tanya/source/tanya/conv.d

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2017-10-10 06:59:34 +02:00
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* This module provides functions for converting between different types.
*
* Copyright: Eugene Wissner 2017.
* License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
* Mozilla Public License, v. 2.0).
* Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
* Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/conv.d,
* tanya/conv.d)
*/
module tanya.conv;
import tanya.memory;
import tanya.memory.op;
import tanya.meta.trait;
version (unittest)
{
import tanya.test.assertion;
}
2017-10-10 06:59:34 +02:00
/**
* Constructs a new object of type $(D_PARAM T) in $(D_PARAM memory) with the
* given arguments.
*
* If $(D_PARAM T) is a $(D_KEYWORD class), emplace returns a class reference
* of type $(D_PARAM T), otherwise a pointer to the constructed object is
* returned.
*
* If $(D_PARAM T) is a nested class inside another class, $(D_PARAM outer)
* should be an instance of the outer class.
*
* $(D_PARAM args) are arguments for the constructor of $(D_PARAM T). If
* $(D_PARAM T) isn't an aggregate type and doesn't have a constructor,
* $(D_PARAM memory) can be initialized to `args[0]` if `Args.length == 1`,
* `Args[0]` should be implicitly convertible to $(D_PARAM T) then.
*
* Params:
* T = Constructed type.
* U = Type of the outer class if $(D_PARAM T) is a nested class.
* Args = Types of the constructor arguments if $(D_PARAM T) has a constructor
* or the type of the initial value.
* outer = Outer class instance if $(D_PARAM T) is a nested class.
* args = Constructor arguments if $(D_PARAM T) has a constructor or the
* initial value.
*
* Returns: New instance of type $(D_PARAM T) constructed in $(D_PARAM memory).
*
* Precondition: `memory.length == stateSize!T`.
* Postcondition: $(D_PARAM memory) and the result point to the same memory.
*/
T emplace(T, U, Args...)(void[] memory, U outer, auto ref Args args)
if (!isAbstractClass!T && isInnerClass!T && is(typeof(T.outer) == U))
in
{
assert(memory.length >= stateSize!T);
}
out (result)
{
assert(memory.ptr is (() @trusted => cast(void*) result)());
}
body
{
copy(typeid(T).initializer, memory);
auto result = (() @trusted => cast(T) memory.ptr)();
result.outer = outer;
static if (is(typeof(result.__ctor(args))))
{
result.__ctor(args);
}
return result;
}
/// ditto
T emplace(T, Args...)(void[] memory, auto ref Args args)
if (is(T == class) && !isAbstractClass!T && !isInnerClass!T)
in
{
assert(memory.length == stateSize!T);
}
out (result)
{
assert(memory.ptr is (() @trusted => cast(void*) result)());
}body
{
copy(typeid(T).initializer, memory);
auto result = (() @trusted => cast(T) memory.ptr)();
static if (is(typeof(result.__ctor(args))))
{
result.__ctor(args);
}
return result;
}
///
@nogc nothrow pure @safe unittest
{
import tanya.memory : stateSize;
class C
{
int i = 5;
class Inner
{
int i;
this(int param) pure nothrow @safe @nogc
{
this.i = param;
}
}
}
ubyte[stateSize!C] memory1;
ubyte[stateSize!(C.Inner)] memory2;
auto c = emplace!C(memory1);
assert(c.i == 5);
auto inner = emplace!(C.Inner)(memory2, c, 8);
assert(c.i == 5);
assert(inner.i == 8);
assert(inner.outer is c);
}
/// ditto
T* emplace(T, Args...)(void[] memory, auto ref Args args)
if (!isAggregateType!T && (Args.length <= 1))
in
{
assert(memory.length >= T.sizeof);
}
out (result)
{
assert(memory.ptr is result);
}
body
{
auto result = (() @trusted => cast(T*) memory.ptr)();
static if (Args.length == 1)
{
*result = T(args[0]);
}
else
{
*result = T.init;
}
return result;
}
/// ditto
T* emplace(T, Args...)(void[] memory, auto ref Args args)
if (!isPolymorphicType!T && isAggregateType!T)
in
{
assert(memory.length >= T.sizeof);
}
out (result)
{
assert(memory.ptr is result);
}
body
{
auto result = (() @trusted => cast(T*) memory.ptr)();
static if (!hasElaborateAssign!T && isAssignable!T)
{
*result = T.init;
}
else
{
static const T init = T.init;
copy((cast(void*) &init)[0 .. T.sizeof], memory);
}
static if (Args.length == 0)
{
static assert(is(typeof({ static T t; })),
"Default constructor is disabled");
}
else static if (is(typeof(T(args))))
{
*result = T(args);
}
else static if (is(typeof(result.__ctor(args))))
{
result.__ctor(args);
}
else
{
static assert(false,
"Unable to construct value with the given arguments");
}
return result;
}
///
@nogc nothrow pure @safe unittest
{
ubyte[4] memory;
auto i = emplace!int(memory);
static assert(is(typeof(i) == int*));
assert(*i == 0);
i = emplace!int(memory, 5);
assert(*i == 5);
static struct S
{
int i;
@disable this();
@disable this(this);
this(int i) @nogc nothrow pure @safe
{
this.i = i;
}
}
auto s = emplace!S(memory, 8);
static assert(is(typeof(s) == S*));
assert(s.i == 8);
}
// Handles "Cannot access frame pointer" error.
@nogc nothrow pure @safe unittest
{
struct F
{
~this() @nogc nothrow pure @safe
{
}
}
static assert(is(typeof(emplace!F((void[]).init))));
}
/**
* Thrown if a type conversion fails.
*/
final class ConvException : Exception
{
/**
* Params:
* msg = The message for the exception.
* file = The file where the exception occurred.
* line = The line number where the exception occurred.
* next = The previous exception in the chain of exceptions, if any.
*/
this(string msg,
string file = __FILE__,
size_t line = __LINE__,
Throwable next = null) @nogc @safe pure nothrow
{
super(msg, file, line, next);
}
}
/**
* If the source type $(D_PARAM From) and the target type $(D_PARAM To) are
* equal, does nothing. If $(D_PARAM From) can be implicitly converted to
* $(D_PARAM To), just returns $(D_PARAM from).
*
* Params:
* To = Target type.
*
* Returns: $(D_PARAM from).
*/
template to(To)
{
/**
* Params:
* From = Source type.
* from = Source value.
*/
ref To to(From)(ref From from)
if (is(To == From))
{
return from;
}
/// ditto
To to(From)(From from)
if (is(Unqual!To == Unqual!From) || (isNumeric!From && isFloatingPoint!To))
{
return from;
}
}
///
@nogc nothrow pure @safe unittest
{
auto val = 5.to!int();
assert(val == 5);
static assert(is(typeof(val) == int));
}
@nogc nothrow pure @safe unittest
{
int val = 5;
assert(val.to!int() == 5);
}
/**
* Performs checked conversion from an integral type $(D_PARAM From) to an
* integral type $(D_PARAM To).
*
* Params:
* From = Source type.
* To = Target type.
* from = Source value.
*
* Returns: $(D_PARAM from) converted to $(D_PARAM To).
*
* Throws: $(D_PSYMBOL ConvException) if $(D_PARAM from) is too small or too
* large to be represented by $(D_PARAM To).
*/
To to(To, From)(From from)
if (isIntegral!From
&& isIntegral!To
&& !is(Unqual!To == Unqual!From)
&& !is(To == enum))
{
static if ((isUnsigned!From && isSigned!To && From.sizeof == To.sizeof)
|| From.sizeof > To.sizeof)
{
if (from > To.max)
{
throw make!ConvException(defaultAllocator,
"Positive integer overflow");
}
}
static if (isSigned!From)
{
static if (isUnsigned!To)
{
if (from < 0)
{
throw make!ConvException(defaultAllocator,
"Negative integer overflow");
}
}
else static if (From.sizeof > To.sizeof)
{
if (from < To.min)
{
throw make!ConvException(defaultAllocator,
"Negative integer overflow");
}
}
}
static if (From.sizeof <= To.sizeof)
{
return from;
}
else static if (isSigned!To)
{
return cast(To) from;
}
else
{
return from & To.max;
}
}
@nogc nothrow pure @safe unittest
{
// ubyte -> ushort
assert((cast(ubyte) 0).to!ushort == 0);
assert((cast(ubyte) 1).to!ushort == 1);
assert((cast(ubyte) (ubyte.max - 1)).to!ushort == ubyte.max - 1);
assert((cast(ubyte) ubyte.max).to!ushort == ubyte.max);
// ubyte -> short
assert((cast(ubyte) 0).to!short == 0);
assert((cast(ubyte) 1).to!short == 1);
assert((cast(ubyte) (ubyte.max - 1)).to!short == ubyte.max - 1);
assert((cast(ubyte) ubyte.max).to!short == ubyte.max);
}
@nogc pure @safe unittest
{
// ubyte <- ushort
assert((cast(ushort) 0).to!ubyte == 0);
assert((cast(ushort) 1).to!ubyte == 1);
assert((cast(ushort) (ubyte.max - 1)).to!ubyte == ubyte.max - 1);
assert((cast(ushort) ubyte.max).to!ubyte == ubyte.max);
// ubyte <- short
assert((cast(short) 0).to!ubyte == 0);
assert((cast(short) 1).to!ubyte == 1);
assert((cast(short) (ubyte.max - 1)).to!ubyte == ubyte.max - 1);
assert((cast(short) ubyte.max).to!ubyte == ubyte.max);
// short <-> int
assert(short.min.to!int == short.min);
assert((short.min + 1).to!int == short.min + 1);
assert((cast(short) -1).to!int == -1);
assert((cast(short) 0).to!int == 0);
assert((cast(short) 1).to!int == 1);
assert((short.max - 1).to!int == short.max - 1);
assert(short.max.to!int == short.max);
assert((cast(int) short.min).to!short == short.min);
assert((cast(int) short.min + 1).to!short == short.min + 1);
assert((cast(int) -1).to!short == -1);
assert((cast(int) 0).to!short == 0);
assert((cast(int) 1).to!short == 1);
assert((cast(int) short.max - 1).to!short == short.max - 1);
assert((cast(int) short.max).to!short == short.max);
// uint <-> int
assert((cast(uint) 0).to!int == 0);
assert((cast(uint) 1).to!int == 1);
assert((cast(uint) (int.max - 1)).to!int == int.max - 1);
assert((cast(uint) int.max).to!int == int.max);
assert((cast(int) 0).to!uint == 0);
assert((cast(int) 1).to!uint == 1);
assert((cast(int) (int.max - 1)).to!uint == int.max - 1);
assert((cast(int) int.max).to!uint == int.max);
}
@nogc pure @safe unittest
{
assertThrown!ConvException(&to!(short, int), int.min);
assertThrown!ConvException(&to!(short, int), int.max);
assertThrown!ConvException(&to!(ushort, uint), uint.max);
assertThrown!ConvException(&to!(uint, int), -1);
}
@nogc nothrow pure @safe unittest
{
enum Test : int
{
one,
two,
}
assert(Test.one.to!int == 0);
assert(Test.two.to!int == 1);
}
/**
* Converts a floating point number to an integral type.
*
* Params:
* From = Source type.
* To = Target type.
* from = Source value.
*
* Returns: Truncated $(D_PARAM from) (everything after the decimal point is
* dropped).
*
* Throws: $(D_PSYMBOL ConvException) if
* $(D_INLINECODE from < To.min || from > To.max).
*/
To to(To, From)(From from)
if (isFloatingPoint!From
&& isIntegral!To
&& !is(Unqual!To == Unqual!From)
&& !is(To == enum))
{
if (from > To.max)
{
throw make!ConvException(defaultAllocator,
"Positive number overflow");
}
else if (from < To.min)
{
throw make!ConvException(defaultAllocator,
"Negative number overflow");
}
return cast(To) from;
}
///
@nogc pure @safe unittest
{
assert(1.5.to!int == 1);
assert(2147483646.5.to!int == 2147483646);
assert((-2147483647.5).to!int == -2147483647);
assert(2147483646.5.to!uint == 2147483646);
}
@nogc pure @safe unittest
{
assertThrown!ConvException(&to!(int, double), 2147483647.5);
assertThrown!ConvException(&to!(int, double), -2147483648.5);
assertThrown!ConvException(&to!(uint, double), -21474.5);
}
/**
* Performs checked conversion from an integral type $(D_PARAM From) to an
* $(D_KEYWORD enum).
*
* Params:
* From = Source type.
* To = Target type.
* from = Source value.
*
* Returns: $(D_KEYWORD enum) value.
*
* Throws: $(D_PSYMBOL ConvException) if $(D_PARAM from) is not a member of
* $(D_PSYMBOL To).
*/
To to(To, From)(From from)
if (isIntegral!From && is(To == enum))
{
foreach (m; EnumMembers!To)
{
if (from == m)
{
return m;
}
}
throw make!ConvException(defaultAllocator,
"Value not found in enum '" ~ To.stringof ~ "'");
}
///
@nogc pure @safe unittest
{
enum Test : int
{
one,
two,
}
static assert(is(typeof(1.to!Test) == Test));
assert(0.to!Test == Test.one);
assert(1.to!Test == Test.two);
}
@nogc pure @safe unittest
{
enum Test : uint
{
one,
two,
}
assertThrown!ConvException(&to!(Test, int), 5);
}