/** * This module contains compiler support determining equality of arrays. * * Copyright: Copyright Digital Mars 2000 - 2020. * License: Distributed under the *      $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost Software License 1.0). *    (See accompanying file LICENSE) * Source: $(DRUNTIMESRC core/internal/_array/_equality.d) */ module core.internal.array.equality; // The compiler lowers `lhs == rhs` to `__equals(lhs, rhs)` for// * dynamic arrays,// * (most) arrays of different (unqualified) element types, and// * arrays of structs with custom opEquals.bool __equals(T1, T2)(scope T1[] lhs, scope T2[] rhs) @trusted{    if (lhs.length != rhs.length)        return false;     if (lhs.length == 0)        return true;     alias PureType = bool function(scope T1[], scope T2[], size_t) @safe pure nothrow @nogc;     return (cast(PureType)&isEqual!(T1,T2))(lhs, rhs, lhs.length);} pragma(inline, true)bool __equals(T1, T2, size_t N)(scope ref T1[N] lhs, scope T2[] rhs) @trusted {    return __equals(lhs[], rhs);} pragma(inline, true)bool __equals(T1, T2, size_t N)(scope T1[] lhs, scope ref T2[N] rhs) @trusted {    return __equals(lhs, rhs[]);} pragma(inline, true)bool __equals(T1, T2, size_t N, size_t M)(scope ref T1[N] lhs, scope ref T2[M] rhs) @trusted {    return __equals(lhs[], rhs[]);} /****************************** * Helper function for __equals(). * Outlined to enable __equals() to be inlined, as dmd cannot inline loops. */privatebool isEqual(T1, T2)(scope T1[] lhs, scope T2[] rhs, size_t length){    static if (is(T1 == T2) &&               (__traits(isIntegral, T1) || is(T1 == char) || is(T1 == wchar) ||                is(T1 == dchar) || is(T1 == bool) || is(T1 == class)))    {        foreach (i; 0 .. length)        {            if (lhs.ptr[i] != rhs.ptr[i])                return false;        }        return true;    }    else    {        // Returns a reference to an array element, eliding bounds check and        // casting void to ubyte.        pragma(inline, true)        static ref at(T)(scope T[] r, size_t i) @trusted        // exclude opaque structs due to https://issues.dlang.org/show_bug.cgi?id=20959        if (!(is(T == struct) && !is(typeof(T.sizeof))))        {            static if (is(T == void))                return (cast(ubyte[]) r)[i];            else                return r[i];        }         foreach (const i; 0 .. length)        {            if (at(lhs, i) != at(rhs, i))                return false;        }        return true;    }} @safe unittest{    assert(__equals([], []));    assert(!__equals([1, 2], [1, 2, 3]));} @safe unittest{    auto a = "hello"c;     assert(a != "hel");    assert(a != "helloo");    assert(a != "betty");    assert(a == "hello");    assert(a != "hxxxx");     float[] fa = [float.nan];    assert(fa != fa);} @safe unittest{    struct A    {        int a;    }     auto arr1 = [A(0), A(2)];    auto arr2 = [A(0), A(1)];    auto arr3 = [A(0), A(1)];     assert(arr1 != arr2);    assert(arr2 == arr3);} @safe unittest{    struct A    {        int a;        int b;         bool opEquals(const A other)        {            return this.a == other.b && this.b == other.a;        }    }     auto arr1 = [A(1, 0), A(0, 1)];    auto arr2 = [A(1, 0), A(0, 1)];    auto arr3 = [A(0, 1), A(1, 0)];     assert(arr1 != arr2);    assert(arr2 == arr3);} // https://issues.dlang.org/show_bug.cgi?id=18252@safe unittest{    string[int][] a1, a2;    assert(__equals(a1, a2));    assert(a1 == a2);    a1 ~= [0: "zero"];    a2 ~= [0: "zero"];    assert(__equals(a1, a2));    assert(a1 == a2);    a2[0][1] = "one";    assert(!__equals(a1, a2));    assert(a1 != a2);} // https://issues.dlang.org/show_bug.cgi?id=21094unittest{    static class C    {        int a;    }    static struct S    {        bool isValid;        C fib;         inout(C) get() pure @safe @nogc nothrow inout        {            return isValid ? fib : C.init;        }        T opCast(T : C)() const { return null; }         alias get this;    }     auto foo(S[] lhs, S[] rhs)    {        return lhs == rhs;    }}