juce_Expression.h

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 /*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   The code included in this file is provided 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.
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce
{
 
//==============================================================================
class JUCE_API  Expression
{
public:
    //==============================================================================
    Expression();
 
    ~Expression();
 
    Expression (const Expression&);
 
    Expression& operator= (const Expression&);
 
    Expression (Expression&&) noexcept;
 
    Expression& operator= (Expression&&) noexcept;
 
    explicit Expression (double constant);
 
    Expression (const String& stringToParse, String& parseError);
 
    String toString() const;
 
    Expression operator+ (const Expression&) const;
    Expression operator- (const Expression&) const;
    Expression operator* (const Expression&) const;
    Expression operator/ (const Expression&) const;
    Expression operator-() const;
 
    static Expression symbol (const String& symbol);
 
    static Expression function (const String& functionName, const Array<Expression>& parameters);
 
    static Expression parse (String::CharPointerType& stringToParse, String& parseError);
 
    //==============================================================================
    class JUCE_API  Scope
    {
    public:
        Scope();
        virtual ~Scope();
 
        virtual String getScopeUID() const;
 
        virtual Expression getSymbolValue (const String& symbol) const;
 
        virtual double evaluateFunction (const String& functionName,
                                         const double* parameters, int numParameters) const;
 
        class Visitor
        {
        public:
            virtual ~Visitor() = default;
            virtual void visit (const Scope&) = 0;
        };
 
        virtual void visitRelativeScope (const String& scopeName, Visitor& visitor) const;
    };
 
    double evaluate() const;
 
    double evaluate (const Scope& scope) const;
 
    double evaluate (const Scope& scope, String& evaluationError) const;
 
    Expression adjustedToGiveNewResult (double targetValue, const Scope& scope) const;
 
    struct Symbol
    {
        Symbol (const String& scopeUID, const String& symbolName);
        bool operator== (const Symbol&) const noexcept;
        bool operator!= (const Symbol&) const noexcept;
 
        String scopeUID;    
        String symbolName;  
    };
 
    Expression withRenamedSymbol (const Symbol& oldSymbol, const String& newName, const Scope& scope) const;
 
    bool referencesSymbol (const Symbol& symbol, const Scope& scope) const;
 
    bool usesAnySymbols() const;
 
    void findReferencedSymbols (Array<Symbol>& results, const Scope& scope) const;
 
    //==============================================================================
    enum Type
    {
        constantType,
        functionType,
        operatorType,
        symbolType
    };
 
    Type getType() const noexcept;
 
    String getSymbolOrFunction() const;
 
    int getNumInputs() const;
 
    Expression getInput (int index) const;
 
private:
    //==============================================================================
    class Term;
    struct Helpers;
    ReferenceCountedObjectPtr<Term> term;
 
    explicit Expression (Term*);
};
 
} // namespace juce