Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jul 18, 2016
+2 −2
Merged

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

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion hardware/arduino/avr/cores/arduino/WString.cpp
View file
Open in desktop
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;
Copy link
Collaborator

@matthijskooijman matthijskooijman Jul 13, 2016

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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)?

Copy link
Contributor Author

@sandeepmistry sandeepmistry Jul 13, 2016

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@matthijskooijman good question!

Maybe it's to avoid memory fragmentation?

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

Copy link
Member

@cmaglie cmaglie Jul 14, 2016

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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".

Expand Down
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