Check in the pristine copy of ICU 4.6...

icu46/source/i18n/regextxt.cpp

+/********************************************************************
+ * COPYRIGHT:
+ * Copyright (c) 2008-2010, International Business Machines Corporation and
+ * others. All Rights Reserved.
+ ********************************************************************/
+//
+//  file:  regextxt.cpp
+//
+//  This file contains utility code for supporting UText in the regular expression engine.
+//
+
+#include "regextxt.h"
+
+U_NAMESPACE_BEGIN
+
+U_CFUNC UChar U_CALLCONV
+uregex_utext_unescape_charAt(int32_t offset, void *ct) {
+    struct URegexUTextUnescapeCharContext *context = (struct URegexUTextUnescapeCharContext *)ct;
+    UChar32 c;
+    if (offset == context->lastOffset + 1) {
+        c = UTEXT_NEXT32(context->text);
+        context->lastOffset++;
+    } else if (offset == context->lastOffset) {
+        c = UTEXT_PREVIOUS32(context->text);
+        UTEXT_NEXT32(context->text);
+    } else {
+        utext_moveIndex32(context->text, offset - context->lastOffset - 1);
+        c = UTEXT_NEXT32(context->text);
+        context->lastOffset = offset;
+    }
+    
+    // !!!: Doesn't handle characters outside BMP
+    if (U_IS_BMP(c)) {
+        return (UChar)c;
+    } else {
+        return 0;
+    }
+}
+
+U_CFUNC UChar U_CALLCONV
+uregex_ucstr_unescape_charAt(int32_t offset, void *context) {
+    return ((UChar *)context)[offset];
+}
+
+U_NAMESPACE_END