Functionality for indexing tables

Upsilon/BaseTypes/IIndexable.cs

@@ -0,0 +1,8 @@
+namespace Upsilon.BaseTypes
+{
+    public interface IIndexable
+    {
+        LuaType Get(string s, int scopeIdentifier);
+        int EvaluatorIdentifier { get; }
+    }
+}

Upsilon/BaseTypes/LuaString.cs

@@ -71,5 +71,10 @@ namespace Upsilon.BaseTypes
         {
             return new LuaString(a.Value + b.Value);
         }
+
+        public override string ToString()
+        {
+            return Value;
+        }
     }
 }

Upsilon/BaseTypes/LuaTable.cs

@@ -4,20 +4,23 @@ using Upsilon.Binder;
 
 namespace Upsilon.BaseTypes
 {
-    public class LuaTable : LuaType
+    public class LuaTable : LuaType, IIndexable
     {
-        private Dictionary<string, VariableSymbol> _variableLookup;
+        private readonly Dictionary<string, VariableSymbol> _variableLookup;
-        private Dictionary<VariableSymbol, LuaType> _map;
+        private readonly Dictionary<VariableSymbol, LuaType> _map;
+        public int EvaluatorIdentifier { get; }
 
-        public LuaTable()
+        public LuaTable(int scopeIdentifier)
         {
+            EvaluatorIdentifier = scopeIdentifier;
             _map = new Dictionary<VariableSymbol, LuaType>();
             _variableLookup = new Dictionary<string, VariableSymbol>();
         }
 
-        public LuaTable(Dictionary<VariableSymbol, LuaType> map)
+        public LuaTable(Dictionary<VariableSymbol, LuaType> map, int scopeIdentifier)
         {
             _map = map;
+            EvaluatorIdentifier = scopeIdentifier;
             _variableLookup = map.ToDictionary(x => x.Key.Name, x => x.Key);
         }
 
@@ -29,5 +32,14 @@ namespace Upsilon.BaseTypes
         }
 
 
+        public LuaType Get(string s, int scopeIdentifier)
+        {
+            if (!_variableLookup.TryGetValue(s, out var variableSymbol))
+                return new LuaNull();
+            if (EvaluatorIdentifier != scopeIdentifier && variableSymbol.Local)
+                return new LuaNull();
+            return _map[variableSymbol];
+        }
+
     }
 }

Upsilon/Binder/Binder.cs

@@ -80,6 +80,8 @@ namespace Upsilon.Binder
                     return BindFunctionCallExpression((FunctionCallExpressionSyntax) e);
                 case SyntaxKind.TableExpression:
                     return BindTableExpression((TableExpressionSyntax) e);
+                case SyntaxKind.IndexExpression:
+                    return BindIndexExpression((IndexExpressionSyntax) e);
                 case SyntaxKind.BadExpression:
                     break;
                 case SyntaxKind.ScriptUnit:
@@ -216,8 +218,16 @@ namespace Upsilon.Binder
 
             var isLocal = e.LocalToken != null;
             if (!Scope.TryGetVariable(name, !isLocal, out var variable))
+            {
+                if (boundExpression.Type == Type.Table)
+                {
+                    var tableExpression = (BoundTableExpression) boundExpression;
+                    variable = new TableVariableSymbol(name, tableExpression.ValueType, isLocal);
+                }
+                else
                 {
                     variable = new VariableSymbol(name, boundExpression.Type, isLocal);
+                }
                 if (isLocal)
                     Scope.SetVariable(variable);
                 else
@@ -375,5 +385,26 @@ namespace Upsilon.Binder
             return new BoundTableExpression(keyType, valueType, dictionary, statements);
         }
 
+        private BoundExpression BindIndexExpression(IndexExpressionSyntax e)
+        {
+            var name = e.Identifier.Name;
+            if (!Scope.TryGetVariable(name, true, out var variable))
+            {
+                _diagnostics.LogUnknownVariable(e.Identifier.Span, name);
+                return new BoundLiteralExpression(new LuaNull());
+            }
+
+            if (variable.Type != Type.Table)
+            {
+                //TODO better error message
+                _diagnostics.LogUnknownVariable(e.Identifier.Span, name);
+                return new BoundLiteralExpression(new LuaNull());
+            }
+
+            var tableVariable = (TableVariableSymbol) variable;
+            var outType = tableVariable.OutType;
+            var index = BindExpression(e.Index);
+            return new BoundIndexExpression(tableVariable, index, outType);
+        }
     }
 }

Upsilon/Binder/BoundExpressions/BoundIndexExpression.cs

@@ -0,0 +1,21 @@
+using Upsilon.BaseTypes;
+using Upsilon.Parser;
+
+namespace Upsilon.Binder
+{
+    public class BoundIndexExpression : BoundExpression
+    {
+        public BoundIndexExpression(TableVariableSymbol identifier, BoundExpression index, Type type)
+        {
+            Identifier = identifier;
+            Index = index;
+            Type = type;
+        }
+
+        public TableVariableSymbol Identifier { get; }
+        public BoundExpression Index { get; }
+
+        public override BoundKind Kind => BoundKind.BoundIndexExpression;
+        public override Type Type { get; }
+    }
+}

Upsilon/Binder/BoundKind.cs

@@ -10,6 +10,7 @@ namespace Upsilon.Binder
         VariableExpression,
         BoundFunctionCallExpression,
         BoundTableExpression,
+        BoundIndexExpression,
 
         // Statements
         BoundAssignmentStatement,

Upsilon/Binder/VariableSymbol.cs

@@ -28,4 +28,15 @@ namespace Upsilon.Binder
             Parameters = parameters;
         }
     }
+
+    public class TableVariableSymbol : VariableSymbol
+    {
+        public Type OutType { get; }
+
+        public TableVariableSymbol(string name, Type outType, bool local)
+        :base (name, Type.Table, local)
+        {
+            OutType = outType;
+        }
+    }
 }

Upsilon/Evaluator/EvaluationScope.cs

@@ -9,6 +9,7 @@ namespace Upsilon.Evaluator
         private readonly EvaluationScope _parentScope;
         internal readonly Dictionary<VariableSymbol, LuaType> Variables;
 
+
         internal EvaluationScope(EvaluationScope parentScope)
         {
             _parentScope = parentScope;

Upsilon/Evaluator/Evaluator.cs

@@ -15,17 +15,26 @@ namespace Upsilon.Evaluator
         private LuaType _returnValue;
         internal EvaluationScope Scope { get; }
         private bool HasReturned { get; set; }
+        public int Identifier { get; }
 
         internal Evaluator(Diagnostics diagnostics, Dictionary<VariableSymbol, LuaType> variables)
         {
             _diagnostics = diagnostics;
             Scope       = new EvaluationScope(variables);
+            Identifier = new Random().Next();
         }
 
         private Evaluator(Diagnostics diagnostics, EvaluationScope parentScope)
         {
             _diagnostics = diagnostics;
             Scope        = new EvaluationScope(parentScope);
+            Identifier   = new Random().Next();
+        }
+        private Evaluator(Diagnostics diagnostics, EvaluationScope parentScope, int identifier)
+        {
+            _diagnostics = diagnostics;
+            Scope        = new EvaluationScope(parentScope);
+            Identifier = identifier;
         }
 
         public LuaType Evaluate(BoundScript e)
@@ -138,6 +147,8 @@ namespace Upsilon.Evaluator
                     return EvaluateBoundFunctionCallExpression((BoundFunctionCallExpression) e);
                 case BoundKind.BoundTableExpression:
                     return EvaluateTableExpression((BoundTableExpression) e);
+                case BoundKind.BoundIndexExpression:
+                    return EvaluateIndexExpression((BoundIndexExpression) e);
                 default:
                     throw new NotImplementedException();
             }
@@ -317,7 +328,25 @@ namespace Upsilon.Evaluator
                 }
                 currentPos++;
             }
-            return new LuaTable(dic);
+            return new LuaTable(dic, innerEvaluator.Identifier);
+        }
+
+        private LuaType EvaluateIndexExpression(BoundIndexExpression e)
+        {
+            if (!Scope.TryGet(e.Identifier, out var val))
+            {
+                throw new Exception($"Cannot find variable: '{e.Identifier.Name}'");
+            }
+
+            if (!(val is IIndexable indexable))
+            {
+                throw new Exception("Variable is not indexable.");
+            }
+
+            var innerEvaluator = new Evaluator(_diagnostics, Scope, indexable.EvaluatorIdentifier);
+            var indexer = EvaluateExpression(e.Index);
+
+            return indexable.Get(indexer.ToString(), Identifier);
         }
     }
 }

Upsilon/Parser/ExpressionSyntax/IndexExpressionSyntax.cs

@@ -0,0 +1,30 @@
+using System.Collections.Generic;
+
+namespace Upsilon.Parser
+{
+    public class IndexExpressionSyntax : ExpressionSyntax
+    {
+        public IdentifierToken Identifier { get; }
+        public SyntaxToken OpenBracket { get; }
+        public ExpressionSyntax Index { get; }
+        public SyntaxToken CloseBracket { get; }
+
+        public IndexExpressionSyntax(IdentifierToken identifier, SyntaxToken openBracket, ExpressionSyntax index,
+            SyntaxToken closeBracket)
+        {
+            Identifier = identifier;
+            OpenBracket = openBracket;
+            Index = index;
+            CloseBracket = closeBracket;
+        }
+
+        public override SyntaxKind Kind => SyntaxKind.IndexExpression;
+        public override IEnumerable<SyntaxNode> ChildNodes()
+        {
+            yield return Identifier;
+            yield return OpenBracket;
+            yield return Index;
+            yield return CloseBracket;
+        }
+    }
+}

Upsilon/Parser/Lexer.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Immutable;
 using System.Text;
 using Upsilon.Text;
@@ -69,6 +70,10 @@ namespace Upsilon.Parser
                     return new SyntaxToken(SyntaxKind.OpenBrace, _position, "{", null);
                 case '}':
                     return new SyntaxToken(SyntaxKind.CloseBrace, _position, "}", null);
+                case '[':
+                    return new SyntaxToken(SyntaxKind.OpenBracket, _position, "[", null);
+                case ']':
+                    return new SyntaxToken(SyntaxKind.CloseBracket, _position, "]", null);
                 case ',':
                     return new SyntaxToken(SyntaxKind.Comma, _position, ",", null);
                 case '"':
@@ -112,6 +117,7 @@ namespace Upsilon.Parser
                     }
                     hasDecimalPoint = true;
                 }
+                if (Next != '_')
                     numStr.Append(Next);
                 _position++;
             }

Upsilon/Parser/Parser.cs

@@ -228,6 +228,8 @@ namespace Upsilon.Parser
                 case SyntaxKind.Identifier:
                     if (Next.Kind == SyntaxKind.OpenParenthesis)
                         return ParseFunctionCallExpression();
+                    if (Next.Kind == SyntaxKind.OpenBracket)
+                        return ParseIndexExpression();
                     var token = MatchToken(SyntaxKind.Identifier);
                     return new VariableExpressionSyntax((IdentifierToken) token);
                 case SyntaxKind.OpenBrace:
@@ -260,6 +262,15 @@ namespace Upsilon.Parser
                 parameters.ToImmutable(), closeParenthesis);
         }
 
+        private ExpressionSyntax ParseIndexExpression()
+        {
+            var identifier = (IdentifierToken)MatchToken(SyntaxKind.Identifier);
+            var openBracket = MatchToken(SyntaxKind.OpenBracket);
+            var index = ParseExpression();
+            var closeBracket = MatchToken(SyntaxKind.CloseBracket);
+            return new IndexExpressionSyntax(identifier, openBracket, index, closeBracket);
+        }
+
         private ExpressionSyntax ParseParenthesizedExpression()
         {
             var l = MatchToken(SyntaxKind.OpenParenthesis);

Upsilon/Parser/SyntaxKind.cs

@@ -23,6 +23,8 @@ namespace Upsilon.Parser
         String,
         OpenBrace,
         CloseBrace,
+        OpenBracket,
+        CloseBracket,
 
         // key words
         TrueKeyword,
@@ -52,6 +54,7 @@ namespace Upsilon.Parser
         FunctionCallExpression,
         BadExpression,
         TableExpression,
+        IndexExpression,
 
         // script unit
         ScriptUnit,

UpsilonTests/TableTests.cs

@@ -0,0 +1,81 @@
+using Upsilon.Evaluator;
+using Xunit;
+
+namespace UpsilonTests
+{
+    public class TableTests
+    {
+        [Fact]
+        public void BasicNumberTable()
+        {
+            const string input = @"
+table = {
+    100, 200, 300
+}
+return table[2]
+";
+            var script = new Script(input);
+            Assert.Empty(script.Diagnostics.Messages);
+            var evaluated = script.Evaluate<long>();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Equal(200, evaluated);
+        }
+
+        [Fact]
+        public void BasicStringTable()
+        {
+            const string input = @"
+table = {
+    test = 100,
+    val = 400,
+    another = 10_000,
+}
+return table[""another""]
+";
+            var script = new Script(input);
+            Assert.Empty(script.Diagnostics.Messages);
+            var evaluated = script.Evaluate<long>();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Equal(10_000, evaluated);
+        }
+
+        [Fact]
+        public void HidesLocalKeys()
+        {
+            const string input = @"
+table = {
+    local test = 100,
+    val = 400,
+    another = 10_000,
+}
+return table[""test""]
+";
+            var script = new Script(input);
+            Assert.Empty(script.Diagnostics.Messages);
+            var evaluated = script.Evaluate();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Null(evaluated);
+        }
+
+        [Fact]
+        public void FunctionsInTable()
+        {
+            const string input = @"
+table = {
+    function() test
+        return 100
+    end
+    val = 400,
+    another = 10_000,
+}
+return table[""test""]()
+";
+            var script = new Script(input);
+            Assert.Empty(script.Diagnostics.Messages);
+            var evaluated = script.Evaluate<long>();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Equal(100, evaluated);
+        }
+
+    }
+}