janet/src/core/value.c

/*
* Copyright (c) 2017 Calvin Rose
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/

#include <dst/dst.h>

/*
 * Define a number of functions that can be used internally on ANY Dst.
 */

/* Check if two values are equal. This is strict equality with no conversion. */
int dst_equals(Dst x, Dst y) {
    int result = 0;
    if (dst_type(x) != dst_type(y)) {
        result = 0;
    } else {
        switch (dst_type(x)) {
        case DST_NIL:
        case DST_TRUE:
        case DST_FALSE:
            result = 1;
            break;
        case DST_REAL:
            result = (dst_unwrap_real(x) == dst_unwrap_real(y));
            break;
        case DST_INTEGER:
            result = (dst_unwrap_integer(x) == dst_unwrap_integer(y));
            break;
        case DST_STRING:
            result = dst_string_equal(dst_unwrap_string(x), dst_unwrap_string(y));
            break;
        case DST_TUPLE:
            result = dst_tuple_equal(dst_unwrap_tuple(x), dst_unwrap_tuple(y));
            break;
        case DST_STRUCT:
            result = dst_struct_equal(dst_unwrap_struct(x), dst_unwrap_struct(y));
            break;
        default:
            /* compare pointers */
            result = (dst_unwrap_pointer(x) == dst_unwrap_pointer(y));
            break;
        }
    }
    return result;
}

/* Computes a hash value for a function */
int32_t dst_hash(Dst x) {
    int32_t hash = 0;
    switch (dst_type(x)) {
    case DST_NIL:
        hash = 0;
        break;
    case DST_FALSE:
        hash = 1;
        break;
    case DST_TRUE:
        hash = 2;
        break;
    case DST_STRING:
    case DST_SYMBOL:
        hash = dst_string_hash(dst_unwrap_string(x));
        break;
    case DST_TUPLE:
        hash = dst_tuple_hash(dst_unwrap_tuple(x));
        break;
    case DST_STRUCT:
        hash = dst_struct_hash(dst_unwrap_struct(x));
        break;
    case DST_INTEGER:
        hash = dst_unwrap_integer(x);
        break;
    default:
        /* TODO - test performance with different hash functions */
        if (sizeof(double) == sizeof(void *)) {
            /* Assuming 8 byte pointer */
            uint64_t i = dst_u64(x);
            hash = (int32_t)(i & 0xFFFFFFFF);
            /* Get a bit more entropy by shifting the low bits out */
            hash >>= 3;
            hash ^= (int32_t) (i >> 32);
        } else {
            /* Assuming 4 byte pointer (or smaller) */
            hash = (int32_t) ((char *)dst_unwrap_pointer(x) - (char *)0);
            hash >>= 2;
        }
        break;
    }
    return hash;
}

/* Compares x to y. If they are equal retuns 0. If x is less, returns -1.
 * If y is less, returns 1. All types are comparable
 * and should have strict ordering. */
int dst_compare(Dst x, Dst y) {
    if (dst_type(x) == dst_type(y)) {
        switch (dst_type(x)) {
            case DST_NIL:
            case DST_FALSE:
            case DST_TRUE:
                return 0;
            case DST_REAL:
                /* Check for nans to ensure total order */
                if (dst_unwrap_real(x) != dst_unwrap_real(x))
                    return dst_unwrap_real(y) != dst_unwrap_real(y)
                        ? 0
                        : -1;
                if (dst_unwrap_real(y) != dst_unwrap_real(y))
                    return 1;

                if (dst_unwrap_real(x) == dst_unwrap_real(y)) {
                    return 0;
                } else {
                    return dst_unwrap_real(x) > dst_unwrap_real(y) ? 1 : -1;
                }
            case DST_INTEGER:
                if (dst_unwrap_integer(x) == dst_unwrap_integer(y)) {
                    return 0;
                } else {
                    return dst_unwrap_integer(x) > dst_unwrap_integer(y) ? 1 : -1;
                }
            case DST_STRING:
            case DST_SYMBOL:
                return dst_string_compare(dst_unwrap_string(x), dst_unwrap_string(y));
            case DST_TUPLE:
                return dst_tuple_compare(dst_unwrap_tuple(x), dst_unwrap_tuple(y));
            case DST_STRUCT:
                return dst_struct_compare(dst_unwrap_struct(x), dst_unwrap_struct(y));
            default:
                if (dst_unwrap_string(x) == dst_unwrap_string(y)) {
                    return 0;
                } else {
                    return dst_unwrap_string(x) > dst_unwrap_string(y) ? 1 : -1;
                }
        }
    } 
    return (dst_type(x) < dst_type(y)) ? -1 : 1;
}

/* Get a value out af an associated data structure. For invalid
 * data structure or invalid key, returns nil. */
Dst dst_get(Dst ds, Dst key) {
    switch (dst_type(ds)) {
    case DST_ARRAY:
        if (dst_checktype(key, DST_INTEGER) &&
                dst_unwrap_integer(key) >= 0 &&
                dst_unwrap_integer(key) < dst_unwrap_array(ds)->count)
            return dst_unwrap_array(ds)->data[dst_unwrap_integer(key)];
        break;
    case DST_TUPLE:
        if (dst_checktype(key, DST_INTEGER) &&
                dst_unwrap_integer(key) >= 0 &&
                dst_unwrap_integer(key) < dst_tuple_length(dst_unwrap_tuple(ds)))
            return dst_unwrap_tuple(ds)[dst_unwrap_integer(key)];
        break;
    case DST_BUFFER:
        if (dst_checktype(key, DST_INTEGER) &&
                dst_unwrap_integer(key) >= 0 &&
                dst_unwrap_integer(key) < dst_unwrap_buffer(ds)->count)
            return dst_wrap_integer(dst_unwrap_buffer(ds)->data[dst_unwrap_integer(key)]);
        break;
    case DST_STRING:
    case DST_SYMBOL:
        if (dst_checktype(key, DST_INTEGER) &&
                dst_unwrap_integer(key) >= 0 &&
                dst_unwrap_integer(key) < dst_string_length(dst_unwrap_string(ds)))
            return dst_wrap_integer(dst_unwrap_string(ds)[dst_unwrap_integer(key)]);
        break;
    case DST_STRUCT:
        return dst_struct_get(dst_unwrap_struct(ds), key);
    case DST_TABLE:
        return dst_table_get(dst_unwrap_table(ds), key);
    default:
        break;
    }
    return dst_wrap_nil();
}

/* Set a value in an associative data structure. Returns possible
 * error message, and NULL if no error. */
void dst_put(Dst ds, Dst key, Dst value) {
    switch (dst_type(ds)) {
    case DST_ARRAY: 
    {
        int32_t index;
        DstArray *array = dst_unwrap_array(ds);
        if (!dst_checktype(key, DST_INTEGER) || dst_unwrap_integer(key) < 0)
            return;
        index = dst_unwrap_integer(key);
        if (index == INT32_MAX) return;
        if (index >= array->count) {
            dst_array_setcount(array, index + 1);
        }
        array->data[index]= value;
        return;
    }
    case DST_BUFFER:
    {
        int32_t index;
        DstBuffer *buffer = dst_unwrap_buffer(ds);
        if (!dst_checktype(key, DST_INTEGER) || dst_unwrap_integer(key) < 0)
            return;
        index = dst_unwrap_integer(key);
        if (index == INT32_MAX) return;
        if (!dst_checktype(value, DST_INTEGER))
            return;
        if (index >= buffer->count) {
            dst_buffer_setcount(buffer, index + 1);
        }
        buffer->data[index] = (uint8_t) (dst_unwrap_integer(value) & 0xFF);
        return;
    }
    case DST_TABLE:
        dst_table_put(dst_unwrap_table(ds), key, value);
        return;
    default:
        return;
    }
}

/* Get the next key in an associative data structure. Used for iterating through an
 * associative data structure. */
const DstKV *dst_next(Dst ds, const DstKV *kv) {
    switch(dst_type(ds)) {
        default:
            return NULL;
        case DST_TABLE:
            return (const DstKV *) dst_table_next(dst_unwrap_table(ds), kv);
        case DST_STRUCT:
            return dst_struct_next(dst_unwrap_struct(ds), kv);
    }
}

/* Get the length of an object. Returns errors for invalid types */
int32_t dst_length(Dst x) {
    switch (dst_type(x)) {
        default:
            return 0;
        case DST_STRING:
            return dst_string_length(dst_unwrap_string(x));
        case DST_ARRAY:
            return dst_unwrap_array(x)->count;
        case DST_BUFFER:
            return dst_unwrap_buffer(x)->count;
        case DST_TUPLE:
            return dst_tuple_length(dst_unwrap_tuple(x));
        case DST_STRUCT:
            return dst_struct_length(dst_unwrap_struct(x));
        case DST_TABLE:
            return dst_unwrap_table(x)->count;
    }
}

/* Index into a data structure. Returns nil for out of bounds or invlalid data structure */
Dst dst_getindex(Dst ds, int32_t index) {
    switch (dst_type(ds)) {
        default:
            return dst_wrap_nil();
        case DST_STRING:
            if (index >= dst_string_length(dst_unwrap_string(ds))) return dst_wrap_nil();
            return dst_wrap_integer(dst_unwrap_string(ds)[index]);
        case DST_ARRAY:
            if (index >= dst_unwrap_array(ds)->count) return dst_wrap_nil();
            return dst_unwrap_array(ds)->data[index];
        case DST_BUFFER:
            if (index >= dst_unwrap_buffer(ds)->count) return dst_wrap_nil();
            return dst_wrap_integer(dst_unwrap_buffer(ds)->data[index]);
        case DST_TUPLE:
            if (index >= dst_tuple_length(dst_unwrap_tuple(ds))) return dst_wrap_nil();
            return dst_unwrap_tuple(ds)[index];
    }
}

/* Set an index in a linear data structure. Does nothing if data structure
 * is invalid */
void dst_setindex(Dst ds, Dst value, int32_t index) {
    switch (dst_type(ds)) {
        default:
            return;
        case DST_ARRAY:
            if (index >= dst_unwrap_array(ds)->count) {
                dst_array_ensure(dst_unwrap_array(ds), 2 * index);
                dst_unwrap_array(ds)->count = index + 1;
            }
            dst_unwrap_array(ds)->data[index] = value;
            return;
        case DST_BUFFER:
            if (!dst_checktype(value, DST_INTEGER)) return;
            if (index >= dst_unwrap_buffer(ds)->count) {
                dst_buffer_ensure(dst_unwrap_buffer(ds), 2 * index);
                dst_unwrap_buffer(ds)->count = index + 1;
            }
            dst_unwrap_buffer(ds)->data[index] = dst_unwrap_integer(value);
            return;
    }
}