Descriptor.h

/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Descriptor.h
 * Holds the metadata (schema) for a Message.
 * Copyright (C) 2011 Simon Newton
 */

#ifndef INCLUDE_OLA_MESSAGING_DESCRIPTOR_H_
#define INCLUDE_OLA_MESSAGING_DESCRIPTOR_H_

#include <ola/messaging/DescriptorVisitor.h>
#include <map>
#include <string>
#include <vector>
#include <utility>

using std::string;
using std::vector;

namespace ola {
namespace messaging {

class FieldDescriptorVisitor;

class FieldDescriptorInterface {
 public:
 virtual ~FieldDescriptorInterface() {}

 // Returns the name of this field
 virtual const string& Name() const = 0;

 // Call back into a FieldDescriptorVisitor
 virtual void Accept(FieldDescriptorVisitor *visitor) const = 0;

 // Returns true if the size of this field is constant
 virtual bool FixedSize() const = 0;

 // True if there is some bound on the field's size.
 virtual bool LimitedSize() const = 0;

 // This is the max size in bytes of the field. This is only valid if
 // LimitedSize() is true, otherwise it returns 0.
 virtual unsigned int MaxSize() const = 0;
};


class FieldDescriptor: public FieldDescriptorInterface {
 public:
 explicit FieldDescriptor(const string &name)
 : m_name(name) {
 }
 virtual ~FieldDescriptor() {}

 // Returns the name of this field
 const string& Name() const { return m_name; }

 private:
 string m_name;
};


class BoolFieldDescriptor: public FieldDescriptor {
 public:
 explicit BoolFieldDescriptor(const string &name)
 : FieldDescriptor(name) {
 }

 bool FixedSize() const { return true; }
 bool LimitedSize() const { return true; }
 unsigned int MaxSize() const { return 1; }

 void Accept(FieldDescriptorVisitor *visitor) const {
 visitor->Visit(this);
 }
};


class IPV4FieldDescriptor: public FieldDescriptor {
 public:
 explicit IPV4FieldDescriptor(const string &name)
 : FieldDescriptor(name) {
 }

 bool FixedSize() const { return true; }
 bool LimitedSize() const { return true; }
 unsigned int MaxSize() const { return 4; }

 void Accept(FieldDescriptorVisitor *visitor) const {
 visitor->Visit(this);
 }
};


class UIDFieldDescriptor: public FieldDescriptor {
 public:
 explicit UIDFieldDescriptor(const string &name)
 : FieldDescriptor(name) {
 }

 bool FixedSize() const { return true; }
 bool LimitedSize() const { return true; }
 unsigned int MaxSize() const { return 6; }

 void Accept(FieldDescriptorVisitor *visitor) const {
 visitor->Visit(this);
 }
};


class StringFieldDescriptor: public FieldDescriptor {
 public:
 StringFieldDescriptor(const string &name,
 uint8_t min_size,
 uint8_t max_size)
 : FieldDescriptor(name),
 m_min_size(min_size),
 m_max_size(max_size) {
 }

 bool FixedSize() const { return m_min_size == m_max_size; }
 bool LimitedSize() const { return true; }
 unsigned int MinSize() const { return m_min_size; }
 unsigned int MaxSize() const { return m_max_size; }

 void Accept(FieldDescriptorVisitor *visitor) const {
 visitor->Visit(this);
 }

 private:
 uint8_t m_min_size, m_max_size;
};


template <typename type>
class IntegerFieldDescriptor: public FieldDescriptor {
 public:
 typedef std::pair<type, type> Interval;
 typedef vector<std::pair<type, type> > IntervalVector;
 typedef std::map<string, type> LabeledValues;

 IntegerFieldDescriptor(const string &name,
 bool little_endian = false,
 int8_t multiplier = 0)
 : FieldDescriptor(name),
 m_little_endian(little_endian),
 m_multipler(multiplier) {
 }

 IntegerFieldDescriptor(const string &name,
 const IntervalVector &intervals,
 const LabeledValues &labels,
 bool little_endian = false,
 int8_t multiplier = 0)
 : FieldDescriptor(name),
 m_little_endian(little_endian),
 m_multipler(multiplier),
 m_intervals(intervals),
 m_labels(labels) {
 }

 bool FixedSize() const { return true; }
 bool LimitedSize() const { return true; }
 unsigned int MaxSize() const { return sizeof(type); }
 int8_t Multiplier() const { return m_multipler; }
 bool IsLittleEndian() const { return m_little_endian; }

 const IntervalVector &Intervals() const { return m_intervals; }

 bool IsValid(type value) const {
 if (m_intervals.empty())
 return true;

 typename IntervalVector::const_iterator iter = m_intervals.begin();
 for (; iter != m_intervals.end(); ++iter) {
 if (value >= iter->first && value <= iter->second)
 return true;
 }
 return false;
 }

 const LabeledValues &Labels() const { return m_labels; }

 bool LookupLabel(const string &label, type *value) const {
 typename LabeledValues::const_iterator iter = m_labels.find(label);
 if (iter == m_labels.end())
 return false;
 *value = iter->second;
 return true;
 }

 const string LookupValue(type value) const {
 typename LabeledValues::const_iterator iter = m_labels.begin();
 for (; iter != m_labels.end(); ++iter) {
 if (iter->second == value)
 return iter->first;
 }
 return "";
 }

 void Accept(FieldDescriptorVisitor *visitor) const {
 visitor->Visit(this);
 }

 private:
 bool m_little_endian;
 int8_t m_multipler;
 IntervalVector m_intervals;
 LabeledValues m_labels;
};


typedef IntegerFieldDescriptor<uint8_t> UInt8FieldDescriptor;
typedef IntegerFieldDescriptor<uint16_t> UInt16FieldDescriptor;
typedef IntegerFieldDescriptor<uint32_t> UInt32FieldDescriptor;
typedef IntegerFieldDescriptor<int8_t> Int8FieldDescriptor;
typedef IntegerFieldDescriptor<int16_t> Int16FieldDescriptor;
typedef IntegerFieldDescriptor<int32_t> Int32FieldDescriptor;


class FieldDescriptorGroup: public FieldDescriptor {
 public:
 static const int16_t UNLIMITED_BLOCKS;

 FieldDescriptorGroup(const string &name,
 const vector<const FieldDescriptor*> &fields,
 uint16_t min_blocks,
 int16_t max_blocks)
 : FieldDescriptor(name),
 m_fields(fields),
 m_min_blocks(min_blocks),
 m_max_blocks(max_blocks),
 m_populated(false),
 m_fixed_size(true),
 m_limited_size(true),
 m_block_size(0),
 m_max_block_size(0) {
 }
 virtual ~FieldDescriptorGroup();

 // This is true iff all fields in a group are of a fixed size and the
 // number of blocks is fixed
 bool FixedSize() const { return FixedBlockSize() && FixedBlockCount(); }

 // True if the number of blocks has some bound, and all fields also have
 // some bound.
 bool LimitedSize() const;

 // This is the max size of the group, which is only valid if LimitedSize()
 // is true, otherwise it returns 0.
 unsigned int MaxSize() const;

 // Field information
 // the number of fields in this group
 unsigned int FieldCount() const { return m_fields.size(); }
 // True if all the fields in this group are a fixed size. This is then a
 // type 2 group as described above.
 bool FixedBlockSize() const;
 // If this block size is fixed, this returns the size of a single block,
 // otherwise it returns 0;
 unsigned int BlockSize() const;
 // If this block size is bounded, this returns the size of the block.
 unsigned int MaxBlockSize() const;

 // Blocks
 // The minimum number of blocks, usually 0 or 1.
 uint16_t MinBlocks() const { return m_min_blocks; }
 // A max size of UNLIMITED_BLOCKS means no restrictions on the number of
 // blocks
 int16_t MaxBlocks() const { return m_max_blocks; }
 // True if the block count is fixed.
 bool FixedBlockCount() const { return m_min_blocks == m_max_blocks; }


 const class FieldDescriptor *GetField(unsigned int index) const {
 if (index < m_fields.size())
 return m_fields[index];
 return NULL;
 }

 virtual void Accept(FieldDescriptorVisitor *visitor) const;

 protected:
 vector<const class FieldDescriptor *> m_fields;

 private:
 uint16_t m_min_blocks;
 int16_t m_max_blocks;
 mutable bool m_populated;
 mutable bool m_fixed_size, m_limited_size;
 mutable unsigned int m_block_size, m_max_block_size;

 void PopulateIfRequired() const;
};


class Descriptor: public FieldDescriptorGroup {
 public:
 Descriptor(const string &name,
 const vector<const FieldDescriptor*> &fields)
 : FieldDescriptorGroup(name, fields, 1, 1) {}

 void Accept(FieldDescriptorVisitor *visitor) const;
};
} // namespace messaging
} // namespace ola

#endif // INCLUDE_OLA_MESSAGING_DESCRIPTOR_H_