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style: Use std::unique_ptr<std::istream> in InputStreamBase #1432

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Merged
thewtex merged 2 commits into from
Jul 25, 2025
Merged

style: Use std::unique_ptr<std::istream> in InputStreamBase #1432

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5570591
style: Use `std::unique_ptr<std::istream>` in InputStreamBase
N-Dekker Jul 23, 2025
965f201
style: Move implementation InputStreamBase from h to cxx file
N-Dekker Jul 23, 2025
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52 changes: 14 additions & 38 deletions include/itkInputStreamBase.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,12 +18,10 @@
#ifndef itkInputStreamBase_h
#define itkInputStreamBase_h

#include "itkPipeline.h"
#include "itkWasmStringStream.h"

#include <ios>
#include <iosfwd> // For istream.
#include <memory> // For unique_ptr.
#include <string>
#include <sstream>
#include <fstream>

#include "WebAssemblyInterfaceExport.h"

Expand Down Expand Up @@ -54,52 +52,30 @@ class WebAssemblyInterface_EXPORT InputStreamBase
std::istream *
GetPointer()
{
return m_IStream;
return m_IStream.get();
}

void
SetJSON(const std::string & json)
{
if (m_DeleteIStream && m_IStream != nullptr)
{
delete m_IStream;
}
m_DeleteIStream = false;
m_WasmStringStream = WasmStringStream::New();
m_WasmStringStream->SetJSON(json.c_str());

m_IStream = &(m_WasmStringStream->GetStringStream());
}
SetJSON(const std::string & json);

virtual void
SetFileName(const std::string & fileName) = 0;

protected:
void
SetFile(const std::string & fileName, const std::ios_base::openmode openMode)
{
if (m_DeleteIStream && m_IStream != nullptr)
{
delete m_IStream;
}
m_IStream = new std::ifstream(fileName, openMode);
m_DeleteIStream = true;
}
SetFile(const std::string & fileName, const std::ios_base::openmode openMode);

InputStreamBase() = default;
virtual ~InputStreamBase()
{
if (m_DeleteIStream && m_IStream != nullptr)
{
delete m_IStream;
}
}

private:
std::istream * m_IStream{ nullptr };
bool m_DeleteIStream{ false };
// Move semantics for its derived classes:
InputStreamBase(InputStreamBase &&) = default;
InputStreamBase &
operator=(InputStreamBase &&) = default;

WasmStringStream::Pointer m_WasmStringStream;
virtual ~InputStreamBase();

private:
std::unique_ptr<std::istream> m_IStream;
};


Expand Down
24 changes: 23 additions & 1 deletion src/itkInputStreamBase.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -16,16 +16,38 @@
*
*=========================================================================*/
#include "itkInputStreamBase.h"
#include "itkPipeline.h"
#include "itkWasmStringStream.h"

#include <string>
#ifndef ITK_WASM_NO_MEMORY_IO
# include "itkWasmExports.h"
#endif

#include <fstream>
#include <sstream>

namespace itk
{
namespace wasm
{
void
InputStreamBase::SetJSON(const std::string & json)
{
const auto wasmStringStream = WasmStringStream::New();
wasmStringStream->SetJSON(json.c_str());
m_IStream = std::make_unique<std::stringstream>(std::move(wasmStringStream->GetStringStream()));
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Copilot AI Jul 25, 2025

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This line attempts to move-construct a stringstream from another stringstream, but the GetStringStream() method likely returns a reference, not a movable object. This could result in compilation errors or unintended copying. Consider using a different approach to transfer the stream data.

Suggested change
m_IStream = std::make_unique<std::stringstream>(std::move(wasmStringStream->GetStringStream()));
std::stringstream tempStream = wasmStringStream->GetStringStream();
m_IStream = std::make_unique<std::stringstream>(tempStream.str());

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@N-Dekker N-Dekker Jul 25, 2025

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The change suggested by Copilot does not compile. Specifically:

    std::stringstream tempStream = wasmStringStream->GetStringStream();

This suggestion would try to copy-construct a std::stringstream, but std::stringstream is not copy-constructible!

std::stringstream is move-construcible, so the stringstream of a WasmStringStream object can be properly moved into another stringstream, as in the proposed PR. Especially because the WasmStringStream object itself is no longer used afterwards.

}


void
InputStreamBase::SetFile(const std::string & fileName, const std::ios_base::openmode openMode)
{
m_IStream = std::make_unique<std::ifstream>(fileName, openMode);
}


InputStreamBase::~InputStreamBase() = default;


bool
lexical_cast(const std::string & input, InputStreamBase & inputStream)
Expand Down
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