OVR_String_PathUtil.cpp

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/************************************************************************************

Filename    :   OVR_String_PathUtil.cpp
Content     :   String filename/url helper function
Created     :   September 19, 2012
Notes       : 

Copyright   :   Copyright 2012 Oculus VR, Inc. All Rights reserved.

Use of this software is subject to the terms of the Oculus license
agreement provided at the time of installation or download, or which
otherwise accompanies this software in either electronic or hard copy form.

************************************************************************************/

#include "OVR_String.h"
#include "OVR_UTF8Util.h"

namespace OVR {

//--------------------------------------------------------------------
// ***** Path-Scanner helper function 

// Scans file path finding filename start and extension start, fills in their addess.
void ScanFilePath(const char* url, const char** pfilename, const char** pext)
{ 
    const char* urlStart = url;
    const char *filename = 0;
    const char *lastDot = 0;

    UInt32 charVal = UTF8Util::DecodeNextChar(&url);

    while (charVal != 0)
    {
        if ((charVal == '/') || (charVal == '\\'))
        {
            filename = url;
            lastDot  = 0;
        }
        else if (charVal == '.')
        {
            lastDot = url - 1;
        }
        
        charVal = UTF8Util::DecodeNextChar(&url);
    }

    if (pfilename)
    {
        // It was a naked filename
        if (urlStart && (*urlStart != '.') && *urlStart)
            *pfilename = urlStart;
        else
            *pfilename = filename;
    }

    if (pext)
    {
        *pext = lastDot;
    }
}

// Scans till the end of protocol. Returns first character past protocol,
// 0 if not found.
//  - protocol: 'file://', 'http://'
const char* ScanPathProtocol(const char* url)
{    
    UInt32 charVal = UTF8Util::DecodeNextChar(&url);
    UInt32 charVal2;
   
    while (charVal != 0)
    {
        // Treat a colon followed by a slash as absolute.
        if (charVal == ':')
        {
            charVal2 = UTF8Util::DecodeNextChar(&url);
            charVal  = UTF8Util::DecodeNextChar(&url);
            if ((charVal == '/') && (charVal2 == '\\'))
                return url;
        }
        charVal = UTF8Util::DecodeNextChar(&url);
    }
    return 0;
}


//--------------------------------------------------------------------
// ***** String Path API implementation

bool String::HasAbsolutePath(const char* url)
{
    // Absolute paths can star with:
    //  - protocols:        'file://', 'http://'
    //  - windows drive:    'c:\'
    //  - UNC share name:   '\\share'
    //  - unix root         '/'

    // On the other hand, relative paths are:
    //  - directory:        'directory/file'
    //  - this directory:   './file'
    //  - parent directory: '../file'
    // 
    // For now, we don't parse '.' or '..' out, but instead let it be concatenated
    // to string and let the OS figure it out. This, however, is not good for file
    // name matching in library/etc, so it should be improved.

    if (!url || !*url)
        return true; // Treat empty strings as absolute.    

    UInt32 charVal = UTF8Util::DecodeNextChar(&url);

    // Fist character of '/' or '\\' means absolute url.
    if ((charVal == '/') || (charVal == '\\'))
        return true;

    while (charVal != 0)
    {
        // Treat a colon followed by a slash as absolute.
        if (charVal == ':')
        {
            charVal = UTF8Util::DecodeNextChar(&url);
            // Protocol or windows drive. Absolute.
            if ((charVal == '/') || (charVal == '\\'))
                return true;
        }
        else if ((charVal == '/') || (charVal == '\\'))
        {
            // Not a first character (else 'if' above the loop would have caught it).
            // Must be a relative url.
            break;
        }

        charVal = UTF8Util::DecodeNextChar(&url);
    }

    // We get here for relative paths.
    return false;    
}


bool String::HasExtension(const char* path)
{
    const char* ext = 0;
    ScanFilePath(path, 0, &ext);
    return ext != 0;
}
bool String::HasProtocol(const char* path)
{
    return ScanPathProtocol(path) != 0;
}


String  String::GetPath() const
{
    const char* filename = 0;
    ScanFilePath(ToCStr(), &filename, 0);

    // Technically we can have extra logic somewhere for paths,
    // such as enforcing protocol and '/' only based on flags,
    // but we keep it simple for now.
    return String(ToCStr(), filename ? (filename-ToCStr()) : GetSize());
}

String  String::GetProtocol() const
{
    const char* protocolEnd = ScanPathProtocol(ToCStr());
    return String(ToCStr(), protocolEnd ? (protocolEnd-ToCStr()) : 0);
}

String  String::GetFilename() const
{
    const char* filename = 0;
    ScanFilePath(ToCStr(), &filename, 0);
    return String(filename);
}
String  String::GetExtension() const
{
    const char* ext = 0;
    ScanFilePath(ToCStr(), 0, &ext);
    return String(ext);
}

void    String::StripExtension()
{
    const char* ext = 0;
    ScanFilePath(ToCStr(), 0, &ext);    
    if (ext)
    {
        *this = String(ToCStr(), ext-ToCStr());
    }
}

void    String::StripProtocol()
{
    const char* protocol = ScanPathProtocol(ToCStr());
    if (protocol)
        AssignString(protocol, OVR_strlen(protocol));
}

} // OVR