Upsilon/Upsilon/Evaluator/EvaluationScope.cs

using System.Collections.Generic;
using Upsilon.BaseTypes;
using Upsilon.Binder;

namespace Upsilon.Evaluator
{
    internal class EvaluationScope
    {
        private readonly EvaluationScope _parentScope;
        private EvaluationScope _getOnlyParentScope;

        internal readonly Dictionary<string, LuaType> Variables;
        internal readonly Dictionary<string, LuaType> LocalVariables;


        internal EvaluationScope(EvaluationScope parentScope)
        {
            _parentScope = parentScope;
            Variables = new Dictionary<string, LuaType>();
            LocalVariables = new Dictionary<string, LuaType>();
        }

        internal EvaluationScope(Dictionary<string, LuaType> vars)
        {
            Variables  = vars;
            LocalVariables = new Dictionary<string, LuaType>();
        }

        internal static EvaluationScope CreateWithGetOnlyParent(EvaluationScope parent)
        {
            var scope = new EvaluationScope(new Dictionary<string, LuaType>()) {_getOnlyParentScope = parent};
            return scope;
        }

        public void Set(VariableSymbol symbol, LuaType obj)
        {
            if (symbol.Local)
            {
                if (LocalVariables.ContainsKey(symbol.Name))
                {
                    LocalVariables[symbol.Name] = obj;
                }
                else
                {
                    LocalVariables.Add(symbol.Name, obj);
                }
            }
            else
            {
                if (Variables.ContainsKey(symbol.Name))
                {
                    Variables[symbol.Name] = obj;
                }
                else
                {
                    Variables.Add(symbol.Name, obj);
                }

            }
        }

        public void SetGlobal(VariableSymbol symbol, LuaType obj)
        {
            if (_parentScope != null)
                _parentScope.SetGlobal(symbol, obj);
            else
            {
                Set(symbol, obj);
            }
        }

        public bool TryGet(VariableSymbol symbol, out LuaType obj)
        {
            if (LocalVariables.TryGetValue(symbol.Name, out obj))
                return true;
            if (Variables.TryGetValue(symbol.Name, out obj))
                return true;
            if (_parentScope != null)
                if (_parentScope.TryGet(symbol, out obj))
                    return true;
            if (_getOnlyParentScope != null)
                if (_getOnlyParentScope.TryGet(symbol, out obj))
                    return true;
            return false;
        }

        public bool TryGet(string variable, out LuaType obj)
        {
            if (LocalVariables.TryGetValue(variable, out obj))
                return true;
            if (Variables.TryGetValue(variable, out obj))
                return true;
            if (_parentScope != null)
                if (_parentScope.TryGet(variable, out obj))
                    return true;
            if (_getOnlyParentScope != null)
                if (_getOnlyParentScope.TryGet(variable, out obj))
                    return true;
            return false;
        }
    }
}