interpreter.h

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/****************************************************************************
**
** Author: Róbert Márki <gsmiko@gmail.com>
** Copyright (c) 2016 Róbert Márki
**
** This file is part of the jmespath.cpp project which is distributed under
** the MIT License (MIT).
**
** Permission is hereby granted, free of charge, to any person obtaining a copy
** of this software and associated documentation files (the "Software"), to
** deal in the Software without restriction, including without limitation the
** rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
** sell copies of the Software, and to permit persons to whom the Software is
** furnished to do so, subject to the following conditions:
**
** The above copyright notice and this permission notice shall be included in
** all copies or substantial portions of the Software.
**
** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
** FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
** DEALINGS IN THE SOFTWARE.
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****************************************************************************/
#ifndef INTERPRETER_H
#define INTERPRETER_H
#include "src/interpreter/abstractvisitor.h"
#include "jmespath/types.h"
#include "src/ast/expressionnode.h"
#include "src/ast/functionexpressionnode.h"
#include <functional>
#include <tuple>
#include <unordered_map>
#include <boost/variant.hpp>

namespace jmespath { namespace ast {

class BinaryExpressionNode;
}} // namespace jmespath::ast

namespace jmespath { namespace interpreter {

using JsonRef = std::reference_wrapper<const Json>;
using ContextValue = boost::variant<Json, JsonRef>;

inline Json&& assignContextValue(Json&& value)
{
    return std::move(value);
}
inline JsonRef assignContextValue(const Json& value)
{
    return std::cref(value);
}

inline const Json& getJsonValue(const ContextValue& contextValue)
{
    return boost::apply_visitor([](const auto& value) -> const Json& {
        return value;
    }, contextValue);
}

class Interpreter : public AbstractVisitor
{
public:
    Interpreter();
    template <typename JsonT>
    std::enable_if_t<std::is_same<std::decay_t<JsonT>, Json>::value, void>
    setContext(JsonT&& value)
    {
        m_context = assignContextValue(std::forward<JsonT>(value));
    }
    const Json &currentContext() const
    {
        return getJsonValue(m_context);
    }
    ContextValue &currentContextValue()
    {
        return m_context;
    }
    virtual void evaluateProjection(const ast::ExpressionNode* expression);

    void visit(const ast::AbstractNode *node) override;
    void visit(const ast::ExpressionNode *node) override;
    void visit(const ast::IdentifierNode *node) override;
    void visit(const ast::RawStringNode *node) override;
    void visit(const ast::LiteralNode* node) override;
    void visit(const ast::SubexpressionNode* node) override;
    void visit(const ast::IndexExpressionNode* node) override;
    void visit(const ast::ArrayItemNode* node) override;
    void visit(const ast::FlattenOperatorNode*) override;
    void visit(const ast::BracketSpecifierNode* node) override;
    void visit(const ast::SliceExpressionNode* node) override;
    void visit(const ast::ListWildcardNode*) override;
    void visit(const ast::HashWildcardNode* node) override;
    void visit(const ast::MultiselectListNode* node) override;
    void visit(const ast::MultiselectHashNode* node) override;
    void visit(const ast::NotExpressionNode* node) override;
    void visit(const ast::ComparatorExpressionNode* node) override;
    void visit(const ast::OrExpressionNode* node) override;
    void visit(const ast::AndExpressionNode* node) override;
    void visit(const ast::ParenExpressionNode* node) override;
    void visit(const ast::PipeExpressionNode* node) override;
    void visit(const ast::CurrentNode*) override;
    void visit(const ast::FilterExpressionNode* node) override;
    void visit(const ast::FunctionExpressionNode* node) override;
    void visit(const ast::ExpressionArgumentNode*) override;
private:
    using FunctionArgument
        = boost::variant<boost::blank, ContextValue, ast::ExpressionNode>;
    using FunctionArgumentList = std::vector<FunctionArgument>;
    using Function = std::function<void(FunctionArgumentList&)>;
    using JsonComparator = std::function<bool(const Json&, const Json&)>;
    using ArgumentArityValidator = std::function<bool(const size_t&)>;
    using FunctionDescriptor = std::tuple<ArgumentArityValidator,
                                          bool,
                                          Function>;
    using FunctionExpressionArgumentList
        = std::vector<ast::FunctionExpressionNode::ArgumentType>;    
    ContextValue m_context;
    std::unordered_map<String, FunctionDescriptor> m_functionMap;
    template <typename JsonT>
    void visit(const ast::IdentifierNode *node, JsonT&& context);
    template <typename JsonT>
    void visit(const ast::ArrayItemNode *node, JsonT&& context);
    template <typename JsonT>
    void visit(const ast::FlattenOperatorNode* node, JsonT&& context);
    template <typename JsonT>
    void visit(const ast::SliceExpressionNode* node, JsonT&& context);
    template <typename JsonT>
    void visit(const ast::HashWildcardNode* node, JsonT&& context);
    template <typename JsonT>
    void visit(const ast::FilterExpressionNode* node, JsonT&& context);
    Index adjustSliceEndpoint(size_t length,
                              Index endpoint,
                              Index step) const;
    bool toBoolean(const Json& json) const;
    template <typename JsonT>
    void evaluateProjection(const ast::ExpressionNode* expression,
                            JsonT&& context);
    void evaluateLogicOperator(const ast::BinaryExpressionNode* node,
                               bool shortCircuitValue);
    FunctionArgumentList evaluateArguments(
            const FunctionExpressionArgumentList& arguments,
            const std::shared_ptr<ContextValue> &contextValue);
    template <typename T>
    T& getArgument(FunctionArgument& argument) const;
    const Json& getJsonArgument(FunctionArgument& argument) const;
    void abs(FunctionArgumentList& arguments);
    void avg(FunctionArgumentList& arguments);
    void contains(FunctionArgumentList& arguments);
    void ceil(FunctionArgumentList& arguments);
    void endsWith(FunctionArgumentList& arguments);
    void floor(FunctionArgumentList& arguments);
    void join(FunctionArgumentList& arguments);
    void keys(FunctionArgumentList& arguments);
    void length(FunctionArgumentList& arguments);
    void map(FunctionArgumentList& arguments);
    template <typename JsonT>
    void map(const ast::ExpressionNode* node, JsonT&& array);
    void merge(FunctionArgumentList& arguments);
    template <typename JsonT>
    void mergeObject(Json* object, JsonT&& sourceObject);
    void notNull(FunctionArgumentList& arguments);
    void reverse(FunctionArgumentList& arguments);
    void reverse(Json&& subject);
    void sort(FunctionArgumentList& arguments);
    void sort(Json&& array);
    void sortBy(FunctionArgumentList& arguments);
    void sortBy(const ast::ExpressionNode* expression, Json&& array);
    void startsWith(FunctionArgumentList& arguments);
    void sum(FunctionArgumentList& arguments);
    void toArray(FunctionArgumentList& arguments);
    template <typename JsonT>
    void toArray(JsonT&& value);
    void toString(FunctionArgumentList& arguments);
    template <typename JsonT>
    void toString(JsonT&& value);
    void toNumber(FunctionArgumentList& arguments);
    template <typename JsonT>
    void toNumber(JsonT&& value);
    void type(FunctionArgumentList& arguments);
    void values(FunctionArgumentList& arguments);
    template <typename JsonT>
    void values(JsonT&& object);
    void max(FunctionArgumentList& arguments, const JsonComparator& comparator);
    template <typename JsonT>
    void max(const JsonComparator* comparator, JsonT&& array);
    void maxBy(FunctionArgumentList& arguments,
               const JsonComparator& comparator = std::less<Json>{});
    template <typename JsonT>
    void maxBy(const ast::ExpressionNode* expression,
               const JsonComparator* comparator,
               JsonT&& array);
    bool isComparableArray(const Json& array) const;
};
}} // namespace jmespath::interpreter
#endif // INTERPRETER_H