freebsd-dev/gnu/usr.bin/dc/dc-stack.c
1996-11-04 04:24:33 +00:00

368 lines
8.2 KiB
C
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/*
* implement stack functions for dc
*
* Copyright (C) 1994 Free Software Foundation, Inc.
*
* This program 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, or (at your option)
* any later version.
*
* This program 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 this program; if not, you can either send email to this
* program's author (see below) or write to: The Free Software Foundation,
* Inc.; 675 Mass Ave. Cambridge, MA 02139, USA.
*/
/* This module is the only one that knows what stacks (both the
* regular evaluation stack and the named register stacks)
* look like.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include "dc.h"
#include "dc-proto.h"
#include "dc-regdef.h"
/* an oft-used error message: */
#define Empty_Stack fprintf(stderr, "%s: stack empty\n", progname)
/* simple linked-list implementaion suffices: */
struct dc_list {
dc_data value;
struct dc_list *link;
};
typedef struct dc_list dc_list;
/* the anonymous evaluation stack */
static dc_list *dc_stack=NULL;
/* the named register stacks */
static dc_list *dc_register[DC_REGCOUNT];
/* allocate a new dc_list item */
static dc_list *
dc_alloc DC_DECLVOID()
{
dc_list *result;
result = dc_malloc(sizeof *result);
result->value.dc_type = DC_UNINITIALIZED;
result->link = NULL;
return result;
}
/* check that there are two numbers on top of the stack,
* then call op with the popped numbers. Construct a dc_data
* value from the dc_num returned by op and push it
* on the stack.
* If the op call doesn't return DC_SUCCESS, then leave the stack
* unmodified.
*/
void
dc_binop DC_DECLARG((op, kscale))
int (*op)DC_PROTO((dc_num, dc_num, int, dc_num *)) DC_DECLSEP
int kscale DC_DECLEND
{
dc_data a;
dc_data b;
dc_data r;
if (!dc_stack || !dc_stack->link){
Empty_Stack;
return;
}
if (dc_stack->value.dc_type!=DC_NUMBER
|| dc_stack->link->value.dc_type!=DC_NUMBER){
fprintf(stderr, "%s: non-numeric value\n", progname);
return;
}
(void)dc_pop(&b);
(void)dc_pop(&a);
if ((*op)(a.v.number, b.v.number, kscale, &r.v.number) == DC_SUCCESS){
r.dc_type = DC_NUMBER;
dc_push(r);
dc_free_num(&a.v.number);
dc_free_num(&b.v.number);
}else{
/* op failed; restore the stack */
dc_push(a);
dc_push(b);
}
}
/* check that there are two numbers on top of the stack,
* then call dc_compare with the popped numbers.
* Return negative, zero, or positive based on the ordering
* of the two numbers.
*/
int
dc_cmpop DC_DECLVOID()
{
int result;
dc_data a;
dc_data b;
if (!dc_stack || !dc_stack->link){
Empty_Stack;
return 0;
}
if (dc_stack->value.dc_type!=DC_NUMBER
|| dc_stack->link->value.dc_type!=DC_NUMBER){
fprintf(stderr, "%s: non-numeric value\n", progname);
return 0;
}
(void)dc_pop(&b);
(void)dc_pop(&a);
result = dc_compare(b.v.number, a.v.number);
dc_free_num(&a.v.number);
dc_free_num(&b.v.number);
return result;
}
/* initialize the register stacks to their initial values */
void
dc_register_init DC_DECLVOID()
{
int i;
for (i=0; i<DC_REGCOUNT; ++i)
dc_register[i] = NULL;
}
/* clear the evaluation stack */
void
dc_clear_stack DC_DECLVOID()
{
dc_list *n;
dc_list *t;
for (n=dc_stack; n; n=t){
t = n->link;
if (n->value.dc_type == DC_NUMBER)
dc_free_num(&n->value.v.number);
else if (n->value.dc_type == DC_STRING)
dc_free_str(&n->value.v.string);
else
dc_garbage("in stack", -1);
free(n);
}
dc_stack = NULL;
}
/* push a value onto the evaluation stack */
void
dc_push DC_DECLARG((value))
dc_data value DC_DECLEND
{
dc_list *n = dc_alloc();
if (value.dc_type!=DC_NUMBER && value.dc_type!=DC_STRING)
dc_garbage("in data being pushed", -1);
n->value = value;
n->link = dc_stack;
dc_stack = n;
}
/* push a value onto the named register stack */
void
dc_register_push DC_DECLARG((stackid, value))
int stackid DC_DECLSEP
dc_data value DC_DECLEND
{
dc_list *n = dc_alloc();
stackid = regmap(stackid);
n->value = value;
n->link = dc_register[stackid];
dc_register[stackid] = n;
}
/* set *result to the value on the top of the evaluation stack */
/* The caller is responsible for duplicating the value if it
* is to be maintained as anything more than a transient identity.
*
* DC_FAIL is returned if the stack is empty (and *result unchanged),
* DC_SUCCESS is returned otherwise
*/
int
dc_top_of_stack DC_DECLARG((result))
dc_data *result DC_DECLEND
{
if (!dc_stack){
Empty_Stack;
return DC_FAIL;
}
if (dc_stack->value.dc_type!=DC_NUMBER
&& dc_stack->value.dc_type!=DC_STRING)
dc_garbage("at top of stack", -1);
*result = dc_stack->value;
return DC_SUCCESS;
}
/* set *result to a dup of the value on the top of the named register stack */
/*
* DC_FAIL is returned if the named stack is empty (and *result unchanged),
* DC_SUCCESS is returned otherwise
*/
int
dc_register_get DC_DECLARG((regid, result))
int regid DC_DECLSEP
dc_data *result DC_DECLEND
{
dc_list *r;
regid = regmap(regid);
r = dc_register[regid];
if ( ! r ){
fprintf(stderr, "%s: register ", progname);
dc_show_id(stderr, regid, " is empty\n");
return DC_FAIL;
}
*result = dc_dup(r->value);
return DC_SUCCESS;
}
/* set the top of the named register stack to the indicated value */
/* If the named stack is empty, craft a stack entry to enter the
* value into.
*/
void
dc_register_set DC_DECLARG((regid, value))
int regid DC_DECLSEP
dc_data value DC_DECLEND
{
dc_list *r;
regid = regmap(regid);
r = dc_register[regid];
if ( ! r )
dc_register[regid] = dc_alloc();
else if (r->value.dc_type == DC_NUMBER)
dc_free_num(&r->value.v.number);
else if (r->value.dc_type == DC_STRING)
dc_free_str(&r->value.v.string);
else
dc_garbage("", regid);
dc_register[regid]->value = value;
}
/* pop from the evaluation stack
*
* DC_FAIL is returned if the stack is empty (and *result unchanged),
* DC_SUCCESS is returned otherwise
*/
int
dc_pop DC_DECLARG((result))
dc_data *result DC_DECLEND
{
dc_list *r;
r = dc_stack;
if (!r){
Empty_Stack;
return DC_FAIL;
}
if (r->value.dc_type!=DC_NUMBER && r->value.dc_type!=DC_STRING)
dc_garbage("at top of stack", -1);
*result = r->value;
dc_stack = r->link;
free(r);
return DC_SUCCESS;
}
/* pop from the named register stack
*
* DC_FAIL is returned if the named stack is empty (and *result unchanged),
* DC_SUCCESS is returned otherwise
*/
int
dc_register_pop DC_DECLARG((stackid, result))
int stackid DC_DECLSEP
dc_data *result DC_DECLEND
{
dc_list *r;
stackid = regmap(stackid);
r = dc_register[stackid];
if (!r){
fprintf(stderr, "%s: stack register ", progname);
dc_show_id(stderr, stackid, " is empty\n");
return DC_FAIL;
}
if (r->value.dc_type!=DC_NUMBER && r->value.dc_type!=DC_STRING)
dc_garbage(" stack", stackid);
*result = r->value;
dc_register[stackid] = r->link;
free(r);
return DC_SUCCESS;
}
/* tell how many entries are currently on the evaluation stack */
int
dc_tell_stackdepth DC_DECLVOID()
{
dc_list *n;
int depth=0;
for (n=dc_stack; n; n=n->link)
++depth;
return depth;
}
/* return the length of the indicated data value;
* if discard_flag is true, the deallocate the value when done
*
* The definition of a datum's length is deligated to the
* appropriate module.
*/
int
dc_tell_length DC_DECLARG((value, discard_flag))
dc_data value DC_DECLSEP
dc_boolean discard_flag DC_DECLEND
{
int length;
if (value.dc_type == DC_NUMBER){
length = dc_numlen(value.v.number);
if (discard_flag == DC_TRUE)
dc_free_num(&value.v.number);
} else if (value.dc_type == DC_STRING) {
length = dc_strlen(value.v.string);
if (discard_flag == DC_TRUE)
dc_free_str(&value.v.string);
} else {
dc_garbage("in tell_length", -1);
/*NOTREACHED*/
length = 0; /*just to suppress spurious compiler warnings*/
}
return length;
}
/* print out all of the values on the evaluation stack */
void
dc_printall DC_DECLARG((obase))
int obase DC_DECLEND
{
dc_list *n;
for (n=dc_stack; n; n=n->link)
dc_print(n->value, obase);
}