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/******************************************************************************
*
* Project: GDAL
* Purpose: "limit" step of "vector pipeline"
* Author: Dan Baston
*
******************************************************************************
* Copyright (c) 2025, ISciences LLC
*
* SPDX-License-Identifier: MIT
****************************************************************************/
#include "gdalalg_vector_limit.h"
#include "gdalalg_vector_pipeline.h"
#include "gdal_priv.h"
#include "ogrsf_frmts.h"
#include "ogr_p.h"
#include <algorithm>
#include <set>
//! @cond Doxygen_Suppress
#ifndef _
#define _(x) (x)
#endif
/************************************************************************/
/* GDALVectorLimitAlgorithm::GDALVectorLimitAlgorithm() */
/************************************************************************/
GDALVectorLimitAlgorithm::GDALVectorLimitAlgorithm(bool standaloneStep)
: GDALVectorPipelineStepAlgorithm(NAME, DESCRIPTION, HELP_URL,
standaloneStep)
{
AddArg("limit", 0, _("Limit the number of features to read per layer"),
&m_featureLimit)
.SetPositional()
.SetRequired();
AddActiveLayerArg(&m_activeLayer);
}
namespace
{
/************************************************************************/
/* GDALVectorReadLimitedLayer */
/************************************************************************/
class GDALVectorReadLimitedLayer : public OGRLayer
{
public:
GDALVectorReadLimitedLayer(OGRLayer &layer, int featureLimit)
: m_srcLayer(layer), m_featureLimit(featureLimit), m_featuresRead(0)
{
}
~GDALVectorReadLimitedLayer() override;
OGRFeature *GetNextFeature() override
{
if (m_featuresRead < m_featureLimit)
{
m_featuresRead++;
return m_srcLayer.GetNextFeature();
}
return nullptr;
}
const OGRFeatureDefn *GetLayerDefn() const override
{
return m_srcLayer.GetLayerDefn();
}
GIntBig GetFeatureCount(int bForce) override
{
return std::min(m_featureLimit, m_srcLayer.GetFeatureCount(bForce));
}
void ResetReading() override
{
m_featuresRead = 0;
m_srcLayer.ResetReading();
}
int TestCapability(const char *pszCap) const override
{
return m_srcLayer.TestCapability(pszCap);
}
private:
OGRLayer &m_srcLayer;
GIntBig m_featureLimit;
GIntBig m_featuresRead;
};
GDALVectorReadLimitedLayer::~GDALVectorReadLimitedLayer() = default;
} // namespace
/************************************************************************/
/* GDALVectorLimitAlgorithm::RunStep() */
/************************************************************************/
bool GDALVectorLimitAlgorithm::RunStep(GDALPipelineStepRunContext &)
{
auto poSrcDS = m_inputDataset[0].GetDatasetRef();
CPLAssert(poSrcDS);
CPLAssert(m_outputDataset.GetName().empty());
CPLAssert(!m_outputDataset.GetDatasetRef());
auto outDS = std::make_unique<GDALVectorOutputDataset>();
for (auto &&poSrcLayer : poSrcDS->GetLayers())
{
if (m_activeLayer.empty() ||
m_activeLayer == poSrcLayer->GetDescription())
{
outDS->AddLayer(std::make_unique<GDALVectorReadLimitedLayer>(
*poSrcLayer, m_featureLimit));
}
else
{
outDS->AddLayer(
std::make_unique<GDALVectorPipelinePassthroughLayer>(
*poSrcLayer));
}
}
m_outputDataset.Set(std::move(outDS));
return true;
}
//! @endcond
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