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arangodb/arangod/Aql/Expression.h

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS 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 Max Neunhoeffer
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_AQL_EXPRESSION_H
#define ARANGOD_AQL_EXPRESSION_H 1
#include "Basics/Common.h"
#include "Aql/AstNode.h"
#include "Aql/Range.h"
#include "Aql/Variable.h"
#include "Aql/types.h"
#include "Basics/JsonHelper.h"
#include <velocypack/Builder.h>
#include <velocypack/Slice.h>
struct TRI_json_t;
namespace arangodb {
class AqlTransaction;
namespace basics {
class Json;
class StringBuffer;
}
namespace aql {
class AqlItemBlock;
struct AqlValue;
class Ast;
class AttributeAccessor;
class Executor;
struct V8Expression;
/// @brief AqlExpression, used in execution plans and execution blocks
class Expression {
enum ExpressionType : uint32_t { UNPROCESSED, JSON, V8, SIMPLE, ATTRIBUTE };
public:
Expression(Expression const&) = delete;
Expression& operator=(Expression const&) = delete;
Expression() = delete;
/// @brief constructor, using an AST start node
Expression(Ast*, AstNode*);
/// @brief constructor, using JSON
Expression(Ast*, arangodb::basics::Json const&);
~Expression();
/// @brief replace the root node
inline void replaceNode (AstNode* node) {
_node = node;
}
/// @brief get the underlying AST node
inline AstNode const* node() const { return _node; }
/// @brief get the underlying AST node
inline AstNode* nodeForModification() const { return _node; }
/// @brief whether or not the expression can throw an exception
inline bool canThrow() {
if (_type == UNPROCESSED) {
analyzeExpression();
}
return _canThrow;
}
/// @brief whether or not the expression can safely run on a DB server
inline bool canRunOnDBServer() {
if (_type == UNPROCESSED) {
analyzeExpression();
}
return _canRunOnDBServer;
}
/// @brief whether or not the expression is deterministic
inline bool isDeterministic() {
if (_type == UNPROCESSED) {
analyzeExpression();
}
return _isDeterministic;
}
/// @brief clone the expression, needed to clone execution plans
Expression* clone() {
// We do not need to copy the _ast, since it is managed by the
// query object and the memory management of the ASTs
return new Expression(_ast, _node);
}
/// @brief return all variables used in the expression
void variables(std::unordered_set<Variable const*>&) const;
/// @brief return a Json representation of the expression
arangodb::basics::Json toJson(TRI_memory_zone_t* zone, bool verbose) const {
return arangodb::basics::Json(zone, _node->toJson(zone, verbose));
}
/// @brief return a VelocyPack representation of the expression
void toVelocyPack(arangodb::velocypack::Builder& builder, bool verbose) const {
_node->toVelocyPack(builder, verbose);
}
/// @brief execute the expression
AqlValue execute(arangodb::AqlTransaction* trx, AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&, bool& mustDestroy);
/// @brief check whether this is a JSON expression
inline bool isJson() {
if (_type == UNPROCESSED) {
analyzeExpression();
}
return _type == JSON;
}
/// @brief check whether this is a V8 expression
inline bool isV8() {
if (_type == UNPROCESSED) {
analyzeExpression();
}
return _type == V8;
}
/// @brief get expression type as string
std::string typeString() {
if (_type == UNPROCESSED) {
analyzeExpression();
}
switch (_type) {
case JSON:
return "json";
case SIMPLE:
return "simple";
case ATTRIBUTE:
return "attribute";
case V8:
return "v8";
case UNPROCESSED: {
}
}
TRI_ASSERT(false);
return "unknown";
}
/// @brief check whether this is an attribute access of any degree (e.g. a.b,
/// a.b.c, ...)
bool isAttributeAccess() const;
/// @brief check whether this is only a reference access
bool isReference() const;
/// @brief check whether this is a constant node
bool isConstant() const;
/// @brief stringify an expression
/// note that currently stringification is only supported for certain node
/// types
void stringify(arangodb::basics::StringBuffer*) const;
/// @brief stringify an expression, if it is not too long
/// if the stringified version becomes too long, this method will throw
/// note that currently stringification is only supported for certain node
/// types
void stringifyIfNotTooLong(arangodb::basics::StringBuffer*) const;
/// @brief replace variables in the expression with other variables
void replaceVariables(std::unordered_map<VariableId, Variable const*> const&);
/// @brief replace a variable reference in the expression with another
/// expression (e.g. inserting c = `a + b` into expression `c + 1` so the
/// latter
/// becomes `a + b + 1`
void replaceVariableReference(Variable const*, AstNode const*);
/// @brief invalidates an expression
/// this only has an effect for V8-based functions, which need to be created,
/// used and destroyed in the same context. when a V8 function is used across
/// multiple V8 contexts, it must be invalidated in between
void invalidate();
private:
void setVariable(Variable const* variable, arangodb::velocypack::Slice value) {
_variables.emplace(variable, value);
}
void clearVariable(Variable const* variable) { _variables.erase(variable); }
/// @brief find a value in an array
bool findInArray(AqlValue const&, AqlValue const&,
arangodb::AqlTransaction*,
AstNode const*) const;
/// @brief analyze the expression (determine its type etc.)
void analyzeExpression();
/// @brief build the expression (if appropriate, compile it into
/// executable code)
void buildExpression();
/// @brief execute an expression of type SIMPLE
AqlValue executeSimpleExpression(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy, bool);
/// @brief execute an expression of type SIMPLE with ATTRIBUTE ACCESS
AqlValue executeSimpleExpressionAttributeAccess(
AstNode const*, arangodb::AqlTransaction*, AqlItemBlock const*, size_t,
std::vector<Variable const*> const&, std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with INDEXED ACCESS
AqlValue executeSimpleExpressionIndexedAccess(
AstNode const*, arangodb::AqlTransaction*, AqlItemBlock const*, size_t,
std::vector<Variable const*> const&, std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with ARRAY
AqlValue executeSimpleExpressionArray(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with OBJECT
AqlValue executeSimpleExpressionObject(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with VALUE
AqlValue executeSimpleExpressionValue(AstNode const*, bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with REFERENCE
AqlValue executeSimpleExpressionReference(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy,
bool);
/// @brief execute an expression of type SIMPLE with FCALL
AqlValue executeSimpleExpressionFCall(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with RANGE
AqlValue executeSimpleExpressionRange(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with NOT
AqlValue executeSimpleExpressionNot(AstNode const*, arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with AND or OR
AqlValue executeSimpleExpressionAndOr(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with COMPARISON
AqlValue executeSimpleExpressionComparison(
AstNode const*, arangodb::AqlTransaction*, AqlItemBlock const*, size_t,
std::vector<Variable const*> const&, std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with ARRAY COMPARISON
AqlValue executeSimpleExpressionArrayComparison(
AstNode const*, arangodb::AqlTransaction*, AqlItemBlock const*, size_t,
std::vector<Variable const*> const&, std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with TERNARY
AqlValue executeSimpleExpressionTernary(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with EXPANSION
AqlValue executeSimpleExpressionExpansion(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with EXPANSION
AqlValue executeSimpleExpressionIterator(AstNode const*,
arangodb::AqlTransaction*,
AqlItemBlock const*, size_t,
std::vector<Variable const*> const&,
std::vector<RegisterId> const&,
bool& mustDestroy);
/// @brief execute an expression of type SIMPLE with BINARY_* (+, -, * , /, %)
AqlValue executeSimpleExpressionArithmetic(
AstNode const*, arangodb::AqlTransaction*, AqlItemBlock const*, size_t,
std::vector<Variable const*> const&, std::vector<RegisterId> const&,
bool& mustDestroy);
private:
/// @brief the AST
Ast* _ast;
/// @brief the V8 executor
Executor* _executor;
/// @brief the AST node that contains the expression to execute
AstNode* _node;
/// @brief a v8 function that will be executed for the expression
/// if the expression is a constant, it will be stored as plain JSON instead
union {
V8Expression* _func;
uint8_t* _data;
AttributeAccessor* _accessor;
};
/// @brief type of expression
ExpressionType _type;
/// @brief whether or not the expression may throw a runtime exception
bool _canThrow;
/// @brief whether or not the expression can be run safely on a DB server
bool _canRunOnDBServer;
/// @brief whether or not the expression is deterministic
bool _isDeterministic;
/// @brief whether or not the top-level attributes of the expression were
/// determined
bool _hasDeterminedAttributes;
/// @brief whether or not the expression has been built/compiled
bool _built;
/// @brief the top-level attributes used in the expression, grouped
/// by variable name
std::unordered_map<Variable const*, std::unordered_set<std::string>>
_attributes;
/// @brief buffer for temporary strings
arangodb::basics::StringBuffer _buffer;
/// @brief variables only temporarily valid during execution
std::unordered_map<Variable const*, arangodb::velocypack::Slice> _variables;
};
} // namespace arangodb::aql
} // namespace arangodb
#endif
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