lbug 0.16.1

An in-process property graph database management system built for query speed and scalability
Documentation 
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#pragma once

#include "binder/expression/scalar_function_expression.h"
#include "expression_evaluator.h"

namespace lbug {
namespace evaluator {

class ListSliceInfo;
class ListEntryTracker;

enum class ListLambdaType : uint8_t {
    LIST_TRANSFORM = 0,
    LIST_FILTER = 1,
    LIST_REDUCE = 2,
    DEFAULT = 3
};

class LambdaParamEvaluator : public ExpressionEvaluator {
    static constexpr EvaluatorType type_ = EvaluatorType::LAMBDA_PARAM;

public:
    explicit LambdaParamEvaluator(std::shared_ptr<binder::Expression> expression)
        : ExpressionEvaluator{type_, std::move(expression), false /* isResultFlat */} {}

    void evaluate() override {}

    bool selectInternal(common::SelectionVector&) override { UNREACHABLE_CODE; }

    std::unique_ptr<ExpressionEvaluator> copy() override {
        return std::make_unique<LambdaParamEvaluator>(expression);
    }

    std::string getVarName() { return this->getExpression()->toString(); }

protected:
    void resolveResultVector(const processor::ResultSet&, storage::MemoryManager*) override {}
};

struct ListLambdaBindData {
    std::vector<LambdaParamEvaluator*> lambdaParamEvaluators;
    std::vector<common::idx_t> paramIndices;
    ExpressionEvaluator* rootEvaluator = nullptr;
    ListSliceInfo* sliceInfo = nullptr;
};

// E.g. for function list_transform([0,1,2], x->x+1)
// ListLambdaEvaluator has one child that is the evaluator of [0,1,2]
// lambdaRootEvaluator is the evaluator of x+1
// lambdaParamEvaluator is the evaluator of x
class ListLambdaEvaluator : public ExpressionEvaluator {
    static constexpr EvaluatorType type_ = EvaluatorType::LIST_LAMBDA;
    static ListLambdaType checkListLambdaTypeWithFunctionName(std::string functionName);

public:
    ListLambdaEvaluator(std::shared_ptr<binder::Expression> expression, evaluator_vector_t children)
        : ExpressionEvaluator{type_, expression, std::move(children)}, memoryManager(nullptr) {
        execFunc = expression->constCast<binder::ScalarFunctionExpression>().getFunction().execFunc;
        listLambdaType = checkListLambdaTypeWithFunctionName(
            expression->constCast<binder::ScalarFunctionExpression>().getFunction().name);
    }

    void setLambdaRootEvaluator(std::unique_ptr<ExpressionEvaluator> evaluator) {
        lambdaRootEvaluator = std::move(evaluator);
    }

    void init(const processor::ResultSet& resultSet, main::ClientContext* clientContext) override;

    void evaluate() override;

    bool selectInternal(common::SelectionVector& selVector) override;

    std::unique_ptr<ExpressionEvaluator> copy() override {
        auto result = std::make_unique<ListLambdaEvaluator>(expression, copyVector(children));
        result->setLambdaRootEvaluator(lambdaRootEvaluator->copy());
        return result;
    }

    std::vector<common::idx_t> getParamIndices();

protected:
    void resolveResultVector(const processor::ResultSet& resultSet,
        storage::MemoryManager* memoryManager) override;

private:
    void evaluateInternal();

    function::scalar_func_exec_t execFunc;
    ListLambdaBindData bindData;

private:
    std::unique_ptr<ExpressionEvaluator> lambdaRootEvaluator;
    std::vector<LambdaParamEvaluator*> lambdaParamEvaluators;
    std::vector<std::shared_ptr<common::ValueVector>> params;
    ListLambdaType listLambdaType;

    storage::MemoryManager* memoryManager;
};

} // namespace evaluator
} // namespace lbug