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Make String::move of an invalidated String result in an invalidated String #5127

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Merged
merged 1 commit into from
Jul 18, 2016
Merged

Make String::move of an invalidated String result in an invalidated String #5127

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2 changes: 1 addition & 1 deletion hardware/arduino/avr/cores/arduino/WString.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -193,7 +193,7 @@ String & String::copy(const __FlashStringHelper *pstr, unsigned int length)
void String::move(String &rhs)
{
if (buffer) {
if (capacity >= rhs.len) {
if (rhs && capacity >= rhs.len) {
strcpy(buffer, rhs.buffer);
len = rhs.len;
rhs.len = 0;
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I wonder why this copy code is even here in the first place? Why not just always take over the buffer of rhs? That would be faster, and the only downside is that the buffer pointer for this string changes (but nobody should rely on it anyway)?

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@matthijskooijman good question!

Maybe it's to avoid memory fragmentation?

@PaulStoffregen @damellis @cmaglie do you have any thoughts on this?

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the only downside is that the buffer pointer for this string changes (but nobody should rely on it anyway)?

there is the c_str() operator and there are PR that pushes for using it outside the string class also for writing :-)

Maybe it's to avoid memory fragmentation?

I guess that's the reason, move is called from the c++11 move-constructor, so it's probably better to keep the original (rvalue) allocation whenever possible to avoid making "holes".

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2 changes: 1 addition & 1 deletion hardware/arduino/sam/cores/arduino/WString.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -195,7 +195,7 @@ String & String::copy(const __FlashStringHelper *pstr, unsigned int length)
void String::move(String &rhs)
{
if (buffer) {
if (capacity >= rhs.len) {
if (rhs && capacity >= rhs.len) {
strcpy(buffer, rhs.buffer);
len = rhs.len;
rhs.len = 0;
Expand Down