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janet/src/core/value.c

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/*
* Copyright (c) 2018 Calvin Rose
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*
* 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:
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*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
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*
* 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>
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/*
* Define a number of functions that can be used internally on ANY Dst.
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*/
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/* 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)) {
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result = 0;
} else {
switch (dst_type(x)) {
case DST_NIL:
case DST_TRUE:
case DST_FALSE:
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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));
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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;
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default:
/* compare pointers */
result = (dst_unwrap_pointer(x) == dst_unwrap_pointer(y));
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break;
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}
}
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;
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break;
case DST_STRING:
case DST_SYMBOL:
hash = dst_string_hash(dst_unwrap_string(x));
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break;
case DST_TUPLE:
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hash = dst_tuple_hash(dst_unwrap_tuple(x));
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break;
case DST_STRUCT:
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hash = dst_struct_hash(dst_unwrap_struct(x));
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break;
case DST_INTEGER:
hash = dst_unwrap_integer(x);
break;
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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) */
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hash = (int32_t) ((char *)dst_unwrap_pointer(x) - (char *)0);
hash >>= 2;
}
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break;
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}
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:
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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)) {
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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;
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}
case DST_STRING:
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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));
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default:
if (dst_unwrap_string(x) == dst_unwrap_string(y)) {
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return 0;
} else {
return dst_unwrap_string(x) > dst_unwrap_string(y) ? 1 : -1;
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}
}
}
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return (dst_type(x) < dst_type(y)) ? -1 : 1;
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}