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#include "stack.h"
stack* stack_new() {
stack* s = (stack*)malloc(sizeof(stack));
s->size = 0;
s->maxsize = 1024;
s->start = (stackitem*)malloc(sizeof(stackitem) * s->maxsize);
return s;
}
stackitem stack_pop(stack* s) {
if (s->size > 0) {
s->size = s->size - 1;
stackitem si = s->start[s->size];
return si;
} else {
// tried to pop empty stack
return 0;
}
}
stackitem stack_peek(stack* s) {
if (s->size > 0) {
return s->start[s->size - 1];
} else {
// tried to pop empty stack
return 0;
}
}
void stack_push(stack *s, stackitem si) {
// fprintf(stderr, "pushing %d", si);
if (s->size >= s->maxsize) {
fprintf(stderr, "Error Stack Overflow");
exit(1);
} else {
s->start[s->size] = si;
s->size = s->size + 1;
}
}
int stack_depth(stack *s) {
return s->size;
}
void stack_printall(stack *s) {
printf("<%d>", s->size);
for (int i = 0; i < s->size; i++) {
printf(" %d", s->start[i]);
}
printf("\n");
}
void stack_roll(stack *s) {
int posfromtop = stack_pop(s); // top is 0, bottom is s->size - 1
const int maxindex = s->size - 1;
int i = maxindex - posfromtop;
if (i >= 0) {
int newtop = s->start[i];
for (; i + 1 < s->size; i++) {
s->start[i] = s->start[i+1];
}
s->start[i] = newtop;
} else {
// no item found
stack_push(s, 0);
}
}
void stack_pick(stack *s) {
int posfromtop = stack_pop(s); // top is 0, bottom is s->size - 1
const int maxindex = s->size - 1;
if (s->size > posfromtop) {
stack_push(s, s->start[maxindex - posfromtop]);
} else {
// no item found
stack_push(s, 0);
}
}
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