JUCE/modules/juce_core/javascript/juce_Javascript.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2016 - ROLI Ltd.

   Permission is granted to use this software under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license/

   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 ISC DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS. IN NO EVENT SHALL ISC 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.

   -----------------------------------------------------------------------------

   To release a closed-source product which uses other parts of JUCE not
   licensed under the ISC terms, commercial licenses are available: visit
   www.juce.com for more information.

  ==============================================================================
*/

#define JUCE_JS_OPERATORS(X) \
    X(semicolon,     ";")        X(dot,          ".")       X(comma,        ",") \
    X(openParen,     "(")        X(closeParen,   ")")       X(openBrace,    "{")    X(closeBrace, "}") \
    X(openBracket,   "[")        X(closeBracket, "]")       X(colon,        ":")    X(question,   "?") \
    X(typeEquals,    "===")      X(equals,       "==")      X(assign,       "=") \
    X(typeNotEquals, "!==")      X(notEquals,    "!=")      X(logicalNot,   "!") \
    X(plusEquals,    "+=")       X(plusplus,     "++")      X(plus,         "+") \
    X(minusEquals,   "-=")       X(minusminus,   "--")      X(minus,        "-") \
    X(timesEquals,   "*=")       X(times,        "*")       X(divideEquals, "/=")   X(divide,     "/") \
    X(moduloEquals,  "%=")       X(modulo,       "%")       X(xorEquals,    "^=")   X(bitwiseXor, "^") \
    X(andEquals,     "&=")       X(logicalAnd,   "&&")      X(bitwiseAnd,   "&") \
    X(orEquals,      "|=")       X(logicalOr,    "||")      X(bitwiseOr,    "|") \
    X(leftShiftEquals,    "<<=") X(lessThanOrEqual,  "<=")  X(leftShift,    "<<")   X(lessThan,   "<") \
    X(rightShiftUnsigned, ">>>") X(rightShiftEquals, ">>=") X(rightShift,   ">>")   X(greaterThanOrEqual, ">=")  X(greaterThan,  ">")

#define JUCE_JS_KEYWORDS(X) \
    X(var,      "var")      X(if_,     "if")     X(else_,  "else")   X(do_,       "do")       X(null_,     "null") \
    X(while_,   "while")    X(for_,    "for")    X(break_, "break")  X(continue_, "continue") X(undefined, "undefined") \
    X(function, "function") X(return_, "return") X(true_,  "true")   X(false_,    "false")    X(new_,      "new") \
    X(typeof_,  "typeof")

namespace TokenTypes
{
    #define JUCE_DECLARE_JS_TOKEN(name, str)  static const char* const name = str;
    JUCE_JS_KEYWORDS  (JUCE_DECLARE_JS_TOKEN)
    JUCE_JS_OPERATORS (JUCE_DECLARE_JS_TOKEN)
    JUCE_DECLARE_JS_TOKEN (eof,        "$eof")
    JUCE_DECLARE_JS_TOKEN (literal,    "$literal")
    JUCE_DECLARE_JS_TOKEN (identifier, "$identifier")
}

#if JUCE_MSVC
 #pragma warning (push)
 #pragma warning (disable: 4702)
#endif

//==============================================================================
struct JavascriptEngine::RootObject   : public DynamicObject
{
    RootObject()
    {
        setMethod ("exec",       exec);
        setMethod ("eval",       eval);
        setMethod ("trace",      trace);
        setMethod ("charToInt",  charToInt);
        setMethod ("parseInt",   IntegerClass::parseInt);
        setMethod ("typeof",     typeof_internal);
        setMethod ("parseFloat", parseFloat);
    }

    Time timeout;

    typedef const var::NativeFunctionArgs& Args;
    typedef const char* TokenType;

    void execute (const String& code)
    {
        ExpressionTreeBuilder tb (code);
        ScopedPointer<BlockStatement> (tb.parseStatementList())->perform (Scope (nullptr, this, this), nullptr);
    }

    var evaluate (const String& code)
    {
        ExpressionTreeBuilder tb (code);
        return ExpPtr (tb.parseExpression())->getResult (Scope (nullptr, this, this));
    }

    //==============================================================================
    static bool areTypeEqual (const var& a, const var& b)
    {
        return a.hasSameTypeAs (b) && isFunction (a) == isFunction (b)
                && (((a.isUndefined() || a.isVoid()) && (b.isUndefined() || b.isVoid())) || a == b);
    }

    static String getTokenName (TokenType t)                  { return t[0] == '$' ? String (t + 1) : ("'" + String (t) + "'"); }
    static bool isFunction (const var& v) noexcept            { return dynamic_cast<FunctionObject*> (v.getObject()) != nullptr; }
    static bool isNumeric (const var& v) noexcept             { return v.isInt() || v.isDouble() || v.isInt64() || v.isBool(); }
    static bool isNumericOrUndefined (const var& v) noexcept  { return isNumeric (v) || v.isUndefined(); }
    static int64 getOctalValue (const String& s)              { BigInteger b; b.parseString (s.initialSectionContainingOnly ("01234567"), 8); return b.toInt64(); }
    static Identifier getPrototypeIdentifier()                { static const Identifier i ("prototype"); return i; }
    static var* getPropertyPointer (DynamicObject* o, const Identifier& i) noexcept   { return o->getProperties().getVarPointer (i); }

    //==============================================================================
    struct CodeLocation
    {
        CodeLocation (const String& code) noexcept        : program (code), location (program.getCharPointer()) {}
        CodeLocation (const CodeLocation& other) noexcept : program (other.program), location (other.location) {}

        void throwError (const String& message) const
        {
            int col = 1, line = 1;

            for (String::CharPointerType i (program.getCharPointer()); i < location && ! i.isEmpty(); ++i)
            {
                ++col;
                if (*i == '\n')  { col = 1; ++line; }
            }

            throw "Line " + String (line) + ", column " + String (col) + " : " + message;
        }

        String program;
        String::CharPointerType location;
    };

    //==============================================================================
    struct Scope
    {
        Scope (const Scope* p, RootObject* r, DynamicObject* s) noexcept : parent (p), root (r), scope (s) {}

        const Scope* parent;
        ReferenceCountedObjectPtr<RootObject> root;
        DynamicObject::Ptr scope;

        var findFunctionCall (const CodeLocation& location, const var& targetObject, const Identifier& functionName) const
        {
            if (auto* o = targetObject.getDynamicObject())
            {
                if (auto* prop = getPropertyPointer (o, functionName))
                    return *prop;

                for (auto* p = o->getProperty (getPrototypeIdentifier()).getDynamicObject(); p != nullptr;
                     p = p->getProperty (getPrototypeIdentifier()).getDynamicObject())
                {
                    if (auto* prop = getPropertyPointer (p, functionName))
                        return *prop;
                }

                // if there's a class with an overridden DynamicObject::hasMethod, this avoids an error
                if (o->hasMethod (functionName))
                    return {};
            }

            if (targetObject.isString())
                if (auto* m = findRootClassProperty (StringClass::getClassName(), functionName))
                    return *m;

            if (targetObject.isArray())
                if (auto* m = findRootClassProperty (ArrayClass::getClassName(), functionName))
                    return *m;

            if (auto* m = findRootClassProperty (ObjectClass::getClassName(), functionName))
                return *m;

            location.throwError ("Unknown function '" + functionName.toString() + "'");
            return {};
        }

        var* findRootClassProperty (const Identifier& className, const Identifier& propName) const
        {
            if (auto* cls = root->getProperty (className).getDynamicObject())
                return getPropertyPointer (cls, propName);

            return nullptr;
        }

        var findSymbolInParentScopes (const Identifier& name) const
        {
            if (auto* v = getPropertyPointer (scope, name))
                return *v;

            return parent != nullptr ? parent->findSymbolInParentScopes (name)
                                     : var::undefined();
        }

        bool findAndInvokeMethod (const Identifier& function, const var::NativeFunctionArgs& args, var& result) const
        {
            auto* target = args.thisObject.getDynamicObject();

            if (target == nullptr || target == scope)
            {
                if (auto* m = getPropertyPointer (scope, function))
                {
                    if (auto fo = dynamic_cast<FunctionObject*> (m->getObject()))
                    {
                        result = fo->invoke (*this, args);
                        return true;
                    }
                }
            }

            const auto& props = scope->getProperties();

            for (int i = 0; i < props.size(); ++i)
                if (auto* o = props.getValueAt (i).getDynamicObject())
                    if (Scope (this, root, o).findAndInvokeMethod (function, args, result))
                        return true;

            return false;
        }

        bool invokeMethod (const var& m, const var::NativeFunctionArgs& args, var& result) const
        {
            if (isFunction (m))
            {
                auto* target = args.thisObject.getDynamicObject();

                if (target == nullptr || target == scope)
                {
                    if (auto fo = dynamic_cast<FunctionObject*> (m.getObject()))
                    {
                        result = fo->invoke (*this, args);
                        return true;
                    }
                }
            }

            return false;
        }

        void checkTimeOut (const CodeLocation& location) const
        {
            if (Time::getCurrentTime() > root->timeout)
                location.throwError (root->timeout == Time() ? "Interrupted" : "Execution timed-out");
        }
    };

    //==============================================================================
    struct Statement
    {
        Statement (const CodeLocation& l) noexcept : location (l) {}
        virtual ~Statement() {}

        enum ResultCode  { ok = 0, returnWasHit, breakWasHit, continueWasHit };
        virtual ResultCode perform (const Scope&, var*) const  { return ok; }

        CodeLocation location;
        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Statement)
    };

    struct Expression  : public Statement
    {
        Expression (const CodeLocation& l) noexcept : Statement (l) {}

        virtual var getResult (const Scope&) const            { return var::undefined(); }
        virtual void assign (const Scope&, const var&) const  { location.throwError ("Cannot assign to this expression!"); }

        ResultCode perform (const Scope& s, var*) const override  { getResult (s); return ok; }
    };

    typedef ScopedPointer<Expression> ExpPtr;

    struct BlockStatement  : public Statement
    {
        BlockStatement (const CodeLocation& l) noexcept : Statement (l) {}

        ResultCode perform (const Scope& s, var* returnedValue) const override
        {
            for (int i = 0; i < statements.size(); ++i)
                if (ResultCode r = statements.getUnchecked(i)->perform (s, returnedValue))
                    return r;

            return ok;
        }

        OwnedArray<Statement> statements;
    };

    struct IfStatement  : public Statement
    {
        IfStatement (const CodeLocation& l) noexcept : Statement (l) {}

        ResultCode perform (const Scope& s, var* returnedValue) const override
        {
            return (condition->getResult(s) ? trueBranch : falseBranch)->perform (s, returnedValue);
        }

        ExpPtr condition;
        ScopedPointer<Statement> trueBranch, falseBranch;
    };

    struct VarStatement  : public Statement
    {
        VarStatement (const CodeLocation& l) noexcept : Statement (l) {}

        ResultCode perform (const Scope& s, var*) const override
        {
            s.scope->setProperty (name, initialiser->getResult (s));
            return ok;
        }

        Identifier name;
        ExpPtr initialiser;
    };

    struct LoopStatement  : public Statement
    {
        LoopStatement (const CodeLocation& l, bool isDo) noexcept : Statement (l), isDoLoop (isDo) {}

        ResultCode perform (const Scope& s, var* returnedValue) const override
        {
            initialiser->perform (s, nullptr);

            while (isDoLoop || condition->getResult (s))
            {
                s.checkTimeOut (location);
                ResultCode r = body->perform (s, returnedValue);

                if (r == returnWasHit)   return r;
                if (r == breakWasHit)    break;

                iterator->perform (s, nullptr);

                if (isDoLoop && r != continueWasHit && ! condition->getResult (s))
                    break;
            }

            return ok;
        }

        ScopedPointer<Statement> initialiser, iterator, body;
        ExpPtr condition;
        bool isDoLoop;
    };

    struct ReturnStatement  : public Statement
    {
        ReturnStatement (const CodeLocation& l, Expression* v) noexcept : Statement (l), returnValue (v) {}

        ResultCode perform (const Scope& s, var* ret) const override
        {
            if (ret != nullptr)  *ret = returnValue->getResult (s);
            return returnWasHit;
        }

        ExpPtr returnValue;
    };

    struct BreakStatement  : public Statement
    {
        BreakStatement (const CodeLocation& l) noexcept : Statement (l) {}
        ResultCode perform (const Scope&, var*) const override  { return breakWasHit; }
    };

    struct ContinueStatement  : public Statement
    {
        ContinueStatement (const CodeLocation& l) noexcept : Statement (l) {}
        ResultCode perform (const Scope&, var*) const override  { return continueWasHit; }
    };

    struct LiteralValue  : public Expression
    {
        LiteralValue (const CodeLocation& l, const var& v) noexcept : Expression (l), value (v) {}
        var getResult (const Scope&) const override   { return value; }
        var value;
    };

    struct UnqualifiedName  : public Expression
    {
        UnqualifiedName (const CodeLocation& l, const Identifier& n) noexcept : Expression (l), name (n) {}

        var getResult (const Scope& s) const override  { return s.findSymbolInParentScopes (name); }

        void assign (const Scope& s, const var& newValue) const override
        {
            if (var* v = getPropertyPointer (s.scope, name))
                *v = newValue;
            else
                s.root->setProperty (name, newValue);
        }

        Identifier name;
    };

    struct DotOperator  : public Expression
    {
        DotOperator (const CodeLocation& l, ExpPtr& p, const Identifier& c) noexcept : Expression (l), parent (p), child (c) {}

        var getResult (const Scope& s) const override
        {
            var p (parent->getResult (s));
            static const Identifier lengthID ("length");

            if (child == lengthID)
            {
                if (Array<var>* array = p.getArray())   return array->size();
                if (p.isString())                       return p.toString().length();
            }

            if (DynamicObject* o = p.getDynamicObject())
                if (const var* v = getPropertyPointer (o, child))
                    return *v;

            return var::undefined();
        }

        void assign (const Scope& s, const var& newValue) const override
        {
            if (DynamicObject* o = parent->getResult (s).getDynamicObject())
                o->setProperty (child, newValue);
            else
                Expression::assign (s, newValue);
        }

        ExpPtr parent;
        Identifier child;
    };

    struct ArraySubscript  : public Expression
    {
        ArraySubscript (const CodeLocation& l) noexcept : Expression (l) {}

        var getResult (const Scope& s) const override
        {
            var arrayVar (object->getResult (s)); // must stay alive for the scope of this method
            var key = index->getResult (s);

            if (const Array<var>* array = arrayVar.getArray())
                if (key.isInt() || key.isInt64() || key.isDouble())
                    return (*array) [static_cast<int> (key)];

            if (DynamicObject* o = arrayVar.getDynamicObject())
                if (key.isString())
                    if (const var* v = getPropertyPointer (o, Identifier (key)))
                        return *v;

            return var::undefined();
        }

        void assign (const Scope& s, const var& newValue) const override
        {
            var arrayVar (object->getResult (s)); // must stay alive for the scope of this method
            var key = index->getResult (s);

            if (Array<var>* array = arrayVar.getArray())
            {
                if (key.isInt() || key.isInt64() || key.isDouble())
                {
                    const int i = key;
                    while (array->size() < i)
                        array->add (var::undefined());

                    array->set (i, newValue);
                    return;
                }
            }

            if (DynamicObject* o = arrayVar.getDynamicObject())
            {
                if (key.isString())
                {
                    o->setProperty (Identifier (key), newValue);
                    return;
                }
            }

            Expression::assign (s, newValue);
        }

        ExpPtr object, index;
    };

    struct BinaryOperatorBase  : public Expression
    {
        BinaryOperatorBase (const CodeLocation& l, ExpPtr& a, ExpPtr& b, TokenType op) noexcept
            : Expression (l), lhs (a), rhs (b), operation (op) {}

        ExpPtr lhs, rhs;
        TokenType operation;
    };

    struct BinaryOperator  : public BinaryOperatorBase
    {
        BinaryOperator (const CodeLocation& l, ExpPtr& a, ExpPtr& b, TokenType op) noexcept
            : BinaryOperatorBase (l, a, b, op) {}

        virtual var getWithUndefinedArg() const                           { return var::undefined(); }
        virtual var getWithDoubles (double, double) const                 { return throwError ("Double"); }
        virtual var getWithInts (int64, int64) const                      { return throwError ("Integer"); }
        virtual var getWithArrayOrObject (const var& a, const var&) const { return throwError (a.isArray() ? "Array" : "Object"); }
        virtual var getWithStrings (const String&, const String&) const   { return throwError ("String"); }

        var getResult (const Scope& s) const override
        {
            var a (lhs->getResult (s)), b (rhs->getResult (s));

            if ((a.isUndefined() || a.isVoid()) && (b.isUndefined() || b.isVoid()))
                return getWithUndefinedArg();

            if (isNumericOrUndefined (a) && isNumericOrUndefined (b))
                return (a.isDouble() || b.isDouble()) ? getWithDoubles (a, b) : getWithInts (a, b);

            if (a.isArray() || a.isObject())
                return getWithArrayOrObject (a, b);

            return getWithStrings (a.toString(), b.toString());
        }

        var throwError (const char* typeName) const
            { location.throwError (getTokenName (operation) + " is not allowed on the " + typeName + " type"); return {}; }
    };

    struct EqualsOp  : public BinaryOperator
    {
        EqualsOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::equals) {}
        var getWithUndefinedArg() const override                               { return true; }
        var getWithDoubles (double a, double b) const override                 { return a == b; }
        var getWithInts (int64 a, int64 b) const override                      { return a == b; }
        var getWithStrings (const String& a, const String& b) const override   { return a == b; }
        var getWithArrayOrObject (const var& a, const var& b) const override   { return a == b; }
    };

    struct NotEqualsOp  : public BinaryOperator
    {
        NotEqualsOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::notEquals) {}
        var getWithUndefinedArg() const override                               { return false; }
        var getWithDoubles (double a, double b) const override                 { return a != b; }
        var getWithInts (int64 a, int64 b) const override                      { return a != b; }
        var getWithStrings (const String& a, const String& b) const override   { return a != b; }
        var getWithArrayOrObject (const var& a, const var& b) const override   { return a != b; }
    };

    struct LessThanOp  : public BinaryOperator
    {
        LessThanOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::lessThan) {}
        var getWithDoubles (double a, double b) const override                 { return a < b; }
        var getWithInts (int64 a, int64 b) const override                      { return a < b; }
        var getWithStrings (const String& a, const String& b) const override   { return a < b; }
    };

    struct LessThanOrEqualOp  : public BinaryOperator
    {
        LessThanOrEqualOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::lessThanOrEqual) {}
        var getWithDoubles (double a, double b) const override                 { return a <= b; }
        var getWithInts (int64 a, int64 b) const override                      { return a <= b; }
        var getWithStrings (const String& a, const String& b) const override   { return a <= b; }
    };

    struct GreaterThanOp  : public BinaryOperator
    {
        GreaterThanOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::greaterThan) {}
        var getWithDoubles (double a, double b) const override                 { return a > b; }
        var getWithInts (int64 a, int64 b) const override                      { return a > b; }
        var getWithStrings (const String& a, const String& b) const override   { return a > b; }
    };

    struct GreaterThanOrEqualOp  : public BinaryOperator
    {
        GreaterThanOrEqualOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::greaterThanOrEqual) {}
        var getWithDoubles (double a, double b) const override                 { return a >= b; }
        var getWithInts (int64 a, int64 b) const override                      { return a >= b; }
        var getWithStrings (const String& a, const String& b) const override   { return a >= b; }
    };

    struct AdditionOp  : public BinaryOperator
    {
        AdditionOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::plus) {}
        var getWithDoubles (double a, double b) const override                 { return a + b; }
        var getWithInts (int64 a, int64 b) const override                      { return a + b; }
        var getWithStrings (const String& a, const String& b) const override   { return a + b; }
    };

    struct SubtractionOp  : public BinaryOperator
    {
        SubtractionOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::minus) {}
        var getWithDoubles (double a, double b) const override { return a - b; }
        var getWithInts (int64 a, int64 b) const override      { return a - b; }
    };

    struct MultiplyOp  : public BinaryOperator
    {
        MultiplyOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::times) {}
        var getWithDoubles (double a, double b) const override { return a * b; }
        var getWithInts (int64 a, int64 b) const override      { return a * b; }
    };

    struct DivideOp  : public BinaryOperator
    {
        DivideOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::divide) {}
        var getWithDoubles (double a, double b) const override  { return b != 0 ? a / b : std::numeric_limits<double>::infinity(); }
        var getWithInts (int64 a, int64 b) const override       { return b != 0 ? var (a / (double) b) : var (std::numeric_limits<double>::infinity()); }
    };

    struct ModuloOp  : public BinaryOperator
    {
        ModuloOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::modulo) {}
        var getWithInts (int64 a, int64 b) const override   { return b != 0 ? var (a % b) : var (std::numeric_limits<double>::infinity()); }
    };

    struct BitwiseOrOp  : public BinaryOperator
    {
        BitwiseOrOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::bitwiseOr) {}
        var getWithInts (int64 a, int64 b) const override   { return a | b; }
    };

    struct BitwiseAndOp  : public BinaryOperator
    {
        BitwiseAndOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::bitwiseAnd) {}
        var getWithInts (int64 a, int64 b) const override   { return a & b; }
    };

    struct BitwiseXorOp  : public BinaryOperator
    {
        BitwiseXorOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::bitwiseXor) {}
        var getWithInts (int64 a, int64 b) const override   { return a ^ b; }
    };

    struct LeftShiftOp  : public BinaryOperator
    {
        LeftShiftOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::leftShift) {}
        var getWithInts (int64 a, int64 b) const override   { return ((int) a) << (int) b; }
    };

    struct RightShiftOp  : public BinaryOperator
    {
        RightShiftOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::rightShift) {}
        var getWithInts (int64 a, int64 b) const override   { return ((int) a) >> (int) b; }
    };

    struct RightShiftUnsignedOp  : public BinaryOperator
    {
        RightShiftUnsignedOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperator (l, a, b, TokenTypes::rightShiftUnsigned) {}
        var getWithInts (int64 a, int64 b) const override   { return (int) (((uint32) a) >> (int) b); }
    };

    struct LogicalAndOp  : public BinaryOperatorBase
    {
        LogicalAndOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperatorBase (l, a, b, TokenTypes::logicalAnd) {}
        var getResult (const Scope& s) const override       { return lhs->getResult (s) && rhs->getResult (s); }
    };

    struct LogicalOrOp  : public BinaryOperatorBase
    {
        LogicalOrOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperatorBase (l, a, b, TokenTypes::logicalOr) {}
        var getResult (const Scope& s) const override       { return lhs->getResult (s) || rhs->getResult (s); }
    };

    struct TypeEqualsOp  : public BinaryOperatorBase
    {
        TypeEqualsOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperatorBase (l, a, b, TokenTypes::typeEquals) {}
        var getResult (const Scope& s) const override       { return areTypeEqual (lhs->getResult (s), rhs->getResult (s)); }
    };

    struct TypeNotEqualsOp  : public BinaryOperatorBase
    {
        TypeNotEqualsOp (const CodeLocation& l, ExpPtr& a, ExpPtr& b) noexcept : BinaryOperatorBase (l, a, b, TokenTypes::typeNotEquals) {}
        var getResult (const Scope& s) const override       { return ! areTypeEqual (lhs->getResult (s), rhs->getResult (s)); }
    };

    struct ConditionalOp  : public Expression
    {
        ConditionalOp (const CodeLocation& l) noexcept : Expression (l) {}

        var getResult (const Scope& s) const override              { return (condition->getResult (s) ? trueBranch : falseBranch)->getResult (s); }
        void assign (const Scope& s, const var& v) const override  { (condition->getResult (s) ? trueBranch : falseBranch)->assign (s, v); }

        ExpPtr condition, trueBranch, falseBranch;
    };

    struct Assignment  : public Expression
    {
        Assignment (const CodeLocation& l, ExpPtr& dest, ExpPtr& source) noexcept : Expression (l), target (dest), newValue (source) {}

        var getResult (const Scope& s) const override
        {
            var value (newValue->getResult (s));
            target->assign (s, value);
            return value;
        }

        ExpPtr target, newValue;
    };

    struct SelfAssignment  : public Expression
    {
        SelfAssignment (const CodeLocation& l, Expression* dest, Expression* source) noexcept
            : Expression (l), target (dest), newValue (source) {}

        var getResult (const Scope& s) const override
        {
            var value (newValue->getResult (s));
            target->assign (s, value);
            return value;
        }

        Expression* target; // Careful! this pointer aliases a sub-term of newValue!
        ExpPtr newValue;
        TokenType op;
    };

    struct PostAssignment  : public SelfAssignment
    {
        PostAssignment (const CodeLocation& l, Expression* dest, Expression* source) noexcept : SelfAssignment (l, dest, source) {}

        var getResult (const Scope& s) const override
        {
            var oldValue (target->getResult (s));
            target->assign (s, newValue->getResult (s));
            return oldValue;
        }
    };

    struct FunctionCall  : public Expression
    {
        FunctionCall (const CodeLocation& l) noexcept : Expression (l) {}

        var getResult (const Scope& s) const override
        {
            if (DotOperator* dot = dynamic_cast<DotOperator*> (object.get()))
            {
                var thisObject (dot->parent->getResult (s));
                return invokeFunction (s, s.findFunctionCall (location, thisObject, dot->child), thisObject);
            }

            var function (object->getResult (s));
            return invokeFunction (s, function, var (s.scope.get()));
        }

        var invokeFunction (const Scope& s, const var& function, const var& thisObject) const
        {
            s.checkTimeOut (location);

            Array<var> argVars;
            for (int i = 0; i < arguments.size(); ++i)
                argVars.add (arguments.getUnchecked(i)->getResult (s));

            const var::NativeFunctionArgs args (thisObject, argVars.begin(), argVars.size());

            if (var::NativeFunction nativeFunction = function.getNativeFunction())
                return nativeFunction (args);

            if (FunctionObject* fo = dynamic_cast<FunctionObject*> (function.getObject()))
                return fo->invoke (s, args);

            if (DotOperator* dot = dynamic_cast<DotOperator*> (object.get()))
                if (DynamicObject* o = thisObject.getDynamicObject())
                    if (o->hasMethod (dot->child)) // allow an overridden DynamicObject::invokeMethod to accept a method call.
                        return o->invokeMethod (dot->child, args);

            location.throwError ("This expression is not a function!"); return {};
        }

        ExpPtr object;
        OwnedArray<Expression> arguments;
    };

    struct NewOperator  : public FunctionCall
    {
        NewOperator (const CodeLocation& l) noexcept : FunctionCall (l) {}

        var getResult (const Scope& s) const override
        {
            var classOrFunc = object->getResult (s);

            const bool isFunc = isFunction (classOrFunc);
            if (! (isFunc || classOrFunc.getDynamicObject() != nullptr))
                return var::undefined();

            DynamicObject::Ptr newObject (new DynamicObject());

            if (isFunc)
                invokeFunction (s, classOrFunc, newObject.get());
            else
                newObject->setProperty (getPrototypeIdentifier(), classOrFunc);

            return newObject.get();
        }
    };

    struct ObjectDeclaration  : public Expression
    {
        ObjectDeclaration (const CodeLocation& l) noexcept : Expression (l) {}

        var getResult (const Scope& s) const override
        {
            DynamicObject::Ptr newObject (new DynamicObject());

            for (int i = 0; i < names.size(); ++i)
                newObject->setProperty (names.getUnchecked(i), initialisers.getUnchecked(i)->getResult (s));

            return newObject.get();
        }

        Array<Identifier> names;
        OwnedArray<Expression> initialisers;
    };

    struct ArrayDeclaration  : public Expression
    {
        ArrayDeclaration (const CodeLocation& l) noexcept : Expression (l) {}

        var getResult (const Scope& s) const override
        {
            Array<var> a;

            for (int i = 0; i < values.size(); ++i)
                a.add (values.getUnchecked(i)->getResult (s));

            return a;
        }

        OwnedArray<Expression> values;
    };

    //==============================================================================
    struct FunctionObject  : public DynamicObject
    {
        FunctionObject() noexcept {}

        FunctionObject (const FunctionObject& other)  : DynamicObject(), functionCode (other.functionCode)
        {
            ExpressionTreeBuilder tb (functionCode);
            tb.parseFunctionParamsAndBody (*this);
        }

        DynamicObject::Ptr clone() override    { return new FunctionObject (*this); }

        void writeAsJSON (OutputStream& out, int /*indentLevel*/, bool /*allOnOneLine*/) override
        {
            out << "function " << functionCode;
        }

        var invoke (const Scope& s, const var::NativeFunctionArgs& args) const
        {
            DynamicObject::Ptr functionRoot (new DynamicObject());

            static const Identifier thisIdent ("this");
            functionRoot->setProperty (thisIdent, args.thisObject);

            for (int i = 0; i < parameters.size(); ++i)
                functionRoot->setProperty (parameters.getReference(i),
                                           i < args.numArguments ? args.arguments[i] : var::undefined());

            var result;
            body->perform (Scope (&s, s.root, functionRoot), &result);
            return result;
        }

        String functionCode;
        Array<Identifier> parameters;
        ScopedPointer<Statement> body;
    };

    //==============================================================================
    struct TokenIterator
    {
        TokenIterator (const String& code) : location (code), p (code.getCharPointer()) { skip(); }

        void skip()
        {
            skipWhitespaceAndComments();
            location.location = p;
            currentType = matchNextToken();
        }

        void match (TokenType expected)
        {
            if (currentType != expected)
                location.throwError ("Found " + getTokenName (currentType) + " when expecting " + getTokenName (expected));

            skip();
        }

        bool matchIf (TokenType expected)                                 { if (currentType == expected)  { skip(); return true; } return false; }
        bool matchesAny (TokenType t1, TokenType t2) const                { return currentType == t1 || currentType == t2; }
        bool matchesAny (TokenType t1, TokenType t2, TokenType t3) const  { return matchesAny (t1, t2) || currentType == t3; }

        CodeLocation location;
        TokenType currentType;
        var currentValue;

    private:
        String::CharPointerType p;

        static bool isIdentifierStart (const juce_wchar c) noexcept   { return CharacterFunctions::isLetter (c)        || c == '_'; }
        static bool isIdentifierBody  (const juce_wchar c) noexcept   { return CharacterFunctions::isLetterOrDigit (c) || c == '_'; }

        TokenType matchNextToken()
        {
            if (isIdentifierStart (*p))
            {
                String::CharPointerType end (p);
                while (isIdentifierBody (*++end)) {}

                const size_t len = (size_t) (end - p);
                #define JUCE_JS_COMPARE_KEYWORD(name, str) if (len == sizeof (str) - 1 && matchToken (TokenTypes::name, len)) return TokenTypes::name;
                JUCE_JS_KEYWORDS (JUCE_JS_COMPARE_KEYWORD)

                currentValue = String (p, end); p = end;
                return TokenTypes::identifier;
            }

            if (p.isDigit())
            {
                if (parseHexLiteral() || parseFloatLiteral() || parseOctalLiteral() || parseDecimalLiteral())
                    return TokenTypes::literal;

                location.throwError ("Syntax error in numeric constant");
            }

            if (parseStringLiteral (*p) || (*p == '.' && parseFloatLiteral()))
                return TokenTypes::literal;

            #define JUCE_JS_COMPARE_OPERATOR(name, str) if (matchToken (TokenTypes::name, sizeof (str) - 1)) return TokenTypes::name;
            JUCE_JS_OPERATORS (JUCE_JS_COMPARE_OPERATOR)

            if (! p.isEmpty())
                location.throwError ("Unexpected character '" + String::charToString (*p) + "' in source");

            return TokenTypes::eof;
        }

        bool matchToken (TokenType name, const size_t len) noexcept
        {
            if (p.compareUpTo (CharPointer_ASCII (name), (int) len) != 0) return false;
            p += (int) len;  return true;
        }

        void skipWhitespaceAndComments()
        {
            for (;;)
            {
                p = p.findEndOfWhitespace();

                if (*p == '/')
                {
                    const juce_wchar c2 = p[1];

                    if (c2 == '/')  { p = CharacterFunctions::find (p, (juce_wchar) '\n'); continue; }

                    if (c2 == '*')
                    {
                        location.location = p;
                        p = CharacterFunctions::find (p + 2, CharPointer_ASCII ("*/"));
                        if (p.isEmpty()) location.throwError ("Unterminated '/*' comment");
                        p += 2; continue;
                    }
                }

                break;
            }
        }

        bool parseStringLiteral (juce_wchar quoteType)
        {
            if (quoteType != '"' && quoteType != '\'')
                return false;

            Result r (JSON::parseQuotedString (p, currentValue));
            if (r.failed()) location.throwError (r.getErrorMessage());
            return true;
        }

        bool parseHexLiteral()
        {
            if (*p != '0' || (p[1] != 'x' && p[1] != 'X')) return false;

            String::CharPointerType t (++p);
            int64 v = CharacterFunctions::getHexDigitValue (*++t);
            if (v < 0) return false;

            for (;;)
            {
                const int digit = CharacterFunctions::getHexDigitValue (*++t);
                if (digit < 0) break;
                v = v * 16 + digit;
            }

            currentValue = v; p = t;
            return true;
        }

        bool parseFloatLiteral()
        {
            int numDigits = 0;
            String::CharPointerType t (p);
            while (t.isDigit())  { ++t; ++numDigits; }

            const bool hasPoint = (*t == '.');

            if (hasPoint)
                while ((++t).isDigit())  ++numDigits;

            if (numDigits == 0)
                return false;

            juce_wchar c = *t;
            const bool hasExponent = (c == 'e' || c == 'E');

            if (hasExponent)
            {
                c = *++t;
                if (c == '+' || c == '-')  ++t;
                if (! t.isDigit()) return false;
                while ((++t).isDigit()) {}
            }

            if (! (hasExponent || hasPoint)) return false;

            currentValue = CharacterFunctions::getDoubleValue (p);  p = t;
            return true;
        }

        bool parseOctalLiteral()
        {
            String::CharPointerType t (p);
            int64 v = *t - '0';
            if (v != 0) return false;  // first digit of octal must be 0

            for (;;)
            {
                const int digit = (int) (*++t - '0');
                if (isPositiveAndBelow (digit, 8))        v = v * 8 + digit;
                else if (isPositiveAndBelow (digit, 10))  location.throwError ("Decimal digit in octal constant");
                else break;
            }

            currentValue = v;  p = t;
            return true;
        }

        bool parseDecimalLiteral()
        {
            int64 v = 0;

            for (;; ++p)
            {
                const int digit = (int) (*p - '0');
                if (isPositiveAndBelow (digit, 10))  v = v * 10 + digit;
                else break;
            }

            currentValue = v;
            return true;
        }
    };

    //==============================================================================
    struct ExpressionTreeBuilder  : private TokenIterator
    {
        ExpressionTreeBuilder (const String code)  : TokenIterator (code) {}

        BlockStatement* parseStatementList()
        {
            ScopedPointer<BlockStatement> b (new BlockStatement (location));

            while (currentType != TokenTypes::closeBrace && currentType != TokenTypes::eof)
                b->statements.add (parseStatement());

            return b.release();
        }

        void parseFunctionParamsAndBody (FunctionObject& fo)
        {
            match (TokenTypes::openParen);

            while (currentType != TokenTypes::closeParen)
            {
                fo.parameters.add (currentValue.toString());
                match (TokenTypes::identifier);

                if (currentType != TokenTypes::closeParen)
                    match (TokenTypes::comma);
            }

            match (TokenTypes::closeParen);
            fo.body = parseBlock();
        }

        Expression* parseExpression()
        {
            ExpPtr lhs (parseLogicOperator());

            if (matchIf (TokenTypes::question))          return parseTernaryOperator (lhs);
            if (matchIf (TokenTypes::assign))            { ExpPtr rhs (parseExpression()); return new Assignment (location, lhs, rhs); }
            if (matchIf (TokenTypes::plusEquals))        return parseInPlaceOpExpression<AdditionOp> (lhs);
            if (matchIf (TokenTypes::minusEquals))       return parseInPlaceOpExpression<SubtractionOp> (lhs);
            if (matchIf (TokenTypes::leftShiftEquals))   return parseInPlaceOpExpression<LeftShiftOp> (lhs);
            if (matchIf (TokenTypes::rightShiftEquals))  return parseInPlaceOpExpression<RightShiftOp> (lhs);

            return lhs.release();
        }

    private:
        void throwError (const String& err) const  { location.throwError (err); }

        template <typename OpType>
        Expression* parseInPlaceOpExpression (ExpPtr& lhs)
        {
            ExpPtr rhs (parseExpression());
            Expression* bareLHS = lhs; // careful - bare pointer is deliberately alised
            return new SelfAssignment (location, bareLHS, new OpType (location, lhs, rhs));
        }

        BlockStatement* parseBlock()
        {
            match (TokenTypes::openBrace);
            ScopedPointer<BlockStatement> b (parseStatementList());
            match (TokenTypes::closeBrace);
            return b.release();
        }

        Statement* parseStatement()
        {
            if (currentType == TokenTypes::openBrace)   return parseBlock();
            if (matchIf (TokenTypes::var))              return parseVar();
            if (matchIf (TokenTypes::if_))              return parseIf();
            if (matchIf (TokenTypes::while_))           return parseDoOrWhileLoop (false);
            if (matchIf (TokenTypes::do_))              return parseDoOrWhileLoop (true);
            if (matchIf (TokenTypes::for_))             return parseForLoop();
            if (matchIf (TokenTypes::return_))          return parseReturn();
            if (matchIf (TokenTypes::break_))           return new BreakStatement (location);
            if (matchIf (TokenTypes::continue_))        return new ContinueStatement (location);
            if (matchIf (TokenTypes::function))         return parseFunction();
            if (matchIf (TokenTypes::semicolon))        return new Statement (location);
            if (matchIf (TokenTypes::plusplus))         return parsePreIncDec<AdditionOp>();
            if (matchIf (TokenTypes::minusminus))       return parsePreIncDec<SubtractionOp>();

            if (matchesAny (TokenTypes::openParen, TokenTypes::openBracket))
                return matchEndOfStatement (parseFactor());

            if (matchesAny (TokenTypes::identifier, TokenTypes::literal, TokenTypes::minus))
                return matchEndOfStatement (parseExpression());

            throwError ("Found " + getTokenName (currentType) + " when expecting a statement");
            return nullptr;
        }

        Expression* matchEndOfStatement (Expression* ex)  { ExpPtr e (ex); if (currentType != TokenTypes::eof) match (TokenTypes::semicolon); return e.release(); }
        Expression* matchCloseParen (Expression* ex)      { ExpPtr e (ex); match (TokenTypes::closeParen); return e.release(); }

        Statement* parseIf()
        {
            ScopedPointer<IfStatement> s (new IfStatement (location));
            match (TokenTypes::openParen);
            s->condition = parseExpression();
            match (TokenTypes::closeParen);
            s->trueBranch = parseStatement();
            s->falseBranch = matchIf (TokenTypes::else_) ? parseStatement() : new Statement (location);
            return s.release();
        }

        Statement* parseReturn()
        {
            if (matchIf (TokenTypes::semicolon))
                return new ReturnStatement (location, new Expression (location));

            ReturnStatement* r = new ReturnStatement (location, parseExpression());
            matchIf (TokenTypes::semicolon);
            return r;
        }

        Statement* parseVar()
        {
            ScopedPointer<VarStatement> s (new VarStatement (location));
            s->name = parseIdentifier();
            s->initialiser = matchIf (TokenTypes::assign) ? parseExpression() : new Expression (location);

            if (matchIf (TokenTypes::comma))
            {
                ScopedPointer<BlockStatement> block (new BlockStatement (location));
                block->statements.add (s.release());
                block->statements.add (parseVar());
                return block.release();
            }

            match (TokenTypes::semicolon);
            return s.release();
        }

        Statement* parseFunction()
        {
            Identifier name;
            var fn = parseFunctionDefinition (name);

            if (name.isNull())
                throwError ("Functions defined at statement-level must have a name");

            ExpPtr nm (new UnqualifiedName (location, name)), value (new LiteralValue (location, fn));
            return new Assignment (location, nm, value);
        }

        Statement* parseForLoop()
        {
            ScopedPointer<LoopStatement> s (new LoopStatement (location, false));
            match (TokenTypes::openParen);
            s->initialiser = parseStatement();

            if (matchIf (TokenTypes::semicolon))
                s->condition = new LiteralValue (location, true);
            else
            {
                s->condition = parseExpression();
                match (TokenTypes::semicolon);
            }

            if (matchIf (TokenTypes::closeParen))
                s->iterator = new Statement (location);
            else
            {
                s->iterator = parseExpression();
                match (TokenTypes::closeParen);
            }

            s->body = parseStatement();
            return s.release();
        }

        Statement* parseDoOrWhileLoop (bool isDoLoop)
        {
            ScopedPointer<LoopStatement> s (new LoopStatement (location, isDoLoop));
            s->initialiser = new Statement (location);
            s->iterator = new Statement (location);

            if (isDoLoop)
            {
                s->body = parseBlock();
                match (TokenTypes::while_);
            }

            match (TokenTypes::openParen);
            s->condition = parseExpression();
            match (TokenTypes::closeParen);

            if (! isDoLoop)
                s->body = parseStatement();

            return s.release();
        }

        Identifier parseIdentifier()
        {
            Identifier i;
            if (currentType == TokenTypes::identifier)
                i = currentValue.toString();

            match (TokenTypes::identifier);
            return i;
        }

        var parseFunctionDefinition (Identifier& functionName)
        {
            const String::CharPointerType functionStart (location.location);

            if (currentType == TokenTypes::identifier)
                functionName = parseIdentifier();

            ScopedPointer<FunctionObject> fo (new FunctionObject());
            parseFunctionParamsAndBody (*fo);
            fo->functionCode = String (functionStart, location.location);
            return var (fo.release());
        }

        Expression* parseFunctionCall (FunctionCall* call, ExpPtr& function)
        {
            ScopedPointer<FunctionCall> s (call);
            s->object = function;
            match (TokenTypes::openParen);

            while (currentType != TokenTypes::closeParen)
            {
                s->arguments.add (parseExpression());
                if (currentType != TokenTypes::closeParen)
                    match (TokenTypes::comma);
            }

            return matchCloseParen (s.release());
        }

        Expression* parseSuffixes (Expression* e)
        {
            ExpPtr input (e);

            if (matchIf (TokenTypes::dot))
                return parseSuffixes (new DotOperator (location, input, parseIdentifier()));

            if (currentType == TokenTypes::openParen)
                return parseSuffixes (parseFunctionCall (new FunctionCall (location), input));

            if (matchIf (TokenTypes::openBracket))
            {
                ScopedPointer<ArraySubscript> s (new ArraySubscript (location));
                s->object = input;
                s->index = parseExpression();
                match (TokenTypes::closeBracket);
                return parseSuffixes (s.release());
            }

            if (matchIf (TokenTypes::plusplus))   return parsePostIncDec<AdditionOp> (input);
            if (matchIf (TokenTypes::minusminus)) return parsePostIncDec<SubtractionOp> (input);

            return input.release();
        }

        Expression* parseFactor()
        {
            if (currentType == TokenTypes::identifier)  return parseSuffixes (new UnqualifiedName (location, parseIdentifier()));
            if (matchIf (TokenTypes::openParen))        return parseSuffixes (matchCloseParen (parseExpression()));
            if (matchIf (TokenTypes::true_))            return parseSuffixes (new LiteralValue (location, (int) 1));
            if (matchIf (TokenTypes::false_))           return parseSuffixes (new LiteralValue (location, (int) 0));
            if (matchIf (TokenTypes::null_))            return parseSuffixes (new LiteralValue (location, var()));
            if (matchIf (TokenTypes::undefined))        return parseSuffixes (new Expression (location));

            if (currentType == TokenTypes::literal)
            {
                var v (currentValue); skip();
                return parseSuffixes (new LiteralValue (location, v));
            }

            if (matchIf (TokenTypes::openBrace))
            {
                ScopedPointer<ObjectDeclaration> e (new ObjectDeclaration (location));

                while (currentType != TokenTypes::closeBrace)
                {
                    auto memberName = currentValue.toString();
                    match ((currentType == TokenTypes::literal && currentValue.isString())
                             ? TokenTypes::literal : TokenTypes::identifier);
                    match (TokenTypes::colon);

                    e->names.add (memberName);
                    e->initialisers.add (parseExpression());

                    if (currentType != TokenTypes::closeBrace)
                        match (TokenTypes::comma);
                }

                match (TokenTypes::closeBrace);
                return parseSuffixes (e.release());
            }

            if (matchIf (TokenTypes::openBracket))
            {
                ScopedPointer<ArrayDeclaration> e (new ArrayDeclaration (location));

                while (currentType != TokenTypes::closeBracket)
                {
                    e->values.add (parseExpression());

                    if (currentType != TokenTypes::closeBracket)
                        match (TokenTypes::comma);
                }

                match (TokenTypes::closeBracket);
                return parseSuffixes (e.release());
            }

            if (matchIf (TokenTypes::function))
            {
                Identifier name;
                var fn = parseFunctionDefinition (name);

                if (name.isValid())
                    throwError ("Inline functions definitions cannot have a name");

                return new LiteralValue (location, fn);
            }

            if (matchIf (TokenTypes::new_))
            {
                ExpPtr name (new UnqualifiedName (location, parseIdentifier()));

                while (matchIf (TokenTypes::dot))
                    name = new DotOperator (location, name, parseIdentifier());

                return parseFunctionCall (new NewOperator (location), name);
            }

            throwError ("Found " + getTokenName (currentType) + " when expecting an expression");
            return nullptr;
        }

        template <typename OpType>
        Expression* parsePreIncDec()
        {
            Expression* e = parseFactor(); // careful - bare pointer is deliberately aliased
            ExpPtr lhs (e), one (new LiteralValue (location, (int) 1));
            return new SelfAssignment (location, e, new OpType (location, lhs, one));
        }

        template <typename OpType>
        Expression* parsePostIncDec (ExpPtr& lhs)
        {
            Expression* e = lhs.release(); // careful - bare pointer is deliberately aliased
            ExpPtr lhs2 (e), one (new LiteralValue (location, (int) 1));
            return new PostAssignment (location, e, new OpType (location, lhs2, one));
        }

        Expression* parseTypeof()
        {
            ScopedPointer<FunctionCall> f (new FunctionCall (location));
            f->object = new UnqualifiedName (location, "typeof");
            f->arguments.add (parseUnary());
            return f.release();
        }

        Expression* parseUnary()
        {
            if (matchIf (TokenTypes::minus))       { ExpPtr a (new LiteralValue (location, (int) 0)), b (parseUnary()); return new SubtractionOp   (location, a, b); }
            if (matchIf (TokenTypes::logicalNot))  { ExpPtr a (new LiteralValue (location, (int) 0)), b (parseUnary()); return new EqualsOp        (location, a, b); }
            if (matchIf (TokenTypes::plusplus))    return parsePreIncDec<AdditionOp>();
            if (matchIf (TokenTypes::minusminus))  return parsePreIncDec<SubtractionOp>();
            if (matchIf (TokenTypes::typeof_))     return parseTypeof();

            return parseFactor();
        }

        Expression* parseMultiplyDivide()
        {
            ExpPtr a (parseUnary());

            for (;;)
            {
                if (matchIf (TokenTypes::times))        { ExpPtr b (parseUnary()); a = new MultiplyOp (location, a, b); }
                else if (matchIf (TokenTypes::divide))  { ExpPtr b (parseUnary()); a = new DivideOp   (location, a, b); }
                else if (matchIf (TokenTypes::modulo))  { ExpPtr b (parseUnary()); a = new ModuloOp   (location, a, b); }
                else break;
            }

            return a.release();
        }

        Expression* parseAdditionSubtraction()
        {
            ExpPtr a (parseMultiplyDivide());

            for (;;)
            {
                if (matchIf (TokenTypes::plus))            { ExpPtr b (parseMultiplyDivide()); a = new AdditionOp    (location, a, b); }
                else if (matchIf (TokenTypes::minus))      { ExpPtr b (parseMultiplyDivide()); a = new SubtractionOp (location, a, b); }
                else break;
            }

            return a.release();
        }

        Expression* parseShiftOperator()
        {
            ExpPtr a (parseAdditionSubtraction());

            for (;;)
            {
                if (matchIf (TokenTypes::leftShift))                { ExpPtr b (parseExpression()); a = new LeftShiftOp          (location, a, b); }
                else if (matchIf (TokenTypes::rightShift))          { ExpPtr b (parseExpression()); a = new RightShiftOp         (location, a, b); }
                else if (matchIf (TokenTypes::rightShiftUnsigned))  { ExpPtr b (parseExpression()); a = new RightShiftUnsignedOp (location, a, b); }
                else break;
            }

            return a.release();
        }

        Expression* parseComparator()
        {
            ExpPtr a (parseShiftOperator());

            for (;;)
            {
                if (matchIf (TokenTypes::equals))                  { ExpPtr b (parseShiftOperator()); a = new EqualsOp             (location, a, b); }
                else if (matchIf (TokenTypes::notEquals))          { ExpPtr b (parseShiftOperator()); a = new NotEqualsOp          (location, a, b); }
                else if (matchIf (TokenTypes::typeEquals))         { ExpPtr b (parseShiftOperator()); a = new TypeEqualsOp         (location, a, b); }
                else if (matchIf (TokenTypes::typeNotEquals))      { ExpPtr b (parseShiftOperator()); a = new TypeNotEqualsOp      (location, a, b); }
                else if (matchIf (TokenTypes::lessThan))           { ExpPtr b (parseShiftOperator()); a = new LessThanOp           (location, a, b); }
                else if (matchIf (TokenTypes::lessThanOrEqual))    { ExpPtr b (parseShiftOperator()); a = new LessThanOrEqualOp    (location, a, b); }
                else if (matchIf (TokenTypes::greaterThan))        { ExpPtr b (parseShiftOperator()); a = new GreaterThanOp        (location, a, b); }
                else if (matchIf (TokenTypes::greaterThanOrEqual)) { ExpPtr b (parseShiftOperator()); a = new GreaterThanOrEqualOp (location, a, b); }
                else break;
            }

            return a.release();
        }

        Expression* parseLogicOperator()
        {
            ExpPtr a (parseComparator());

            for (;;)
            {
                if (matchIf (TokenTypes::logicalAnd))       { ExpPtr b (parseComparator()); a = new LogicalAndOp (location, a, b); }
                else if (matchIf (TokenTypes::logicalOr))   { ExpPtr b (parseComparator()); a = new LogicalOrOp  (location, a, b); }
                else if (matchIf (TokenTypes::bitwiseAnd))  { ExpPtr b (parseComparator()); a = new BitwiseAndOp (location, a, b); }
                else if (matchIf (TokenTypes::bitwiseOr))   { ExpPtr b (parseComparator()); a = new BitwiseOrOp  (location, a, b); }
                else if (matchIf (TokenTypes::bitwiseXor))  { ExpPtr b (parseComparator()); a = new BitwiseXorOp (location, a, b); }
                else break;
            }

            return a.release();
        }

        Expression* parseTernaryOperator (ExpPtr& condition)
        {
            ScopedPointer<ConditionalOp> e (new ConditionalOp (location));
            e->condition = condition;
            e->trueBranch = parseExpression();
            match (TokenTypes::colon);
            e->falseBranch = parseExpression();
            return e.release();
        }

        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ExpressionTreeBuilder)
    };

    //==============================================================================
    static var get (Args a, int index) noexcept            { return index < a.numArguments ? a.arguments[index] : var(); }
    static bool isInt (Args a, int index) noexcept         { return get (a, index).isInt() || get (a, index).isInt64(); }
    static int getInt (Args a, int index) noexcept         { return get (a, index); }
    static double getDouble (Args a, int index) noexcept   { return get (a, index); }
    static String getString (Args a, int index) noexcept   { return get (a, index).toString(); }

    //==============================================================================
    struct ObjectClass  : public DynamicObject
    {
        ObjectClass()
        {
            setMethod ("dump",  dump);
            setMethod ("clone", cloneFn);
        }

        static Identifier getClassName()   { static const Identifier i ("Object"); return i; }
        static var dump  (Args a)          { DBG (JSON::toString (a.thisObject)); ignoreUnused (a); return var::undefined(); }
        static var cloneFn (Args a)        { return a.thisObject.clone(); }
    };

    //==============================================================================
    struct ArrayClass  : public DynamicObject
    {
        ArrayClass()
        {
            setMethod ("contains", contains);
            setMethod ("remove",   remove);
            setMethod ("join",     join);
            setMethod ("push",     push);
            setMethod ("splice",   splice);
            setMethod ("indexOf",  indexOf);
        }

        static Identifier getClassName()   { static const Identifier i ("Array"); return i; }

        static var contains (Args a)
        {
            if (const Array<var>* array = a.thisObject.getArray())
                return array->contains (get (a, 0));

            return false;
        }

        static var remove (Args a)
        {
            if (Array<var>* array = a.thisObject.getArray())
                array->removeAllInstancesOf (get (a, 0));

            return var::undefined();
        }

        static var join (Args a)
        {
            StringArray strings;

            if (const Array<var>* array = a.thisObject.getArray())
                for (int i = 0; i < array->size(); ++i)
                    strings.add (array->getReference(i).toString());

            return strings.joinIntoString (getString (a, 0));
        }

        static var push (Args a)
        {
            if (Array<var>* array = a.thisObject.getArray())
            {
                for (int i = 0; i < a.numArguments; ++i)
                    array->add (a.arguments[i]);

                return array->size();
            }

            return var::undefined();
        }

        static var splice (Args a)
        {
            if (Array<var>* array = a.thisObject.getArray())
            {
                const int arraySize = array->size();
                int start = get (a, 0);

                if (start < 0)
                    start = jmax (0, arraySize + start);
                else if (start > arraySize)
                    start = arraySize;

                const int num = a.numArguments > 1 ? jlimit (0, arraySize - start, getInt (a, 1))
                                                   : arraySize - start;

                Array<var> itemsRemoved;
                itemsRemoved.ensureStorageAllocated (num);

                for (int i = 0; i < num; ++i)
                    itemsRemoved.add (array->getReference (start + i));

                array->removeRange (start, num);

                for (int i = 2; i < a.numArguments; ++i)
                    array->insert (start++, get (a, i));

                return itemsRemoved;
            }

            return var::undefined();
        }

        static var indexOf (Args a)
        {
            if (const Array<var>* array = a.thisObject.getArray())
            {
                const var target (get (a, 0));

                for (int i = (a.numArguments > 1 ? getInt (a, 1) : 0); i < array->size(); ++i)
                    if (array->getReference(i) == target)
                        return i;
            }

            return -1;
        }
    };

    //==============================================================================
    struct StringClass  : public DynamicObject
    {
        StringClass()
        {
            setMethod ("substring",     substring);
            setMethod ("indexOf",       indexOf);
            setMethod ("charAt",        charAt);
            setMethod ("charCodeAt",    charCodeAt);
            setMethod ("fromCharCode",  fromCharCode);
            setMethod ("split",         split);
        }

        static Identifier getClassName()  { static const Identifier i ("String"); return i; }

        static var fromCharCode (Args a)  { return String::charToString (static_cast<juce_wchar> (getInt (a, 0))); }
        static var substring (Args a)     { return a.thisObject.toString().substring (getInt (a, 0), getInt (a, 1)); }
        static var indexOf (Args a)       { return a.thisObject.toString().indexOf (getString (a, 0)); }
        static var charCodeAt (Args a)    { return (int) a.thisObject.toString() [getInt (a, 0)]; }
        static var charAt (Args a)        { int p = getInt (a, 0); return a.thisObject.toString().substring (p, p + 1); }

        static var split (Args a)
        {
            const String str (a.thisObject.toString());
            const String sep (getString (a, 0));
            StringArray strings;

            if (sep.isNotEmpty())
                strings.addTokens (str, sep.substring (0, 1), "");
            else // special-case for empty separator: split all chars separately
                for (String::CharPointerType pos = str.getCharPointer(); ! pos.isEmpty(); ++pos)
                    strings.add (String::charToString (*pos));

            var array;
            for (int i = 0; i < strings.size(); ++i)
                array.append (strings[i]);

            return array;
        }
    };

    //==============================================================================
    struct MathClass  : public DynamicObject
    {
        MathClass()
        {
            setMethod ("abs",       Math_abs);              setMethod ("round",     Math_round);
            setMethod ("random",    Math_random);           setMethod ("randInt",   Math_randInt);
            setMethod ("min",       Math_min);              setMethod ("max",       Math_max);
            setMethod ("range",     Math_range);            setMethod ("sign",      Math_sign);
            setMethod ("toDegrees", Math_toDegrees);        setMethod ("toRadians", Math_toRadians);
            setMethod ("sin",       Math_sin);              setMethod ("asin",      Math_asin);
            setMethod ("sinh",      Math_sinh);             setMethod ("asinh",     Math_asinh);
            setMethod ("cos",       Math_cos);              setMethod ("acos",      Math_acos);
            setMethod ("cosh",      Math_cosh);             setMethod ("acosh",     Math_acosh);
            setMethod ("tan",       Math_tan);              setMethod ("atan",      Math_atan);
            setMethod ("tanh",      Math_tanh);             setMethod ("atanh",     Math_atanh);
            setMethod ("log",       Math_log);              setMethod ("log10",     Math_log10);
            setMethod ("exp",       Math_exp);              setMethod ("pow",       Math_pow);
            setMethod ("sqr",       Math_sqr);              setMethod ("sqrt",      Math_sqrt);
            setMethod ("ceil",      Math_ceil);             setMethod ("floor",     Math_floor);

            setProperty ("PI", double_Pi);
            setProperty ("E", exp (1.0));
        }

        static var Math_random    (Args)   { return Random::getSystemRandom().nextDouble(); }
        static var Math_randInt   (Args a) { return Random::getSystemRandom().nextInt (Range<int> (getInt (a, 0), getInt (a, 1))); }
        static var Math_abs       (Args a) { return isInt (a, 0) ? var (std::abs   (getInt (a, 0))) : var (std::abs   (getDouble (a, 0))); }
        static var Math_round     (Args a) { return isInt (a, 0) ? var (roundToInt (getInt (a, 0))) : var (roundToInt (getDouble (a, 0))); }
        static var Math_sign      (Args a) { return isInt (a, 0) ? var (sign       (getInt (a, 0))) : var (sign       (getDouble (a, 0))); }
        static var Math_range     (Args a) { return isInt (a, 0) ? var (jlimit (getInt (a, 1), getInt (a, 2), getInt (a, 0))) : var (jlimit (getDouble (a, 1), getDouble (a, 2), getDouble (a, 0))); }
        static var Math_min       (Args a) { return (isInt (a, 0) && isInt (a, 1)) ? var (jmin (getInt (a, 0), getInt (a, 1))) : var (jmin (getDouble (a, 0), getDouble (a, 1))); }
        static var Math_max       (Args a) { return (isInt (a, 0) && isInt (a, 1)) ? var (jmax (getInt (a, 0), getInt (a, 1))) : var (jmax (getDouble (a, 0), getDouble (a, 1))); }
        static var Math_toDegrees (Args a) { return radiansToDegrees (getDouble (a, 0)); }
        static var Math_toRadians (Args a) { return degreesToRadians (getDouble (a, 0)); }
        static var Math_sin       (Args a) { return sin   (getDouble (a, 0)); }
        static var Math_asin      (Args a) { return asin  (getDouble (a, 0)); }
        static var Math_cos       (Args a) { return cos   (getDouble (a, 0)); }
        static var Math_acos      (Args a) { return acos  (getDouble (a, 0)); }
        static var Math_sinh      (Args a) { return sinh  (getDouble (a, 0)); }
        static var Math_asinh     (Args a) { return asinh (getDouble (a, 0)); }
        static var Math_cosh      (Args a) { return cosh  (getDouble (a, 0)); }
        static var Math_acosh     (Args a) { return acosh (getDouble (a, 0)); }
        static var Math_tan       (Args a) { return tan   (getDouble (a, 0)); }
        static var Math_tanh      (Args a) { return tanh  (getDouble (a, 0)); }
        static var Math_atan      (Args a) { return atan  (getDouble (a, 0)); }
        static var Math_atanh     (Args a) { return atanh (getDouble (a, 0)); }
        static var Math_log       (Args a) { return log   (getDouble (a, 0)); }
        static var Math_log10     (Args a) { return log10 (getDouble (a, 0)); }
        static var Math_exp       (Args a) { return exp   (getDouble (a, 0)); }
        static var Math_pow       (Args a) { return pow   (getDouble (a, 0), getDouble (a, 1)); }
        static var Math_sqr       (Args a) { double x = getDouble (a, 0); return x * x; }
        static var Math_sqrt      (Args a) { return std::sqrt  (getDouble (a, 0)); }
        static var Math_ceil      (Args a) { return std::ceil  (getDouble (a, 0)); }
        static var Math_floor     (Args a) { return std::floor (getDouble (a, 0)); }

        static Identifier getClassName()   { static const Identifier i ("Math"); return i; }
        template <typename Type> static Type sign (Type n) noexcept  { return n > 0 ? (Type) 1 : (n < 0 ? (Type) -1 : 0); }
    };

    //==============================================================================
    struct JSONClass  : public DynamicObject
    {
        JSONClass()                        { setMethod ("stringify", stringify); }
        static Identifier getClassName()   { static const Identifier i ("JSON"); return i; }
        static var stringify (Args a)      { return JSON::toString (get (a, 0)); }
    };

    //==============================================================================
    struct IntegerClass  : public DynamicObject
    {
        IntegerClass()                     { setMethod ("parseInt",  parseInt); }
        static Identifier getClassName()   { static const Identifier i ("Integer"); return i; }

        static var parseInt (Args a)
        {
            const String s (getString (a, 0).trim());

            return s[0] == '0' ? (s[1] == 'x' ? s.substring(2).getHexValue64() : getOctalValue (s))
                               : s.getLargeIntValue();
        }
    };

    //==============================================================================
    static var trace (Args a)      { Logger::outputDebugString (JSON::toString (a.thisObject)); return var::undefined(); }
    static var charToInt (Args a)  { return (int) (getString (a, 0)[0]); }
    static var parseFloat (Args a) { return getDouble (a, 0); }

    static var typeof_internal (Args a)
    {
        var v (get (a, 0));

        if (v.isVoid())                      return "void";
        if (v.isString())                    return "string";
        if (isNumeric (v))                   return "number";
        if (isFunction (v) || v.isMethod())  return "function";
        if (v.isObject())                    return "object";

        return "undefined";
    }

    static var exec (Args a)
    {
        if (RootObject* root = dynamic_cast<RootObject*> (a.thisObject.getObject()))
            root->execute (getString (a, 0));

        return var::undefined();
    }

    static var eval (Args a)
    {
        if (RootObject* root = dynamic_cast<RootObject*> (a.thisObject.getObject()))
            return root->evaluate (getString (a, 0));

        return var::undefined();
    }
};

//==============================================================================
JavascriptEngine::JavascriptEngine()  : maximumExecutionTime (15.0), root (new RootObject())
{
    registerNativeObject (RootObject::ObjectClass  ::getClassName(),  new RootObject::ObjectClass());
    registerNativeObject (RootObject::ArrayClass   ::getClassName(),  new RootObject::ArrayClass());
    registerNativeObject (RootObject::StringClass  ::getClassName(),  new RootObject::StringClass());
    registerNativeObject (RootObject::MathClass    ::getClassName(),  new RootObject::MathClass());
    registerNativeObject (RootObject::JSONClass    ::getClassName(),  new RootObject::JSONClass());
    registerNativeObject (RootObject::IntegerClass ::getClassName(),  new RootObject::IntegerClass());
}

JavascriptEngine::~JavascriptEngine() {}

void JavascriptEngine::prepareTimeout() const noexcept   { root->timeout = Time::getCurrentTime() + maximumExecutionTime; }
void JavascriptEngine::stop() noexcept                   { root->timeout = {}; }

void JavascriptEngine::registerNativeObject (const Identifier& name, DynamicObject* object)
{
    root->setProperty (name, object);
}

Result JavascriptEngine::execute (const String& code)
{
    try
    {
        prepareTimeout();
        root->execute (code);
    }
    catch (String& error)
    {
        return Result::fail (error);
    }

    return Result::ok();
}

var JavascriptEngine::evaluate (const String& code, Result* result)
{
    try
    {
        prepareTimeout();
        if (result != nullptr) *result = Result::ok();
        return root->evaluate (code);
    }
    catch (String& error)
    {
        if (result != nullptr) *result = Result::fail (error);
    }

    return var::undefined();
}

var JavascriptEngine::callFunction (const Identifier& function, const var::NativeFunctionArgs& args, Result* result)
{
    var returnVal (var::undefined());

    try
    {
        prepareTimeout();
        if (result != nullptr) *result = Result::ok();
        RootObject::Scope (nullptr, root, root).findAndInvokeMethod (function, args, returnVal);
    }
    catch (String& error)
    {
        if (result != nullptr) *result = Result::fail (error);
    }

    return returnVal;
}

var JavascriptEngine::callFunctionObject (DynamicObject* objectScope, const var& functionObject,
                                          const var::NativeFunctionArgs& args, Result* result)
{
    var returnVal (var::undefined());

    try
    {
        prepareTimeout();
        if (result != nullptr) *result = Result::ok();
        RootObject::Scope rootScope (nullptr, root, root);
        RootObject::Scope (&rootScope, root, objectScope).invokeMethod (functionObject, args, returnVal);
    }
    catch (String& error)
    {
        if (result != nullptr) *result = Result::fail (error);
    }

    return returnVal;
}

const NamedValueSet& JavascriptEngine::getRootObjectProperties() const noexcept
{
    return root->getProperties();
}

#if JUCE_MSVC
 #pragma warning (pop)
#endif