shuntyard

Djiskstra's 'Shunting Yard' algorithm
git clone git://src.gearsix.net/shuntyard
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stack.c (602B)

      1 #include "stack.h"
      2 
      3 struct stack *stack_new()
      4 {
      5 	const size_t siz = 1024;
      6 
      7 	struct stack *s = malloc(sizeof(struct stack *));
      8 	s->s = malloc(siz);
      9 	s->sp = -1;
     10 	s->siz = siz;
     11 
     12 	return s;
     13 }
     14 
     15 int stack_isempty(struct stack *s)
     16 {
     17 	return (s->sp == -1);
     18 }
     19 
     20 int stack_isfull(struct stack *s)
     21 {
     22 	return (s->sp == s->siz);
     23 }
     24 
     25 int stack_peek(struct stack *s)
     26 {
     27 	if (!stack_isempty(s))
     28 		return s->s[s->sp];
     29 	return 0;
     30 }
     31 
     32 void stack_push(struct stack *s, int item)
     33 {
     34 	if (!stack_isfull(s))
     35 		s->s[++s->sp] = item;
     36 }
     37 
     38 int stack_pop(struct stack *s)
     39 {
     40 	if (!stack_isempty(s))
     41 		return s->s[s->sp--];
     42 	return 0;
     43 }