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Commit 98b396e7 authored by Jooyung Han's avatar Jooyung Han
Browse files

String16 is moveable (noexcept) 

String16 is still in use by AIDL compiler. Because String16 is not
noexcept-move-constructible, the C++ compiler will complain when it is
used with non-copyable types (such as ParcelFileDescriptor).

For example, when vector<Foo> is resized, copy-ctor of Foo is called,
which is not available.

  parcelable Foo {
    String s;
    ParcelFileDescriptor[] pfds;
  }

By providing noexcept move-ctor for String16, vector<Foo> can be resized
with no problem.

Btw, copy from StaticString16 is specialized for efficiency and move
from StaticString16 don't need to be different from copy.

Bug: 192136980
Test: libutils_test
Change-Id: I13744a2ceebf5781c3ef7f3a04237a6750b0db0a
parent c037bdbc

libutils/String16.cpp

+13 −0
Original line number Diff line number Diff line
@@ -96,6 +96,12 @@ String16::String16(const String16& o) 
    acquire();

}



String16::String16(String16&& o) noexcept

    : mString(o.mString)

{

    o.mString = getEmptyString();

}



String16::String16(const String16& o, size_t len, size_t begin)

    : mString(getEmptyString())

{
@@ -126,6 +132,13 @@ String16::~String16() 
    release();

}



String16& String16::operator=(String16&& other) noexcept {

    release();

    mString = other.mString;

    other.mString = getEmptyString();

    return *this;

}



size_t String16::size() const

{

    if (isStaticString()) {

libutils/String16_test.cpp

+19 −2
Original line number Diff line number Diff line
@@ -64,6 +64,13 @@ TEST(String16Test, Move) { 
    EXPECT_STR16EQ(u"Verify me", another);

}



TEST(String16Test, MoveAssign) {

    String16 tmp("Verify me");

    String16 another;

    another = std::move(tmp);

    EXPECT_STR16EQ(u"Verify me", another);

}



TEST(String16Test, Size) {

    String16 tmp("Verify me");

    EXPECT_EQ(9U, tmp.size());
@@ -123,6 +130,10 @@ TEST(String16Test, StaticStringMove) { 
    String16 another(std::move(tmp));

    EXPECT_STR16EQ(u"Verify me", another);

    EXPECT_TRUE(another.isStaticString());

    // move/copy from StaticString16 is specialized (just copy the handle).

    // no extra actions required.

    EXPECT_STR16EQ(u"Verify me", tmp);

    EXPECT_TRUE(tmp.isStaticString());

}



TEST(String16Test, StaticStringSize) {
@@ -174,10 +185,16 @@ TEST(String16Test, StringSetToStaticString) { 
    EXPECT_STR16EQ(u"Verify me", another);

}



TEST(String16Test, StringMoveFromStaticString) {

TEST(String16Test, StringMoveAssignFromStaticString) {

    StaticString16 tmp(u"Verify me");

    String16 another(std::move(tmp));

    String16 another(u"nonstatic");

    another = std::move(tmp);

    EXPECT_STR16EQ(u"Verify me", another);

    EXPECT_TRUE(another.isStaticString());

    // move/copy from StaticString16 is specialized (just copy handle).

    // no extra actions required.

    EXPECT_STR16EQ(u"Verify me", tmp);

    EXPECT_TRUE(tmp.isStaticString());

}



TEST(String16Test, EmptyStringIsStatic) {

libutils/include/utils/String16.h

+8 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ class String16 
public:

                                String16();

                                String16(const String16& o);

                                String16(String16&& o) noexcept;

                                String16(const String16& o,

                                         size_t len,

                                         size_t begin=0);
@@ -69,6 +70,7 @@ public: 
            status_t            append(const char16_t* other, size_t len);



    inline  String16&           operator=(const String16& other);

            String16&           operator=(String16&& other) noexcept;



    inline  String16&           operator+=(const String16& other);

    inline  String16            operator+(const String16& other) const;
@@ -176,6 +178,12 @@ protected: 
public:

    template <size_t N>

    explicit constexpr String16(const StaticString16<N>& s) : mString(s.mString) {}

    template <size_t N>

    constexpr String16& operator=(const StaticString16<N>& s) {

        release();

        mString = s.mString;

        return *this;

    }

};



// String16 can be trivially moved using memcpy() because moving does not