// =================================================================================================
// Copyright 2002-2008 Adobe Systems Incorporated
// All Rights Reserved.
//
// NOTICE:	Adobe permits you to use, modify, and distribute this file in accordance with the terms
// of the Adobe license agreement accompanying it.
// =================================================================================================

#include "XMP_Environment.h"	// ! This must be the first include!
#include "XMPCore_Impl.hpp"
#include "XMPUtils.hpp"

#include <time.h>
#include <string.h>
#include <stdlib.h>
#include <locale.h>
#include <errno.h>

#include <stdio.h>	// For snprintf.

namespace DngXmpSdk {

#if XMP_WinBuild
    #pragma warning ( disable : 4800 )	// forcing value to bool 'true' or 'false' (performance warning)
#endif

// =================================================================================================
// Local Types and Constants
// =========================

typedef unsigned long	UniCodePoint;

enum UniCharKind {
    UCK_normal,
    UCK_space,
    UCK_comma,
    UCK_semicolon,
    UCK_quote,
    UCK_control
};
typedef enum UniCharKind	UniCharKind;

#define UnsByte(c)	((unsigned char)(c))
#define UCP(u)		((UniCodePoint)(u))
    // ! Needed on Windows (& PC Linux?) for inequalities with literals to avoid sign extension.

#ifndef TraceMultiFile
    #define TraceMultiFile	0
#endif

// =================================================================================================
// Static Variables
// ================

// =================================================================================================
// Local Utilities
// ===============

// -------------------------------------------------------------------------------------------------
// ClassifyCharacter
// -----------------

static void
ClassifyCharacter ( XMP_StringPtr fullString, size_t offset,
                    UniCharKind * charKind, size_t * charSize, UniCodePoint * uniChar )
{
    *charKind = UCK_normal; // Assume typical case.

    unsigned char	currByte = UnsByte ( fullString[offset] );

    if ( currByte < UnsByte(0x80) ) {

        // ----------------------------------------
        // We've got a single byte ASCII character.

        *charSize = 1;
        *uniChar = currByte;

        if ( currByte > UnsByte(0x22) ) {

            if ( currByte == UnsByte(0x2C) ) {
                *charKind = UCK_comma;
            } else if ( currByte == UnsByte(0x3B) ) {
                *charKind = UCK_semicolon;
            } else if ( (currByte == UnsByte(0x5B)) || (currByte == UnsByte(0x5D)) ) {
                *charKind = UCK_quote;	// ! ASCII '[' and ']' are used as quotes in Chinese and Korean.
            }

        } else {	// currByte <= 0x22

            if ( currByte == UnsByte(0x22) ) {
                *charKind = UCK_quote;
            } else if ( currByte == UnsByte(0x21) ) {
                *charKind = UCK_normal;
            } else if ( currByte == UnsByte(0x20) ) {
                *charKind = UCK_space;
            } else {
                *charKind = UCK_control;
            }

        }

    } else {	// currByte >= 0x80

        // ---------------------------------------------------------------------------------------
        // We've got a multibyte Unicode character. The first byte has the number of bytes and the
        // highest order bits. The other bytes each add 6 more bits. Compose the UTF-32 form so we
        // can classify directly with the Unicode code points. Order the upperBits tests to be
        // fastest for Japan, probably the most common non-ASCII usage.

        *charSize = 0;
        *uniChar = currByte;
        while ( (*uniChar & 0x80) != 0 ) {	// Count the leading 1 bits in the byte.
            ++(*charSize);
            *uniChar = *uniChar << 1;
        }
        XMP_Assert ( (offset + *charSize) <= strlen(fullString) );

        *uniChar = *uniChar & 0x7F;			// Put the character bits in the bottom of uniChar.
        *uniChar = *uniChar >> *charSize;

        for ( size_t i = (offset + 1); i < (offset + *charSize); ++i ) {
            *uniChar = (*uniChar << 6) | (UnsByte(fullString[i]) & 0x3F);
        }

        XMP_Uns32 upperBits = *uniChar >> 8;	// First filter on just the high order 24 bits.

        if ( upperBits == 0xFF ) {			// U+FFxx

            if ( *uniChar == UCP(0xFF0C) ) {
                *charKind = UCK_comma;			// U+FF0C, full width comma.
            } else if ( *uniChar == UCP(0xFF1B) ) {
                *charKind = UCK_semicolon;		// U+FF1B, full width semicolon.
            } else if ( *uniChar == UCP(0xFF64) ) {
                *charKind = UCK_comma;			// U+FF64, half width ideographic comma.
            }

        } else if ( upperBits == 0xFE ) {	// U+FE--

            if ( *uniChar == UCP(0xFE50) ) {
                *charKind = UCK_comma;			// U+FE50, small comma.
            } else if ( *uniChar == UCP(0xFE51) ) {
                *charKind = UCK_comma;			// U+FE51, small ideographic comma.
            } else if ( *uniChar == UCP(0xFE54) ) {
                *charKind = UCK_semicolon;		// U+FE54, small semicolon.
            }

        } else if ( upperBits == 0x30 ) {	// U+30--

            if ( *uniChar == UCP(0x3000) ) {
                *charKind = UCK_space;			// U+3000, ideographic space.
            } else if ( *uniChar == UCP(0x3001) ) {
                *charKind = UCK_comma;			// U+3001, ideographic comma.
            } else if ( (UCP(0x3008) <= *uniChar) && (*uniChar <= UCP(0x300F)) ) {
                *charKind = UCK_quote;			// U+3008..U+300F, various quotes.
            } else if ( *uniChar == UCP(0x303F) ) {
                *charKind = UCK_space;			// U+303F, ideographic half fill space.
            } else if ( (UCP(0x301D) <= *uniChar) && (*uniChar <= UCP(0x301F)) ) {
                *charKind = UCK_quote;			// U+301D..U+301F, double prime quotes.
            }

        } else if ( upperBits == 0x20 ) {	// U+20--

            if ( (UCP(0x2000) <= *uniChar) && (*uniChar <= UCP(0x200B)) ) {
                *charKind = UCK_space;			// U+2000..U+200B, en quad through zero width space.
            } else if ( *uniChar == UCP(0x2015) ) {
                *charKind = UCK_quote;			// U+2015, dash quote.
            } else if ( (UCP(0x2018) <= *uniChar) && (*uniChar <= UCP(0x201F)) ) {
                *charKind = UCK_quote;			// U+2018..U+201F, various quotes.
            } else if ( *uniChar == UCP(0x2028) ) {
                *charKind = UCK_control;			// U+2028, line separator.
            } else if ( *uniChar == UCP(0x2029) ) {
                *charKind = UCK_control;			// U+2029, paragraph separator.
            } else if ( (*uniChar == UCP(0x2039)) || (*uniChar == UCP(0x203A)) ) {
                *charKind = UCK_quote;			// U+2039 and U+203A, guillemet quotes.
            }

        } else if ( upperBits == 0x06 ) {	// U+06--

            if ( *uniChar == UCP(0x060C) ) {
                *charKind = UCK_comma;			// U+060C, Arabic comma.
            } else if ( *uniChar == UCP(0x061B) ) {
                *charKind = UCK_semicolon;		// U+061B, Arabic semicolon.
            }

        } else if ( upperBits == 0x05 ) {	// U+05--

            if ( *uniChar == UCP(0x055D) ) {
                *charKind = UCK_comma;			// U+055D, Armenian comma.
            }

        } else if ( upperBits == 0x03 ) {	// U+03--

            if ( *uniChar == UCP(0x037E) ) {
                *charKind = UCK_semicolon;		// U+037E, Greek "semicolon" (really a question mark).
            }

        } else if ( upperBits == 0x00 ) {	// U+00--

            if ( (*uniChar == UCP(0x00AB)) || (*uniChar == UCP(0x00BB)) ) {
                *charKind = UCK_quote;			// U+00AB and U+00BB, guillemet quotes.
            }

        }

    }

}	// ClassifyCharacter


// -------------------------------------------------------------------------------------------------
// IsClosingingQuote
// -----------------

static inline bool
IsClosingingQuote ( UniCodePoint uniChar, UniCodePoint openQuote, UniCodePoint closeQuote )
{

    if ( (uniChar == closeQuote) ||
         ( (openQuote == UCP(0x301D)) && ((uniChar == UCP(0x301E)) || (uniChar == UCP(0x301F))) ) ) {
        return true;
    } else {
        return false;
    }

}	// IsClosingingQuote


// -------------------------------------------------------------------------------------------------
// IsSurroundingQuote
// ------------------

static inline bool
IsSurroundingQuote ( UniCodePoint uniChar, UniCodePoint openQuote, UniCodePoint closeQuote )
{

    if ( (uniChar == openQuote) || IsClosingingQuote ( uniChar, openQuote, closeQuote ) ) {
        return true;
    } else {
        return false;
    }

}	// IsSurroundingQuote


// -------------------------------------------------------------------------------------------------
// GetClosingQuote
// ---------------

static UniCodePoint
GetClosingQuote ( UniCodePoint openQuote )
{
    UniCodePoint	closeQuote;

    switch ( openQuote ) {

        case UCP(0x0022) : closeQuote = UCP(0x0022);	// ! U+0022 is both opening and closing.
                           break;
        case UCP(0x005B) : closeQuote = UCP(0x005D);
                           break;
        case UCP(0x00AB) : closeQuote = UCP(0x00BB);	// ! U+00AB and U+00BB are reversible.
                           break;
        case UCP(0x00BB) : closeQuote = UCP(0x00AB);
                           break;
        case UCP(0x2015) : closeQuote = UCP(0x2015);	// ! U+2015 is both opening and closing.
                           break;
        case UCP(0x2018) : closeQuote = UCP(0x2019);
                           break;
        case UCP(0x201A) : closeQuote = UCP(0x201B);
                           break;
        case UCP(0x201C) : closeQuote = UCP(0x201D);
                           break;
        case UCP(0x201E) : closeQuote = UCP(0x201F);
                           break;
        case UCP(0x2039) : closeQuote = UCP(0x203A);	// ! U+2039 and U+203A are reversible.
                           break;
        case UCP(0x203A) : closeQuote = UCP(0x2039);
                           break;
        case UCP(0x3008) : closeQuote = UCP(0x3009);
                           break;
        case UCP(0x300A) : closeQuote = UCP(0x300B);
                           break;
        case UCP(0x300C) : closeQuote = UCP(0x300D);
                           break;
        case UCP(0x300E) : closeQuote = UCP(0x300F);
                           break;
        case UCP(0x301D) : closeQuote = UCP(0x301F);	// ! U+301E also closes U+301D.
                           break;
        default			 : closeQuote = 0;
                           break;

    }

    return closeQuote;

}	// GetClosingQuote


// -------------------------------------------------------------------------------------------------
// CodePointToUTF8
// ---------------

static void
CodePointToUTF8 ( UniCodePoint uniChar, XMP_VarString & utf8Str )
{
    size_t i, byteCount;
    XMP_Uns8 buffer [8];
    UniCodePoint cpTemp;

    if ( uniChar <= 0x7F ) {

        i = 7;
        byteCount = 1;
        buffer[7] = char(uniChar);

    } else {

        // ---------------------------------------------------------------------------------------
        // Copy the data bits from the low order end to the high order end, include the 0x80 mask.

        i = 8;
        cpTemp = uniChar;
        while ( cpTemp != 0 ) {
            -- i;	// Exit with i pointing to the last byte stored.
            buffer[i] = UnsByte(0x80) | (UnsByte(cpTemp) & 0x3F);
            cpTemp = cpTemp >> 6;
        }
        byteCount = 8 - i;	// The total number of bytes needed.
        XMP_Assert ( (2 <= byteCount) && (byteCount <= 6) );

        // -------------------------------------------------------------------------------------
        // Make sure the high order byte can hold the byte count mask, compute and set the mask.

        size_t bitCount = 0;	// The number of data bits in the first byte.
        for ( cpTemp = (buffer[i] & UnsByte(0x3F)); cpTemp != 0; cpTemp = cpTemp >> 1 ) bitCount += 1;
        if ( bitCount > (8 - (byteCount + 1)) ) byteCount += 1;

        i = 8 - byteCount;	// First byte index and mask shift count.
        XMP_Assert ( (0 <= i) && (i <= 6) );
        buffer[i] |= (UnsByte(0xFF) << i) & UnsByte(0xFF);	// AUDIT: Safe, i is between 0 and 6.

    }

    utf8Str.assign ( (char*)(&buffer[i]), byteCount );

}	// CodePointToUTF8


// -------------------------------------------------------------------------------------------------
// ApplyQuotes
// -----------

static void
ApplyQuotes ( XMP_VarString * item, UniCodePoint openQuote, UniCodePoint closeQuote, bool allowCommas )
{
    bool	prevSpace	= false;
    size_t	charOffset, charLen;
    UniCharKind		charKind;
    UniCodePoint	uniChar;

    // -----------------------------------------------------------------------------------------
    // See if there are any separators in the value. Stop at the first occurrence. This is a bit
    // tricky in order to make typical typing work conveniently. The purpose of applying quotes
    // is to preserve the values when splitting them back apart. That is CatenateContainerItems
    // and SeparateContainerItems must round trip properly. For the most part we only look for
    // separators here. Internal quotes, as in -- Irving "Bud" Jones -- won't cause problems in
    // the separation. An initial quote will though, it will make the value look quoted.

    charOffset = 0;
    ClassifyCharacter ( item->c_str(), charOffset, &charKind, &charLen, &uniChar );

    if ( charKind != UCK_quote ) {

    for ( charOffset = 0; size_t(charOffset) < item->size(); charOffset += charLen ) {

            ClassifyCharacter ( item->c_str(), charOffset, &charKind, &charLen, &uniChar );

            if ( charKind == UCK_space ) {
                if ( prevSpace ) break; // Multiple spaces are a separator.
                prevSpace = true;
            } else {
                prevSpace = false;
                if ( (charKind == UCK_semicolon) || (charKind == UCK_control) ) break;
                if ( (charKind == UCK_comma) && (! allowCommas) ) break;
            }

        }

    }

    if ( size_t(charOffset) < item->size() ) {

        // --------------------------------------------------------------------------------------
        // Create a quoted copy, doubling any internal quotes that match the outer ones. Internal
        // quotes did not stop the "needs quoting" search, but they do need doubling. So we have
        // to rescan the front of the string for quotes. Handle the special case of U+301D being
        // closed by either U+301E or U+301F.

        XMP_VarString	newItem;
        size_t			splitPoint;

        for ( splitPoint = 0; splitPoint <= charOffset; ++splitPoint ) {
            ClassifyCharacter ( item->c_str(), splitPoint, &charKind, &charLen, &uniChar );
            if ( charKind == UCK_quote ) break;
        }

        CodePointToUTF8 ( openQuote, newItem );
        newItem.append ( *item, 0, splitPoint );	// Copy the leading "normal" portion.

        for ( charOffset = splitPoint; size_t(charOffset) < item->size(); charOffset += charLen ) {
            ClassifyCharacter ( item->c_str(), charOffset, &charKind, &charLen, &uniChar );
            newItem.append ( *item, charOffset, charLen );
            if ( (charKind == UCK_quote) && IsSurroundingQuote ( uniChar, openQuote, closeQuote ) ) {
                newItem.append ( *item, charOffset, charLen );
            }
        }

        XMP_VarString closeStr;
        CodePointToUTF8 ( closeQuote, closeStr );
        newItem.append ( closeStr );

        *item = newItem;

    }

}	// ApplyQuotes


// -------------------------------------------------------------------------------------------------
// IsInternalProperty
// ------------------

// *** Need static checks of the schema prefixes!

#define IsExternalProperty(s,p) (! IsInternalProperty ( s, p ))

static bool
IsInternalProperty ( const XMP_VarString & schema, const XMP_VarString & prop )
{
    bool isInternal = false;

    if ( schema == kXMP_NS_DC ) {

        if ( (prop == "dc:format")	||
             (prop == "dc:language") ) {
            isInternal = true;
        }

    } else if ( schema == kXMP_NS_XMP ) {

        if ( (prop == "xmp:BaseURL")		||
             (prop == "xmp:CreatorTool")	||
             (prop == "xmp:Format")			||
             (prop == "xmp:Locale")			||
             (prop == "xmp:MetadataDate")	||
             (prop == "xmp:ModifyDate") ) {
            isInternal = true;
        }

    } else if ( schema == kXMP_NS_PDF ) {

        if ( (prop == "pdf:BaseURL")	||
             (prop == "pdf:Creator")	||
             (prop == "pdf:ModDate")	||
             (prop == "pdf:PDFVersion") ||
             (prop == "pdf:Producer") ) {
            isInternal = true;
        }

    } else if ( schema == kXMP_NS_TIFF ) {

        isInternal = true;	// ! The TIFF properties are internal by default.
        if ( (prop == "tiff:ImageDescription")	||	// ! ImageDescription, Artist, and Copyright are aliased.
             (prop == "tiff:Artist")			||
             (prop == "tiff:Copyright") ) {
            isInternal = false;
        }

    } else if ( schema == kXMP_NS_EXIF ) {

        isInternal = true;	// ! The EXIF properties are internal by default.
        if ( prop == "exif:UserComment" ) isInternal = false;

    } else if ( schema == kXMP_NS_EXIF_Aux ) {

        isInternal = true;	// ! The EXIF Aux properties are internal by default.

    } else if ( schema == kXMP_NS_Photoshop ) {

        if ( prop == "photoshop:ICCProfile" ) isInternal = true;

    } else if ( schema == kXMP_NS_CameraRaw ) {

        if ( (prop == "crs:Version")		||
             (prop == "crs:RawFileName")	||
             (prop == "crs:ToneCurveName") ) {
            isInternal = true;
        }

    } else if ( schema == kXMP_NS_AdobeStockPhoto ) {

        isInternal = true;	// ! The bmsp schema has only internal properties.

    } else if ( schema == kXMP_NS_XMP_MM ) {

        isInternal = true;	// ! The xmpMM schema has only internal properties.

    } else if ( schema == kXMP_NS_XMP_Text ) {

        isInternal = true;	// ! The xmpT schema has only internal properties.

    } else if ( schema == kXMP_NS_XMP_PagedFile ) {

        isInternal = true;	// ! The xmpTPg schema has only internal properties.

    } else if ( schema == kXMP_NS_XMP_Graphics ) {

        isInternal = true;	// ! The xmpG schema has only internal properties.

    } else if ( schema == kXMP_NS_XMP_Image ) {

        isInternal = true;	// ! The xmpGImg schema has only internal properties.

    } else if ( schema == kXMP_NS_XMP_Font ) {

        isInternal = true;	// ! The stFNT schema has only internal properties.

    }

    return isInternal;

}	// IsInternalProperty


// -------------------------------------------------------------------------------------------------
// RemoveSchemaChildren
// --------------------

static void
RemoveSchemaChildren ( XMP_NodePtrPos schemaPos, bool doAll )
{
    XMP_Node * schemaNode = *schemaPos;
    XMP_Assert ( XMP_NodeIsSchema ( schemaNode->options ) );

    // ! Iterate backwards to reduce shuffling as children are erased and to simplify the logic for
    // ! denoting the current child. (Erasing child n makes the old n+1 now be n.)

    size_t		   propCount = schemaNode->children.size();
    XMP_NodePtrPos beginPos	 = schemaNode->children.begin();

    for ( size_t propNum = propCount-1, propLim = (size_t)(-1); propNum != propLim; --propNum ) {
        XMP_NodePtrPos currProp = beginPos + propNum;
        if ( doAll || IsExternalProperty ( schemaNode->name, (*currProp)->name ) ) {
            delete *currProp;	// ! Both delete the node and erase the pointer from the parent.
            schemaNode->children.erase ( currProp );
        }
    }

    if ( schemaNode->children.empty() ) {
        XMP_Node * tree = schemaNode->parent;
        tree->children.erase ( schemaPos );
        delete schemaNode;
    }

}	// RemoveSchemaChildren


// -------------------------------------------------------------------------------------------------
// ItemValuesMatch
// ---------------
//
// Does the value comparisons for array merging as part of XMPUtils::AppendProperties.

static bool
ItemValuesMatch ( const XMP_Node * leftNode, const XMP_Node * rightNode )
{
    const XMP_OptionBits leftForm  = leftNode->options & kXMP_PropCompositeMask;
    const XMP_OptionBits rightForm = leftNode->options & kXMP_PropCompositeMask;

    if ( leftForm != rightForm ) return false;

    if ( leftForm == 0 ) {

        // Simple nodes, check the values and xml:lang qualifiers.

        if ( leftNode->value != rightNode->value ) return false;
        if ( (leftNode->options & kXMP_PropHasLang) != (rightNode->options & kXMP_PropHasLang) ) return false;
        if ( leftNode->options & kXMP_PropHasLang ) {
            if ( leftNode->qualifiers[0]->value != rightNode->qualifiers[0]->value ) return false;
        }

    } else if ( leftForm == kXMP_PropValueIsStruct ) {

        // Struct nodes, see if all fields match, ignoring order.

        if ( leftNode->children.size() != rightNode->children.size() ) return false;

        for ( size_t leftNum = 0, leftLim = leftNode->children.size(); leftNum != leftLim; ++leftNum ) {
            const XMP_Node * leftField	= leftNode->children[leftNum];
            const XMP_Node * rightField = FindConstChild ( rightNode, leftField->name.c_str() );
            if ( (rightField == 0) || (! ItemValuesMatch ( leftField, rightField )) ) return false;
        }

    } else {

        // Array nodes, see if the "leftNode" values are present in the "rightNode", ignoring order, duplicates,
        // and extra values in the rightNode-> The rightNode is the destination for AppendProperties.

        XMP_Assert ( leftForm & kXMP_PropValueIsArray );

        for ( size_t leftNum = 0, leftLim = leftNode->children.size(); leftNum != leftLim; ++leftNum ) {

            const XMP_Node * leftItem = leftNode->children[leftNum];

            size_t rightNum, rightLim;
            for ( rightNum = 0, rightLim = rightNode->children.size(); rightNum != rightLim; ++rightNum ) {
                const XMP_Node * rightItem = rightNode->children[rightNum];
                if ( ItemValuesMatch ( leftItem, rightItem ) ) break;
            }
            if ( rightNum == rightLim ) return false;

        }

    }

    return true;	// All of the checks passed.

}	// ItemValuesMatch


// -------------------------------------------------------------------------------------------------
// AppendSubtree
// -------------
//
// The main implementation of XMPUtils::AppendProperties. See the description in TXMPMeta.hpp.

static void
AppendSubtree ( const XMP_Node * sourceNode, XMP_Node * destParent, const bool replaceOld, const bool deleteEmpty )
{
    XMP_NodePtrPos destPos;
    XMP_Node * destNode = FindChildNode ( destParent, sourceNode->name.c_str(), kXMP_ExistingOnly, &destPos );

    bool valueIsEmpty = false;
    if ( deleteEmpty ) {
        if ( XMP_PropIsSimple ( sourceNode->options ) ) {
            valueIsEmpty = sourceNode->value.empty();
        } else {
            valueIsEmpty = sourceNode->children.empty();
        }
    }

    if ( deleteEmpty & valueIsEmpty ) {

        if ( destNode != 0 ) {
            delete ( destNode );
            destParent->children.erase ( destPos );
        }

    } else if ( destNode == 0 ) {

        // The one easy case, the destination does not exist.
        CloneSubtree ( sourceNode, destParent );

    } else if ( replaceOld ) {

        // The destination exists and should be replaced.

        destNode->value	  = sourceNode->value;	// *** Should use SetNode.
        destNode->options = sourceNode->options;
        destNode->RemoveChildren();
        destNode->RemoveQualifiers();
        CloneOffspring ( sourceNode, destNode );

        #if 0	// *** XMP_DebugBuild
            destNode->_valuePtr = destNode->value.c_str();
        #endif

    } else {

        // The destination exists and is not totally replaced. Structs and arrays are merged.

        XMP_OptionBits sourceForm = sourceNode->options & kXMP_PropCompositeMask;
        XMP_OptionBits destForm	  = destNode->options & kXMP_PropCompositeMask;
        if ( sourceForm != destForm ) return;

        if ( sourceForm == kXMP_PropValueIsStruct ) {

            // To merge a struct process the fields recursively. E.g. add simple missing fields. The
            // recursive call to AppendSubtree will handle deletion for fields with empty values.

            for ( size_t sourceNum = 0, sourceLim = sourceNode->children.size(); sourceNum != sourceLim; ++sourceNum ) {
                const XMP_Node * sourceField = sourceNode->children[sourceNum];
                AppendSubtree ( sourceField, destNode, replaceOld, deleteEmpty );
                if ( deleteEmpty && destNode->children.empty() ) {
                    delete ( destNode );
                    destParent->children.erase ( destPos );
                }
            }

        } else if ( sourceForm & kXMP_PropArrayIsAltText ) {

            // Merge AltText arrays by the xml:lang qualifiers. Make sure x-default is first. Make a
            // special check for deletion of empty values. Meaningful in AltText arrays because the
            // xml:lang qualifier provides unambiguous source/dest correspondence.

            for ( size_t sourceNum = 0, sourceLim = sourceNode->children.size(); sourceNum != sourceLim; ++sourceNum ) {

                const XMP_Node * sourceItem = sourceNode->children[sourceNum];
                if ( sourceItem->qualifiers.empty() || (sourceItem->qualifiers[0]->name != "xml:lang") ) continue;

                XMP_Index  destIndex = LookupLangItem ( destNode, sourceItem->qualifiers[0]->value );

                if ( deleteEmpty && sourceItem->value.empty() ) {

                    if ( destIndex != -1 ) {
                        delete ( destNode->children[destIndex] );
                        destNode->children.erase ( destNode->children.begin() + destIndex );
                        if ( destNode->children.empty() ) {
                            delete ( destNode );
                            destParent->children.erase ( destPos );
                        }
                    }

                } else {

                    if (  destIndex != -1 ) continue;	// Not replacing, keep the existing item.

                    if ( (sourceItem->qualifiers[0]->value != "x-default") || destNode->children.empty() ) {
                        CloneSubtree ( sourceItem, destNode );
                    } else {
                        XMP_Node * destItem = new XMP_Node ( destNode, sourceItem->name, sourceItem->value, sourceItem->options );
                        CloneOffspring ( sourceItem, destItem );
                        destNode->children.insert ( destNode->children.begin(), destItem );
                }

                }

            }

        } else if ( sourceForm & kXMP_PropValueIsArray ) {

            // Merge other arrays by item values. Don't worry about order or duplicates. Source
            // items with empty values do not cause deletion, that conflicts horribly with merging.

            for ( size_t sourceNum = 0, sourceLim = sourceNode->children.size(); sourceNum != sourceLim; ++sourceNum ) {
                const XMP_Node * sourceItem = sourceNode->children[sourceNum];

                size_t	destNum, destLim;
                for ( destNum = 0, destLim = destNode->children.size(); destNum != destLim; ++destNum ) {
                    const XMP_Node * destItem = destNode->children[destNum];
                    if ( ItemValuesMatch ( sourceItem, destItem ) ) break;
                }
                if ( destNum == destLim ) CloneSubtree ( sourceItem, destNode );

            }

        }

    }

}	// AppendSubtree


// =================================================================================================
// Class Static Functions
// ======================

// -------------------------------------------------------------------------------------------------
// CatenateArrayItems
// ------------------

/* class static */ void
XMPUtils::CatenateArrayItems ( const XMPMeta & xmpObj,
                               XMP_StringPtr   schemaNS,
                               XMP_StringPtr   arrayName,
                               XMP_StringPtr   separator,
                               XMP_StringPtr   quotes,
                               XMP_OptionBits  options,
                               XMP_StringPtr * catedStr,
                               XMP_StringLen * catedLen )
{
    XMP_Assert ( (schemaNS != 0) && (arrayName != 0) ); // ! Enforced by wrapper.
    XMP_Assert ( (separator != 0) && (quotes != 0) && (catedStr != 0) && (catedLen != 0) ); // ! Enforced by wrapper.

    size_t		 strLen, strPos, charLen;
    UniCharKind	 charKind;
    UniCodePoint currUCP, openQuote, closeQuote;

    const bool allowCommas = ((options & kXMPUtil_AllowCommas) != 0);

    const XMP_Node * arrayNode = 0; // ! Move up to avoid gcc complaints.
    XMP_OptionBits	 arrayForm = 0;
    const XMP_Node * currItem  = 0;

    // Make sure the separator is OK. It must be one semicolon surrounded by zero or more spaces.
    // Any of the recognized semicolons or spaces are allowed.

    strPos = 0;
    strLen = strlen ( separator );
    bool haveSemicolon = false;

    while ( strPos < strLen ) {
        ClassifyCharacter ( separator, strPos, &charKind, &charLen, &currUCP );
        strPos += charLen;
        if ( charKind == UCK_semicolon ) {
            if ( haveSemicolon ) XMP_Throw ( "Separator can have only one semicolon",  kXMPErr_BadParam );
            haveSemicolon = true;
        } else if ( charKind != UCK_space ) {
            XMP_Throw ( "Separator can have only spaces and one semicolon",	 kXMPErr_BadParam );
        }
    };
    if ( ! haveSemicolon ) XMP_Throw ( "Separator must have one semicolon",	 kXMPErr_BadParam );

    // Make sure the open and close quotes are a legitimate pair.

    strLen = strlen ( quotes );
    ClassifyCharacter ( quotes, 0, &charKind, &charLen, &openQuote );
    if ( charKind != UCK_quote ) XMP_Throw ( "Invalid quoting character", kXMPErr_BadParam );

    if ( charLen == strLen ) {
        closeQuote = openQuote;
    } else {
        strPos = charLen;
        ClassifyCharacter ( quotes, strPos, &charKind, &charLen, &closeQuote );
        if ( charKind != UCK_quote ) XMP_Throw ( "Invalid quoting character", kXMPErr_BadParam );
        if ( (strPos + charLen) != strLen ) XMP_Throw ( "Quoting string too long", kXMPErr_BadParam );
    }
    if ( closeQuote != GetClosingQuote ( openQuote ) ) XMP_Throw ( "Mismatched quote pair", kXMPErr_BadParam );

    // Return an empty result if the array does not exist, hurl if it isn't the right form.

    sCatenatedItems->erase();

    XMP_ExpandedXPath arrayPath;
    ExpandXPath ( schemaNS, arrayName, &arrayPath );

    arrayNode = FindConstNode ( &xmpObj.tree, arrayPath );
    if ( arrayNode == 0 ) goto EXIT;	// ! Need to set the output pointer and length.

    arrayForm = arrayNode->options & kXMP_PropCompositeMask;
    if ( (! (arrayForm & kXMP_PropValueIsArray)) || (arrayForm & kXMP_PropArrayIsAlternate) ) {
        XMP_Throw ( "Named property must be non-alternate array", kXMPErr_BadParam );
    }
    if ( arrayNode->children.empty() ) goto EXIT;	// ! Need to set the output pointer and length.

    // Build the result, quoting the array items, adding separators. Hurl if any item isn't simple.
    // Start the result with the first value, then add the rest with a preceding separator.

    currItem = arrayNode->children[0];

    if ( (currItem->options & kXMP_PropCompositeMask) != 0 ) XMP_Throw ( "Array items must be simple", kXMPErr_BadParam );
    *sCatenatedItems = currItem->value;
    ApplyQuotes ( sCatenatedItems, openQuote, closeQuote, allowCommas );

    for ( size_t itemNum = 1, itemLim = arrayNode->children.size(); itemNum != itemLim; ++itemNum ) {
        const XMP_Node * currItem = arrayNode->children[itemNum];
        if ( (currItem->options & kXMP_PropCompositeMask) != 0 ) XMP_Throw ( "Array items must be simple", kXMPErr_BadParam );
        XMP_VarString tempStr ( currItem->value );
        ApplyQuotes ( &tempStr, openQuote, closeQuote, allowCommas );
        *sCatenatedItems += separator;
        *sCatenatedItems += tempStr;
    }

EXIT:
    *catedStr = sCatenatedItems->c_str();
    *catedLen = sCatenatedItems->size();

}	// CatenateArrayItems


// -------------------------------------------------------------------------------------------------
// SeparateArrayItems
// ------------------

/* class static */ void
XMPUtils::SeparateArrayItems ( XMPMeta *	  xmpObj,
                               XMP_StringPtr  schemaNS,
                               XMP_StringPtr  arrayName,
                               XMP_OptionBits options,
                               XMP_StringPtr  catedStr )
{
    XMP_Assert ( (schemaNS != 0) && (arrayName != 0) && (catedStr != 0) );	// ! Enforced by wrapper.

    XMP_VarString itemValue;
    size_t itemStart, itemEnd;
    size_t nextSize, charSize = 0;	// Avoid VS uninit var warnings.
    UniCharKind	  nextKind, charKind = UCK_normal;
    UniCodePoint  nextChar, uniChar = 0;

    // Extract "special" option bits, verify and normalize the others.

    bool preserveCommas = false;
    if ( options & kXMPUtil_AllowCommas ) {
        preserveCommas = true;
        options ^= kXMPUtil_AllowCommas;
    }

    options = VerifySetOptions ( options, 0 );	// Keep a zero value, has special meaning below.
    if ( options & ~kXMP_PropArrayFormMask ) XMP_Throw ( "Options can only provide array form", kXMPErr_BadOptions );

    // Find the array node, make sure it is OK. Move the current children aside, to be readded later if kept.

    XMP_ExpandedXPath arrayPath;
    ExpandXPath ( schemaNS, arrayName, &arrayPath );
    XMP_Node * arrayNode = FindNode ( &xmpObj->tree, arrayPath, kXMP_ExistingOnly );

    if ( arrayNode != 0 ) {
        // The array exists, make sure the form is compatible. Zero arrayForm means take what exists.
        XMP_OptionBits arrayForm = arrayNode->options & kXMP_PropArrayFormMask;
        if ( (arrayForm == 0) || (arrayForm & kXMP_PropArrayIsAlternate) ) {
            XMP_Throw ( "Named property must be non-alternate array", kXMPErr_BadXPath );
        }
        if ( (options != 0) && (options != arrayForm) ) XMP_Throw ( "Mismatch of specified and existing array form", kXMPErr_BadXPath );	// *** Right error?
    } else {
        // The array does not exist, try to create it.
        arrayNode = FindNode ( &xmpObj->tree, arrayPath, kXMP_CreateNodes, (options | kXMP_PropValueIsArray) );
        if ( arrayNode == 0 ) XMP_Throw ( "Failed to create named array", kXMPErr_BadXPath );
    }

    XMP_NodeOffspring oldChildren ( arrayNode->children );
    size_t oldChildCount = oldChildren.size();
    arrayNode->children.clear();

    // Extract the item values one at a time, until the whole input string is done. Be very careful
    // in the extraction about the string positions. They are essentially byte pointers, while the
    // contents are UTF-8. Adding or subtracting 1 does not necessarily move 1 Unicode character!

    size_t endPos = strlen ( catedStr );

    itemEnd = 0;
    while ( itemEnd < endPos ) {

        // Skip any leading spaces and separation characters. Always skip commas here. They can be
        // kept when within a value, but not when alone between values.

        for ( itemStart = itemEnd; itemStart < endPos; itemStart += charSize ) {
            ClassifyCharacter ( catedStr, itemStart, &charKind, &charSize, &uniChar );
            if ( (charKind == UCK_normal) || (charKind == UCK_quote) ) break;
        }
        if ( itemStart >= endPos ) break;

        if ( charKind != UCK_quote ) {

            // This is not a quoted value. Scan for the end, create an array item from the substring.

            for ( itemEnd = itemStart; itemEnd < endPos; itemEnd += charSize ) {

                ClassifyCharacter ( catedStr, itemEnd, &charKind, &charSize, &uniChar );

                if ( (charKind == UCK_normal) || (charKind == UCK_quote) ) continue;
                if ( (charKind == UCK_comma) && preserveCommas ) continue;
                if ( charKind != UCK_space ) break;

                if ( (itemEnd + charSize) >= endPos ) break;	// Anything left?
                ClassifyCharacter ( catedStr, (itemEnd+charSize), &nextKind, &nextSize, &nextChar );
                if ( (nextKind == UCK_normal) || (nextKind == UCK_quote) ) continue;
                if ( (nextKind == UCK_comma) && preserveCommas ) continue;
                break;	// Have multiple spaces, or a space followed by a separator.

            }

            itemValue.assign ( catedStr, itemStart, (itemEnd - itemStart) );

        } else {

            // Accumulate quoted values into a local string, undoubling internal quotes that
            // match the surrounding quotes. Do not undouble "unmatching" quotes.

            UniCodePoint openQuote = uniChar;
            UniCodePoint closeQuote = GetClosingQuote ( openQuote );

            itemStart += charSize;	// Skip the opening quote;
            itemValue.erase();

            for ( itemEnd = itemStart; itemEnd < endPos; itemEnd += charSize ) {

                ClassifyCharacter ( catedStr, itemEnd, &charKind, &charSize, &uniChar );

                if ( (charKind != UCK_quote) || (! IsSurroundingQuote ( uniChar, openQuote, closeQuote)) ) {

                    // This is not a matching quote, just append it to the item value.
                    itemValue.append ( catedStr, itemEnd, charSize );

                } else {

                    // This is a "matching" quote. Is it doubled, or the final closing quote? Tolerate
                    // various edge cases like undoubled opening (non-closing) quotes, or end of input.

                    if ( (itemEnd + charSize) < endPos ) {
                        ClassifyCharacter ( catedStr, itemEnd+charSize, &nextKind, &nextSize, &nextChar );
                    } else {
                        nextKind = UCK_semicolon; nextSize = 0; nextChar = 0x3B;
                    }

                    if ( uniChar == nextChar ) {
                        // This is doubled, copy it and skip the double.
                        itemValue.append ( catedStr, itemEnd, charSize );
                        itemEnd += nextSize;	// Loop will add in charSize.
                    } else if ( ! IsClosingingQuote ( uniChar, openQuote, closeQuote ) ) {
                        // This is an undoubled, non-closing quote, copy it.
                        itemValue.append ( catedStr, itemEnd, charSize );
                    } else {
                        // This is an undoubled closing quote, skip it and exit the loop.
                        itemEnd += charSize;
                        break;
                    }

                }

            }	// Loop to accumulate the quoted value.

        }

        // Add the separated item to the array. Keep a matching old value in case it had separators.

        size_t oldChild;
        for ( oldChild = 0; oldChild < oldChildCount; ++oldChild ) {
            if ( (oldChildren[oldChild] != 0) && (itemValue == oldChildren[oldChild]->value) ) break;
        }

        XMP_Node * newItem = 0;
        if ( oldChild == oldChildCount ) {
            newItem = new XMP_Node ( arrayNode, kXMP_ArrayItemName, itemValue.c_str(), 0 );
        } else {
            newItem = oldChildren[oldChild];
            oldChildren[oldChild] = 0;	// ! Don't match again, let duplicates be seen.
        }
        arrayNode->children.push_back ( newItem );

    }	// Loop through all of the returned items.

    // Delete any of the old children that were not kept.
    for ( size_t i = 0; i < oldChildCount; ++i ) {
        if ( oldChildren[i] != 0 ) delete oldChildren[i];
    }

}	// SeparateArrayItems


// -------------------------------------------------------------------------------------------------
// RemoveProperties
// ----------------

/* class static */ void
XMPUtils::RemoveProperties ( XMPMeta *		xmpObj,
                             XMP_StringPtr	schemaNS,
                             XMP_StringPtr	propName,
                             XMP_OptionBits options )
{
    XMP_Assert ( (schemaNS != 0) && (propName != 0) );	// ! Enforced by wrapper.

    const bool doAll = XMP_TestOption (options, kXMPUtil_DoAllProperties );
    const bool includeAliases = XMP_TestOption ( options, kXMPUtil_IncludeAliases );

    if ( *propName != 0 ) {

        // Remove just the one indicated property. This might be an alias, the named schema might
        // not actually exist. So don't lookup the schema node.

        if ( *schemaNS == 0 ) XMP_Throw ( "Property name requires schema namespace", kXMPErr_BadParam );

        XMP_ExpandedXPath expPath;
        ExpandXPath ( schemaNS, propName, &expPath );

        XMP_NodePtrPos propPos;
        XMP_Node * propNode = FindNode ( &(xmpObj->tree), expPath, kXMP_ExistingOnly, kXMP_NoOptions, &propPos );
        if ( propNode != 0 ) {
            if ( doAll || IsExternalProperty ( expPath[kSchemaStep].step, expPath[kRootPropStep].step ) ) {
                XMP_Node * parent = propNode->parent;	// *** Should have XMP_Node::RemoveChild(pos).
                delete propNode;	// ! Both delete the node and erase the pointer from the parent.
                parent->children.erase ( propPos );
                DeleteEmptySchema ( parent );
            }
        }

    } else if ( *schemaNS != 0 ) {

        // Remove all properties from the named schema. Optionally include aliases, in which case
        // there might not be an actual schema node.

        XMP_NodePtrPos schemaPos;
        XMP_Node * schemaNode = FindSchemaNode ( &xmpObj->tree, schemaNS, kXMP_ExistingOnly, &schemaPos );
        if ( schemaNode != 0 ) RemoveSchemaChildren ( schemaPos, doAll );

        if ( includeAliases ) {

            // We're removing the aliases also. Look them up by their namespace prefix. Yes, the
            // alias map is sorted so we could process just that portion. But that takes more code
            // and the extra speed isn't worth it. (Plus this way we avoid a dependence on the map
            // implementation.) Lookup the XMP node from the alias, to make sure the actual exists.

            XMP_StringPtr nsPrefix;
            XMP_StringLen nsLen;
            (void) XMPMeta::GetNamespacePrefix ( schemaNS, &nsPrefix, &nsLen );

            XMP_AliasMapPos currAlias = sRegisteredAliasMap->begin();
            XMP_AliasMapPos endAlias  = sRegisteredAliasMap->end();

            for ( ; currAlias != endAlias; ++currAlias ) {
                if ( strncmp ( currAlias->first.c_str(), nsPrefix, nsLen ) == 0 ) {
                    XMP_NodePtrPos actualPos;
                    XMP_Node * actualProp = FindNode ( &xmpObj->tree, currAlias->second, kXMP_ExistingOnly, kXMP_NoOptions, &actualPos );
                    if ( actualProp != 0 ) {
                        XMP_Node * rootProp = actualProp;
                        while ( ! XMP_NodeIsSchema ( rootProp->parent->options ) ) rootProp = rootProp->parent;
                        if ( doAll || IsExternalProperty ( rootProp->parent->name, rootProp->name ) ) {
                            XMP_Node * parent = actualProp->parent;
                            delete actualProp;	// ! Both delete the node and erase the pointer from the parent.
                            parent->children.erase ( actualPos );
                            DeleteEmptySchema ( parent );
                        }
                    }
                }
            }

        }

    } else {

        // Remove all appropriate properties from all schema. In this case we don't have to be
        // concerned with aliases, they are handled implicitly from the actual properties.

        // ! Iterate backwards to reduce shuffling if schema are erased and to simplify the logic
        // ! for denoting the current schema. (Erasing schema n makes the old n+1 now be n.)

        size_t		   schemaCount = xmpObj->tree.children.size();
        XMP_NodePtrPos beginPos	   = xmpObj->tree.children.begin();

        for ( size_t schemaNum = schemaCount-1, schemaLim = (size_t)(-1); schemaNum != schemaLim; --schemaNum ) {
            XMP_NodePtrPos currSchema = beginPos + schemaNum;
            RemoveSchemaChildren ( currSchema, doAll );
        }

    }

}	// RemoveProperties


// -------------------------------------------------------------------------------------------------
// AppendProperties
// ----------------

/* class static */ void
XMPUtils::AppendProperties ( const XMPMeta & source,
                             XMPMeta *		 dest,
                             XMP_OptionBits	 options )
{
    XMP_Assert ( dest != 0 );	// ! Enforced by wrapper.

    const bool doAll	   = ((options & kXMPUtil_DoAllProperties) != 0);
    const bool replaceOld  = ((options & kXMPUtil_ReplaceOldValues) != 0);
    const bool deleteEmpty = ((options & kXMPUtil_DeleteEmptyValues) != 0);

    for ( size_t schemaNum = 0, schemaLim = source.tree.children.size(); schemaNum != schemaLim; ++schemaNum ) {

        const XMP_Node * sourceSchema = source.tree.children[schemaNum];

        // Make sure we have a destination schema node. Remember if it is newly created.

        XMP_Node * destSchema = FindSchemaNode ( &dest->tree, sourceSchema->name.c_str(), kXMP_ExistingOnly );
        const bool newDestSchema = (destSchema == 0);
        if ( newDestSchema ) {
            destSchema = new XMP_Node ( &dest->tree, sourceSchema->name, sourceSchema->value, kXMP_SchemaNode );
            dest->tree.children.push_back ( destSchema );
        }

        // Process the source schema's children. Do this backwards in case deleteEmpty is set.

        for ( long propNum = ((long)sourceSchema->children.size() - 1); propNum >= 0; --propNum ) {
            const XMP_Node * sourceProp = sourceSchema->children[propNum];
            if ( doAll || IsExternalProperty ( sourceSchema->name, sourceProp->name ) ) {
                AppendSubtree ( sourceProp, destSchema, replaceOld, deleteEmpty );
// ***				RemoveMultiValueInfo ( dest, sourceSchema->name.c_str(), sourceProp->name.c_str() );
            }
        }

        if ( destSchema->children.empty() ) {
            if ( newDestSchema ) {
                delete ( destSchema );
                dest->tree.children.pop_back();
            } else if ( deleteEmpty ) {
                DeleteEmptySchema ( destSchema );
            }
        }

    }

}	// AppendProperties


// -------------------------------------------------------------------------------------------------
// DuplicateSubtree
// ----------------

/* class static */ void
XMPUtils::DuplicateSubtree ( const XMPMeta & source,
                             XMPMeta *		 dest,
                             XMP_StringPtr	 sourceNS,
                             XMP_StringPtr	 sourceRoot,
                             XMP_StringPtr	 destNS,
                             XMP_StringPtr	 destRoot,
                             XMP_OptionBits	 options )
{
    options = options;	// Avoid unused parameter warning.

    bool fullSourceTree = false;
    bool fullDestTree   = false;

    XMP_ExpandedXPath sourcePath, destPath;

    const XMP_Node * sourceNode = 0;
    XMP_Node * destNode = 0;

    XMP_Assert ( (sourceNS != 0) && (*sourceNS != 0) );
    XMP_Assert ( (sourceRoot != 0) && (*sourceRoot != 0) );
    XMP_Assert ( (dest != 0) && (destNS != 0) && (destRoot != 0) );

    if ( *destNS == 0 )	  destNS   = sourceNS;
    if ( *destRoot == 0 ) destRoot = sourceRoot;

    if ( XMP_LitMatch ( sourceNS, "*" ) ) fullSourceTree = true;
    if ( XMP_LitMatch ( destNS, "*" ) )   fullDestTree   = true;

    if ( (&source == dest) && (fullSourceTree | fullDestTree) ) {
        XMP_Throw ( "Can't duplicate tree onto itself", kXMPErr_BadParam );
    }

    if ( fullSourceTree & fullDestTree ) XMP_Throw ( "Use Clone for full tree to full tree", kXMPErr_BadParam );

    if ( fullSourceTree ) {

        // The destination must be an existing empty struct, copy all of the source top level as fields.

        ExpandXPath ( destNS, destRoot, &destPath );
        destNode = FindNode ( &dest->tree, destPath, kXMP_ExistingOnly );

        if ( (destNode == 0) || (! XMP_PropIsStruct ( destNode->options )) ) {
            XMP_Throw ( "Destination must be an existing struct", kXMPErr_BadXPath );
        }

        if ( ! destNode->children.empty() ) {
            if ( options & kXMP_DeleteExisting ) {
                destNode->RemoveChildren();
            } else {
                XMP_Throw ( "Destination must be an empty struct", kXMPErr_BadXPath );
            }
        }

        for ( size_t schemaNum = 0, schemaLim = source.tree.children.size(); schemaNum < schemaLim; ++schemaNum ) {

            const XMP_Node * currSchema = source.tree.children[schemaNum];

            for ( size_t propNum = 0, propLim = currSchema->children.size(); propNum < propLim; ++propNum ) {
                sourceNode = currSchema->children[propNum];
                XMP_Node * copyNode = new XMP_Node ( destNode, sourceNode->name, sourceNode->value, sourceNode->options );
                destNode->children.push_back ( copyNode );
                CloneOffspring ( sourceNode, copyNode );
            }

        }

    } else if ( fullDestTree ) {

        // The source node must be an existing struct, copy all of the fields to the dest top level.

        XMP_ExpandedXPath sourcePath;
        ExpandXPath ( sourceNS, sourceRoot, &sourcePath );
        sourceNode = FindConstNode ( &source.tree, sourcePath );

        if ( (sourceNode == 0) || (! XMP_PropIsStruct ( sourceNode->options )) ) {
            XMP_Throw ( "Source must be an existing struct", kXMPErr_BadXPath );
        }

        destNode = &dest->tree;

        if ( ! destNode->children.empty() ) {
            if ( options & kXMP_DeleteExisting ) {
                destNode->RemoveChildren();
            } else {
                XMP_Throw ( "Destination tree must be empty", kXMPErr_BadXPath );
            }
        }

        std::string   nsPrefix;
        XMP_StringPtr nsURI;
        XMP_StringLen nsLen;

        for ( size_t fieldNum = 0, fieldLim = sourceNode->children.size(); fieldNum < fieldLim; ++fieldNum ) {

            const XMP_Node * currField = sourceNode->children[fieldNum];

            size_t colonPos = currField->name.find ( ':' );
            nsPrefix.assign ( currField->name.c_str(), colonPos );
            bool nsOK = XMPMeta::GetNamespaceURI ( nsPrefix.c_str(), &nsURI, &nsLen );
            if ( ! nsOK ) XMP_Throw ( "Source field namespace is not global", kXMPErr_BadSchema );

            XMP_Node * destSchema = FindSchemaNode ( &dest->tree, nsURI, kXMP_CreateNodes );
            if ( destSchema == 0 ) XMP_Throw ( "Failed to find destination schema", kXMPErr_BadSchema );

            XMP_Node * copyNode = new XMP_Node ( destSchema, currField->name, currField->value, currField->options );
            destSchema->children.push_back ( copyNode );
            CloneOffspring ( currField, copyNode );

        }

    } else {

        // Find the root nodes for the source and destination subtrees.

        ExpandXPath ( sourceNS, sourceRoot, &sourcePath );
        ExpandXPath ( destNS, destRoot, &destPath );

        sourceNode = FindConstNode ( &source.tree, sourcePath );
        if ( sourceNode == 0 ) XMP_Throw ( "Can't find source subtree", kXMPErr_BadXPath );

        destNode = FindNode ( &dest->tree, destPath, kXMP_ExistingOnly );	// Dest must not yet exist.
        if ( destNode != 0 ) XMP_Throw ( "Destination subtree must not exist", kXMPErr_BadXPath );

        destNode = FindNode ( &dest->tree, destPath, kXMP_CreateNodes );	// Now create the dest.
        if ( destNode == 0 ) XMP_Throw ( "Can't create destination root node", kXMPErr_BadXPath );

        // Make sure the destination is not within the source! The source can't be inside the destination
        // because the source already existed and the destination was just created.

        if ( &source == dest ) {
            for ( XMP_Node * testNode = destNode; testNode != 0; testNode = testNode->parent ) {
                if ( testNode == sourceNode ) {
                    // *** delete the just-created dest root node
                    XMP_Throw ( "Destination subtree is within the source subtree", kXMPErr_BadXPath );
                }
            }
        }

        // *** Could use a CloneTree util here and maybe elsewhere.

        destNode->value	  = sourceNode->value;	// *** Should use SetNode.
        destNode->options = sourceNode->options;
        CloneOffspring ( sourceNode, destNode );

    }

}	// DuplicateSubtree

} // namespace DngXmpSdk
// =================================================================================================
