568 lines
13 KiB
D
568 lines
13 KiB
D
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/**
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* This module provides functions for converting between different types.
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*
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* Copyright: Eugene Wissner 2017-2020.
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* License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
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* Mozilla Public License, v. 2.0).
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* Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
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* Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/conv.d,
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* tanya/conv.d)
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*/
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module tanya.conv;
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import std.traits : Unsigned, isNumeric;
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import tanya.container.string;
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import tanya.memory.allocator;
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import tanya.meta.trait;
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import tanya.meta.transform;
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import tanya.range;
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/**
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* Thrown if a type conversion fails.
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*/
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final class ConvException : Exception
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{
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/**
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* Params:
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* msg = The message for the exception.
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* file = The file where the exception occurred.
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* line = The line number where the exception occurred.
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* next = The previous exception in the chain of exceptions, if any.
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*/
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this(string msg,
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string file = __FILE__,
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size_t line = __LINE__,
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Throwable next = null) @nogc @safe pure nothrow
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{
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super(msg, file, line, next);
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}
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}
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/*
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* Converts a string $(D_PARAM range) into an integral value of type
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* $(D_PARAM T) in $(D_PARAM base).
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*
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* The convertion stops when $(D_PARAM range) is empty of if the next character
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* cannot be converted because it is not a digit (with respect to the
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* $(D_PARAM base)) or if the reading the next character would cause integer
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* overflow. The function returns the value converted so far then. The front
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* element of the $(D_PARAM range) points to the first character cannot be
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* converted or $(D_PARAM range) is empty if the whole string could be
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* converted.
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*
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* Base must be between 2 and 36 inclursive. Default base is 10.
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*
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* The function doesn't handle the sign (+ or -) or number prefixes (like 0x).
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*/
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package T readIntegral(T, R)(ref R range, const ubyte base = 10)
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if (isInputRange!R
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&& isSomeChar!(ElementType!R)
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&& isIntegral!T
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&& isUnsigned!T)
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in
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{
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assert(base >= 2);
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assert(base <= 36);
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}
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do
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{
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T boundary = cast(T) (T.max / base);
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if (range.empty)
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{
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return T.init;
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}
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T n;
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int digit;
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do
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{
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if (range.front >= 'a')
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{
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digit = range.front - 'W';
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}
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else if (range.front >= 'A' && range.front <= 'Z')
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{
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digit = range.front - '7';
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}
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else if (range.front >= '0' && range.front <= '9')
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{
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digit = range.front - '0';
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}
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else
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{
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return n;
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}
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if (digit >= base)
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{
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return n;
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}
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n = cast(T) (n * base + digit);
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range.popFront();
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if (range.empty)
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{
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return n;
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}
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}
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while (n < boundary);
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if (range.front >= 'a')
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{
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digit = range.front - 'W';
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}
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else if (range.front >= 'A')
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{
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digit = range.front - '7';
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}
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else if (range.front >= '0')
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{
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digit = range.front - '0';
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}
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else
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{
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return n;
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}
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if (n > cast(T) ((T.max - digit) / base))
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{
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return n;
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}
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n = cast(T) (n * base + digit);
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range.popFront();
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return n;
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}
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/**
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* If the source type $(D_PARAM From) and the target type $(D_PARAM To) are
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* equal, does nothing. If $(D_PARAM From) can be implicitly converted to
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* $(D_PARAM To), just returns $(D_PARAM from).
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*
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* Params:
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* To = Target type.
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*
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* Returns: $(D_PARAM from).
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*/
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template to(To)
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{
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/**
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* Params:
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* From = Source type.
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* from = Source value.
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*/
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ref To to(From)(ref From from)
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if (is(To == From))
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{
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return from;
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}
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/// ditto
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To to(From)(From from)
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if (is(Unqual!To == Unqual!From) || (isNumeric!From && isFloatingPoint!To))
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{
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return from;
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}
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}
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///
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@nogc nothrow pure @safe unittest
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{
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auto val = 5.to!int();
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assert(val == 5);
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static assert(is(typeof(val) == int));
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}
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/**
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* Performs checked conversion from an integral type $(D_PARAM From) to an
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* integral type $(D_PARAM To).
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*
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* Params:
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* From = Source type.
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* To = Target type.
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* from = Source value.
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*
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* Returns: $(D_PARAM from) converted to $(D_PARAM To).
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*
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* Throws: $(D_PSYMBOL ConvException) if $(D_PARAM from) is too small or too
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* large to be represented by $(D_PARAM To).
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*/
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To to(To, From)(From from)
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if (isIntegral!From
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&& isIntegral!To
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&& !is(Unqual!To == Unqual!From)
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&& !is(To == enum))
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{
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static if ((isUnsigned!From && isSigned!To && From.sizeof == To.sizeof)
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|| From.sizeof > To.sizeof)
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{
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if (from > To.max)
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{
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throw make!ConvException(defaultAllocator,
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"Positive integer overflow");
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}
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}
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static if (isSigned!From)
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{
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static if (isUnsigned!To)
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{
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if (from < 0)
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{
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throw make!ConvException(defaultAllocator,
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"Negative integer overflow");
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}
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}
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else static if (From.sizeof > To.sizeof)
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{
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if (from < To.min)
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{
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throw make!ConvException(defaultAllocator,
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"Negative integer overflow");
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}
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}
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}
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static if (From.sizeof <= To.sizeof)
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{
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return from;
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}
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else static if (isSigned!To)
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{
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return cast(To) from;
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}
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else
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{
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return from & To.max;
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}
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}
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/**
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* Converts a floating point number to an integral type.
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*
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* Params:
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* From = Source type.
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* To = Target type.
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* from = Source value.
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*
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* Returns: Truncated $(D_PARAM from) (everything after the decimal point is
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* dropped).
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*
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* Throws: $(D_PSYMBOL ConvException) if
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* $(D_INLINECODE from < To.min || from > To.max).
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*/
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To to(To, From)(From from)
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if (isFloatingPoint!From
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&& isIntegral!To
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&& !is(Unqual!To == Unqual!From)
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&& !is(To == enum))
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{
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if (from > To.max)
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{
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throw make!ConvException(defaultAllocator,
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"Positive number overflow");
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}
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else if (from < To.min)
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{
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throw make!ConvException(defaultAllocator,
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"Negative number overflow");
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}
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return cast(To) from;
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}
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///
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@nogc pure @safe unittest
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{
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assert(1.5.to!int == 1);
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assert(2147483646.5.to!int == 2147483646);
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assert((-2147483647.5).to!int == -2147483647);
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assert(2147483646.5.to!uint == 2147483646);
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}
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/**
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* Performs checked conversion from an integral type $(D_PARAM From) to an
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* $(D_KEYWORD enum).
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*
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* Params:
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* From = Source type.
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* To = Target type.
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* from = Source value.
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*
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* Returns: $(D_KEYWORD enum) value.
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*
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* Throws: $(D_PSYMBOL ConvException) if $(D_PARAM from) is not a member of
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* $(D_PSYMBOL To).
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*/
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To to(To, From)(From from)
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if (isIntegral!From && is(To == enum))
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{
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foreach (m; EnumMembers!To)
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{
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if (from == m)
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{
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return m;
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}
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}
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throw make!ConvException(defaultAllocator,
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"Value not found in enum '" ~ To.stringof ~ "'");
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}
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///
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@nogc pure @safe unittest
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{
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enum Test : int
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{
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one,
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two,
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}
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static assert(is(typeof(1.to!Test) == Test));
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assert(0.to!Test == Test.one);
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assert(1.to!Test == Test.two);
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}
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/**
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* Converts $(D_PARAM from) to a boolean.
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*
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* If $(D_PARAM From) is a numeric type, then `1` becomes $(D_KEYWORD true),
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* `0` $(D_KEYWORD false). Otherwise $(D_PSYMBOL ConvException) is thrown.
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*
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* If $(D_PARAM To) is a string (built-in string or $(D_PSYMBOL String)),
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* then `"true"` or `"false"` are converted to the appropriate boolean value.
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* Otherwise $(D_PSYMBOL ConvException) is thrown.
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*
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* Params:
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* From = Source type.
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* To = Target type.
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* from = Source value.
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*
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* Returns: $(D_KEYWORD from) converted to a boolean.
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*
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* Throws: $(D_PSYMBOL ConvException) if $(D_PARAM from) isn't convertible.
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*/
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To to(To, From)(From from)
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if (isNumeric!From && is(Unqual!To == bool) && !is(Unqual!To == Unqual!From))
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{
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if (from == 0)
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{
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return false;
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}
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else if (from < 0)
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{
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throw make!ConvException(defaultAllocator,
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"Negative number overflow");
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}
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else if (from <= 1)
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{
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return true;
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}
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throw make!ConvException(defaultAllocator,
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"Positive number overflow");
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}
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///
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@nogc pure @safe unittest
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{
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assert(!0.0.to!bool);
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assert(0.2.to!bool);
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assert(0.5.to!bool);
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assert(1.0.to!bool);
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assert(!0.to!bool);
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assert(1.to!bool);
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}
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/// ditto
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To to(To, From)(auto ref const From from)
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if ((is(From == String) || isSomeString!From) && is(Unqual!To == bool))
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{
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if (from == "true")
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{
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return true;
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}
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else if (from == "false")
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{
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return false;
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}
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throw make!ConvException(defaultAllocator,
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"String doesn't contain a boolean value");
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}
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///
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@nogc pure @safe unittest
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{
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assert("true".to!bool);
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assert(!"false".to!bool);
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assert(String("true").to!bool);
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assert(!String("false").to!bool);
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}
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/**
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* Converts a boolean to $(D_PARAM To).
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*
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* If $(D_PARAM To) is a numeric type, then $(D_KEYWORD true) becomes `1`,
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* $(D_KEYWORD false) `0`.
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*
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* If $(D_PARAM To) is a $(D_PSYMBOL String), then `"true"` or `"false"`
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* is returned.
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*
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* Params:
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* From = Source type.
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* To = Target type.
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* from = Source value.
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*
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* Returns: $(D_PARAM from) converted to $(D_PARAM To).
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*/
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To to(To, From)(From from)
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if (is(Unqual!From == bool) && isNumeric!To && !is(Unqual!To == Unqual!From))
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{
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return from;
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}
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///
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@nogc nothrow pure @safe unittest
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{
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assert(true.to!float == 1.0);
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assert(true.to!double == 1.0);
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assert(true.to!ubyte == 1);
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assert(true.to!byte == 1);
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assert(true.to!ushort == 1);
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assert(true.to!short == 1);
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assert(true.to!uint == 1);
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assert(true.to!int == 1);
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assert(false.to!float == 0);
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assert(false.to!double == 0);
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assert(false.to!ubyte == 0);
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assert(false.to!byte == 0);
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assert(false.to!ushort == 0);
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assert(false.to!short == 0);
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assert(false.to!uint == 0);
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assert(false.to!int == 0);
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}
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/**
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* Converts a stringish range to an integral value.
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*
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* Params:
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* From = Source type.
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* To = Target type.
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* from = Source value.
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*
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* Returns: $(D_PARAM from) converted to $(D_PARAM To).
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*
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* Throws: $(D_PSYMBOL ConvException) if $(D_PARAM from) doesn't contain an
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* integral value.
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*/
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To to(To, From)(auto ref From from)
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if (isInputRange!From && isSomeChar!(ElementType!From) && isIntegral!To)
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{
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if (from.empty)
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{
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throw make!ConvException(defaultAllocator, "Input range is empty");
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}
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static if (isSigned!To)
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{
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bool negative;
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}
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if (from.front == '-')
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{
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static if (isUnsigned!To)
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{
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throw make!ConvException(defaultAllocator,
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"Negative integer overflow");
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}
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else
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{
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negative = true;
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from.popFront();
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}
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}
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if (from.empty)
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{
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throw make!ConvException(defaultAllocator, "Input range is empty");
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}
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ubyte base = 10;
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if (from.front == '0')
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{
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from.popFront();
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if (from.empty)
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{
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return To.init;
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}
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else if (from.front == 'x' || from.front == 'X')
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{
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base = 16;
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from.popFront();
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}
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else if (from.front == 'b' || from.front == 'B')
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{
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base = 2;
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from.popFront();
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}
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else
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{
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base = 8;
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}
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}
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auto unsigned = readIntegral!(Unsigned!To, From)(from, base);
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if (!from.empty)
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{
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throw make!ConvException(defaultAllocator, "Integer overflow");
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}
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static if (isSigned!To)
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{
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if (negative)
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{
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auto predecessor = cast(Unsigned!To) (unsigned - 1);
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if (predecessor > cast(Unsigned!To) To.max)
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{
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throw make!ConvException(defaultAllocator,
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"Negative integer overflow");
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}
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return cast(To) (-(cast(Largest!(To, ptrdiff_t)) predecessor) - 1);
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}
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else if (unsigned > cast(Unsigned!To) To.max)
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{
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throw make!ConvException(defaultAllocator, "Integer overflow");
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}
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else
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{
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return unsigned;
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}
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}
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else
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{
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return unsigned;
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}
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}
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///
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@nogc pure @safe unittest
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{
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assert("1234".to!uint() == 1234);
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assert("1234".to!int() == 1234);
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assert("1234".to!int() == 1234);
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assert("0".to!int() == 0);
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assert("-0".to!int() == 0);
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assert("0x10".to!int() == 16);
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assert("0X10".to!int() == 16);
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assert("-0x10".to!int() == -16);
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assert("0b10".to!int() == 2);
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assert("0B10".to!int() == 2);
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assert("-0b10".to!int() == -2);
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assert("010".to!int() == 8);
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assert("-010".to!int() == -8);
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assert("-128".to!byte == cast(byte) -128);
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}
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