ChakraCore/lib/Runtime/ByteCode/Scope.h

//-------------------------------------------------------------------------------------------------------
// Copyright (C) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
//-------------------------------------------------------------------------------------------------------

enum ScopeType
{
    ScopeType_Unknown,
    ScopeType_Global,
    ScopeType_GlobalEvalBlock,
    ScopeType_FunctionBody,
    ScopeType_FuncExpr,
    ScopeType_Block,
    ScopeType_Catch,
    ScopeType_CatchParamPattern,
    ScopeType_With,
    ScopeType_Parameter
};

class Scope
{
private:
    Scope *enclosingScope;
    Js::RegSlot location;
    FuncInfo *func;
    SymbolTable *symbolTable;
    Symbol *m_symList;
    int m_count;
    ArenaAllocator *alloc;
    uint scopeSlotCount; // count of slots in the local scope
    uint innerScopeIndex;
    ScopeType const scopeType;
    BYTE isDynamic : 1;
    BYTE isObject : 1;
    BYTE canMerge : 1;
    BYTE capturesAll : 1;
    BYTE mustInstantiate : 1;
    BYTE hasCrossScopeFuncAssignment : 1;
public:
#if DBG
    BYTE isRestored : 1;
#endif
    Scope(ArenaAllocator *alloc, ScopeType scopeType, bool useSymbolTable = false, int capacity = 0) :
        alloc(alloc),
        func(nullptr),
        enclosingScope(nullptr),
        isDynamic(false),
        isObject(false),
        canMerge(true),
        capturesAll(false),
        mustInstantiate(false),
        hasCrossScopeFuncAssignment(false),
        location(Js::Constants::NoRegister),
        symbolTable(nullptr),
        m_symList(nullptr),
        m_count(0),
        scopeSlotCount(0),
        innerScopeIndex((uint)-1),
        scopeType(scopeType)
#if DBG
        , isRestored(false)
#endif
    {
        if (useSymbolTable)
        {
            symbolTable = Anew(alloc, SymbolTable, alloc, capacity);
        }
    }

    ~Scope()
    {
        if (symbolTable)
        {
            Adelete(alloc, symbolTable);
            symbolTable = nullptr;
        }
    }

    Symbol *FindLocalSymbol(SymbolName const& key)
    {
        Symbol *sym = nullptr;
        if (symbolTable)
        {
            return symbolTable->Lookup(key);
        }
        for (sym = m_symList; sym; sym = sym->GetNext())
        {
            if (sym->GetName() == key)
            {
                break;
            }
        }
        return sym;
    }

    template<class Fn>
    void ForEachSymbol(Fn fn)
    {
        if (symbolTable)
        {
            symbolTable->Map(fn);
        }
        else
        {
            for (Symbol *sym = m_symList; sym;)
            {
                Symbol *next = sym->GetNext();
                fn(sym);
                sym = next;
            }
        }
    }

    template<class Fn>
    void ForEachSymbolUntil(Fn fn)
    {
        if (symbolTable)
        {
            symbolTable->MapUntil(fn);
        }
        else
        {
            for (Symbol *sym = m_symList; sym;)
            {
                Symbol *next = sym->GetNext();
                if (fn(sym))
                {
                    return;
                }
                sym = next;
            }
        }
    }

    // For JScript, this should not return NULL because
    // there is always an enclosing global scope.
    Symbol *FindSymbol(SymbolName const& name, SymbolType symbolType, bool fCreate = true)
    {
        Symbol *sym = FindLocalSymbol(name);
        if (sym == nullptr)
        {
            if (enclosingScope != nullptr)
            {
                sym = enclosingScope->FindSymbol(name, symbolType);
            }
            else if (fCreate)
            {
                sym = Anew(alloc, Symbol, name, nullptr, symbolType);
                AddNewSymbol(sym);
            }
        }
        return sym;
    }

    void AddSymbol(Symbol *sym)
    {
        if (enclosingScope == nullptr)
        {
            sym->SetIsGlobal(true);
        }
        sym->SetScope(this);
        if (symbolTable)
        {
            symbolTable->AddNew(sym);
        }
        else
        {
            for (Symbol *symInList = m_symList; symInList; symInList = symInList->GetNext())
            {
                if (symInList->GetName() == sym->GetName())
                {
                    return;
                }
            }
            sym->SetNext(m_symList);
            m_symList = sym;
            m_count++;
        }
    }

    void AddNewSymbol(Symbol *sym)
    {
        if (scopeType == ScopeType_Global)
        {
            sym->SetIsGlobal(true);
        }
        sym->SetScope(this);
        if (symbolTable)
        {
            symbolTable->Add(sym);
        }
        else
        {
            sym->SetNext(m_symList);
            m_symList = sym;
            m_count++;
        }
    }

    bool HasStaticPathToAncestor(Scope const * target) const
    {
        return target == this || (!isDynamic && enclosingScope != nullptr && enclosingScope->HasStaticPathToAncestor(target));
    }

    void SetEnclosingScope(Scope *enclosingScope)
    {
        // Check for scope cycles
        Assert(enclosingScope != this);
        Assert(enclosingScope == nullptr || this != enclosingScope->GetEnclosingScope());
        this->enclosingScope = enclosingScope;
    }

    Scope *GetEnclosingScope() const
    {
        return enclosingScope;
    }

    ScopeType GetScopeType() const
    {
        return this->scopeType;
    }

    bool IsInnerScope() const
    {
        return scopeType == ScopeType_Block || scopeType == ScopeType_Catch || scopeType == ScopeType_CatchParamPattern || scopeType == ScopeType_GlobalEvalBlock;
    }

    int Count() const
    {
        if (symbolTable)
        {
            return symbolTable->Count();
        }
        return m_count;
    }

    void SetFunc(FuncInfo *func)
    {
        this->func = func;
    }

    FuncInfo *GetFunc() const
    {
        return func;
    }

    FuncInfo *GetEnclosingFunc()
    {
        Scope *scope = this;
        while (scope && scope->func == nullptr)
        {
            scope = scope->GetEnclosingScope();
        }
        AnalysisAssert(scope);
        return scope->func;
    }

    void SetLocation(Js::RegSlot loc) { location = loc; }
    Js::RegSlot GetLocation() const { return location; }

    void SetIsDynamic(bool is) { isDynamic = is; }
    bool GetIsDynamic() const { return isDynamic; }

    bool IsEmpty() const;

    bool IsBlockScope(FuncInfo *funcInfo);

    void SetIsObject();
    bool GetIsObject() const { return isObject; }

    void SetCapturesAll(bool does) { capturesAll = does; }
    bool GetCapturesAll() const { return capturesAll; }

    void SetMustInstantiate(bool must) { mustInstantiate = must; }
    bool GetMustInstantiate() const { return mustInstantiate; }

    void SetCanMerge(bool can) { canMerge = can; }
    bool GetCanMerge() const { return canMerge && !mustInstantiate && !isObject; }

    void SetScopeSlotCount(uint i) { scopeSlotCount = i; }
    uint GetScopeSlotCount() const { return scopeSlotCount; }

    void SetHasLocalInClosure(bool has);

    bool HasInnerScopeIndex() const { return innerScopeIndex != (uint)-1; }
    uint GetInnerScopeIndex() const { return innerScopeIndex; }
    void SetInnerScopeIndex(uint index) { Assert(innerScopeIndex == (uint)-1 || innerScopeIndex == index); innerScopeIndex = index; }

    int AddScopeSlot();

    void SetHasCrossScopeFuncAssignment() { hasCrossScopeFuncAssignment = true; }

    void ForceAllSymbolNonLocalReference(ByteCodeGenerator *byteCodeGenerator);

    bool IsGlobalEvalBlockScope() const;

    static void MergeParamAndBodyScopes(ParseNode *pnodeScope, ByteCodeGenerator * byteCodeGenerator);
};