Context.h

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/*
* Copyright Disney Enterprises, Inc.  All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License
* and the following modification to it: Section 6 Trademarks.
* deleted and replaced with:
*
* 6. Trademarks. This License does not grant permission to use the
* trade names, trademarks, service marks, or product names of the
* Licensor and its affiliates, except as required for reproducing
* the content of the NOTICE file.
*
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
*/
#pragma once

#include <map>
#include <string>

namespace SeExpr2 {

class Context {
  public:
    bool lookupParameter(const std::string& parameterName, std::string& value) const {
        ParameterMap::const_iterator it = _parameters.find(parameterName);
        if (it != _parameters.end()) {
            value = it->second;
            return true;
        } else if (_parent)
            return _parent->lookupParameter(parameterName, value);
        else
            return false;
    }
    void setParameter(const std::string& parameterName, const std::string& value);
    Context* createChildContext() const;

    // Parent access uses pointers as it is acceptable to set/get a NULL parent
    void setParent(const Context* context) { _parent = context; }
    const Context* getParent() const { return _parent; }

    bool hasContext(const Context* context) const {
        if (this == context) return true;
        if (_parent) return _parent->hasContext(context);
        return false;
    }

    static Context& global();

  private:
    Context(const Context&);
    Context& operator=(const Context&);

    Context(const Context* parent);
    const Context* _parent;

    // TODO: Use std::map until C++11 is ubiq.
    typedef std::map<std::string, std::string> ParameterMap;
    ParameterMap _parameters;
};
}