/*
* implement stack functions for dc
*
* Copyright (C) 1994, 1997, 1998, 2000, 2005, 2006, 2008, 2012, 2016
* 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 3, 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, see <http://www.gnu.org/licenses/>.
*
*/
/* 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>
#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif
#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 implementation suffices: */
struct dc_list {
dc_data value;
struct dc_array *array; /* opaque */
struct dc_list *link;
};
typedef struct dc_list dc_list;
/* the anonymous evaluation stack */
static dc_list *dc_stack=NULL;
/* the named register stacks */
typedef dc_list *dc_listp;
static dc_listp 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->array = NULL;
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 == NULL || dc_stack->link == NULL){
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 op with the popped numbers. Construct two dc_data
* values from the dc_num's returned by op and push them
* on the stack.
* If the op call doesn't return DC_SUCCESS, then leave the stack
* unmodified.
*/
void
dc_binop2 DC_DECLARG((op, kscale))
int (*op)DC_PROTO((dc_num, dc_num, int, dc_num *, dc_num *)) DC_DECLSEP
int kscale DC_DECLEND
{
dc_data a;
dc_data b;
dc_data r1;
dc_data r2;
if (dc_stack == NULL || dc_stack->link == NULL){
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,
&r1.v.number, &r2.v.number) == DC_SUCCESS){
r1.dc_type = DC_NUMBER;
dc_push(r1);
r2.dc_type = DC_NUMBER;
dc_push(r2);
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 == NULL || dc_stack->link == NULL){
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;
}
/* check that there are three 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_triop DC_DECLARG((op, kscale))
int (*op)DC_PROTO((dc_num, dc_num, dc_num, int, dc_num *)) DC_DECLSEP
int kscale DC_DECLEND
{
dc_data a;
dc_data b;
dc_data c;
dc_data r;
if (dc_stack == NULL
|| dc_stack->link == NULL
|| dc_stack->link->link == NULL){
Empty_Stack;
return;
}
if (dc_stack->value.dc_type!=DC_NUMBER
|| dc_stack->link->value.dc_type!=DC_NUMBER
|| dc_stack->link->link->value.dc_type!=DC_NUMBER){
fprintf(stderr, "%s: non-numeric value\n", progname);
return;
}
(void)dc_pop(&c);
(void)dc_pop(&b);
(void)dc_pop(&a);
if ((*op)(a.v.number, b.v.number, c.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);
dc_free_num(&c.v.number);
}else{
/* op failed; restore the stack */
dc_push(a);
dc_push(b);
dc_push(c);
}
}
/* 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!=NULL; 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);
dc_array_free(n->array);
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 == NULL){
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,
* or 0 (zero) if the stack is empty */
/*
* DC_FAIL is returned if an internal bug is detected
* 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==NULL){
*result = dc_int2data(0);
}else if (r->value.dc_type==DC_UNINITIALIZED){
fprintf(stderr, "%s: BUG: register ", progname);
dc_show_id(stderr, regid, " exists but is uninitialized?\n");
return DC_FAIL;
}else{
*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 == NULL)
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 if (r->value.dc_type == DC_UNINITIALIZED)
;
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==NULL || r->value.dc_type==DC_UNINITIALIZED){
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;
dc_array_free(r->array);
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==NULL || r->value.dc_type==DC_UNINITIALIZED){
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;
dc_array_free(r->array);
free(r);
return DC_SUCCESS;
}
/* cyclically rotate the "n" topmost elements of the stack;
* negative "n" rotates forward (topomost element becomes n-th deep)
* positive "n" rotates backward (topmost element becomes 2nd deep)
*
* If stack depth is less than "n", whole stack is rotated
* (without raising an error).
*/
void
dc_stack_rotate(int n)
{
dc_list *p; /* becomes bottom of sub-stack */
dc_list *r; /* predecessor of "p" */
int absn = n<0 ? -n : n;
/* always do nothing for empty stack or degenerate rotation depth */
if (!dc_stack || absn < 2)
return;
/* find bottom of rotation sub-stack */
r = NULL;
for (p=dc_stack; p->link && --absn>0; p=p->link)
r = p;
/* if stack has only one element, treat rotation as no-op */
if (!r)
return;
/* do the rotation, in appropriate direction */
if (n > 0) {
r->link = p->link;
p->link = dc_stack;
dc_stack = p;
} else {
dc_list *new_tos = dc_stack->link;
dc_stack->link = p->link;
p->link = dc_stack;
dc_stack = new_tos;
}
}
/* 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!=NULL; n=n->link)
++depth;
return depth;
}
/* return the length of the indicated data value;
* if discard_p is DC_TOSS, 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_p))
dc_data value DC_DECLSEP
dc_discard discard_p DC_DECLEND
{
int length;
if (value.dc_type == DC_NUMBER){
length = dc_numlen(value.v.number);
if (discard_p == DC_TOSS)
dc_free_num(&value.v.number);
} else if (value.dc_type == DC_STRING) {
length = (int) dc_strlen(value.v.string);
if (discard_p == DC_TOSS)
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!=NULL; n=n->link)
dc_print(n->value, obase, DC_WITHNL, DC_KEEP);
}
/* get the current array head for the named array */
struct dc_array *
dc_get_stacked_array DC_DECLARG((array_id))
int array_id DC_DECLEND
{
dc_list *r = dc_register[regmap(array_id)];
return r == NULL ? NULL : r->array;
}
/* set the current array head for the named array */
void
dc_set_stacked_array DC_DECLARG((array_id, new_head))
int array_id DC_DECLSEP
struct dc_array *new_head DC_DECLEND
{
dc_list *r;
array_id = regmap(array_id);
r = dc_register[array_id];
if (r == NULL)
r = dc_register[array_id] = dc_alloc();
r->array = new_head;
}
/*
* Local Variables:
* mode: C
* tab-width: 4
* End:
* vi: set ts=4 :
*/