NODE **nodes;		/* permanent repository of field nodes */
static int *FIELDWIDTHS = NULL;

void
init_fields()
{
	NODE *n;

	emalloc(fields_arr, NODE **, sizeof(NODE *), "init_fields");
	emalloc(nodes, NODE **, sizeof(NODE *), "init_fields");
	getnode(n);
	*n = *Nnull_string;
	fields_arr[0] = nodes[0] = n;
	parse_extent = fields_arr[0]->stptr;
	save_FS = dupnode(FS_node->var_value);
	field0_valid = 1;
}


static void
grow_fields_arr(num)
int num;
{
	register int t;
	register NODE *n;

	erealloc(fields_arr, NODE **, (num + 1) * sizeof(NODE *), "set_field");
	erealloc(nodes, NODE **, (num+1) * sizeof(NODE *), "set_field");
	for (t = nf_high_water+1; t <= num; t++) {
		getnode(n);
		*n = *Nnull_string;
		fields_arr[t] = nodes[t] = n;
	}
	nf_high_water = num;
}

/*ARGSUSED*/
static void
set_field(num, str, len, dummy)
int num;
char *str;
int len;
NODE *dummy;	/* not used -- just to make interface same as set_element */
{
	register NODE *n;

	if (num > nf_high_water)
		grow_fields_arr(num);
	n = nodes[num];
	n->stptr = str;
	n->stlen = len;
	n->flags = (PERM|STR|STRING|MAYBE_NUM);
	fields_arr[num] = n;
}

/* Someone assigned a value to $(something).  Fix up $0 to be right */
static void
rebuild_record()
{
	register int tlen;
	register NODE *tmp;
	NODE *ofs;
	char *ops;
	register char *cops;
	register NODE **ptr;
	register int ofslen;

	tlen = 0;
	ofs = force_string(OFS_node->var_value);
	ofslen = ofs->stlen;
	ptr = &fields_arr[NF];
	while (ptr > &fields_arr[0]) {
		tmp = force_string(*ptr);
		tlen += tmp->stlen;
		ptr--;
	}
	tlen += (NF - 1) * ofslen;
	if (tlen < 0)
	    tlen = 0;
	emalloc(ops, char *, tlen + 2, "fix_fields");
	cops = ops;
	ops[0] = '\0';
	for (ptr = &fields_arr[1]; ptr <= &fields_arr[NF]; ptr++) {
		tmp = *ptr;
		if (tmp->stlen == 1)
			*cops++ = tmp->stptr[0];
		else if (tmp->stlen != 0) {
			memcpy(cops, tmp->stptr, tmp->stlen);
			cops += tmp->stlen;
		}
		if (ptr != &fields_arr[NF]) {
			if (ofslen == 1)
				*cops++ = ofs->stptr[0];
			else if (ofslen != 0) {
				memcpy(cops, ofs->stptr, ofslen);
				cops += ofslen;
			}
		}
	}
	tmp = make_str_node(ops, tlen, ALREADY_MALLOCED);
	unref(fields_arr[0]);
	fields_arr[0] = tmp;
	field0_valid = 1;
}

/*
 * setup $0, but defer parsing rest of line until reference is made to $(>0)
 * or to NF.  At that point, parse only as much as necessary.
 */
void
set_record(buf, cnt, freeold)
char *buf;
int cnt;
int freeold;
{
	register int i;

	NF = -1;
	for (i = 1; i <= parse_high_water; i++) {
		unref(fields_arr[i]);
	}
	parse_high_water = 0;
	if (freeold) {
		unref(fields_arr[0]);
		if (resave_fs) {
			resave_fs = 0;
			unref(save_FS);
			save_FS = dupnode(FS_node->var_value);
		}
		nodes[0]->stptr = buf;
		nodes[0]->stlen = cnt;
		nodes[0]->stref = 1;
		nodes[0]->flags = (STRING|STR|PERM|MAYBE_NUM);
		fields_arr[0] = nodes[0];
	}
	fields_arr[0]->flags |= MAYBE_NUM;
	field0_valid = 1;
}

void
reset_record()
{
	(void) force_string(fields_arr[0]);
	set_record(fields_arr[0]->stptr, fields_arr[0]->stlen, 0);
}

void
set_NF()
{
	register int i;

	NF = (int) force_number(NF_node->var_value);
	if (NF > nf_high_water)
		grow_fields_arr(NF);
	for (i = parse_high_water + 1; i <= NF; i++) {
		unref(fields_arr[i]);
		fields_arr[i] = Nnull_string;
	}
	field0_valid = 0;
}

/*
 * this is called both from get_field() and from do_split()
 * via (*parse_field)().  This variation is for when FS is a regular
 * expression -- either user-defined or because RS=="" and FS==" "
 */
static int
re_parse_field(up_to, buf, len, fs, rp, set, n)
int up_to;	/* parse only up to this field number */
char **buf;	/* on input: string to parse; on output: point to start next */
int len;
NODE *fs;
Regexp *rp;
void (*set) ();	/* routine to set the value of the parsed field */
NODE *n;
{
	register char *scan = *buf;
	register int nf = parse_high_water;
	register char *field;
	register char *end = scan + len;

	if (up_to == HUGE)
		nf = 0;
	if (len == 0)
		return nf;

	if (*RS == 0 && default_FS)
		while (scan < end && isspace(*scan))
			scan++;
	field = scan;
	while (scan < end
	       && research(rp, scan, 0, (int)(end - scan), 1) != -1
	       && nf < up_to) {
		if (REEND(rp, scan) == RESTART(rp, scan)) {	/* null match */
			scan++;
			if (scan == end) {
				(*set)(++nf, field, scan - field, n);
				up_to = nf;
				break;
			}
			continue;
		}
		(*set)(++nf, field, scan + RESTART(rp, scan) - field, n);
		scan += REEND(rp, scan);
		field = scan;
		if (scan == end)	/* FS at end of record */
			(*set)(++nf, field, 0, n);
	}
	if (nf != up_to && scan < end) {
		(*set)(++nf, scan, (int)(end - scan), n);
		scan = end;
	}
	*buf = scan;
	return (nf);
}

/*
 * this is called both from get_field() and from do_split()
 * via (*parse_field)().  This variation is for when FS is a single space
 * character.
 */
static int
def_parse_field(up_to, buf, len, fs, rp, set, n)
int up_to;	/* parse only up to this field number */
char **buf;	/* on input: string to parse; on output: point to start next */
int len;
NODE *fs;
Regexp *rp;
void (*set) ();	/* routine to set the value of the parsed field */
NODE *n;
{
	register char *scan = *buf;
	register int nf = parse_high_water;
	register char *field;
	register char *end = scan + len;
	char sav;

	if (up_to == HUGE)
		nf = 0;
	if (len == 0)
		return nf;

	/* before doing anything save the char at *end */
	sav = *end;
	/* because it will be destroyed now: */

	*end = ' ';	/* sentinel character */
	for (; nf < up_to; scan++) {
		/*
		 * special case:  fs is single space, strip leading whitespace 
		 */
		while (scan < end && (*scan == ' ' || *scan == '\t'))
			scan++;
		if (scan >= end)
			break;
		field = scan;
		while (*scan != ' ' && *scan != '\t')
			scan++;
		(*set)(++nf, field, (int)(scan - field), n);
		if (scan == end)
			break;
	}

	/* everything done, restore original char at *end */
	*end = sav;

	*buf = scan;
	return nf;