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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIUnicodeDecoder_h___
+#define nsIUnicodeDecoder_h___
+
+#include "nscore.h"
+#include "nsISupports.h"
+
+// Interface ID for our Unicode Decoder interface
+// {25359602-FC70-4d13-A9AB-8086D3827C0D}
+//NS_DECLARE_ID(kIUnicodeDecoderIID,
+// 0x25359602, 0xfc70, 0x4d13, 0xa9, 0xab, 0x80, 0x86, 0xd3, 0x82, 0x7c, 0xd);
+
+#define NS_IUNICODEDECODER_IID \
+ { 0x25359602, 0xfc70, 0x4d13, \
+ { 0xa9, 0xab, 0x80, 0x86, 0xd3, 0x82, 0x7c, 0xd }}
+
+
+#define NS_UNICODEDECODER_CONTRACTID_BASE "@mozilla.org/intl/unicode/decoder;1?charset="
+
+/**
+ * Interface for a Converter from a Charset into Unicode.
+ *
+ * @created 23/Nov/1998
+ * @author Catalin Rotaru [CATA]
+ */
+class nsIUnicodeDecoder : public nsISupports
+{
+public:
+ NS_DECLARE_STATIC_IID_ACCESSOR(NS_IUNICODEDECODER_IID)
+
+ enum {
+ kOnError_Recover, // on an error, recover and continue
+ kOnError_Signal // on an error, stop and signal
+ };
+
+ /**
+ * Converts the data from one Charset to Unicode.
+ *
+ * About the byte ordering:
+ * - For input, if the converter cares (that depends of the charset, for
+ * example a singlebyte will ignore the byte ordering) it should assume
+ * network order. If necessary and requested, we can add a method
+ * SetInputByteOrder() so that the reverse order can be used, too. That
+ * method would have as default the assumed network order.
+ * - The output stream is Unicode, having the byte order which is internal
+ * for the machine on which the converter is running on.
+ *
+ * Unless there is not enough output space, this method must consume all the
+ * available input data! The eventual incomplete final character data will be
+ * stored internally in the converter and used when the method is called
+ * again for continuing the conversion. This way, the caller will not have to
+ * worry about managing incomplete input data by mergeing it with the next
+ * buffer.
+ *
+ * Error conditions:
+ * If the read value does not belong to this character set, one should
+ * replace it with the Unicode special 0xFFFD. When an actual input error is
+ * encountered, like a format error, the converter stop and return error.
+ * However, we should keep in mind that we need to be lax in decoding. When
+ * a decoding error is returned to the caller, it is the caller's
+ * responsibility to advance over the bad byte (unless aSrcLength is -1 in
+ * which case the caller should call the decoder with 0 offset again) and
+ * reset the decoder before trying to call the decoder again.
+ *
+ * Converter required behavior:
+ * In this order: when output space is full - return right away. When input
+ * data is wrong, return input pointer right after the wrong byte. When
+ * partial input, it will be consumed and cached. All the time input pointer
+ * will show how much was actually consumed and how much was actually
+ * written.
+ *
+ * @param aSrc [IN] the source data buffer
+ * @param aSrcLength [IN/OUT] the length of source data buffer; after
+ * conversion will contain the number of bytes read or
+ * -1 on error to indicate that the caller should re-push
+ * the same buffer after resetting the decoder
+ * @param aDest [OUT] the destination data buffer
+ * @param aDestLength [IN/OUT] the length of the destination data buffer;
+ * after conversion will contain the number of Unicode
+ * characters written
+ * @return NS_ERROR_UDEC_ILLEGALINPUT if an illegal input sequence
+ * was encountered and the behavior was set to "signal";
+ * the caller must skip over one byte, reset the decoder
+ * and retry.
+ * NS_OK_UDEC_MOREOUTPUT if only a partial conversion
+ * was done; more output space is needed to continue
+ * NS_OK_UDEC_MOREINPUT if the input ended in the middle
+ * of an input code unit sequence. If this is the last
+ * result the caller has at the end of the stream, the
+ * caller must append one U+FFFD to the output.
+ * NS_OK if the input ended after a complete input code
+ * unit sequence.
+ */
+ NS_IMETHOD Convert(const char * aSrc, int32_t * aSrcLength,
+ char16_t * aDest, int32_t * aDestLength) = 0;
+
+ /**
+ * Returns a quick estimation of the size of the buffer needed to hold the
+ * converted data. Remember: this estimation is >= with the actual size of
+ * the buffer needed. It will be computed for the "worst case"
+ *
+ * @param aSrc [IN] the source data buffer
+ * @param aSrcLength [IN] the length of source data buffer
+ * @param aDestLength [OUT] the needed size of the destination buffer
+ * @return NS_EXACT_LENGTH if an exact length was computed
+ * NS_ERROR_OUT_OF_MEMORY if OOM
+ * NS_OK is all we have is an approximation
+ */
+ MOZ_MUST_USE NS_IMETHOD GetMaxLength(const char* aSrc,
+ int32_t aSrcLength,
+ int32_t* aDestLength) = 0;
+
+ /**
+ * Resets the charset converter so it may be recycled for a completely
+ * different and urelated buffer of data.
+ */
+ NS_IMETHOD Reset() = 0;
+
+ /**
+ * Specify what to do when a character cannot be mapped into unicode
+ *
+ * @param aBehavior [IN] the desired behavior
+ * @see kOnError_Recover
+ * @see kOnError_Signal
+ */
+ virtual void SetInputErrorBehavior(int32_t aBehavior) = 0;
+
+ /**
+ * return the UNICODE character for unmapped character
+ */
+ virtual char16_t GetCharacterForUnMapped() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIUnicodeDecoder, NS_IUNICODEDECODER_IID)
+
+#endif /* nsIUnicodeDecoder_h___ */