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// Copyright 2018 Mimecast Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "stack.h"
stack_s *stack_new()
{
stack_s *s = Malloc(stack_s);
*s = (stack_s) {
.top = NULL, .size = 0
};
return s;
}
void stack_destroy(stack_s *s)
{
stack_elem_s *current = s->top;
while (current) {
stack_elem_s *next = current->next;
free(current);
current = next;
}
free(s);
}
void stack_push(stack_s *s, void *data)
{
stack_elem_s *new_top = Malloc(stack_elem_s);
*new_top = (stack_elem_s) {
.next = s->top,
.data = data
};
s->top = new_top;
s->size++;
}
void* stack_pop(stack_s *s)
{
if (s->top == NULL) {
return NULL;
}
stack_elem_s *old_top = s->top;
void *data = old_top->data;
s->top = old_top->next;
free(old_top);
s->size--;
return data;
}
int stack_is_empty(stack_s *s)
{
return s->top == NULL;
}
stack_s* stack_new_reverse_from(stack_s *s)
{
stack_s* r = stack_new();
while (!stack_is_empty(s)) {
stack_push(r, stack_pop(s));
}
stack_destroy(s);
return r;
}
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