/* attr.h
 * Copyright (c) 2011, Peter Ohler
 * All rights reserved.
 */

#ifndef OX_ATTR_H
#define OX_ATTR_H

#include <ruby.h>

#define ATTR_STACK_INC 8

typedef struct _attr {
    const char *name;
    const char *value;
} *Attr;

typedef struct _attrStack {
    struct _attr base[ATTR_STACK_INC];
    Attr         head; /* current stack */
    Attr         end;  /* stack end */
    Attr         tail; /* pointer to one past last element name on stack */
} *AttrStack;

inline static void attr_stack_init(AttrStack stack) {
    stack->head       = stack->base;
    stack->end        = stack->base + sizeof(stack->base) / sizeof(struct _attr);
    stack->tail       = stack->head;
    stack->head->name = 0;
}

inline static int attr_stack_empty(AttrStack stack) {
    return (stack->head == stack->tail);
}

inline static void attr_stack_cleanup(AttrStack stack) {
    if (stack->base != stack->head) {
        xfree(stack->head);
        stack->head = stack->base;
    }
}

inline static void attr_stack_push(AttrStack stack, const char *name, const char *value) {
    if (stack->end <= stack->tail + 1) {
        size_t len  = stack->end - stack->head;
        size_t toff = stack->tail - stack->head;

        if (stack->base == stack->head) {
            stack->head = ALLOC_N(struct _attr, len + ATTR_STACK_INC);
            memcpy(stack->head, stack->base, sizeof(struct _attr) * len);
        } else {
            REALLOC_N(stack->head, struct _attr, len + ATTR_STACK_INC);
        }
        stack->tail = stack->head + toff;
        stack->end  = stack->head + len + ATTR_STACK_INC;
    }
    stack->tail->name  = name;
    stack->tail->value = value;
    stack->tail++;
    stack->tail->name = 0;  // terminate
}

inline static Attr attr_stack_peek(AttrStack stack) {
    if (stack->head < stack->tail) {
        return stack->tail - 1;
    }
    return 0;
}

inline static Attr attr_stack_pop(AttrStack stack) {
    if (stack->head < stack->tail) {
        stack->tail--;
        return stack->tail;
    }
    return 0;
}

#endif /* OX_ATTR_H */