cpl_string.cpp

开源的电子海图程序

{
    char **papszPtr;
    int nLen;

    if (pszName == NULL || pszValue==NULL)
        return papszList;

    nLen = strlen(pszName);
    papszPtr = papszList;
    while(papszPtr && *papszPtr != NULL)
    {
        if (EQUALN(*papszPtr, pszName, nLen)
            && ( (*papszPtr)[nLen] == '=' || 
                 (*papszPtr)[nLen] == ':' ) )
        {
            /* Found it!  
             * Change the value... make sure to keep the ':' or '='
             */
            char cSep;
            cSep = (*papszPtr)[nLen];

            CPLFree(*papszPtr);
            *papszPtr = (char *) CPLMalloc(strlen(pszName)+strlen(pszValue)+2);
            sprintf( *papszPtr, "%s%c%s", pszName, cSep, pszValue );
            return papszList;
        }
        papszPtr++;
    }

    /* The name does not exist yet... create a new entry
     */
    return CSLAddNameValue(papszList, pszName, pszValue);
}

/************************************************************************/
/*                      CSLSetNameValueSeparator()                      */
/************************************************************************/

/**
 * Replace the default separator (":" or "=") with the passed separator
 * in the given name/value list. 
 *
 * Note that if a separator other than ":" or "=" is used, the resulting
 * list will not be manipulatable by the CSL name/value functions any more.
 *
 * The CPLParseNameValue() function is used to break the existing lines, 
 * and it also strips white space from around the existing delimiter, thus
 * the old separator, and any white space will be replaced by the new
 * separator.  For formatting purposes it may be desireable to include some
 * white space in the new separator.  eg. ": " or " = ".
 * 
 * @param papszList the list to update.  Component strings may be freed
 * but the list array will remain at the same location.
 *
 * @param pszSeparator the new separator string to insert.  
 *
 */

void CSLSetNameValueSeparator( char ** papszList, const char *pszSeparator )

{
    int         nLines = CSLCount(papszList), iLine;

    for( iLine = 0; iLine < nLines; iLine++ )
    {
        char        *pszKey = NULL;
        const char  *pszValue;
        char        *pszNewLine;

        pszValue = CPLParseNameValue( papszList[iLine], &pszKey );
        
        pszNewLine = (char *) CPLMalloc( strlen(pszValue) + strlen(pszKey)
                                         + strlen(pszSeparator) + 1 );
        strcpy( pszNewLine, pszKey );
        strcat( pszNewLine, pszSeparator );
        strcat( pszNewLine, pszValue );
        CPLFree( papszList[iLine] );
        papszList[iLine] = pszNewLine;
    }
}

/************************************************************************/
/*                          CPLEscapeString()                           */
/************************************************************************/

/**
 * Apply escaping to string to preserve special characters.
 *
 * This function will "escape" a variety of special characters
 * to make the string suitable to embed within a string constant
 * or to write within a text stream but in a form that can be
 * reconstitued to it's original form.  The escaping will even preserve
 * zero bytes allowing preservation of raw binary data.
 *
 * CPLES_BackslashQuotable(0): This scheme turns a binary string into 
 * a form suitable to be placed within double quotes as a string constant.
 * The backslash, quote, '\0' and newline characters are all escaped in 
 * the usual C style. 
 *
 * CPLES_XML(1): This scheme converts the '<', '<' and '&' characters into
 * their XML/HTML equivelent (&gt;, &lt; and &amp;) making a string safe
 * to embed as CDATA within an XML element.  The '\0' is not escaped and 
 * should not be included in the input.
 *
 * CPLES_URL(2): Everything except alphanumerics and the underscore are 
 * converted to a percent followed by a two digit hex encoding of the character
 * (leading zero supplied if needed).  This is the mechanism used for encoding
 * values to be passed in URLs.
 *
 * @param pszInput the string to escape.  
 * @param nLength The number of bytes of data to preserve.  If this is -1
 * the strlen(pszString) function will be used to compute the length.
 * @param nScheme the encoding scheme to use.  
 *
 * @return an escaped, zero terminated string that should be freed with 
 * CPLFree() when no longer needed.
 */

char *CPLEscapeString( const char *pszInput, int nLength, 
                       int nScheme )

{
    char        *pszOutput;
    char        *pszShortOutput;

    if( nLength == -1 )
        nLength = strlen(pszInput);

    pszOutput = (char *) CPLMalloc( nLength * 6 + 1 );
    
    if( nScheme == CPLES_BackslashQuotable )
    {
        int iOut = 0, iIn;

        for( iIn = 0; iIn < nLength; iIn++ )
        {
            if( pszInput[iIn] == '\0' )
            {
                pszOutput[iOut++] = '\\';
                pszOutput[iOut++] = '0';
            }
            else if( pszInput[iIn] == '"' )
            {
                pszOutput[iOut++] = '\\';
                pszOutput[iOut++] = 'n';
            }
            else if( pszInput[iIn] == '\\' )
            {
                pszOutput[iOut++] = '\\';
                pszOutput[iOut++] = '\\';
            }
            else
                pszOutput[iOut++] = pszInput[iIn];
        }
        pszOutput[iOut] = '\0';
    }
    else if( nScheme == CPLES_URL ) /* Untested at implementation */
    {
        int iOut = 0, iIn;

        for( iIn = 0; iIn < nLength; iIn++ )
        {
            if( (pszInput[iIn] >= 'a' && pszInput[iIn] <= 'z')
                || (pszInput[iIn] >= 'A' && pszInput[iIn] <= 'Z')
                || (pszInput[iIn] >= '0' && pszInput[iIn] <= '9')
                || pszInput[iIn] == '_' )
            {
                pszOutput[iOut++] = pszInput[iIn];
            }
            else
            {
                sprintf( pszOutput, "%%%02X", pszInput[iIn] );
                iOut += 3;
            }
        }
        pszOutput[iOut] = '\0';
    }
    else if( nScheme == CPLES_XML )
    {
        int iOut = 0, iIn;

        for( iIn = 0; iIn < nLength; iIn++ )
        {
            if( pszInput[iIn] == '<' )
            {
                pszOutput[iOut++] = '&';
                pszOutput[iOut++] = 'l';
                pszOutput[iOut++] = 't';
                pszOutput[iOut++] = ';';
            }
            else if( pszInput[iIn] == '>' )
            {
                pszOutput[iOut++] = '&';
                pszOutput[iOut++] = 'g';
                pszOutput[iOut++] = 't';
                pszOutput[iOut++] = ';';
            }
            else if( pszInput[iIn] == '&' )
            {
                pszOutput[iOut++] = '&';
                pszOutput[iOut++] = 'a';
                pszOutput[iOut++] = 'm';
                pszOutput[iOut++] = 'p';
                pszOutput[iOut++] = ';';
            }
            else if( pszInput[iIn] == '"' )
            {
                pszOutput[iOut++] = '&';
                pszOutput[iOut++] = 'q';
                pszOutput[iOut++] = 'u';
                pszOutput[iOut++] = 'o';
                pszOutput[iOut++] = 't';
                pszOutput[iOut++] = ';';
            }
            else
                pszOutput[iOut++] = pszInput[iIn];
        }
        pszOutput[iOut] = '\0';
    }
    else
    {
        pszOutput[0] = '\0';
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Undefined escaping scheme (%d) in CPLEscapeString()",
                  nScheme );
    }

    pszShortOutput = CPLStrdup( pszOutput );
    CPLFree( pszOutput );

    return pszShortOutput;
}

/************************************************************************/
/*                         CPLUnescapeString()                          */
/************************************************************************/

/**
 * Unescape a string.
 *
 * This function does the opposite of CPLEscapeString().  Given a string
 * with special values escaped according to some scheme, it will return a
 * new copy of the string returned to it's original form. 
 *
 * @param pszInput the input string.  This is a zero terminated string.
 * @param pnLength location to return the length of the unescaped string, 
 * which may in some cases include embedded '\0' characters.
 * @param nScheme the escaped scheme to undo (see CPLEscapeString() for a
 * list). 
 * 
 * @return a copy of the unescaped string that should be freed by the 
 * application using CPLFree() when no longer needed.
 */

char *CPLUnescapeString( const char *pszInput, int *pnLength, int nScheme )

{
    char *pszOutput;
    int iOut=0, iIn;

    pszOutput = (char *) CPLMalloc(strlen(pszInput)+1);
    pszOutput[0] = '\0';

    if( nScheme == CPLES_XML )
    {
        for( iIn = 0; pszInput[iIn] != '\0'; iIn++ )
        {
            if( EQUALN(pszInput+iIn,"&lt;",4) )
            {
                pszOutput[iOut++] = '<';
                iIn += 3;
            }
            else if( EQUALN(pszInput+iIn,"&gt;",4) )
            {
                pszOutput[iOut++] = '>';
                iIn += 3;
            }
            else if( EQUALN(pszInput+iIn,"&amp;",5) )
            {
                pszOutput[iOut++] = '&';
                iIn += 4;
            }
            else if( EQUALN(pszInput+iIn,"&quot;",6) )
            {
                pszOutput[iOut++] = '"';
                iIn += 5;
            }
            else
            {
                pszOutput[iOut++] = pszInput[iIn];
            }
        }
    }
    else if( nScheme == CPLES_URL )
    {
        for( iIn = 0; pszInput[iIn] != '\0'; iIn++ )
        {
            if( pszInput[iIn] == '%' 
                && pszInput[iIn+1] != '\0' 
                && pszInput[iIn+2] != '\0' )
            {
                int nHexChar = 0;

                if( pszInput[iIn+1] >= 'A' && pszInput[iIn+1] <= 'F' )
                    nHexChar += 16 * (pszInput[iIn+1] - 'A' + 10);
                else if( pszInput[iIn+1] >= 'a' && pszInput[iIn+1] <= 'f' )
                    nHexChar += 16 * (pszInput[iIn+1] - 'a' + 10);
                else if( pszInput[iIn+1] >= '0' && pszInput[iIn+1] <= '9' )
                    nHexChar += 16 * (pszInput[iIn+1] - '0');
                else
                    CPLDebug( "CPL", 
                              "Error unescaping CPLES_URL text, percent not "
                              "followed by two hex digits." );
                    
                if( pszInput[iIn+2] >= 'A' && pszInput[iIn+2] <= 'F' )
                    nHexChar += pszInput[iIn+2] - 'A' + 10;
                else if( pszInput[iIn+2] >= 'a' && pszInput[iIn+2] <= 'f' )
                    nHexChar += pszInput[iIn+2] - 'a' + 10;
                else if( pszInput[iIn+2] >= '0' && pszInput[iIn+2] <= '9' )
                    nHexChar += pszInput[iIn+2] - '0';
                else
                    CPLDebug( "CPL", 
                              "Error unescaping CPLES_URL text, percent not "
                              "followed by two hex digits." );

                pszOutput[iOut++] = (char) nHexChar;
                iIn += 2;
            }
            else if( pszInput[iIn] == '+' )
            {
                pszOutput[iOut++] = ' ';
            }   
            else
            {
                pszOutput[iOut++] = pszInput[iIn];
            }
        }
    }
    else /* if( nScheme == CPLES_BackslashQuoteable ) */
    {
        for( iIn = 0; pszInput[iIn] != '\0'; iIn++ )
        {
            if( pszInput[iIn] == '\\' )
            {
                iIn++;
                if( pszInput[iIn] == 'n' )
                    pszOutput[iOut++] = '\n';
                else if( pszInput[iIn] == '0' )
                    pszOutput[iOut++] = '\0';
                else 
                    pszOutput[iOut++] = pszInput[iIn];
            }
            else
            {
                pszOutput[iOut++] = pszInput[iIn];
            }
        }
    }

    pszOutput[iOut] = '\0';

    if( pnLength != NULL )
        *pnLength = iOut;

    return pszOutput;
}