xahaud/modules/beast_core/containers/Variant.cpp

//------------------------------------------------------------------------------
/*
    This file is part of Beast: https://github.com/vinniefalco/Beast
    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>

    Portions of this file are from JUCE.
    Copyright (c) 2013 - Raw Material Software Ltd.
    Please visit http://www.juce.com

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

enum VariantStreamMarkers
{
    varMarker_Int       = 1,
    varMarker_BoolTrue  = 2,
    varMarker_BoolFalse = 3,
    varMarker_Double    = 4,
    varMarker_String    = 5,
    varMarker_Int64     = 6,
    varMarker_Array     = 7,
    varMarker_Binary    = 8
};

//==============================================================================
class var::VariantType
{
public:
    VariantType() noexcept {}
    virtual ~VariantType() noexcept {}

    virtual int toInt (const ValueUnion&) const noexcept                        { return 0; }
    virtual int64 toInt64 (const ValueUnion&) const noexcept                    { return 0; }
    virtual double toDouble (const ValueUnion&) const noexcept                  { return 0; }
    virtual String toString (const ValueUnion&) const                           { return String::empty; }
    virtual bool toBool (const ValueUnion&) const noexcept                      { return false; }
    virtual SharedObject* toObject (const ValueUnion&) const noexcept { return nullptr; }
    virtual Array<var>* toArray (const ValueUnion&) const noexcept              { return nullptr; }
    virtual MemoryBlock* toBinary (const ValueUnion&) const noexcept            { return nullptr; }

    virtual bool isVoid() const noexcept      { return false; }
    virtual bool isInt() const noexcept       { return false; }
    virtual bool isInt64() const noexcept     { return false; }
    virtual bool isBool() const noexcept      { return false; }
    virtual bool isDouble() const noexcept    { return false; }
    virtual bool isString() const noexcept    { return false; }
    virtual bool isObject() const noexcept    { return false; }
    virtual bool isArray() const noexcept     { return false; }
    virtual bool isBinary() const noexcept    { return false; }
    virtual bool isMethod() const noexcept    { return false; }

    virtual void cleanUp (ValueUnion&) const noexcept {}
    virtual void createCopy (ValueUnion& dest, const ValueUnion& source) const      { dest = source; }
    virtual bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept = 0;
    virtual void writeToStream (const ValueUnion& data, OutputStream& output) const = 0;
};

//==============================================================================
class var::VariantType_Void  : public var::VariantType
{
public:
    VariantType_Void() noexcept {}
    static const VariantType_Void instance;

    bool isVoid() const noexcept    { return true; }
    bool equals (const ValueUnion&, const ValueUnion&, const VariantType& otherType) const noexcept { return otherType.isVoid(); }
    void writeToStream (const ValueUnion&, OutputStream& output) const   { output.writeCompressedInt (0); }
};

//==============================================================================
class var::VariantType_Int  : public var::VariantType
{
public:
    VariantType_Int() noexcept {}
    static const VariantType_Int instance;

    int toInt (const ValueUnion& data) const noexcept       { return data.intValue; };
    int64 toInt64 (const ValueUnion& data) const noexcept   { return (int64) data.intValue; };
    double toDouble (const ValueUnion& data) const noexcept { return (double) data.intValue; }
    String toString (const ValueUnion& data) const          { return String (data.intValue); }
    bool toBool (const ValueUnion& data) const noexcept     { return data.intValue != 0; }
    bool isInt() const noexcept                             { return true; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        return otherType.toInt (otherData) == data.intValue;
    }

    void writeToStream (const ValueUnion& data, OutputStream& output) const
    {
        output.writeCompressedInt (5);
        output.writeByte (varMarker_Int);
        output.writeInt (data.intValue);
    }
};

//==============================================================================
class var::VariantType_Int64  : public var::VariantType
{
public:
    VariantType_Int64() noexcept {}
    static const VariantType_Int64 instance;

    int toInt (const ValueUnion& data) const noexcept       { return (int) data.int64Value; };
    int64 toInt64 (const ValueUnion& data) const noexcept   { return data.int64Value; };
    double toDouble (const ValueUnion& data) const noexcept { return (double) data.int64Value; }
    String toString (const ValueUnion& data) const          { return String (data.int64Value); }
    bool toBool (const ValueUnion& data) const noexcept     { return data.int64Value != 0; }
    bool isInt64() const noexcept                           { return true; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        return otherType.toInt64 (otherData) == data.int64Value;
    }

    void writeToStream (const ValueUnion& data, OutputStream& output) const
    {
        output.writeCompressedInt (9);
        output.writeByte (varMarker_Int64);
        output.writeInt64 (data.int64Value);
    }
};

//==============================================================================
class var::VariantType_Double   : public var::VariantType
{
public:
    VariantType_Double() noexcept {}
    static const VariantType_Double instance;

    int toInt (const ValueUnion& data) const noexcept       { return (int) data.doubleValue; };
    int64 toInt64 (const ValueUnion& data) const noexcept   { return (int64) data.doubleValue; };
    double toDouble (const ValueUnion& data) const noexcept { return data.doubleValue; }
    String toString (const ValueUnion& data) const          { return String (data.doubleValue); }
    bool toBool (const ValueUnion& data) const noexcept     { return data.doubleValue != 0; }
    bool isDouble() const noexcept                          { return true; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        return std::abs (otherType.toDouble (otherData) - data.doubleValue) < std::numeric_limits<double>::epsilon();
    }

    void writeToStream (const ValueUnion& data, OutputStream& output) const
    {
        output.writeCompressedInt (9);
        output.writeByte (varMarker_Double);
        output.writeDouble (data.doubleValue);
    }
};

//==============================================================================
class var::VariantType_Bool   : public var::VariantType
{
public:
    VariantType_Bool() noexcept {}
    static const VariantType_Bool instance;

    int toInt (const ValueUnion& data) const noexcept       { return data.boolValue ? 1 : 0; };
    int64 toInt64 (const ValueUnion& data) const noexcept   { return data.boolValue ? 1 : 0; };
    double toDouble (const ValueUnion& data) const noexcept { return data.boolValue ? 1.0 : 0.0; }
    String toString (const ValueUnion& data) const          { return String::charToString (data.boolValue ? (beast_wchar) '1' : (beast_wchar) '0'); }
    bool toBool (const ValueUnion& data) const noexcept     { return data.boolValue; }
    bool isBool() const noexcept                            { return true; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        return otherType.toBool (otherData) == data.boolValue;
    }

    void writeToStream (const ValueUnion& data, OutputStream& output) const
    {
        output.writeCompressedInt (1);
        output.writeByte (data.boolValue ? (char) varMarker_BoolTrue : (char) varMarker_BoolFalse);
    }
};

//==============================================================================
class var::VariantType_String   : public var::VariantType
{
public:
    VariantType_String() noexcept {}
    static const VariantType_String instance;

    void cleanUp (ValueUnion& data) const noexcept                       { getString (data)-> ~String(); }
    void createCopy (ValueUnion& dest, const ValueUnion& source) const   { new (dest.stringValue) String (*getString (source)); }

    bool isString() const noexcept                          { return true; }
    int toInt (const ValueUnion& data) const noexcept       { return getString (data)->getIntValue(); };
    int64 toInt64 (const ValueUnion& data) const noexcept   { return getString (data)->getLargeIntValue(); };
    double toDouble (const ValueUnion& data) const noexcept { return getString (data)->getDoubleValue(); }
    String toString (const ValueUnion& data) const          { return *getString (data); }
    bool toBool (const ValueUnion& data) const noexcept     { return getString (data)->getIntValue() != 0
                                                                      || getString (data)->trim().equalsIgnoreCase ("true")
                                                                      || getString (data)->trim().equalsIgnoreCase ("yes"); }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        return otherType.toString (otherData) == *getString (data);
    }

    void writeToStream (const ValueUnion& data, OutputStream& output) const
    {
        const String* const s = getString (data);
        const size_t len = s->getNumBytesAsUTF8() + 1;
        HeapBlock<char> temp (len);
        s->copyToUTF8 (temp, len);
        output.writeCompressedInt ((int) (len + 1));
        output.writeByte (varMarker_String);
        output.write (temp, len);
    }

private:
    static inline const String* getString (const ValueUnion& data) noexcept { return reinterpret_cast <const String*> (data.stringValue); }
    static inline String* getString (ValueUnion& data) noexcept             { return reinterpret_cast <String*> (data.stringValue); }
};

//==============================================================================
class var::VariantType_Object   : public var::VariantType
{
public:
    VariantType_Object() noexcept {}
    static const VariantType_Object instance;

    void cleanUp (ValueUnion& data) const noexcept                      { if (data.objectValue != nullptr) data.objectValue->decReferenceCount(); }

    void createCopy (ValueUnion& dest, const ValueUnion& source) const
    {
        dest.objectValue = source.objectValue;
        if (dest.objectValue != nullptr)
            dest.objectValue->incReferenceCount();
    }

    String toString (const ValueUnion& data) const                            { return "Object 0x" + String::toHexString ((int) (pointer_sized_int) data.objectValue); }
    bool toBool (const ValueUnion& data) const noexcept                       { return data.objectValue != 0; }
    SharedObject* toObject (const ValueUnion& data) const noexcept  { return data.objectValue; }
    bool isObject() const noexcept                                            { return true; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        return otherType.toObject (otherData) == data.objectValue;
    }

    void writeToStream (const ValueUnion&, OutputStream& output) const
    {
        bassertfalse; // Can't write an object to a stream!
        output.writeCompressedInt (0);
    }
};

//==============================================================================
class var::VariantType_Array   : public var::VariantType
{
public:
    VariantType_Array() noexcept {}
    static const VariantType_Array instance;

    void cleanUp (ValueUnion& data) const noexcept                      { delete data.arrayValue; }
    void createCopy (ValueUnion& dest, const ValueUnion& source) const  { dest.arrayValue = new Array<var> (*(source.arrayValue)); }

    String toString (const ValueUnion&) const                           { return "[Array]"; }
    bool isArray() const noexcept                                       { return true; }
    Array<var>* toArray (const ValueUnion& data) const noexcept         { return data.arrayValue; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        const Array<var>* const otherArray = otherType.toArray (otherData);
        return otherArray != nullptr && *otherArray == *(data.arrayValue);
    }

    void writeToStream (const ValueUnion& data, OutputStream& output) const
    {
        MemoryOutputStream buffer (512);
        const int numItems = data.arrayValue->size();
        buffer.writeCompressedInt (numItems);

        for (int i = 0; i < numItems; ++i)
            data.arrayValue->getReference(i).writeToStream (buffer);

        output.writeCompressedInt (1 + (int) buffer.getDataSize());
        output.writeByte (varMarker_Array);
        output << buffer;
    }
};

//==============================================================================
class var::VariantType_Binary   : public var::VariantType
{
public:
    VariantType_Binary() noexcept {}

    static const VariantType_Binary instance;

    void cleanUp (ValueUnion& data) const noexcept                      { delete data.binaryValue; }
    void createCopy (ValueUnion& dest, const ValueUnion& source) const  { dest.binaryValue = new MemoryBlock (*source.binaryValue); }

    String toString (const ValueUnion& data) const                      { return data.binaryValue->toBase64Encoding(); }
    bool isBinary() const noexcept                                      { return true; }
    MemoryBlock* toBinary (const ValueUnion& data) const noexcept       { return data.binaryValue; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        const MemoryBlock* const otherBlock = otherType.toBinary (otherData);
        return otherBlock != nullptr && *otherBlock == *data.binaryValue;
    }

    void writeToStream (const ValueUnion& data, OutputStream& output) const
    {
        output.writeCompressedInt (1 + (int) data.binaryValue->getSize());
        output.writeByte (varMarker_Binary);
        output << *data.binaryValue;
    }
};

//==============================================================================
class var::VariantType_Method   : public var::VariantType
{
public:
    VariantType_Method() noexcept {}
    static const VariantType_Method instance;

    String toString (const ValueUnion&) const               { return "Method"; }
    bool toBool (const ValueUnion& data) const noexcept     { return data.methodValue != nullptr; }
    bool isMethod() const noexcept                          { return true; }

    bool equals (const ValueUnion& data, const ValueUnion& otherData, const VariantType& otherType) const noexcept
    {
        return otherType.isMethod() && otherData.methodValue == data.methodValue;
    }

    void writeToStream (const ValueUnion&, OutputStream& output) const
    {
        bassertfalse; // Can't write a method to a stream!
        output.writeCompressedInt (0);
    }
};

//==============================================================================
const var::VariantType_Void    var::VariantType_Void::instance;
const var::VariantType_Int     var::VariantType_Int::instance;
const var::VariantType_Int64   var::VariantType_Int64::instance;
const var::VariantType_Bool    var::VariantType_Bool::instance;
const var::VariantType_Double  var::VariantType_Double::instance;
const var::VariantType_String  var::VariantType_String::instance;
const var::VariantType_Object  var::VariantType_Object::instance;
const var::VariantType_Array   var::VariantType_Array::instance;
const var::VariantType_Binary  var::VariantType_Binary::instance;
const var::VariantType_Method  var::VariantType_Method::instance;


//==============================================================================
var::var() noexcept : type (&VariantType_Void::instance)
{
}

var::~var() noexcept
{
    type->cleanUp (value);
}

const var var::null;

//==============================================================================
var::var (const var& valueToCopy)  : type (valueToCopy.type)
{
    type->createCopy (value, valueToCopy.value);
}

var::var (const int v) noexcept       : type (&VariantType_Int::instance)    { value.intValue = v; }
var::var (const int64 v) noexcept     : type (&VariantType_Int64::instance)  { value.int64Value = v; }
var::var (const bool v) noexcept      : type (&VariantType_Bool::instance)   { value.boolValue = v; }
var::var (const double v) noexcept    : type (&VariantType_Double::instance) { value.doubleValue = v; }
var::var (MethodFunction m) noexcept  : type (&VariantType_Method::instance) { value.methodValue = m; }
var::var (const Array<var>& v)        : type (&VariantType_Array::instance)  { value.arrayValue = new Array<var> (v); }
var::var (const String& v)            : type (&VariantType_String::instance) { new (value.stringValue) String (v); }
var::var (const char* const v)        : type (&VariantType_String::instance) { new (value.stringValue) String (v); }
var::var (const wchar_t* const v)     : type (&VariantType_String::instance) { new (value.stringValue) String (v); }
var::var (const void* v, size_t sz)   : type (&VariantType_Binary::instance) { value.binaryValue = new MemoryBlock (v, sz); }
var::var (const MemoryBlock& v)       : type (&VariantType_Binary::instance) { value.binaryValue = new MemoryBlock (v); }

var::var (SharedObject* const object)  : type (&VariantType_Object::instance)
{
    value.objectValue = object;

    if (object != nullptr)
        object->incReferenceCount();
}


//==============================================================================
bool var::isVoid() const noexcept       { return type->isVoid(); }
bool var::isInt() const noexcept        { return type->isInt(); }
bool var::isInt64() const noexcept      { return type->isInt64(); }
bool var::isBool() const noexcept       { return type->isBool(); }
bool var::isDouble() const noexcept     { return type->isDouble(); }
bool var::isString() const noexcept     { return type->isString(); }
bool var::isObject() const noexcept     { return type->isObject(); }
bool var::isArray() const noexcept      { return type->isArray(); }
bool var::isBinaryData() const noexcept { return type->isBinary(); }
bool var::isMethod() const noexcept     { return type->isMethod(); }

var::operator int() const noexcept                      { return type->toInt (value); }
var::operator int64() const noexcept                    { return type->toInt64 (value); }
var::operator bool() const noexcept                     { return type->toBool (value); }
var::operator float() const noexcept                    { return (float) type->toDouble (value); }
var::operator double() const noexcept                   { return type->toDouble (value); }
String var::toString() const                            { return type->toString (value); }
var::operator String() const                            { return type->toString (value); }
SharedObject* var::getObject() const noexcept { return type->toObject (value); }
Array<var>* var::getArray() const noexcept              { return type->toArray (value); }
MemoryBlock* var::getBinaryData() const noexcept        { return type->toBinary (value); }
DynamicObject* var::getDynamicObject() const noexcept   { return dynamic_cast <DynamicObject*> (getObject()); }

//==============================================================================
void var::swapWith (var& other) noexcept
{
    std::swap (type, other.type);
    std::swap (value, other.value);
}

var& var::operator= (const var& v)               { type->cleanUp (value); type = v.type; type->createCopy (value, v.value); return *this; }
var& var::operator= (const int v)                { type->cleanUp (value); type = &VariantType_Int::instance; value.intValue = v; return *this; }
var& var::operator= (const int64 v)              { type->cleanUp (value); type = &VariantType_Int64::instance; value.int64Value = v; return *this; }
var& var::operator= (const bool v)               { type->cleanUp (value); type = &VariantType_Bool::instance; value.boolValue = v; return *this; }
var& var::operator= (const double v)             { type->cleanUp (value); type = &VariantType_Double::instance; value.doubleValue = v; return *this; }
var& var::operator= (const char* const v)        { type->cleanUp (value); type = &VariantType_String::instance; new (value.stringValue) String (v); return *this; }
var& var::operator= (const wchar_t* const v)     { type->cleanUp (value); type = &VariantType_String::instance; new (value.stringValue) String (v); return *this; }
var& var::operator= (const String& v)            { type->cleanUp (value); type = &VariantType_String::instance; new (value.stringValue) String (v); return *this; }
var& var::operator= (const Array<var>& v)        { var v2 (v); swapWith (v2); return *this; }
var& var::operator= (SharedObject* v)  { var v2 (v); swapWith (v2); return *this; }
var& var::operator= (MethodFunction v)           { var v2 (v); swapWith (v2); return *this; }

#if BEAST_COMPILER_SUPPORTS_MOVE_SEMANTICS
var::var (var&& other) noexcept
    : type (other.type),
      value (other.value)
{
    other.type = &VariantType_Void::instance;
}

var& var::operator= (var&& other) noexcept
{
    swapWith (other);
    return *this;
}

var::var (String&& v)  : type (&VariantType_String::instance)
{
    new (value.stringValue) String (static_cast<String&&> (v));
}

var::var (MemoryBlock&& v)  : type (&VariantType_Binary::instance)
{
    value.binaryValue = new MemoryBlock (static_cast<MemoryBlock&&> (v));
}

var& var::operator= (String&& v)
{
    type->cleanUp (value);
    type = &VariantType_String::instance;
    new (value.stringValue) String (static_cast<String&&> (v));
    return *this;
}
#endif

//==============================================================================
bool var::equals (const var& other) const noexcept
{
    return type->equals (value, other.value, *other.type);
}

bool var::equalsWithSameType (const var& other) const noexcept
{
    return type == other.type && equals (other);
}

bool operator== (const var& v1, const var& v2) noexcept     { return v1.equals (v2); }
bool operator!= (const var& v1, const var& v2) noexcept     { return ! v1.equals (v2); }
bool operator== (const var& v1, const String& v2)           { return v1.toString() == v2; }
bool operator!= (const var& v1, const String& v2)           { return v1.toString() != v2; }
bool operator== (const var& v1, const char* const v2)       { return v1.toString() == v2; }
bool operator!= (const var& v1, const char* const v2)       { return v1.toString() != v2; }


//==============================================================================
var var::operator[] (const Identifier propertyName) const
{
    if (DynamicObject* const o = getDynamicObject())
        return o->getProperty (propertyName);

    return var::null;
}

var var::operator[] (const char* const propertyName) const
{
    return operator[] (Identifier (propertyName));
}

var var::getProperty (const Identifier propertyName, const var& defaultReturnValue) const
{
    if (DynamicObject* const o = getDynamicObject())
        return o->getProperties().getWithDefault (propertyName, defaultReturnValue);

    return defaultReturnValue;
}

var var::invoke (const Identifier method, const var* arguments, int numArguments) const
{
    if (DynamicObject* const o = getDynamicObject())
        return o->invokeMethod (method, arguments, numArguments);

    return var::null;
}

var var::invokeMethod (DynamicObject* const target, const var* const arguments, const int numArguments) const
{
    bassert (target != nullptr);

    if (isMethod())
        return (target->*(value.methodValue)) (arguments, numArguments);

    return var::null;
}

var var::call (const Identifier method) const
{
    return invoke (method, nullptr, 0);
}

var var::call (const Identifier method, const var& arg1) const
{
    return invoke (method, &arg1, 1);
}

var var::call (const Identifier method, const var& arg1, const var& arg2) const
{
    var args[] = { arg1, arg2 };
    return invoke (method, args, 2);
}

var var::call (const Identifier method, const var& arg1, const var& arg2, const var& arg3)
{
    var args[] = { arg1, arg2, arg3 };
    return invoke (method, args, 3);
}

var var::call (const Identifier method, const var& arg1, const var& arg2, const var& arg3, const var& arg4) const
{
    var args[] = { arg1, arg2, arg3, arg4 };
    return invoke (method, args, 4);
}

var var::call (const Identifier method, const var& arg1, const var& arg2, const var& arg3, const var& arg4, const var& arg5) const
{
    var args[] = { arg1, arg2, arg3, arg4, arg5 };
    return invoke (method, args, 5);
}

//==============================================================================
int var::size() const
{
    if (const Array<var>* const array = getArray())
        return array->size();

    return 0;
}

const var& var::operator[] (int arrayIndex) const
{
    const Array<var>* const array = getArray();

    // When using this method, the var must actually be an array, and the index
    // must be in-range!
    bassert (array != nullptr && isPositiveAndBelow (arrayIndex, array->size()));

    return array->getReference (arrayIndex);
}

var& var::operator[] (int arrayIndex)
{
    const Array<var>* const array = getArray();

    // When using this method, the var must actually be an array, and the index
    // must be in-range!
    bassert (array != nullptr && isPositiveAndBelow (arrayIndex, array->size()));

    return array->getReference (arrayIndex);
}

Array<var>* var::convertToArray()
{
    Array<var>* array = getArray();

    if (array == nullptr)
    {
        const Array<var> tempVar;
        var v (tempVar);
        array = v.value.arrayValue;

        if (! isVoid())
            array->add (*this);

        swapWith (v);
    }

    return array;
}

void var::append (const var& n)
{
    convertToArray()->add (n);
}

void var::remove (const int index)
{
    if (Array<var>* const array = getArray())
        array->remove (index);
}

void var::insert (const int index, const var& n)
{
    convertToArray()->insert (index, n);
}

void var::resize (const int numArrayElementsWanted)
{
    convertToArray()->resize (numArrayElementsWanted);
}

int var::indexOf (const var& n) const
{
    if (const Array<var>* const array = getArray())
        return array->indexOf (n);

    return -1;
}

//==============================================================================
void var::writeToStream (OutputStream& output) const
{
    type->writeToStream (value, output);
}

var var::readFromStream (InputStream& input)
{
    const int numBytes = input.readCompressedInt();

    if (numBytes > 0)
    {
        switch (input.readByte())
        {
            case varMarker_Int:         return var (input.readInt());
            case varMarker_Int64:       return var (input.readInt64());
            case varMarker_BoolTrue:    return var (true);
            case varMarker_BoolFalse:   return var (false);
            case varMarker_Double:      return var (input.readDouble());
            case varMarker_String:
            {
                MemoryOutputStream mo;
                mo.writeFromInputStream (input, numBytes - 1);
                return var (mo.toUTF8());
            }

            case varMarker_Binary:
            {
                MemoryBlock mb ((size_t) numBytes - 1);

                if (numBytes > 1)
                {
                    const int numRead = input.read (mb.getData(), numBytes - 1);
                    mb.setSize ((size_t) numRead);
                }

                return var (mb);
            }

            case varMarker_Array:
            {
                var v;
                Array<var>* const destArray = v.convertToArray();

                for (int i = input.readCompressedInt(); --i >= 0;)
                    destArray->add (readFromStream (input));

                return v;
            }

            default:
                input.skipNextBytes (numBytes - 1); break;
        }
    }

    return var::null;
}