diff --git a/qse/include/qse/cmn/str.h b/qse/include/qse/cmn/str.h
index ef286fb6..41b62e61 100644
--- a/qse/include/qse/cmn/str.h
+++ b/qse/include/qse/cmn/str.h
@@ -1,5 +1,5 @@
 /*
- * $Id: str.h 323 2010-04-05 12:50:01Z hyunghwan.chung $
+ * $Id: str.h 324 2010-04-29 13:14:13Z hyunghwan.chung $
  *
     Copyright 2006-2009 Chung, Hyung-Hwan.
     This file is part of QSE.
@@ -25,8 +25,7 @@
 #include <qse/macros.h>
 
 /** @file
- *  <qse/cmn/str.h> defines various functions, types, macros to manipulate
- *  a string.
+ *  Various functions, types, macros for string manipulation.
  *
  *  The qse_cstr_t type and the qse_xstr_t defined in <qse/types.h> helps you
  *  dealing with a string pointer and length.
@@ -39,7 +38,11 @@
 #define QSE_STR_SIZER(s)     ((s)->sizer)    /**< buffer resizer function */
 
 typedef struct qse_str_t qse_str_t;
-typedef qse_size_t (*qse_str_sizer_t) (qse_str_t* data, qse_size_t hint);
+
+typedef qse_size_t (*qse_str_sizer_t) (
+	qse_str_t* data,
+	qse_size_t hint
+);
 
 /**
  * The qse_str_t type defines a dynamically resizable string.
@@ -53,6 +56,18 @@ struct qse_str_t
 	qse_size_t      capa;  /**< buffer capacity */
 };
 
+/**
+ * The qse_strxsubst_subst_t type defines a callback function
+ * for qse_strxsubst() to substitue a new value for an identifier @a ident.
+ */
+typedef qse_char_t* (*qse_strxsubst_subst_t) (
+	qse_char_t*       buf, 
+	qse_size_t        bsz, 
+	const qse_cstr_t* ident, 
+	void*             ctx
+);
+
+
 /* int qse_chartonum (qse_char_t c, int base) */
 #define QSE_CHARTONUM(c,base) \
 	((c>=QSE_T('0') && c<=QSE_T('9'))? ((c-QSE_T('0')<base)? (c-QSE_T('0')): base): \
@@ -168,14 +183,35 @@ qse_size_t qse_strxncpy (
 	qse_size_t        len
 );
 
+/**
+ * The qse_strxput() function copies the string @a str into the buffer @a buf
+ * of the size @a bsz. Unlike qse_strxcpy(), it does not null-terminate the
+ * buffer.
+ */
+qse_size_t qse_strxput (
+        qse_char_t*       buf, 
+	qse_size_t        bsz,
+	const qse_char_t* str
+);
+
+qse_size_t qse_strxnput (
+        qse_char_t*       buf,
+	qse_size_t        bsz,
+	const qse_char_t* str,
+	qse_size_t        len
+);
+
 /**
  * The qse_strfcpy() function formats a string by position.
  * The position specifier is a number enclosed in ${ and }.
  * When ${ is preceeded by a backslash, it is treated literally. 
- * A sameple format string containing the position specifiers are shown below:
+ * See the example below:
  * @code
- *  "${1} ${3} ${2} \\${1} string"
+ *  qse_char_t buf[256]
+ *  qse_char_t* colors[] = { QSE_T("blue"), QSE_T("green"), QSE_T("red") };
+ *  qse_strfcpy(buf, QSE_T("RGB: ${2}, ${1}, ${0}"), colors);
  * @endcode
+ * @sa qse_strfncpy, qse_strxfcpy, qse_strxfncpy
  */
 qse_size_t qse_strfcpy (
 	qse_char_t*       buf,
@@ -185,6 +221,9 @@ qse_size_t qse_strfcpy (
 
 /**
  * The qse_strfncpy() function formats a string by position.
+ * It differs from qse_strfcpy() in that @str is an array of the 
+ * #qse_cstr_t type.
+ * @sa qse_strfcpy, qse_strxfcpy, qse_strxfncpy
  */
 qse_size_t qse_strfncpy (
         qse_char_t*       buf,
@@ -194,6 +233,14 @@ qse_size_t qse_strfncpy (
 
 /**
  * The qse_strxfcpy() function formats a string by position.
+ * It differs from qse_strfcpy() in that @a buf is length-bounded of @a bsz
+ * characters.
+ * @code
+ *  qse_char_t buf[256]
+ *  qse_char_t* colors[] = { QSE_T("blue"), QSE_T("green"), QSE_T("red") };
+ *  qse_strxfcpy(buf, QSE_COUNTOF(buf), QSE_T("RGB: ${2}, ${1}, ${0}"), colors);
+ * @endcode
+ * @sa qse_strfcpy, qse_strfncpy, qse_strxfncpy
  */
 qse_size_t qse_strxfcpy (
 	qse_char_t*       buf,
@@ -204,6 +251,9 @@ qse_size_t qse_strxfcpy (
 
 /**
  * The qse_strxfncpy() function formats a string by position.
+ * It differs from qse_strfcpy() in that @a buf is length-bounded of @a bsz
+ * characters and @a str is an array of the #qse_cstr_t type.
+ * @sa qse_strfcpy, qse_strfncpy, qse_strxfcpy
  */
 qse_size_t qse_strxfncpy (
         qse_char_t*       buf,
@@ -212,6 +262,32 @@ qse_size_t qse_strxfncpy (
 	const qse_cstr_t  str[]
 );
 
+/**
+ * The qse_strxsubst() function expands @a fmt into a buffer @a buf of the size
+ * @a bsz by substituting new values for ${} segments within it. The actual
+ * substitution is made by invoking the callback function @a subst. 
+ * @code
+ * qse_char_t* subst (qse_char_t* buf, qse_size_t bsz, const qse_cstr_t* ident, void* ctx)
+ * { 
+ *   if (qse_strxcmp (ident->ptr, ident->len, QSE_T("USER")) == 0)
+ *     return buf + qse_strxput (buf, bsz, QSE_T("sam"));	
+ *   else if (qse_strxcmp (ident->ptr, ident->len, QSE_T("GROUP")) == 0)
+ *     return buf + qse_strxput (buf, bsz, QSE_T("coders"));	
+ *   return buf; 
+ * }
+ * 
+ * qse_char_t buf[25];
+ * qse_strxsubst (buf, i, QSE_T("user=${USER},group=${GROUP}"), subst, QSE_NULL);
+ * @endcode
+ */
+qse_size_t qse_strxsubst (
+        qse_char_t*            buf,
+	qse_size_t             bsz,
+	const qse_char_t*      fmt,
+	qse_strxsubst_subst_t  subst,
+        void*                  ctx
+);
+
 qse_size_t qse_strxcat (
 	qse_char_t*       buf,
 	qse_size_t        bsz, 
diff --git a/qse/lib/cmn/str_bas.c b/qse/lib/cmn/str_bas.c
index e1d48521..79ea6ef1 100644
--- a/qse/lib/cmn/str_bas.c
+++ b/qse/lib/cmn/str_bas.c
@@ -1,5 +1,5 @@
 /*
- * $Id: str_bas.c 323 2010-04-05 12:50:01Z hyunghwan.chung $
+ * $Id: str_bas.c 324 2010-04-29 13:14:13Z hyunghwan.chung $
  *
     Copyright 2006-2009 Chung, Hyung-Hwan.
     This file is part of QSE.
@@ -122,6 +122,39 @@ qse_size_t qse_strxncpy (
 	return n;
 }
 
+qse_size_t qse_strxput (
+	qse_char_t* buf, qse_size_t bsz, const qse_char_t* str)
+{
+	qse_char_t* p, * p2;
+
+	p = buf; p2 = buf + bsz;
+
+	while (p < p2) 
+	{
+		if (*str == QSE_T('\0')) break;
+		*p++ = *str++;
+	}
+
+	return p - buf;
+}
+
+qse_size_t qse_strxnput (
+	qse_char_t* buf, qse_size_t bsz, const qse_char_t* str, qse_size_t len)
+{
+	qse_char_t* p, * p2; 
+	const qse_char_t* end;
+
+	p = buf; p2 = buf + bsz; end = str + len;
+
+	while (p < p2) 
+	{
+		if (str >= end) break;
+		*p++ = *str++;
+	}
+
+	return p - buf;
+}
+
 qse_size_t qse_strfcpy (
 	qse_char_t* buf, const qse_char_t* fmt, const qse_char_t* str[])
 {
@@ -326,6 +359,62 @@ fini:
 	return b - buf;
 }
 
+qse_size_t qse_strxsubst (
+	qse_char_t* buf, qse_size_t bsz, const qse_char_t* fmt, 
+	qse_strxsubst_subst_t subst, void* ctx)
+{
+	qse_char_t* b = buf;
+	qse_char_t* end = buf + bsz - 1;
+	const qse_char_t* f = fmt;
+
+	if (bsz <= 0) return 0;
+
+	while (*f != QSE_T('\0'))
+	{
+		if (*f == QSE_T('$'))
+		{
+			if (f[1] == QSE_T('{'))
+			{
+				const qse_char_t* tmp;
+				qse_cstr_t ident;
+
+				f += 2; /* skip ${ */ 
+				tmp = f; /* mark the beginning */
+
+				/* scan an enclosed segment */
+				while (*f != QSE_T('\0') && *f != QSE_T('}')) f++;
+	
+				if (*f != QSE_T('}'))
+				{
+					/* restore to the position of $ */
+					f = tmp - 2;
+					goto normal;
+				}
+
+				f++; /* skip } */
+			
+				ident.ptr = tmp;
+				ident.len = f - tmp - 1;
+
+				b = subst (b, end - b, &ident, ctx);
+				if (b >= end) goto fini;
+
+				continue;
+			}
+			else if (f[1] == QSE_T('$')) f++;
+		}
+
+	normal:
+		if (b >= end) break;
+		*b++ = *f++;
+	}
+
+fini:
+	*b = QSE_T('\0');
+	return b - buf;
+}
+
+
 qse_size_t qse_strxcat (qse_char_t* buf, qse_size_t bsz, const qse_char_t* str)
 {
 	qse_char_t* p, * p2;
diff --git a/qse/samples/cmn/str.c b/qse/samples/cmn/str.c
index da185fef..29fbc630 100644
--- a/qse/samples/cmn/str.c
+++ b/qse/samples/cmn/str.c
@@ -508,7 +508,44 @@ static int test11 (void)
 	return 0;
 }
 
+qse_char_t* subst (qse_char_t* buf, qse_size_t bsz, const qse_cstr_t* ident, void* ctx)
+{
+	if (qse_strxcmp (ident->ptr, ident->len, QSE_T("USER")) == 0)
+	{
+		return buf + qse_strxput (buf, bsz, QSE_T("sam"));	
+	}
+	else if (qse_strxcmp (ident->ptr, ident->len, QSE_T("GROUP")) == 0)
+	{
+		return buf + qse_strxput (buf, bsz, QSE_T("coders"));	
+	}
+
+	/* don't do anything */
+	return buf;
+}
+
 static int test12 (void)
+{
+	qse_char_t buf[24];
+	qse_size_t i, j;
+
+	for (i = 0; i <= QSE_COUNTOF(buf); i++)
+	{
+		qse_strcpy (buf, QSE_T("AAAAAAAAAAAAAAAAAAAAAAA"));
+		qse_strxsubst (buf, i, QSE_T("user=${USER},group=${GROUP}"), subst, QSE_NULL);
+		qse_printf (QSE_T("bufsize=%02d, buf=[%-25s] "), i, buf);
+
+		qse_printf (QSE_T("["));
+		for (j = 0; j < QSE_COUNTOF(buf); j++)
+		{
+			if (buf[j] == QSE_T('\0')) qse_printf (QSE_T("*"));
+			else qse_printf (QSE_T("%c"), buf[j]);
+		}
+		qse_printf (QSE_T("]\n"));
+	}
+	return 0;
+}
+
+static int test13 (void)
 {
 	qse_char_t a1[] = QSE_T("   this is a test string    ");
 	qse_char_t a2[] = QSE_T("   this is a test string    ");
@@ -527,7 +564,7 @@ static int test12 (void)
 	return 0;
 }
 
-static int test13 (void)
+static int test14 (void)
 {
 	qse_char_t a1[] = QSE_T("abcdefghijklmnopqrstuvwxyz");
 	qse_str_t x;
@@ -571,6 +608,7 @@ int main ()
 	R (test11);
 	R (test12);
 	R (test13);
+	R (test14);
 
 	return 0;
 }