arangodb/arangod/IResearch/ExpressionFilter.h

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2017 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Andrey Abramov
/// @author Vasiliy Nabatchikov
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGODB_IRESEARCH__IRESEARCH_EXPRESSION_FILTER
#define ARANGODB_IRESEARCH__IRESEARCH_EXPRESSION_FILTER 1

#include "Aql/Expression.h"
#include "IResearch/IResearchExpressionContext.h"

#include "search/filter.hpp"

namespace arangodb {

namespace aql {
struct AstNode;
class Ast;
class ExecutionPlan;
}  // namespace aql

namespace iresearch {

///////////////////////////////////////////////////////////////////////////////
/// @struct ExpressionCompilationContext
///////////////////////////////////////////////////////////////////////////////
struct ExpressionCompilationContext {
  bool operator==(ExpressionCompilationContext const& rhs) const noexcept {
    return plan == rhs.plan && ast == rhs.ast && node == rhs.node;
  }

  bool operator!=(ExpressionCompilationContext const& rhs) const noexcept {
    return !(*this == rhs);
  }

  explicit operator bool() const noexcept { return plan && ast && node; }

  size_t hash() const noexcept;

  arangodb::aql::ExecutionPlan const* plan{};
  arangodb::aql::Ast* ast{};
  std::shared_ptr<arangodb::aql::AstNode> node{};
};  // ExpressionCompilationContext

///////////////////////////////////////////////////////////////////////////////
/// @struct ExpressionExecutionContext
///////////////////////////////////////////////////////////////////////////////
struct ExpressionExecutionContext : irs::attribute {
  DECLARE_ATTRIBUTE_TYPE();

  ExpressionExecutionContext() = default;

  explicit ExpressionExecutionContext(arangodb::transaction::Methods& trx) noexcept
      : trx(&trx) {}

  ExpressionExecutionContext(arangodb::transaction::Methods& trx,
                             arangodb::iresearch::ViewExpressionContextBase& ctx) noexcept
      : ctx(&ctx), trx(&trx) {}

  explicit operator bool() const noexcept { return trx && ctx; }

  // FIXME change 'ctx' to be 'arangodb::aql::ExpressionContext'
  // once IResearchView will be able to evaluate epxressions
  // with loop variable in SEARCH expressions
  arangodb::iresearch::ViewExpressionContextBase* ctx{};
  arangodb::transaction::Methods* trx{};
};  // ExpressionFilterContext

///////////////////////////////////////////////////////////////////////////////
/// @class ByExpression
/// @brief user-side filter based on arbitrary ArangoDB `Expression`
///////////////////////////////////////////////////////////////////////////////
class ByExpression final : public irs::filter {
 public:
  DECLARE_FACTORY();
  DECLARE_FILTER_TYPE();

  ByExpression() noexcept;

  void init(aql::ExecutionPlan const& plan, aql::Ast& ast, arangodb::aql::AstNode& node) noexcept {
    _ctx.plan = &plan;
    _ctx.ast = &ast;
    _ctx.node.reset(&node, [](arangodb::aql::AstNode*) {});
  }

  void init(aql::ExecutionPlan const& plan, aql::Ast& ast,
            std::shared_ptr<arangodb::aql::AstNode>&& node) noexcept {
    _ctx.plan = &plan;
    _ctx.ast = &ast;
    _ctx.node = std::move(node);
  }

  using irs::filter::prepare;

  virtual irs::filter::prepared::ptr prepare(irs::index_reader const& index,
                                             irs::order::prepared const& ord,
                                             irs::boost_t boost,
                                             irs::attribute_view const& ctx) const override;

  virtual size_t hash() const noexcept override;

  ExpressionCompilationContext const& context() const noexcept { return _ctx; }

  explicit operator bool() const noexcept { return bool(_ctx); }

 protected:
  virtual bool equals(irs::filter const& rhs) const noexcept override;

 private:
  ExpressionCompilationContext _ctx;
};  // ByExpression

}  // namespace iresearch
}  // namespace arangodb

#endif  // ARANGODB_IRESEARCH__IRESEARCH_EXPRESSION_FILTER