UT_JSONWriter.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UT_JSONWriter.h ( UT Library, C++)
 *
 * COMMENTS:
 */

#ifndef __UT_JSONWriter__
#define __UT_JSONWriter__

#include "UT_API.h"
#include "UT_Compression.h"
#include "UT_IntArray.h"
#include "UT_JSONDefines.h"
#include "UT_NonCopyable.h"
#include "UT_Set.h"
#include "UT_StringMap.h"
#include "UT_WorkBuffer.h"
#include <ostream>
#include <streambuf>
#include <string>

class UT_Options;
class UT_BitArray;
class UT_JSONValue;

/// @brief Class which writes ASCII or binary JSON streams
///
/// The JSON format (http://www.json.org) is a generic way to store data.
/// Houdini extends JSON to a byte-stream binary encoding (see UT_JID for
/// details).  The UT_JSONWriter class is used to write JSON (binary or
/// ASCII) to a stream.
/// @see UT_JID, UT_JSONValue, UT_AutoJSONWriter
class UT_API UT_JSONWriter
{
public:
    /// @param options @n
    /// A UT_Options class which sets specific format options.
    /// @see setOptions()
             UT_JSONWriter(const UT_Options *options=0);
    virtual ~UT_JSONWriter();

    UT_JSONWriter(const UT_JSONWriter &) = delete;
    UT_JSONWriter &operator=(const UT_JSONWriter &) = delete;

    /// Allocate a JSON Writer which will fill a UT_WorkBuffer.
    /// Please delete when finished with the writer.
    static UT_JSONWriter        *allocWriter(UT_WorkBuffer &buffer);

    /// Allocate a JSON Writer which writes to an output stream.
    /// Please delete when finished with the writer.
    static UT_JSONWriter *allocWriter(
                                std::ostream &os,
                                bool binary,
                                UT_CompressionType compressionType = UT_COMPRESSION_TYPE_NONE);

    /// Allocate a JSON Writer which writes to a named file.
    /// Please delete when finished with the writer.
    static UT_JSONWriter *allocWriter(
                                const char *filename,
                                bool binary,
                                UT_CompressionType compressionType = UT_COMPRESSION_TYPE_NONE);

    /// Allocate a JSON Writer which writes into a given UT_JSONValue.  The
    /// value will only be set properly at the conclusion of writing.
    /// Please delete when finished with the writer.
    static UT_JSONWriter        *allocWriter(UT_JSONValue &value);

    /// Set formatting/control options base on the UT_Options.  The following
    /// options are scanned:
    /// - @b int @b "json:precision" -- ASCII float precision [9].
    ///   Note half-precision floats will use half this precision, while double
    ///   precision will use twice the digits.
    /// - @b int @b "json:indentstep" -- ASCII indent step for maps/arrays [8]
    /// - @b int @b "json:textwidth" -- ASCII wrap lines after byte count [256]
    /// - @b bool @b "json:comments" -- Allow comments in ASCII stream [false]
    /// - @b bool @b "json:prettyprint" -- Pretty print ASCII stream [true]
    /// - @b bool @b "json:usetokens" -- Binary string token compression [true]
    /// - @b bool @b "json:prettycompact" -- Add a space after separators, a
    ///   more compact pretty print matching Python [false]
    void        setOptions(const UT_Options &options);

    /// Get the current options.  This will set the token/values in
    /// the UT_Options based on options from setOptions()
    void        getOptions(UT_Options &options) const;

    /// Direct access to options.
    void        setPrecision(int precision) { myPrecision = SYSmax(1, precision); }
    int         getPrecision() const { return myPrecision; }
    void        setIndentStep(int indentstep) { myIndentStep = indentstep; }
    int         getIndentStep() const { return myIndentStep; }
    void        setUseTokens(bool usetokens) { myTokenStrings = usetokens; }
    bool        getUseTokens() const { return myTokenStrings; }
    void        setTextWidth(int width) { myTextWidth = width; }
    int         getTextWidth() const { return myTextWidth; }
    void        setComments(bool comment) { myComments = comment; }
    bool        getComments() const { return myComments; }
    void        setPrettyPrint(bool prettyprint) { myPrettyPrint = prettyprint; }
    bool        getPrettyPrint() const { return myPrettyPrint; }
    void        setPrettyCompact(bool compact) { myPrettyCompact = compact; }
    bool        getPrettyCompact() const { return myPrettyCompact; }

    /// Turn the JSON writer into a binary JSON (bJSON) writer.
    /// @warning This method must be called before any other data is written to
    /// the JSON file.  It's a @b good idea to call in the sub-class
    /// constructor.
    bool        setBinary(bool bin);

    /// Return whether writing binary or ASCII JSON
    bool        getBinary() const       { return myBinary; }

    /// Get the number of bytes written to output so far.
    int64       getNumBytesWritten() const { return myCurrentFilePosition; }

    /// Start a new embedded file
    void        startNewFile();

    /// End a started embedded file
    void        endNewFile();

    /// Output a comment in the JSON stream.  Not all JSON parsers (actually
    /// very few) support comments.  The json:comments must be enabled for this
    /// statement to have any effect.
    bool        jsonComment(const char *format, ...)
                    SYS_PRINTF_CHECK_ATTRIBUTE(2, 3);

    // Standard JSON types
    /// Write a @b null to the stream
    bool        jsonNull();
    /// Write true/false
    bool        jsonBool(bool value);
    /// Write an integer value
    bool        jsonInt(int32 value);
    /// Write a 64 bit integer value
    bool        jsonInt(int64 value);
    /// Write a 64 bit integer as a 64 bit integer
    bool        jsonInt64(int64 value);
    /// Write a 16 bit real
    bool        jsonReal(fpreal16 value);
    bool        jsonRealPreserveType(fpreal16 value);
    /// Write a 32 bit real
    bool        jsonReal(fpreal32 value);
    bool        jsonRealPreserveType(fpreal32 value);
    /// Write a 64 bit real
    bool        jsonReal(fpreal64 value);
    bool        jsonRealPreserveType(fpreal64 value);
    /// Write a quoted string.
    /// @warning Please use jsonKey() to write key strings.
    /// @note Use jsonStringToken() to take advantage of token compression
    /// (this can be turned off with the @c usetokens option in the
    /// constructor).
    /// @see UT_JID
    bool        jsonString(const char *value, int64 length=0);

    /// For binary streams, common strings can be output more efficiently using
    /// the token interface.  Token strings will appear as strings in ASCII
    /// streams.
    bool        jsonStringToken(const UT_StringRef &value);
    bool        jsonStringToken(const char *value, int64 length)
    {
        UT_StringRef            result;
        if (length <= 0)
            result.reference(value);
        else
            result.fastReferenceWithStrlen(value, length);
        return jsonStringToken(result);
    }

    /// @{
    /// Write a standard JSON value to the stream.  Overloaded method to allow
    /// convenient use in templated code.
    bool        jsonValue(bool value) { return jsonBool(value); }
    bool        jsonValue(int8 value) { return jsonInt((int32)value); }
    bool        jsonValue(int16 value) { return jsonInt((int32)value); }
    bool        jsonValue(int32 value) { return jsonInt(value); }
    bool        jsonValue(unsigned value) { return jsonInt((int32)value); }
    bool        jsonValue(int64 value) { return jsonInt(value); }
    bool        jsonValue(fpreal16 value) { return jsonReal(value); }
    bool        jsonValue(fpreal32 value) { return jsonReal(value); }
    bool        jsonValue(fpreal64 value) { return jsonReal(value); }
    bool        jsonValue(const char *v) { return jsonStringToken(v); }
    bool        jsonValue(const UT_String &v)
                    { return jsonStringToken(v.c_str(), v.length()); }
    bool        jsonValue(const std::string &v)
                    { return jsonStringToken(v.c_str(), v.length()); }
    bool        jsonValue(const UT_StringRef &v) { return jsonStringToken(v); }
    bool        jsonValue(const UT_Int16Array &v)
                    { return jsonUniformArray(v); }
    bool        jsonValue(const UT_Int32Array &v)
                    { return jsonUniformArray(v); }
    bool        jsonValue(const UT_Int64Array &v)
                    { return jsonUniformArray(v); }
    bool        jsonValue(const UT_Fpreal32Array &v)
                    { return jsonUniformArray(v); }
    bool        jsonValue(const UT_Fpreal64Array &v)
                    { return jsonUniformArray(v); }
    bool        jsonValue(const UT_StringArray &v)
                    { return jsonStringTokenArray(v); }
    bool        jsonValue(const UT_JSONValue &v);
    template <typename T>
    bool        jsonValue(const UT_Set<T>& v)
    {
                    return jsonSetAsArray(v);
    }
    /// @}

    /// Begin a map/object dictionary
    bool        jsonBeginMap();
    /// Write a quoted key for the object
    /// @note Use jsonKeyToken() to take advantage of token compression
    /// (this can be turned off with the @c usetokens option in the
    /// constructor).
    /// @see UT_JID
    bool        jsonKey(const char *value, int64 length=0);
    /// For binary streams, common key strings can be output more efficiently
    /// using the token interface.  Token key strings will appear as strings in
    /// ASCII streams.
    bool        jsonKeyToken(const UT_StringRef &value);
    bool        jsonKeyToken(const char *value, int64 length)
    {
        UT_StringRef            result;
        if (length <= 0)
            result.reference(value);
        else
            result.fastReferenceWithStrlen(value, length);
        return jsonKeyToken(result);
    }

    /// @{
    /// Convenience method to write the key/value pair to a map
    template <typename T> SYS_FORCE_INLINE bool
    jsonKeyValue(const UT_StringRef &key, const T &value)
    {
        bool    ok = jsonKeyToken(key);
        return ok && jsonValue(value);
    }

    template <typename T> SYS_FORCE_INLINE bool
    jsonKeyTokenValue(const UT_StringRef &key, const T &value)
    {
        bool    ok = jsonKeyToken(key);
        return ok && jsonValue(value);
    }
    /// @}

    /// End the object
    bool        jsonEndMap();

    /// Begin a generic array object
    bool        jsonBeginArray();
    /// End a generic array object
    /// By default, a new line will be output for pretty printing.  The newline
    /// can give a hint to omit the new line before the end of the array
    /// marker.
    bool        jsonEndArray(bool newline=true);

    /// When writing binary JSON files, uniform arrays can be encoded without
    /// repetition of the type information which results in a more compressed
    /// data format.
    ///
    /// @c beingUniformArray() starts a uniform array.
    /// The @c id should be one of:
    /// - UT_JID_BOOL
    /// - UT_JID_INT8
    /// - UT_JID_INT16
    /// - UT_JID_INT32
    /// - UT_JID_INT64
    /// - UT_JID_UINT8
    /// - UT_JID_UINT16
    /// - UT_JID_REAL16
    /// - UT_JID_REAL32
    /// - UT_JID_REAL64
    /// - UT_JID_STRING
    bool        beginUniformArray(int64 length, UT_JID id);
    /// Write a bool value to a uniform array.  The bool values are packed into
    /// a bit array (where each 32-bit word stores 32 bits).
    bool          uniformWrite(bool value);
    /// Write an 8 bit integer value to the uniform array
    bool          uniformWrite(int8 value);
    /// Write an 16 bit integer value to the uniform array
    bool          uniformWrite(int16 value);
    /// Write an 32 bit integer value to the uniform array
    bool          uniformWrite(int32 value);
    /// Write an 64 bit integer value to the uniform array
    bool          uniformWrite(int64 value);
    /// Write an 16 bit float/real value to the uniform array
    bool          uniformWrite(fpreal16 value);
    /// Write an 32 bit float/real value to the uniform array
    bool          uniformWrite(fpreal32 value);
    /// Write an 64 bit float/real value to the uniform array
    bool          uniformWrite(fpreal64 value);
    /// Write an 8 bit unsigned integer value to the uniform array
    bool          uniformWrite(uint8 value);
    /// Write an 16 bit unsigned integer value to the uniform array
    bool          uniformWrite(uint16 value);
    /// Write a string to the uniform array
    bool          uniformWrite(const char *value, int64 length=0);
    /// Write a block of 8 bit integer values to the uniform array
    bool          uniformBlockWrite(const int8 *value, int64 count);
    /// Write a block of 16 bit integer values to the uniform array
    bool          uniformBlockWrite(const int16 *value, int64 count);
    /// Write a block of 32 bit integer values to the uniform array
    bool          uniformBlockWrite(const int32 *value, int64 count);
    /// Write a block of 64 bit integer values to the uniform array
    bool          uniformBlockWrite(const int64 *value, int64 count);
    /// Write a block of 16 bit float/real values to the uniform array
    bool          uniformBlockWrite(const fpreal16 *value, int64 count);
    /// Write a block of 32 bit float/real values to the uniform array
    bool          uniformBlockWrite(const fpreal32 *value, int64 count);
    /// Write a block of 64 bit float/real values to the uniform array
    bool          uniformBlockWrite(const fpreal64 *value, int64 count);
    /// Write a block of 8 bit unsigned integer values to the uniform array
    bool          uniformBlockWrite(const uint8 *value, int64 count);
    /// Write a block of 16 bit unsigned integer values to the uniform array
    bool          uniformBlockWrite(const uint16 *value, int64 count);
    /// End the uniform array.
    /// @param nwritten @n
    /// If provided, the number of items written is returned.
    /// @note The JSONWriter class will automatically clamp or fill the uniform
    /// array with 0, but nwritten will return the actual number of calls to
    /// uniformWrite().
    bool        endUniformArray(int64 *nwritten=0);

    /// Internally called to write raw data to output.
    virtual bool        writeData(const void *data, int64 bytes);

    /// Returns the JID that matches the given type.
    static UT_JID       jidFromValue(const bool *) { return UT_JID_BOOL; }
    static UT_JID       jidFromValue(const int8 *) { return UT_JID_INT8; }
    static UT_JID       jidFromValue(const int16 *) { return UT_JID_INT16; }
    static UT_JID       jidFromValue(const int32 *) { return UT_JID_INT32; }
    static UT_JID       jidFromValue(const int64 *) { return UT_JID_INT64; }
    static UT_JID       jidFromValue(const fpreal16 *) { return UT_JID_REAL16; }
    static UT_JID       jidFromValue(const fpreal32 *) { return UT_JID_REAL32; }
    static UT_JID       jidFromValue(const fpreal64 *) { return UT_JID_REAL64; }
    static UT_JID       jidFromValue(const uint8 *) { return UT_JID_UINT8; }
    static UT_JID       jidFromValue(const uint16 *) { return UT_JID_UINT16; }

    /// Efficent method of writing a uniform array of int8 values
    bool        jsonUniformArray(int64 length, const int8 *value);
    /// Efficent method of writing a uniform array of int16 values
    bool        jsonUniformArray(int64 length, const int16 *value);
    /// Efficent method of writing a uniform array of int32 values
    bool        jsonUniformArray(int64 length, const int32 *value);
    /// Efficent method of writing a uniform array of int64 values
    bool        jsonUniformArray(int64 length, const int64 *value);
    /// Efficent method of writing a uniform array of fpreal16 values
    bool        jsonUniformArray(int64 length, const fpreal16 *value);
    /// Efficent method of writing a uniform array of fpreal32 values
    bool        jsonUniformArray(int64 length, const fpreal32 *value);
    /// Efficent method of writing a uniform array of fpreal64 values
    bool        jsonUniformArray(int64 length, const fpreal64 *value);

    /// Efficent method of writing a uniform array of uint8 values
    bool        jsonUniformArray(int64 length, const uint8 *value);
    /// Efficent method of writing a uniform array of uint16 values
    bool        jsonUniformArray(int64 length, const uint16 *value);

    /// Efficient method of writing a uniform array of bool values
    bool        jsonUniformArray(int64 length, const UT_BitArray &value,
                                 bool verbose_ascii = false);

    /// @{
    /// Convenience method for saving common array types
    bool        jsonUniformArray(const UT_Int16Array &a)
                    { return jsonUniformArray(a.size(), a.data()); }
    bool        jsonUniformArray(const UT_Int32Array &a)
                    { return jsonUniformArray(a.size(), a.data()); }
    bool        jsonUniformArray(const UT_Int64Array &a)
                    { return jsonUniformArray(a.size(), a.data()); }
    bool        jsonUniformArray(const UT_Fpreal32Array &a)
                    { return jsonUniformArray(a.size(), a.data()); }
    bool        jsonUniformArray(const UT_Fpreal64Array &a)
                    { return jsonUniformArray(a.size(), a.data()); }
    /// @}

    /// Convenience method to save a set as an array of strings
    template <typename T>
    bool        jsonSetAsArray(const UT_Set<T>& a)
    {
        if (!jsonBeginArray())
            return false;

        for (auto&& v : a)
            jsonValue(v);

        return jsonEndArray();
    }

    /// Convenience method to save an array of strings
    bool        jsonStringArray(const UT_StringArray &a);
    /// Convenience method to save an array of strings (as tokens)
    bool        jsonStringTokenArray(const UT_StringArray &a);

    /// A TiledStream allows you to write a blob of binary data to a JSON
    /// stream in an efficient manner.  The data is buffered into uniform
    /// arrays which are output into a standard JSON array.  The resulting data
    /// looks something like: @code
    ///   [ {options} tile1-data tile2-data ]
    /// @endcode
    /// The tile-data is written as JSON string objects.  You can read these
    /// yourself, or use the TiledStream in UT_JSONParser.
    ///
    /// You should never write to the JSONWriter while the TiledStream is open.
    ///
    /// An example of using this might be something like: @code
    /// bool storeStream(UT_IStream &is)
    /// {
    ///  UT_JSONWriter::TiledStream     os(writer);
    ///  char                           buffer[128];
    ///  int                            nread;
    ///  while ((nread = is.bread(buffer, 128)) > 0)
    ///     if (!os.write(buffer, nread)) return false;
    ///  return true;
    /// }
    /// @endcode
    class UT_API TiledStreamBuf : public std::streambuf
    {
    public:
         TiledStreamBuf(UT_JSONWriter &w);
        ~TiledStreamBuf() override;

        TiledStreamBuf(const TiledStreamBuf &) = delete;
        TiledStreamBuf &operator=(const TiledStreamBuf &) = delete;

    protected:
        // write one character
        int_type overflow(int_type c) override;

        // write multiple characters
        std::streamsize xsputn(const char* s, std::streamsize num) override;

    private:
        bool    write(const void *data, exint bytes);
        void    close();

        bool    writeTile(const char *data, exint bytes);
        bool    flush();
        UT_JSONWriter   &myWriter;
        char            *myBuffer;
        exint            myLength;
    };

    class UT_API TiledStream : public std::ostream
    {
    public:
        TiledStream(UT_JSONWriter &w);
        ~TiledStream() override;

        UT_NON_COPYABLE(TiledStream)

    private:
        TiledStreamBuf          myBuf;
    };

protected:
    /// The sub-class must implement this method to write data
    virtual bool        subclassWriteData(const void* data, int64 bytes) = 0;

protected:
    /// Get the nesting level (i.e. how deeply nested in maps/arrays)
    int         getNesting() const      { return myStack.entries(); }
private:
    int         precision16() const     { return (myPrecision+1)/2; }
    int         precision32() const     { return myPrecision; }
    int         precision64() const     { return myPrecision*2; }
    /// @private: ASCII indent
    bool        indent();
    /// @private: ASCII prefix
    bool        prefix();
    /// @private: Convenience method to write a UT_JID
    bool        writeId(UT_JID id);
    /// @private: Convenience method to write an encoded length @see UT_JID
    bool        writeLength(int64 length);
    /// @private: Write a token string
    bool        writeTokenString(const UT_StringRef &str);
    /// @private: Write a string of data (not quoted)
    bool        writeString(const char *str, int64 bytes=0);
    /// @private: Write a quoted string
    bool        quotedString(const char *str, int64 bytes=0);
    /// @private: Write an ASCII "bool" value
    bool        writeAB(bool i);
    /// @private: Write an ASCII "integer" value
    bool        writeAI(int64 i);
    /// @private: Write an ASCII "float" value
    bool        writeAF(fpreal64 i, int precision);
    /// @private: Write an ASCII "float" value and ensure it has a decimal point
    bool        writeAFPreserveType(fpreal64, int precision);
    /// @private: Start an array (possibly uniform encoding)
    bool        startArray(UT_JID id, UT_JID type=UT_JID_NULL);
    /// @private: Finish array
    bool        finishArray(UT_JID id, bool newline=true);
    /// @private: Flush bits for a uniform array of bools
    bool        flushBits();
    /// @private: Push nesting of map/array
    void        pushState(UT_JID id);
    /// @private: Pop state
    void        popState(UT_JID id);
    /// @private: Set the prefix for ASCII encoding
    void        setPrefix();
    /// @private: Build indent string
    void        bumpIndent(int dir);
    /// @private: New line & indent
    bool        newLine(bool force=false);

    /// Method to detail with long lines in ASCII files
    bool        countAndWrite(const void *data, int64 bytes);

    template <typename T> bool
        uniformArrayI(UT_JID id, int64 length, const T *data);
    template <typename T> bool
        uniformArrayF(UT_JID id, int64 length, const T *data);
    template <typename T> bool
        uniformBlockWriteImplI(const T *data, int64 count);
    template <typename T> bool
        uniformBlockWriteImplF(const T *data, int64 count, int prec);

    enum
    {
        PREFIX_FIRST,   // First element (no prefix)
        PREFIX_ARRAY,   // Use array prefix
        PREFIX_MAP,     // Use object prefix
    };

    UT_IntArray          myStack;
    UT_WorkBuffer        myIndentString;
    // Note - carefully test performance if you are switching this to a
    // different hash table like UT_ArrayStringMap (see bug 122906)
    UT_StringMap<int64>  myTokens;
    UT_Int64Array        myTokenCountStack;
    int64                myCurrentFilePosition;
    int64                myUWriteSize;  // Uniform write size
    int64                myUWriteCount; // Uniform entities written
    int64                myTokenCount;
    UT_JID               myUniform;     // Type of data for fixed array
    uint32               myBitValue;    // For packing bit arrays
    int                  myBitCount;
    int                  myPrefix;

    bool                 myBinary;      // ASCII or binary

    // Options
    int                  myPrecision;   // ASCII float precision
    int                  myIndentStep;  // ASCII indent step
    int                  myTextWidth;   // ASCII max line length
    bool                 myTokenStrings;        // Use token strings
    bool                 myComments;    // Emit comments
    bool                 myPrettyPrint; // Pretty print
    bool                 myPrettyCompact;      // Python style, spaces after sepators, no newlines.

    // State required for formatting.
    bool                 myNewLine;     // Pending newline, for line wrapping
    bool                 myJoinNext;
    int                  myIndent;      // ASCII indent level
    int                  myLineLength;  // ASCII line length
};

/// Convenience class to allocate a writer which is automatically deleted
/// For example: @code
/// bool save(UT_JSONWriter &w) { ... }   // Method to save to standard writer
///
/// bool save(UT_WorkBuffer &buffer)    // Save to a UT_WorkBuffer
/// {
///      UT_AutoJSONWriter  w(buffer);
///      return save(w);
/// }
/// bool save(UT_JSONValue &value)      // Save to a UT_JSONValue
/// {
///      UT_AutoJSONWriter  w(value);
///      return save(w);
/// }
/// @endcode
class UT_API UT_AutoJSONWriter
{
public:
    /// Write directly to the UT_WorkBuffer
    UT_AutoJSONWriter(UT_WorkBuffer &b)
        : myWriter(UT_JSONWriter::allocWriter(b))
    {
    }
    /// Write to the given ostream (binary and optionally gzipped)
    UT_AutoJSONWriter(std::ostream &os,
            bool binary,
            UT_CompressionType compressionType = UT_COMPRESSION_TYPE_NONE )
        : myWriter(UT_JSONWriter::allocWriter(os, binary, compressionType))
    {
    }
    /// Write to the given filename (binary and optionally gzipped)
    UT_AutoJSONWriter(const char *filename,
            bool binary,
            UT_CompressionType compressionType = UT_COMPRESSION_TYPE_NONE)
        : myWriter(UT_JSONWriter::allocWriter(filename, binary, compressionType))
    {
    }
    /// Write directly to the UT_JSONValue
    UT_AutoJSONWriter(UT_JSONValue &value)
        : myWriter(UT_JSONWriter::allocWriter(value))
    {
    }
    ~UT_AutoJSONWriter()
    {
        delete myWriter;
    }

    UT_AutoJSONWriter(const UT_AutoJSONWriter &) = delete;
    UT_AutoJSONWriter &operator=(const UT_AutoJSONWriter &) = delete;

    /// @{
    /// Access to the writer
    UT_JSONWriter       &writer() const         { return *myWriter; }
    UT_JSONWriter       &operator*() const      { return *myWriter; }
    UT_JSONWriter       *operator->() const     { return myWriter; }
    /// @}

    /// Allow implicit casting between an auto-writer and the underlying writer
    operator            UT_JSONWriter &()       { return *myWriter; }

    /// Close the stream (causing all data to be flushed)
    void                close()
                        {
                            delete myWriter;
                            myWriter = NULL;
                        }
private:
    UT_JSONWriter       *myWriter;
};

#endif