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Query.h
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125 lines (104 loc) · 3.24 KB
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//
// Query.h
//
// Library: JSON
// Package: JSON
// Module: Query
//
// Definition of the Query class.
//
// Copyright (c) 2012, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef JSON_JSONQuery_INCLUDED
#define JSON_JSONQuery_INCLUDED
#include "Poco/JSON/JSON.h"
#include "Poco/JSON/Object.h"
#include "Poco/JSON/Array.h"
namespace Poco {
namespace JSON {
class JSON_API Query
/// Class that can be used to search for a value in a JSON object or array.
{
public:
Query(const Dynamic::Var& source);
/// Creates a Query/
///
/// Source must be JSON Object, Array, Object::Ptr,
/// Array::Ptr or empty Var. Any other type will trigger throwing of
/// InvalidArgumentException.
///
/// Creating Query holding Ptr will typically result in faster
/// performance.
virtual ~Query();
/// Destroys the Query.
Object::Ptr findObject(const std::string& path) const;
/// Search for an object.
///
/// When the object can't be found, a zero Ptr is returned;
/// otherwise, a shared pointer to internally held object
/// is returned.
/// If object (as opposed to a pointer to object) is held
/// internally, a shared pointer to new (heap-allocated) Object is
/// returned; this may be expensive operation.
Object& findObject(const std::string& path, Object& obj) const;
/// Search for an object.
///
/// If object is found, it is assigned to the
/// Object through the reference passed in. When the object can't be
/// found, the provided Object is emptied and returned.
Array::Ptr findArray(const std::string& path) const;
/// Search for an array.
///
/// When the array can't be found, a zero Ptr is returned;
/// otherwise, a shared pointer to internally held array
/// is returned.
/// If array (as opposed to a pointer to array) is held
/// internally, a shared pointer to new (heap-allocated) Object is
/// returned; this may be expensive operation.
Array& findArray(const std::string& path, Array& obj) const;
/// Search for an array.
///
/// If array is found, it is assigned to the
/// Object through the reference passed in. When the array can't be
/// found, the provided Object is emptied and returned.
Dynamic::Var find(const std::string& path) const;
/// Searches a value.
///
/// Example: "person.children[0].name" will return the
/// the name of the first child. When the value can't be found
/// an empty value is returned.
template<typename T>
T findValue(const std::string& path, const T& def) const
/// Searches for a value will convert it to the given type.
/// When the value can't be found or has an invalid type
/// the default value will be returned.
{
T result = def;
Dynamic::Var value = find(path);
if (!value.isEmpty())
{
try
{
result = value.convert<T>();
}
catch (...)
{
}
}
return result;
}
std::string findValue(const char* path, const char* def) const
/// Searches for a value will convert it to the given type.
/// When the value can't be found or has an invalid type
/// the default value will be returned.
{
return findValue<std::string>(path, def);
}
private:
Dynamic::Var _source;
};
} } // namespace Poco::JSON
#endif // JSON_JSONQuery_INCLUDED