Merged String and Unicode object types. Added new functions to

	the puplic API:  Tcl_NewUnicodeObj, Tcl_SetUnicodeObj,
	Tcl_GetUnicode, Tcl_GetUniChar, Tcl_GetCharLength, Tcl_GetRange,
	Tcl_AppendUnicodeToObj.

Note: some stringObj tests are still failing--the teststringobj command
still needs to be updated.

1 files changed, 1002 insertions, 75 deletions

diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index c70bcb9..8dc6e90 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -9,13 +9,29 @@
  *	track of the extra space.  Objects with this internal
  *	representation are called "expandable string objects".
  *
+ * Since some string operations work with UTF strings and others require Unicode
+ format, the string obeject type stores one or both formats.  If the object is
+ created with a Unicode string, then UTF form is not stored until it is
+ required by a string operation.  The string object always stores the number of
+ characters, so if the object is created with a UTF string, we automatically
+ convert it to unicode (as this costs little more than
+
+A Unicode string
+ * is an internationalized string.  Conceptually, a Unicode string is an
+ * array of 16-bit quantities organized as a sequence of properly formed
+ * UTF-8 characters.  There is a one-to-one map between Unicode and UTF
+ * characters.  The Unicode ojbect is opitmized for the case where each UTF
+ * char in a string is only one byte.  In this case, we store the value of
+ * numChars, but we don't copy the bytes to the unicodeObj->chars.  Before
+ * accessing obj->chars, check if unicodeObj->numChars == obj->length.
+ *
  * Copyright (c) 1995-1997 Sun Microsystems, Inc.
  * Copyright (c) 1999 by Scriptics Corporation.
  *
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclStringObj.c,v 1.7 1999/06/08 02:59:25 hershey Exp $
+ * RCS: @(#) $Id: tclStringObj.c,v 1.8 1999/06/15 01:16:25 hershey Exp $
  */
 
 #include "tclInt.h"
@@ -24,7 +40,20 @@
  * Prototypes for procedures defined later in this file:
  */
 
-static void		ConvertToStringType _ANSI_ARGS_((Tcl_Obj *objPtr));
+static void		AppendUnicodeToUnicodeRep _ANSI_ARGS_((
+    			    Tcl_Obj *objPtr, Tcl_UniChar *unicode,
+			    int appendNumChars));
+static void		AppendUnicodeToUtfRep _ANSI_ARGS_((
+    			    Tcl_Obj *objPtr, Tcl_UniChar *unicode,
+			    int numChars));
+static void		AppendUtfToUnicodeRep _ANSI_ARGS_((Tcl_Obj *objPtr,
+    			    char *bytes, int numBytes));
+static void		AppendUtfToUtfRep _ANSI_ARGS_((Tcl_Obj *objPtr,
+    			    char *bytes, int numBytes));
+
+static void		FillUnicodeRep _ANSI_ARGS_((Tcl_Obj *objPtr));
+
+static void		FreeStringInternalRep _ANSI_ARGS_((Tcl_Obj *objPtr));
 static void		DupStringInternalRep _ANSI_ARGS_((Tcl_Obj *objPtr,
 			    Tcl_Obj *copyPtr));
 static int		SetStringFromAny _ANSI_ARGS_((Tcl_Interp *interp,
@@ -38,11 +67,46 @@ static void		UpdateStringOfString _ANSI_ARGS_((Tcl_Obj *objPtr));
 
 Tcl_ObjType tclStringType = {
     "string",				/* name */
-    (Tcl_FreeInternalRepProc *) NULL,	/* freeIntRepProc */
+    FreeStringInternalRep,		/* freeIntRepPro */
     DupStringInternalRep,		/* dupIntRepProc */
     UpdateStringOfString,		/* updateStringProc */
     SetStringFromAny			/* setFromAnyProc */
 };
+
+/*
+ * The following structure is the internal rep for a String object.
+ * It keeps track of how much memory has been used and how much has been
+ * allocated for the Unicode and UTF string to enable growing and
+ * shrinking of the UTF and Unicode reps of the String object with fewer
+ * mallocs.  To optimize string length and indexing operations, this
+ * structure also stores the number of characters (same of UTF and Unicode!)
+ * once that value has been computede.
+ */
+
+typedef struct String {
+    int numChars;		/* The number of chars in the string.
+				 * -1 means this value has not been
+				 * calculated. >= 0 means that there is a
+				 * valid Unicode rep, or that the number
+				 * of UTF bytes == the number of chars. */
+    size_t allocated;		/* The amount of space actually allocated
+				 * for the UTF string (minus 1 byte for
+				 * the termination char). */
+    size_t uallocated;		/* The amount of space actually allocated
+				 * for the Unicode string. 0 means the
+				 * Unicode string rep is invalid. */
+    Tcl_UniChar unicode[2];	/* The array of Unicode chars.  The actual
+				 * size of this field depends on the
+				 * 'uallocated' field above. */
+} String;
+
+#define STRING_SIZE(len)	\
+		((unsigned) (sizeof(String) + ((len-1) * sizeof(Tcl_UniChar))))
+#define GET_STRING(objPtr) \
+		((String *) (objPtr)->internalRep.otherValuePtr)
+#define SET_STRING(objPtr, stringPtr) \
+		(objPtr)->internalRep.otherValuePtr = (VOID *) (stringPtr)
+
 
 /*
  *----------------------------------------------------------------------
@@ -182,6 +246,327 @@ Tcl_DbNewStringObj(bytes, length, file, line)
 #endif /* TCL_MEM_DEBUG */
 
 /*
+ *---------------------------------------------------------------------------
+ *
+ * TclNewUnicodeObj --
+ *
+ *	This procedure is creates a new String object and initializes
+ *	it from the given Utf String.  If the Utf String is the same size
+ *	as the Unicode string, don't duplicate the data.
+ *
+ * Results:
+ *	The newly created object is returned.  This object will have no
+ *	initial string representation.  The returned object has a ref count
+ *	of 0.
+ *
+ * Side effects:
+ *	Memory allocated for new object and copy of Unicode argument.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+Tcl_Obj *
+Tcl_NewUnicodeObj(unicode, numChars)
+    Tcl_UniChar *unicode;	/* The unicode string used to initialize
+				 * the new object. */
+    int numChars;		/* Number of characters in the unicode
+				 * string. */
+{
+    Tcl_Obj *objPtr;
+    String *stringPtr;
+    int uallocated = (numChars + 1) * sizeof(Tcl_UniChar);
+
+    /*
+     * Create a new obj with an invalid string rep.
+     */
+
+    TclNewObj(objPtr);
+    Tcl_InvalidateStringRep(objPtr);
+    objPtr->typePtr = &tclStringType;
+
+    stringPtr = (String *) ckalloc(STRING_SIZE(uallocated));
+    stringPtr->numChars = numChars;
+    stringPtr->uallocated = uallocated;
+    stringPtr->allocated = 0;
+    memcpy((VOID *) stringPtr->unicode, (VOID *) unicode,
+	    (size_t) (numChars * sizeof(Tcl_UniChar)));
+    stringPtr->unicode[numChars] = 0;
+    SET_STRING(objPtr, stringPtr);
+    return objPtr;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetCharLength --
+ *
+ *	Get the length of the Unicode string from the Tcl object.
+ *
+ * Results:
+ *	Pointer to unicode string representing the unicode object.
+ *
+ * Side effects:
+ *	Frees old internal rep.  Allocates memory for new "String"
+ *	internal rep.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetCharLength(objPtr)
+    Tcl_Obj *objPtr;	/* The String object to get the num chars of. */
+{
+    String *stringPtr;
+    
+    SetStringFromAny(NULL, objPtr);
+    stringPtr = GET_STRING(objPtr);
+
+/*     if (objPtr->bytes == NULL) { */
+/* 	printf("called Tcl_GetCharLength with unicode str.\n"); */
+/*     } else { */
+/* 	printf("called Tcl_GetCharLength with str = %s\n", objPtr->bytes); */
+/*     } */
+    
+    /*
+     * If numChars is unknown, then calculate the number of characaters
+     * while populating the Unicode string.
+     */
+    
+    if (stringPtr->numChars == -1) {
+
+	stringPtr->numChars = Tcl_NumUtfChars(objPtr->bytes, objPtr->length);
+
+ 	if (stringPtr->numChars == objPtr->length) {
+
+	    /*
+	     * Since we've just calucalated the number of chars, and all
+	     * UTF chars are 1-byte long, we don't need to store the
+	     * unicode string.
+	     */
+	    
+	    stringPtr->uallocated = 0;
+
+	} else {
+    
+	    /*
+	     * Since we've just calucalated the number of chars, and not
+	     * all UTF chars are 1-byte long, go ahead and populate the
+	     * unicode string.
+	     */
+
+	    FillUnicodeRep(objPtr);
+
+	    /*
+	     * We need to fetch the pointer again because we have just
+	     * reallocated the structure to make room for the Unicode data.
+	     */
+	    
+	    stringPtr = GET_STRING(objPtr);
+	}
+    }
+    return stringPtr->numChars;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetUniChar --
+ *
+ *	Get the index'th Unicode character from the String object.  The
+ *	index is assumed to be in the appropriate range.
+ *
+ * Results:
+ *	Returns the index'th Unicode character in the Object.
+ *
+ * Side effects:
+ *	Fills unichar with the index'th Unicode character.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_UniChar
+Tcl_GetUniChar(objPtr, index)
+    Tcl_Obj *objPtr;	/* The object to get the Unicode charater from. */
+    int index;		/* Get the index'th Unicode character. */
+{
+    Tcl_UniChar unichar;
+    String *stringPtr;
+    
+    SetStringFromAny(NULL, objPtr);
+    stringPtr = GET_STRING(objPtr);
+
+/*     if (objPtr->bytes == NULL) { */
+/* 	printf("called Tcl_GetUniChar with unicode str.\n"); */
+/*     } else { */
+/* 	printf("called Tcl_GetUniChar with str = %s\n", objPtr->bytes); */
+/*     } */
+    
+    if (stringPtr->numChars == -1) {
+
+	/*
+	 * We haven't yet calculated the length, so we don't have the
+	 * Unicode str.  We need to know the number of chars before we
+	 * can do indexing.
+	 */
+
+	Tcl_GetCharLength(objPtr);
+
+	/*
+	 * We need to fetch the pointer again because we may have just
+	 * reallocated the structure.
+	 */
+	
+	stringPtr = GET_STRING(objPtr);
+    }
+    if (stringPtr->uallocated == 0) {
+	char *bytes;
+
+	/*
+	 * All of the characters in the Utf string are 1 byte chars,
+	 * so we don't store the unicode char.  We get the Utf string
+	 * and convert the index'th byte to a Unicode character.
+	 */
+	
+	bytes = Tcl_GetString(objPtr);
+	Tcl_UtfToUniChar(&bytes[index], &unichar);	
+    } else {
+	unichar = stringPtr->unicode[index];
+    }
+    return unichar;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetUnicode --
+ *
+ *	Get the index'th Unicode character from the String object.  If
+ *	the object is not already a String object, it will be converted
+ *	to one.  If the String object does not have a Unicode rep, then
+ *	one is create from the UTF string format.
+ *
+ * Results:
+ *	Returns a pointer to the object's internal Unicode string.
+ *
+ * Side effects:
+ *	Converts the object to have the String internal rep.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_UniChar *
+Tcl_GetUnicode(objPtr)
+    Tcl_Obj *objPtr;	/* The object to find the unicode string for. */
+{
+    String *stringPtr;
+    
+    SetStringFromAny(NULL, objPtr);
+    stringPtr = GET_STRING(objPtr);
+    
+/*     if (objPtr->bytes == NULL) { */
+/* 	printf("called Tcl_GetUnicode with unicode str.\n"); */
+/*     } else { */
+/* 	printf("called Tcl_GetUnicode with str = %s\n", objPtr->bytes); */
+/*     } */
+    
+    if ((stringPtr->numChars == -1) || (stringPtr->uallocated == 0)) {
+
+	/*
+	 * We haven't yet calculated the length, or all of the characters
+	 * in the Utf string are 1 byte chars (so we didn't store the
+	 * unicode str).  Since this function must return a unicode string,
+	 * and one has not yet been stored, force the Unicode to be
+	 * calculated and stored now.
+	 */
+
+	FillUnicodeRep(objPtr);
+
+	/*
+	 * We need to fetch the pointer again because we have just
+	 * reallocated the structure to make room for the Unicode data.
+	 */
+	
+	stringPtr = GET_STRING(objPtr);
+    }
+    return stringPtr->unicode;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetRange --
+ *
+ *	Create a Tcl Object that contains the chars between first and last
+ *	of the object indicated by "objPtr".  If the object is not already
+ *	a String object, convert it to one.  The first and last indices
+ *	are assumed to be in the appropriate range.
+ *
+ * Results:
+ *	Returns a new Tcl Object of the String type.
+ *
+ * Side effects:
+ *	Changes the internal rep of "objPtr" to the String type.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Obj*
+Tcl_GetRange(objPtr, first, last)
+   
+ Tcl_Obj *objPtr;		/* The Tcl object to find the range of. */
+    int first;			/* First index of the range. */
+    int last;			/* Last index of the range. */
+{
+    Tcl_Obj *newObjPtr;		/* The Tcl object to find the range of. */
+    String *stringPtr;
+    
+    SetStringFromAny(NULL, objPtr);
+    stringPtr = GET_STRING(objPtr);
+
+    if (stringPtr->numChars == -1) {
+    
+	/*
+	 * We haven't yet calculated the length, so we don't have the
+	 * Unicode str.  We need to know the number of chars before we
+	 * can do indexing.
+	 */
+
+	Tcl_GetCharLength(objPtr);
+
+	/*
+	 * We need to fetch the pointer again because we may have just
+	 * reallocated the structure.
+	 */
+	
+	stringPtr = GET_STRING(objPtr);
+    }
+
+    if (stringPtr->numChars == objPtr->length) {
+	char *str = Tcl_GetString(objPtr);
+
+	/*
+	 * All of the characters in the Utf string are 1 byte chars,
+	 * so we don't store the unicode char.  Create a new string
+	 * object containing the specified range of chars.
+	 */
+	
+	newObjPtr = Tcl_NewStringObj(&str[first], last-first+1);
+
+	/*
+	 * Since we know the new string only has 1-byte chars, we
+	 * can set it's numChars field.
+	 */
+	
+/* 	stringPtr = GET_STRING(newObjPtr); */
+/* 	stringPtr->numChars = last-first+1; */
+    } else {
+	newObjPtr = Tcl_NewUnicodeObj(stringPtr->unicode + first,
+		last-first+1);
+    }
+    return newObjPtr;
+}
+
+/*
  *----------------------------------------------------------------------
  *
  * Tcl_SetStringObj --
@@ -237,6 +622,7 @@ Tcl_SetStringObj(objPtr, bytes, length)
 	length = (bytes? strlen(bytes) : 0);
     }
     TclInitStringRep(objPtr, bytes, length);
+/*     printf("called Tcl_SetStringObj with str = %s\n", objPtr->bytes); */
 }
 
 /*
@@ -272,15 +658,23 @@ Tcl_SetObjLength(objPtr, length)
 				 * terminating null byte. */
 {
     char *new;
+    String *stringPtr;
 
     if (Tcl_IsShared(objPtr)) {
 	panic("Tcl_SetObjLength called with shared object");
     }
-    if (objPtr->typePtr != &tclStringType) {
-	ConvertToStringType(objPtr);
-    }
-    
-    if ((long)length > objPtr->internalRep.longValue) {
+    SetStringFromAny(NULL, objPtr);
+        
+    /*
+     * Invalidate the unicode data.
+     */
+
+    stringPtr = GET_STRING(objPtr);
+    stringPtr->numChars = -1;
+    stringPtr->uallocated = 0;
+
+    if (length > stringPtr->allocated) {
+
 	/*
 	 * Not enough space in current string. Reallocate the string
 	 * space and free the old string.
@@ -290,11 +684,13 @@ Tcl_SetObjLength(objPtr, length)
 	if (objPtr->bytes != NULL) {
 	    memcpy((VOID *) new, (VOID *) objPtr->bytes,
 		    (size_t) objPtr->length);
+/* 	    new[objPtr->length] = 0; */
 	    Tcl_InvalidateStringRep(objPtr);
 	}
 	objPtr->bytes = new;
-	objPtr->internalRep.longValue = (long) length;
+	stringPtr->allocated = length;
     }
+    
     objPtr->length = length;
     if ((objPtr->bytes != NULL) && (objPtr->bytes != tclEmptyStringRep)) {
 	objPtr->bytes[length] = 0;
@@ -302,6 +698,60 @@ Tcl_SetObjLength(objPtr, length)
 }
 
 /*
+ *---------------------------------------------------------------------------
+ *
+ * TclSetUnicodeObj --
+ *
+ *	Modify an object to hold the Unicode string indicated by "unicode".
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Memory allocated for new "String" internal rep.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+void
+Tcl_SetUnicodeObj(objPtr, unicode, numChars)
+    Tcl_Obj *objPtr;		/* The object to set the string of. */
+    Tcl_UniChar *unicode;	/* The unicode string used to initialize
+				 * the object. */
+    int numChars;		/* Number of characters in the unicode
+				 * string. */
+{
+    Tcl_ObjType *typePtr;
+    String *stringPtr;
+    size_t uallocated = (numChars + 1) * sizeof(Tcl_UniChar);
+
+    /*
+     * Free the internal rep if one exists, and invalidate the string rep.
+     */
+
+    typePtr = objPtr->typePtr;
+    if ((typePtr != NULL) && (typePtr->freeIntRepProc) != NULL) {
+	(*typePtr->freeIntRepProc)(objPtr);
+    }
+    objPtr->typePtr = &tclStringType;
+
+    /*
+     * Allocate enough space for the String structure + Unicode string.
+     */
+	
+    stringPtr = (String *) ckalloc(STRING_SIZE(uallocated));
+    stringPtr->numChars = numChars;
+    stringPtr->uallocated = uallocated;
+    stringPtr->allocated = 0;
+    memcpy((VOID *) stringPtr->unicode, (VOID *) unicode,
+	    (size_t) (numChars * sizeof(Tcl_UniChar)));
+    stringPtr->unicode[numChars] = 0;
+    SET_STRING(objPtr, stringPtr);
+    Tcl_InvalidateStringRep(objPtr);
+    return;
+}
+
+/*
  *----------------------------------------------------------------------
  *
  * Tcl_AppendToObj --
@@ -327,37 +777,106 @@ Tcl_AppendToObj(objPtr, bytes, length)
 				 * "bytes". If < 0, then append all bytes
 				 * up to NULL byte. */
 {
-    int newLength, oldLength;
+    String *stringPtr;
 
     if (Tcl_IsShared(objPtr)) {
 	panic("Tcl_AppendToObj called with shared object");
     }
-    if (objPtr->typePtr != &tclStringType) {
-	ConvertToStringType(objPtr);
-    }
+    
+    SetStringFromAny(NULL, objPtr);
+
     if (length < 0) {
-	length = (bytes? strlen(bytes) : 0);
+	length = (bytes ? strlen(bytes) : 0);
     }
     if (length == 0) {
 	return;
     }
-    oldLength = objPtr->length;
-    newLength = length + oldLength;
-    if ((long)newLength > objPtr->internalRep.longValue) {
-	/*
-	 * There isn't currently enough space in the string
-	 * representation so allocate additional space.  In fact,
-	 * overallocate so that there is room for future growth without
-	 * having to reallocate again.
-	 */
 
-	Tcl_SetObjLength(objPtr, 2*newLength);
+    /*
+     * TEMPORARY!!!  This is terribly inefficient, but it works, and Don
+     * needs for me to check this stuff in ASAP.  -Melissa
+     */
+    
+/*     printf("called Tcl_AppendToObj with str = %s\n", bytes); */
+    UpdateStringOfString(objPtr);
+    AppendUtfToUtfRep(objPtr, bytes, length);
+    return;
+
+    /*
+     * If objPtr has a valid Unicode rep, then append the Unicode
+     * conversion of "bytes" to the objPtr's Unicode rep, otherwise
+     * append "bytes" to objPtr's string rep.
+     */
+
+    stringPtr = GET_STRING(objPtr);
+    if (stringPtr->allocated > 0) {
+	AppendUtfToUnicodeRep(objPtr, bytes, length);
+
+	stringPtr = GET_STRING(objPtr);
+/* 	printf(" ended Tcl_AppendToObj with %d unicode chars.\n", */
+/* 		stringPtr->numChars); */
+    } else {
+	AppendUtfToUtfRep(objPtr, bytes, length);
+/* 	printf(" ended Tcl_AppendToObj with str = %s\n", objPtr->bytes); */
     }
-    if (length > 0) {
-	memcpy((VOID *) (objPtr->bytes + oldLength), (VOID *) bytes,
-	       (size_t) length);
-	objPtr->length = newLength;
-	objPtr->bytes[objPtr->length] = 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_AppendUnicodeToObj --
+ *
+ *	This procedure appends a Unicode string to an object in the
+ *	most efficient manner possible.  Length must be >= 0.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Invalidates the string rep and creates a new Unicode string.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_AppendUnicodeToObj(objPtr, unicode, length)
+    register Tcl_Obj *objPtr;	/* Points to the object to append to. */
+    Tcl_UniChar *unicode;	/* The unicode string to append to the
+			         * object. */
+    int length;			/* Number of chars in "unicode". */
+{
+    String *stringPtr;
+
+    if (Tcl_IsShared(objPtr)) {
+	panic("Tcl_AppendUnicodeToObj called with shared object");
+    }
+
+    if (length == 0) {
+	return;
+    }
+
+    SetStringFromAny(NULL, objPtr);
+
+    /*
+     * TEMPORARY!!!  This is terribly inefficient, but it works, and Don
+     * needs for me to check this stuff in ASAP.  -Melissa
+     */
+    
+    UpdateStringOfString(objPtr);
+    AppendUnicodeToUtfRep(objPtr, unicode, length);
+    return;
+
+    /*
+     * If objPtr has a valid Unicode rep, then append the "unicode"
+     * to the objPtr's Unicode rep, otherwise the UTF conversion of
+     * "unicode" to objPtr's string rep.
+     */
+
+    stringPtr = GET_STRING(objPtr);
+    if (stringPtr->allocated > 0) {
+	AppendUnicodeToUnicodeRep(objPtr, unicode, length);
+    } else {
+	AppendUnicodeToUtfRep(objPtr, unicode, length);
     }
 }
 
@@ -367,6 +886,7 @@ Tcl_AppendToObj(objPtr, bytes, length)
  * Tcl_AppendObjToObj --
  *
  *	This procedure appends the string rep of one object to another.
+ *	"objPtr" cannot be a shared object.
  *
  * Results:
  *	None.
@@ -383,7 +903,273 @@ Tcl_AppendObjToObj(objPtr, appendObjPtr)
     Tcl_Obj *objPtr;		/* Points to the object to append to. */
     Tcl_Obj *appendObjPtr;	/* Object to append. */
 {
-    TclAppendObjToUnicodeObj(objPtr, appendObjPtr);
+    String *stringPtr;
+    int length;
+    char *bytes;
+
+    SetStringFromAny(NULL, objPtr);
+
+    /*
+     * TEMPORARY!!!  This is terribly inefficient, but it works, and Don
+     * needs for me to check this stuff in ASAP.  -Melissa
+     */
+
+    UpdateStringOfString(objPtr);
+    bytes = Tcl_GetStringFromObj(appendObjPtr, &length);
+    AppendUtfToUtfRep(objPtr, bytes, length);
+    return;
+
+    /*
+     * If objPtr has a valid Unicode rep, then get a Unicode string
+     * from appendObjPtr and append it.
+     */
+
+    stringPtr = GET_STRING(objPtr);
+    if (stringPtr->allocated > 0) {
+	
+	/*
+	 * If appendObjPtr is not of the "String" type, don't convert it.
+	 */
+
+	if (appendObjPtr->typePtr == &tclStringType) {
+	    stringPtr = GET_STRING(appendObjPtr);
+	    if ((stringPtr->numChars == -1)
+		    || (stringPtr->uallocated == 0)) {
+		
+		/*
+		 * If appendObjPtr is a string obj with no valide Unicode
+		 * rep, then fill its unicode rep.
+		 */
+
+		FillUnicodeRep(appendObjPtr);
+		stringPtr = GET_STRING(appendObjPtr);
+	    }
+	    AppendUnicodeToUnicodeRep(objPtr, stringPtr->unicode,
+		    stringPtr->numChars);
+	} else {
+	    bytes = Tcl_GetStringFromObj(appendObjPtr, &length);
+	    AppendUtfToUnicodeRep(objPtr, bytes, length);
+	}
+	return;
+    }
+
+    /*
+     * Append to objPtr's UTF string rep.
+     */
+
+    bytes = Tcl_GetStringFromObj(appendObjPtr, &length);
+    AppendUtfToUtfRep(objPtr, bytes, length);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AppendUnicodeToUnicodeRep --
+ *
+ *	This procedure appends the contents of "unicode" to the Unicode
+ *	rep of "objPtr".  objPtr must already have a valid Unicode rep.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	objPtr's internal rep is reallocated.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AppendUnicodeToUnicodeRep(objPtr, unicode, appendNumChars)
+    Tcl_Obj *objPtr;	      /* Points to the object to append to. */
+    Tcl_UniChar *unicode;     /* String to append. */
+    int appendNumChars;	      /* Number of chars of "unicode" to append. */
+{
+    String *stringPtr;
+    int numChars;
+    size_t newSize;
+
+    if (appendNumChars == 0) {
+	return;
+    }
+
+    SetStringFromAny(NULL, objPtr);
+    stringPtr = GET_STRING(objPtr);
+    
+    /*
+     * Make the buffer big enough for the result.
+     */
+
+    numChars = stringPtr->numChars + appendNumChars;
+    newSize = (numChars + 1) * sizeof(Tcl_UniChar);
+
+    if (newSize > stringPtr->uallocated) {
+	stringPtr->uallocated = newSize * 2;
+	stringPtr = (String *) ckrealloc((char*)stringPtr,
+		STRING_SIZE(stringPtr->uallocated));
+	SET_STRING(objPtr, stringPtr);
+    }
+
+    /*
+     * Copy the new string onto the end of the old string, then add the
+     * trailing null.
+     */
+
+    memcpy((VOID*) (stringPtr->unicode + stringPtr->numChars), unicode,
+	    appendNumChars * sizeof(Tcl_UniChar));
+    stringPtr->unicode[numChars] = 0;
+    stringPtr->numChars = numChars;
+
+    SET_STRING(objPtr, stringPtr);
+    Tcl_InvalidateStringRep(objPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AppendUnicodeToUtfRep --
+ *
+ *	This procedure converts the contents of "unicode" to UTF and
+ *	appends the UTF to the string rep of "objPtr".
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	objPtr's internal rep is reallocated.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AppendUnicodeToUtfRep(objPtr, unicode, numChars)
+    Tcl_Obj *objPtr;	      /* Points to the object to append to. */
+    Tcl_UniChar *unicode;     /* String to convert to UTF. */
+    int numChars;	      /* Number of chars of "unicode" to convert. */
+{
+    Tcl_DString dsPtr;
+    int length = numChars * sizeof(Tcl_UniChar);
+    char *bytes;
+    
+    if (numChars == 0) {
+	return;
+    }
+
+    Tcl_DStringInit(&dsPtr);
+    bytes = (char *)Tcl_UniCharToUtfDString(unicode, numChars, &dsPtr);
+    AppendUtfToUtfRep(objPtr, bytes, Tcl_DStringLength(&dsPtr));
+    Tcl_DStringFree(&dsPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AppendUtfToUnicodeRep --
+ *
+ *	This procedure converts the contents of "bytes" to Unicode and
+ *	appends the Unicode to the Unicode rep of "objPtr".  objPtr must
+ *	already have a valid Unicode rep.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	objPtr's internal rep is reallocated.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AppendUtfToUnicodeRep(objPtr, bytes, numBytes)
+    Tcl_Obj *objPtr;	/* Points to the object to append to. */
+    char *bytes;		/* String to convert to Unicode. */
+    int numBytes;	/* Number of bytes of "bytes" to convert. */
+{
+    Tcl_DString dsPtr;
+    int numChars;
+    Tcl_UniChar *unicode;
+
+    if (numBytes < 0) {
+	numBytes = (bytes ? strlen(bytes) : 0);
+    }
+    if (numBytes == 0) {
+	return;
+    }
+    
+    Tcl_DStringInit(&dsPtr);
+    numChars = Tcl_NumUtfChars(bytes, numBytes);
+    unicode = (Tcl_UniChar *)Tcl_UtfToUniCharDString(bytes, numBytes, &dsPtr);
+    AppendUnicodeToUnicodeRep(objPtr, unicode, numChars);
+    Tcl_DStringFree(&dsPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AppendUtfToUtfRep --
+ *
+ *	This procedure appends "numBytes" bytes of "bytes" to the UTF string
+ *	rep of "objPtr".  objPtr must already have a valid String rep.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	objPtr's internal rep is reallocated.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AppendUtfToUtfRep(objPtr, bytes, numBytes)
+    Tcl_Obj *objPtr;	/* Points to the object to append to. */
+    char *bytes;	/* String to append. */
+    int numBytes;	/* Number of bytes of "bytes" to append. */
+{
+    String *stringPtr;
+    int newLength, oldLength;
+
+    if (numBytes < 0) {
+	numBytes = (bytes ? strlen(bytes) : 0);
+    }
+    if (numBytes == 0) {
+	return;
+    }
+
+    /*
+     * Copy the new string onto the end of the old string, then add the
+     * trailing null.
+     */
+
+    oldLength = objPtr->length;
+    newLength = numBytes + oldLength;
+
+    stringPtr = GET_STRING(objPtr);
+    if (newLength > stringPtr->allocated) {
+
+	/*
+	 * There isn't currently enough space in the string
+	 * representation so allocate additional space.  If the current
+	 * string representation isn't empty (i.e. it looks like we're
+	 * doing a series of appends) then overallocate the space so
+	 * that we won't have to do as much reallocation in the future.
+	 */
+
+	Tcl_SetObjLength(objPtr,
+		(oldLength == 0) ? newLength : 2*newLength);
+    } else {
+
+	/*
+	 * Invalidate the unicode data.
+	 */
+	
+	stringPtr->numChars = -1;
+	stringPtr->uallocated = 0;
+    }
+    
+    memcpy((VOID *) (objPtr->bytes + oldLength), (VOID *) bytes,
+	    (size_t) numBytes);
+    objPtr->bytes[newLength] = 0;
+    objPtr->length = newLength;
 }
 
 /*
@@ -409,6 +1195,7 @@ Tcl_AppendStringsToObjVA (objPtr, argList)
     Tcl_Obj *objPtr;		/* Points to the object to append to. */
     va_list argList;		/* Variable argument list. */
 {
+    String *stringPtr;
     va_list tmpArgList;
     int newLength, oldLength;
     register char *string, *dst;
@@ -416,9 +1203,8 @@ Tcl_AppendStringsToObjVA (objPtr, argList)
     if (Tcl_IsShared(objPtr)) {
 	panic("Tcl_AppendStringsToObj called with shared object");
     }
-    if (objPtr->typePtr != &tclStringType) {
-	ConvertToStringType(objPtr);
-    }
+
+    SetStringFromAny(NULL, objPtr);
 
     /*
      * Figure out how much space is needed for all the strings, and
@@ -440,7 +1226,9 @@ Tcl_AppendStringsToObjVA (objPtr, argList)
 	return;
     }
 
-    if ((long)newLength > objPtr->internalRep.longValue) {
+    stringPtr = GET_STRING(objPtr);
+    if (newLength > stringPtr->allocated) {
+
 	/*
 	 * There isn't currently enough space in the string
 	 * representation so allocate additional space.  If the current
@@ -514,45 +1302,64 @@ Tcl_AppendStringsToObj TCL_VARARGS_DEF(Tcl_Obj *,arg1)
 }
 
 /*
- *----------------------------------------------------------------------
+ *---------------------------------------------------------------------------
  *
- * ConvertToStringType --
+ * FillUnicodeRep --
  *
- *	This procedure converts the internal representation of an object
- *	to "expandable string" type.
+ *	Populate the Unicode internal rep with the Unicode form of its string
+ *	rep.  The object must alread have a "String" internal rep.
  *
  * Results:
  *	None.
  *
  * Side effects:
- *	Any old internal reputation for objPtr is freed and the
- *	internal representation is set to that for an expandable string
- *	(the field internalRep.longValue holds 1 less than the allocated
- *	length of objPtr's string representation).
+ *	Reallocates the String internal rep.
  *
- *----------------------------------------------------------------------
+ *---------------------------------------------------------------------------
  */
 
 static void
-ConvertToStringType(objPtr)
-    register Tcl_Obj *objPtr;	/* Pointer to object.  Must have a
-				 * typePtr that isn't &tclStringType. */
+FillUnicodeRep(objPtr)
+    Tcl_Obj *objPtr;	/* The object in which to fill the unicode rep. */
 {
-    if (objPtr->typePtr != NULL) {
-	if (objPtr->bytes == NULL) {
-	    objPtr->typePtr->updateStringProc(objPtr);
-	}
-	if (objPtr->typePtr->freeIntRepProc != NULL) {
-	    objPtr->typePtr->freeIntRepProc(objPtr);
-	}
+    String *stringPtr;
+    size_t uallocated;
+    char *src, *srcEnd;
+    Tcl_UniChar *dst;
+    src = objPtr->bytes;
+    
+    stringPtr = GET_STRING(objPtr);
+    if (stringPtr->numChars == -1) {
+	stringPtr->numChars = Tcl_NumUtfChars(src, objPtr->length);
     }
-    objPtr->typePtr = &tclStringType;
-    if (objPtr->bytes != NULL) {
-	objPtr->internalRep.longValue = (long)objPtr->length;
-    } else {
-	objPtr->internalRep.longValue = 0;
-	objPtr->length = 0;
+
+    uallocated = stringPtr->numChars * sizeof(Tcl_UniChar);
+    if (uallocated > stringPtr->uallocated) {
+    
+	/*
+	 * If not enought space has been allocated for the unicode rep,
+	 * reallocate the internal rep object with double the amount of
+	 * space needed, so the unicode string can grow without being
+	 * reallocated.
+	 */
+
+	uallocated *= 2;
+	stringPtr = (String *) ckrealloc((char*) stringPtr,
+		STRING_SIZE(uallocated));
+	stringPtr->uallocated = uallocated;
+    }
+
+    /*
+     * Convert src to Unicode and store the coverted data in "unicode".
+     */
+    
+    srcEnd = src + objPtr->length;
+    for (dst = stringPtr->unicode; src < srcEnd; dst++) {
+	src += Tcl_UtfToUniChar(src, dst);
     }
+    *dst = 0;
+    
+    SET_STRING(objPtr, stringPtr);
 }
 
 /*
@@ -581,13 +1388,40 @@ DupStringInternalRep(srcPtr, copyPtr)
     register Tcl_Obj *copyPtr;	/* Object with internal rep to set.  Must
 				 * not currently have an internal rep.*/
 {
+    String *srcStringPtr = GET_STRING(srcPtr);
+    String *copyStringPtr;
+    
+    /*
+     * If the src obj is a string of 1-byte Utf chars, then copy the
+     * string rep of the source object and create an "empty" Unicode
+     * internal rep for the new object.  Otherwise, copy Unicode
+     * internal rep, and invalidate the string rep of the new object.
+     */
+    
+    if (srcStringPtr->numChars == srcPtr->length) {
+	copyStringPtr = (String *) ckalloc(STRING_SIZE(0));
+	copyStringPtr->uallocated = 0;
+    } else {
+	copyStringPtr = (String *) ckalloc(
+	    STRING_SIZE(srcStringPtr->uallocated));
+	copyStringPtr->uallocated = srcStringPtr->uallocated;
+
+	memcpy((VOID *) copyStringPtr->unicode,
+		(VOID *) srcStringPtr->unicode,
+		(size_t) srcStringPtr->numChars * sizeof(Tcl_UniChar));
+	copyStringPtr->unicode[srcStringPtr->numChars] = 0;
+    }
+    copyStringPtr->numChars = srcStringPtr->numChars;
+
     /*
      * Tricky point: the string value was copied by generic object
      * management code, so it doesn't contain any extra bytes that
      * might exist in the source object.
      */
 
-    copyPtr->internalRep.longValue = (long)copyPtr->length;
+    copyStringPtr->allocated = copyPtr->length;
+
+    SET_STRING(copyPtr, copyStringPtr);
     copyPtr->typePtr = &tclStringType;
 }
 
@@ -596,15 +1430,14 @@ DupStringInternalRep(srcPtr, copyPtr)
  *
  * SetStringFromAny --
  *
- *	Create an internal representation of type "expandable string"
- *	for an object.
+ *	Create an internal representation of type "String" for an object.
  *
  * Results:
  *	This operation always succeeds and returns TCL_OK.
  *
  * Side effects:
- *	This procedure does nothing; there is no advantage in converting
- *	the internal representation now, so we just defer it.
+ *	Any old internal reputation for objPtr is freed and the
+ *	internal representation is set to "String".
  *
  *----------------------------------------------------------------------
  */
@@ -614,6 +1447,42 @@ SetStringFromAny(interp, objPtr)
     Tcl_Interp *interp;		/* Used for error reporting if not NULL. */
     Tcl_Obj *objPtr;		/* The object to convert. */
 {
+    String *stringPtr;
+
+    /*
+     * The Unicode object is opitmized for the case where each UTF char
+     * in a string is only one byte.  In this case, we store the value of
+     * numChars, but we don't copy the bytes to the unicodeObj->unicode.
+     */
+
+    if (objPtr->typePtr != &tclStringType) {
+
+	if (objPtr->typePtr != NULL) {
+	    if (objPtr->bytes == NULL) {
+		objPtr->typePtr->updateStringProc(objPtr);
+	    }
+	    if ((objPtr->typePtr->freeIntRepProc) != NULL) {
+		(*objPtr->typePtr->freeIntRepProc)(objPtr);
+	    }
+	}
+	objPtr->typePtr = &tclStringType;
+
+	/*
+	 * Allocate enough space for the basic String structure.
+	 */
+
+	stringPtr = (String *) ckalloc(STRING_SIZE(0));
+	stringPtr->numChars = -1;
+	stringPtr->uallocated = 0;
+
+	if (objPtr->bytes != NULL) {
+	    stringPtr->allocated = objPtr->length;	    
+ 	    objPtr->bytes[objPtr->length] = 0;
+	} else {
+	    objPtr->length = 0;
+	}
+	SET_STRING(objPtr, stringPtr);
+    }
     return TCL_OK;
 }
 
@@ -623,13 +1492,14 @@ SetStringFromAny(interp, objPtr)
  * UpdateStringOfString --
  *
  *	Update the string representation for an object whose internal
- *	representation is "expandable string".
+ *	representation is "String".
  *
  * Results:
  *	None.
  *
  * Side effects:
- *	None.
+ *	The object's string may be set by converting its Unicode
+ *	represention to UTF format.
  *
  *----------------------------------------------------------------------
  */
@@ -638,16 +1508,73 @@ static void
 UpdateStringOfString(objPtr)
     Tcl_Obj *objPtr;		/* Object with string rep to update. */
 {
-    /*
-     * The string is almost always valid already, in which case there's
-     * nothing for us to do. The only case we have to worry about is if
-     * the object is totally null. In this case, set the string rep to
-     * an empty string.
-     */
+    int i, length, size;
+    Tcl_UniChar *unicode;
+    char dummy[TCL_UTF_MAX];
+    char *dst;
+    String *stringPtr;
 
-    if (objPtr->bytes == NULL) {
-	objPtr->bytes = tclEmptyStringRep;
-	objPtr->length = 0;
+    stringPtr = GET_STRING(objPtr);
+    if ((objPtr->bytes == NULL) || (stringPtr->allocated == 0)) {
+
+	if (stringPtr->numChars <= 0) {
+
+	    /*
+	     * If there is no Unicode rep, or the string has 0 chars,
+	     * then set the string rep to an empty string.
+	     */
+
+	    objPtr->bytes = tclEmptyStringRep;
+	    objPtr->length = 0;
+	    return;
+	}
+
+	unicode = stringPtr->unicode;
+	length = stringPtr->numChars * sizeof(Tcl_UniChar);
+
+	/*
+	 * Translate the Unicode string to UTF.  "size" will hold the
+	 * amount of space the UTF string needs.
+	 */
+
+	size = 0;
+	for (i = 0; i < stringPtr->numChars; i++) {
+	    size += Tcl_UniCharToUtf((int) unicode[i], dummy);
+	}
+	
+	dst = (char *) ckalloc((unsigned) (size + 1));
+	objPtr->bytes = dst;
+	objPtr->length = size;
+	stringPtr->allocated = size;
+
+	for (i = 0; i < stringPtr->numChars; i++) {
+	    dst += Tcl_UniCharToUtf(unicode[i], dst);
+	}
+	*dst = '\0';
     }
     return;
 }
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FreeStringInternalRep --
+ *
+ *	Deallocate the storage associated with a String data object's
+ *	internal representation.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Frees memory. 
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+FreeStringInternalRep(objPtr)
+    Tcl_Obj *objPtr;		/* Object with internal rep to free. */
+{
+    ckfree((char *) GET_STRING(objPtr));
+}