NetBSD/gnu/usr.bin/gawk-2.15.2/array.c

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1993-07-08 02:18:43 +04:00
/*
* array.c - routines for associative arrays.
*/
/*
* 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 NODE *assoc_find P((NODE *symbol, NODE *subs, int hash1));
NODE *
concat_exp(tree)
register NODE *tree;
{
register NODE *r;
char *str;
char *s;
unsigned len;
int offset;
int subseplen;
char *subsep;
if (tree->type != Node_expression_list)
return force_string(tree_eval(tree));
r = force_string(tree_eval(tree->lnode));
if (tree->rnode == NULL)
return r;
subseplen = SUBSEP_node->lnode->stlen;
subsep = SUBSEP_node->lnode->stptr;
len = r->stlen + subseplen + 2;
emalloc(str, char *, len, "concat_exp");
memcpy(str, r->stptr, r->stlen+1);
s = str + r->stlen;
free_temp(r);
tree = tree->rnode;
while (tree) {
if (subseplen == 1)
*s++ = *subsep;
else {
memcpy(s, subsep, subseplen+1);
s += subseplen;
}
r = force_string(tree_eval(tree->lnode));
len += r->stlen + subseplen;
offset = s - str;
erealloc(str, char *, len, "concat_exp");
s = str + offset;
memcpy(s, r->stptr, r->stlen+1);
s += r->stlen;
free_temp(r);
tree = tree->rnode;
}
r = make_str_node(str, s - str, ALREADY_MALLOCED);
r->flags |= TEMP;
return r;
}
/* Flush all the values in symbol[] before doing a split() */
void
assoc_clear(symbol)
NODE *symbol;
{
int i;
NODE *bucket, *next;
if (symbol->var_array == 0)
return;
for (i = 0; i < HASHSIZE; i++) {
for (bucket = symbol->var_array[i]; bucket; bucket = next) {
next = bucket->ahnext;
unref(bucket->ahname);
unref(bucket->ahvalue);
freenode(bucket);
}
symbol->var_array[i] = 0;
}
}
/*
* calculate the hash function of the string in subs
*/
unsigned int
hash(s, len)
register char *s;
register int len;
{
register unsigned long h = 0, g;
while (len--) {
h = (h << 4) + *s++;
g = (h & 0xf0000000);
if (g) {
h = h ^ (g >> 24);
h = h ^ g;
}
}
if (h < HASHSIZE)
return h;
else
return h%HASHSIZE;
}
/*
* locate symbol[subs]
*/
static NODE * /* NULL if not found */
assoc_find(symbol, subs, hash1)
NODE *symbol;
register NODE *subs;
int hash1;
{
register NODE *bucket, *prev = 0;
for (bucket = symbol->var_array[hash1]; bucket; bucket = bucket->ahnext) {
if (cmp_nodes(bucket->ahname, subs) == 0) {
if (prev) { /* move found to front of chain */
prev->ahnext = bucket->ahnext;
bucket->ahnext = symbol->var_array[hash1];
symbol->var_array[hash1] = bucket;
}
return bucket;
} else
prev = bucket; /* save previous list entry */
}
return NULL;
}
/*
* test whether the array element symbol[subs] exists or not
*/
int
in_array(symbol, subs)
NODE *symbol, *subs;
{
register int hash1;
if (symbol->type == Node_param_list)
symbol = stack_ptr[symbol->param_cnt];
if (symbol->var_array == 0)
return 0;
subs = concat_exp(subs); /* concat_exp returns a string node */
hash1 = hash(subs->stptr, subs->stlen);
if (assoc_find(symbol, subs, hash1) == NULL) {
free_temp(subs);
return 0;
} else {
free_temp(subs);
return 1;
}
}
/*
* SYMBOL is the address of the node (or other pointer) being dereferenced.
* SUBS is a number or string used as the subscript.
*
* Find SYMBOL[SUBS] in the assoc array. Install it with value "" if it
* isn't there. Returns a pointer ala get_lhs to where its value is stored
*/
NODE **
assoc_lookup(symbol, subs)
NODE *symbol, *subs;
{
register int hash1;
register NODE *bucket;
(void) force_string(subs);
hash1 = hash(subs->stptr, subs->stlen);
if (symbol->var_array == 0) { /* this table really should grow
* dynamically */
unsigned size;
size = sizeof(NODE *) * HASHSIZE;
emalloc(symbol->var_array, NODE **, size, "assoc_lookup");
memset((char *)symbol->var_array, 0, size);
symbol->type = Node_var_array;
} else {
bucket = assoc_find(symbol, subs, hash1);
if (bucket != NULL) {
free_temp(subs);
return &(bucket->ahvalue);
}
}
/* It's not there, install it. */
if (do_lint && subs->stlen == 0)
warning("subscript of array `%s' is null string",
symbol->vname);
getnode(bucket);
bucket->type = Node_ahash;
if (subs->flags & TEMP)
bucket->ahname = dupnode(subs);
else {
unsigned int saveflags = subs->flags;
subs->flags &= ~MALLOC;
bucket->ahname = dupnode(subs);
subs->flags = saveflags;
}
free_temp(subs);
/* array subscripts are strings */
bucket->ahname->flags &= ~NUMBER;
bucket->ahname->flags |= STRING;
bucket->ahvalue = Nnull_string;
bucket->ahnext = symbol->var_array[hash1];
symbol->var_array[hash1] = bucket;
return &(bucket->ahvalue);
}
void
do_delete(symbol, tree)
NODE *symbol, *tree;
{
register int hash1;
register NODE *bucket, *last;
NODE *subs;
if (symbol->type == Node_param_list)
symbol = stack_ptr[symbol->param_cnt];
if (symbol->var_array == 0)
return;
subs = concat_exp(tree); /* concat_exp returns string node */
hash1 = hash(subs->stptr, subs->stlen);
last = NULL;
for (bucket = symbol->var_array[hash1]; bucket; last = bucket, bucket = bucket->ahnext)
if (cmp_nodes(bucket->ahname, subs) == 0)
break;
free_temp(subs);
if (bucket == NULL)
return;
if (last)
last->ahnext = bucket->ahnext;
else
symbol->var_array[hash1] = bucket->ahnext;
unref(bucket->ahname);
unref(bucket->ahvalue);
freenode(bucket);
}
void
assoc_scan(symbol, lookat)
NODE *symbol;
struct search *lookat;
{
if (!symbol->var_array) {
lookat->retval = NULL;
return;
}
lookat->arr_ptr = symbol->var_array;
lookat->arr_end = lookat->arr_ptr + HASHSIZE; /* added */
lookat->bucket = symbol->var_array[0];
assoc_next(lookat);
}
void
assoc_next(lookat)
struct search *lookat;
{
while (lookat->arr_ptr < lookat->arr_end) {
if (lookat->bucket != 0) {
lookat->retval = lookat->bucket->ahname;
lookat->bucket = lookat->bucket->ahnext;
return;
}
lookat->arr_ptr++;
if (lookat->arr_ptr < lookat->arr_end)
lookat->bucket = *(lookat->arr_ptr);
else
lookat->retval = NULL;
}
return;
}