file_path_class.h

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/*! \file
  \brief  A class to handle file paths.

  \par Copyright Information

  Copyright (c) 2017 by The DiSTI Corporation.<br>
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*/
#ifndef INCLUDED_DISTI_FILE_PATH_CLASS_H
#define INCLUDED_DISTI_FILE_PATH_CLASS_H

#include "disti_metadata.h"
#include "gls_cpp_lang_support.h"
#include "util.h" // This is glstudio specific
#include <string>
#include <fstream>

namespace disti
{
/** \class FilePathClass
  * 
  * The FilePathClass represents a single absolute path.
  * There are methods for getting the directory, filename, 
  * file extension, and checking the validity of the path.
  * You can get a relative path string by comparing two FilePathClass objects. 
  * FilePathClass also has methods for reading/writing absolute or relative
  * path strings, the class remembers which was last read and writes out
  * the same way.  You can change this behavior by modifying the
  * WriteAsAbsolutePath() flag.
  */
class FilePathClass
{
protected:
    /** The complete path: format is "<directory>/<filename>.<extension>" where /
      * is last slash and . is the first dot after the last slash */
    std::string _path;

    /** Controls how the Path is written out when WritePathString is called
      * Defaults to false */
    bool _writeAsAbsolutePath;

public:
    /** Default construction. Path() is initially "" and invalid */
    GLS_EXPORT FilePathClass();

    /** Implicit conversion - Path() is set to stringPath */
    GLS_EXPORT FilePathClass( const std::string& stringPath );

    /** Implicit conversion - Path() is set to stringPath */
    GLS_EXPORT FilePathClass( const char* stringPath );

    /** Copy construction */
    GLS_EXPORT FilePathClass( const FilePathClass& other )
    {
        *this = other;
    }

    /** Copy assignment */
    GLS_EXPORT FilePathClass& operator=( const FilePathClass& other )
    {
        if( this != &other )
        {
            _path                = other._path;
            _writeAsAbsolutePath = other._writeAsAbsolutePath;
        }
        return *this;
    }

#if defined( DISTI_HAS_RVAL_REFS )
    /** Move construction */
    FilePathClass( FilePathClass&& other )
    {
        *this = std::move( other );
    }

    /** Move assignment */
    FilePathClass& operator=( FilePathClass&& other )
    {
        if( this != &other )
        {
            _path                = std::move( other._path );
            _writeAsAbsolutePath = other._writeAsAbsolutePath;
        }
        return *this;
    }
#endif

    /** Return true if the path points to a directory or file that COULD exist 
      * (i.e. Path() will return a valid path as close as we can verify it.)*/
    GLS_EXPORT bool IsValid() const;

    /** Return a string containing the characters that invalid to use in a path */
    static GLS_EXPORT const std::string& InvalidPathChars();

    /** Return true if this file path references a file that exists.
      * Applies only to files; returns false for directories.
      * Returns true for symbolic links that exist, regardless whether the link's target exists.
      */
    GLS_EXPORT bool FileExists() const;

    /** Return a string containing the relative path
      * to this path from the given path's Directory
      * Returns Path() if the relative path cannot be determined */
    GLS_EXPORT std::string PathRelativeTo( const FilePathClass& basePath ) const;

    /** Return a string containing the complete path
      * \note this method returns whatever is stored
      * in the path whether it is valid or not */
    const std::string& Path() const { return _path; }

    /** Get the directory containing the referenced file (includes trailing slash)
      * "" if the Path is not valid */
    GLS_EXPORT std::string Directory() const;

    /** Get the filename of the file (including the extension)
      * "" if the Path is not valid or doesn't reference a file */
    GLS_EXPORT std::string FileName() const;

    /** Get the file extension for the file (everything after the last ".")
      * "" if the Path is not valid, doesn't reference a file, or the file has no extension */
    GLS_EXPORT std::string FileExtension() const;

    /** Replace the current file extension with the specified string.
      * This will also insert a '.' into the filename if needed.
      * \param ext The new extension (e.g. "txt")
      */
    GLS_EXPORT void FileExtension( const std::string& ext );

    /** Equality operators
      * If paths are equal they reference the same file
      * If paths are not equal it doesn't guarantee that they reference different files */
    GLS_EXPORT bool operator==( const FilePathClass& path ) const;
    inline bool     operator!=( const FilePathClass& path ) const { return !( *this == path ); }

    friend std::ostream& operator<<( std::ostream& outstr, const FilePathClass& path )
    {
        outstr << path.Path();
        return outstr;
    }

    friend std::istream& operator>>( std::istream& instr, FilePathClass& path )
    {
        instr >> path._path;
        return instr;
    }

    /** Set this object to point to the current working directory 
      * \return true on success, false if there was an error */
    GLS_EXPORT bool SetToCWD();

    /** Get a file path set to the Current Working Directory. */
    static GLS_EXPORT FilePathClass GetCWD()
    {
        FilePathClass path;
        path.SetToCWD();
        return path;
    }

    /** return true if the given string contains an absolute path */
    static GLS_EXPORT bool StringIsAbsolutePath( const std::string& strPath );

    /** return true if the given string contains an relative path */
    static GLS_EXPORT bool StringIsRelativePath( const std::string& strPath );

    /** return true if the given string contains a valid or absolute path as close as we can verify it */
    static GLS_EXPORT bool StringIsValidPath( const std::string& strPath );

    /** Get and set the WriteAsAbsolutePath flag */
    inline void WriteAsAbsolutePath( bool value ) { _writeAsAbsolutePath = value; }
    inline bool WriteAsAbsolutePath() { return _writeAsAbsolutePath; }

    /** Read a relative or absolute path from a string
      * \pre None
      * \post If strPath was an absolute path or invalid then this path will be set to strPath and WriteAsAbsolutePath() will be true
      *       If strPath was relative, this path will be set to basePath + strPath and WriteAsAbsolutePath() will be false
      * \param basePath Used to build a complete path if strPath contains a relative path
      * \param strPath The string to read into
      * \returns true on success or false if there was an error (basePath or strPath are invalid)
      */
    GLS_EXPORT bool ReadPathString( const FilePathClass& basePath, const std::string& strPath );

    /** Get the path string to write to a file
      * This strPath will be either the absolute or relative path depending
      * on the current setting of the WriteAsAbsolutePath() flag
      * \param basePath Used to build a relative path if WriteAsAbsolutePath is false
      * \param strPath The string to write to   
      */
    GLS_EXPORT void WritePathString( const FilePathClass& basePath, std::string* strPath );
};

/** Attribute for reading and writing FilePathClass objects as a clear string. */
class DistiAttributeFilePathClass : public DistiAttributeBase
{
protected:
    FilePathClass*               _attribPtr;        // Pointer to the actual storage location
    FilePathClass                _localStoragePath; // only used by local storage constructor
    const FilePathClass&         _basePath;         // Used for reading relative paths
    bool                         _useEmptyTag;      /**< true to use _emptyTag when writing path with WriteValue() if path does not have a filename */
    static GLS_EXPORT const char _emptyTag[];

public:
    /** This constructor has the storage external 
      * \param basePath
      * \param callback
      * \param name
      * \param attribPtr
      * \param useEmptyTag [optional, defaults to false]  true to use _emptyTag when writing path with WriteValue()
      *                    if path does not have a filename
      */
    GLS_EXPORT DistiAttributeFilePathClass( const FilePathClass& basePath, CallbackMethodCallerBase* callback, const AttributeName& name, FilePathClass* attribPtr, bool useEmptyTag = false )
        : DistiAttributeBase( callback, name, false )
        , _attribPtr( attribPtr )
        , _basePath( basePath )
        , _useEmptyTag( useEmptyTag )
    {
    }

    /** Creates local storage, and will resize as needed
      * \param basePath
      * \param callback
      * \param name
      * \param initialValue
      * \param useEmptyTag [optional, defaults to false]  true to use _emptyTag when writing path with WriteValue()
      *                    if path does not have a filename
      */
    GLS_EXPORT DistiAttributeFilePathClass( const FilePathClass& basePath, CallbackMethodCallerBase* callback, const AttributeName& name, FilePathClass initialValue, bool useEmptyTag = false )
        : DistiAttributeBase( callback, name, true )
        , _attribPtr( &_localStoragePath )
        , _localStoragePath( initialValue )
        , _basePath( basePath )
        , _useEmptyTag( useEmptyTag )
    {
    }

    static const char* GetEmptyTag() { return _emptyTag; }

    virtual GLS_EXPORT DistiAttributeBase& operator=( const DistiAttributeBase& oldClass )
    {
        const DistiAttributeFilePathClass* ptr;
        ptr = dynamic_cast<const DistiAttributeFilePathClass*>( &oldClass );
        if( ptr )
        {
            *_attribPtr = *( ptr->_attribPtr );
            CallCallback();
        }
        else
        {
            return DistiAttributeBase::operator=( oldClass );
        }
        return *this;
    }

    virtual GLS_EXPORT std::ostream& WriteValue( std::ostream& outstr )
    {
        if( _attribPtr )
        {
            std::string strPath;

            if( _useEmptyTag && _attribPtr->FileName().empty() )
            {
                strPath = _emptyTag;
            }
            else
            {
                _attribPtr->WritePathString( _basePath, &strPath );
            }

            outstr << strPath;
        }

        return outstr;
    }
    virtual GLS_EXPORT std::istream& ReadValue( std::istream& instr )
    {
        std::string strPath;
        GetToEnd( instr, strPath, true );

        if( _attribPtr )
        {
            // We have to always check for the empty tag
            // for any backward compatability
            if( strPath == _emptyTag )
            {
                strPath = "";
            }

            _attribPtr->ReadPathString( _basePath, strPath );
            CallCallback();
        }

        return instr;
    }
};

/** This is a FilePathClass attribute that will save/read the path relative to the current working directory. */
class DistiAttributeCWDRelativePath : public DistiAttributeFilePathClass
{
    FilePathClass _parentDocumentPath; // The parent document path, this is updated when we read and write
public:
    /** This constructor has the storage external */
    GLS_EXPORT DistiAttributeCWDRelativePath( CallbackMethodCallerBase* callback, const AttributeName& name, FilePathClass* attribPtr, bool useEmptyTag = false )
        : DistiAttributeFilePathClass( _parentDocumentPath, callback, name, attribPtr, useEmptyTag )
    {
    }

    /** Creates local storage, and will resize as needed */
    GLS_EXPORT DistiAttributeCWDRelativePath( CallbackMethodCallerBase* callback, const AttributeName& name, FilePathClass initialValue, bool useEmptyTag = false )
        : DistiAttributeFilePathClass( _parentDocumentPath, callback, name, initialValue, useEmptyTag )
    {
    }

    virtual GLS_EXPORT std::ostream& WriteValue( std::ostream& outstr )
    {
        // update base path
        _parentDocumentPath.SetToCWD();

        // write value as normal
        return DistiAttributeFilePathClass::WriteValue( outstr );
    }
    virtual GLS_EXPORT std::istream& ReadValue( std::istream& instr )
    {
        // update base path
        _parentDocumentPath.SetToCWD();

        // read value as normal
        return DistiAttributeFilePathClass::ReadValue( instr );
    }
};

} // end namespace disti

#endif //_PATH_CLASS_H