/*      $OpenBSD: stack.c,v 1.15 2017/12/06 13:48:05 otto Exp $ */

/*
 * Copyright (c) 2003, Otto Moerbeek <otto@drijf.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <err.h>
#include <stdlib.h>
#include <string.h>

#include "extern.h"

static __inline bool    stack_empty(const struct stack *);
static void             stack_grow(struct stack *);
static struct array     *array_new(void);
static __inline void    array_free(struct array *);
static struct array *   array_dup(const struct array *);
static __inline void    array_grow(struct array *, size_t);
static __inline void    array_assign(struct array *, size_t, const struct value *);
static __inline struct value    *array_retrieve(const struct array *, size_t);

void
stack_init(struct stack *stack)
{
        stack->size = 0;
        stack->sp = -1;
        stack->stack = NULL;
}

static __inline bool
stack_empty(const struct stack *stack)
{
        bool empty = stack->sp == -1;
        if (empty)
                warnx("stack empty");
        return empty;
}

/* Clear number or string, but leave value itself */
void
stack_free_value(struct value *v)
{
        switch (v->type) {
        case BCODE_NONE:
                break;
        case BCODE_NUMBER:
                free_number(v->u.num);
                break;
        case BCODE_STRING:
                free(v->u.string);
                break;
        }
        array_free(v->array);
        v->array = NULL;
}

/* Copy number or string content into already allocated target */
struct value *
stack_dup_value(const struct value *a, struct value *copy)
{
        copy->type = a->type;

        switch (a->type) {
        case BCODE_NONE:
                break;
        case BCODE_NUMBER:
                copy->u.num = dup_number(a->u.num);
                break;
        case BCODE_STRING:
                copy->u.string = bstrdup(a->u.string);
                break;
        }

        copy->array = a->array == NULL ? NULL : array_dup(a->array);

        return copy;
}

size_t
stack_size(const struct stack *stack)
{
        return stack->sp + 1;
}

void
stack_dup(struct stack *stack)
{
        struct value    *value;
        struct value    copy;

        value = stack_tos(stack);
        if (value == NULL) {
                warnx("stack empty");
                return;
        }
        stack_push(stack, stack_dup_value(value, &copy));
}

void
stack_swap(struct stack *stack)
{
        struct value    copy;

        if (stack->sp < 1) {
                warnx("stack empty");
                return;
        }
        copy = stack->stack[stack->sp];
        stack->stack[stack->sp] = stack->stack[stack->sp-1];
        stack->stack[stack->sp-1] = copy;
}

static void
stack_grow(struct stack *stack)
{
        size_t new_size;

        if (++stack->sp == stack->size) {
                new_size = stack->size * 2 + 1;
                stack->stack = breallocarray(stack->stack,
                    new_size, sizeof(*stack->stack));
                stack->size = new_size;
        }
}

void
stack_pushnumber(struct stack *stack, struct number *b)
{
        stack_grow(stack);
        stack->stack[stack->sp].type = BCODE_NUMBER;
        stack->stack[stack->sp].u.num = b;
        stack->stack[stack->sp].array = NULL;
}

void
stack_pushstring(struct stack *stack, char *string)
{
        stack_grow(stack);
        stack->stack[stack->sp].type = BCODE_STRING;
        stack->stack[stack->sp].u.string = string;
        stack->stack[stack->sp].array = NULL;
}

void
stack_push(struct stack *stack, struct value *v)
{
        switch (v->type) {
        case BCODE_NONE:
                stack_grow(stack);
                stack->stack[stack->sp].type = BCODE_NONE;
                break;
        case BCODE_NUMBER:
                stack_pushnumber(stack, v->u.num);
                break;
        case BCODE_STRING:
                stack_pushstring(stack, v->u.string);
                break;
        }
        stack->stack[stack->sp].array = v->array == NULL ?
            NULL : array_dup(v->array);
}

struct value *
stack_tos(const struct stack *stack)
{
        if (stack->sp == -1)
                return NULL;
        return &stack->stack[stack->sp];
}

void
stack_set_tos(struct stack *stack, struct value *v)
{
        if (stack->sp == -1)
                stack_push(stack, v);
        else {
                stack_free_value(&stack->stack[stack->sp]);
                stack->stack[stack->sp] = *v;
                stack->stack[stack->sp].array = v->array == NULL ?
                    NULL : array_dup(v->array);
        }
}

struct value *
stack_pop(struct stack *stack)
{
        if (stack_empty(stack))
                return NULL;
        return &stack->stack[stack->sp--];
}

struct number *
stack_popnumber(struct stack *stack)
{
        if (stack_empty(stack))
                return NULL;
        array_free(stack->stack[stack->sp].array);
        stack->stack[stack->sp].array = NULL;
        if (stack->stack[stack->sp].type != BCODE_NUMBER) {
                warnx("not a number"); /* XXX remove */
                return NULL;
        }
        return stack->stack[stack->sp--].u.num;
}

char *
stack_popstring(struct stack *stack)
{
        if (stack_empty(stack))
                return NULL;
        array_free(stack->stack[stack->sp].array);
        stack->stack[stack->sp].array = NULL;
        if (stack->stack[stack->sp].type != BCODE_STRING) {
                warnx("not a string"); /* XXX remove */
                return NULL;
        }
        return stack->stack[stack->sp--].u.string;
}

void
stack_clear(struct stack *stack)
{
        while (stack->sp >= 0)
                stack_free_value(&stack->stack[stack->sp--]);
        free(stack->stack);
        stack_init(stack);
}

void
stack_print(FILE *f, const struct stack *stack, const char *prefix, u_int base)
{
        ssize_t i;

        for (i = stack->sp; i >= 0; i--) {
                print_value(f, &stack->stack[i], prefix, base);
                (void)putc('\n', f);
        }
}


static struct array *
array_new(void)
{
        struct array *a;

        a = bmalloc(sizeof(*a));
        a->data = NULL;
        a->size = 0;
        return a;
}

static __inline void
array_free(struct array *a)
{
        size_t i;

        if (a == NULL)
                return;
        for (i = 0; i < a->size; i++)
                stack_free_value(&a->data[i]);
        free(a->data);
        free(a);
}

static struct array *
array_dup(const struct array *a)
{
        struct array    *n;
        size_t          i;

        if (a == NULL)
                return NULL;
        n = array_new();
        array_grow(n, a->size);
        for (i = 0; i < a->size; i++)
                (void)stack_dup_value(&a->data[i], &n->data[i]);
        return n;
}

static __inline void
array_grow(struct array *array, size_t newsize)
{
        size_t i;

        array->data = breallocarray(array->data, newsize, sizeof(*array->data));
        for (i = array->size; i < newsize; i++) {
                array->data[i].type = BCODE_NONE;
                array->data[i].array = NULL;
        }
        array->size = newsize;
}

static __inline void
array_assign(struct array *array, size_t index, const struct value *v)
{
        if (index >= array->size)
                array_grow(array, index+1);
        stack_free_value(&array->data[index]);
        array->data[index] = *v;
}

static __inline struct value *
array_retrieve(const struct array *array, size_t index)
{
        if (index >= array->size)
                return NULL;
        return &array->data[index];
}

void
frame_assign(struct stack *stack, size_t index, const struct value *v)
{
        struct array *a;
        struct value n;

        if (stack->sp == -1) {
                n.type = BCODE_NONE;
                n.array = NULL;
                stack_push(stack, &n);
        }

        a = stack->stack[stack->sp].array;
        if (a == NULL)
                a = stack->stack[stack->sp].array = array_new();
        array_assign(a, index, v);
}

struct value *
frame_retrieve(const struct stack *stack, size_t index)
{
        struct array *a;

        if (stack->sp == -1)
                return NULL;
        a = stack->stack[stack->sp].array;
        if (a == NULL)
                a = stack->stack[stack->sp].array = array_new();
        return array_retrieve(a, index);
}