Implement handling of goto. Allow functions to be part of an expressi…

…on (e.g. function call in if() statement)
ethanmoffat · Jan 30, 2022 · 4421603 · 4421603
1 parent 81a0279
commit 4421603
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Showing 10 changed files with 91 additions and 55 deletions.
diff --git a/EOBot/EOBot.csproj b/EOBot/EOBot.csproj
@@ -105,6 +105,7 @@
     <Compile Include="Interpreter\States\ExpressionEvaluator.cs" />
     <Compile Include="Interpreter\States\ExpressionTailEvaluator.cs" />
     <Compile Include="Interpreter\States\FunctionEvaluator.cs" />
+    <Compile Include="Interpreter\States\GotoEvaluator.cs" />
     <Compile Include="Interpreter\States\IfEvaluator.cs" />
     <Compile Include="Interpreter\States\IScriptEvaluator.cs" />
     <Compile Include="Interpreter\States\KeywordEvaluator.cs" />
@@ -126,7 +127,6 @@
     <Compile Include="Interpreter\Variables\IIdentifiable.cs" />
     <Compile Include="Interpreter\Variables\IntVariable.cs" />
     <Compile Include="Interpreter\Variables\IVariable.cs" />
-    <Compile Include="Interpreter\Variables\LabelIdentifier.cs" />
     <Compile Include="Interpreter\Variables\StringVariable.cs" />
     <Compile Include="NamesList.cs" />
     <Compile Include="Program.cs" />

diff --git a/EOBot/Interpreter/BotInterpreter.cs b/EOBot/Interpreter/BotInterpreter.cs
@@ -58,6 +58,7 @@ public void Run(ArgumentsParser parsedArgs, IReadOnlyList<BotToken> tokens)
             evaluators.Add(new ExpressionTailEvaluator(evaluators));
             evaluators.Add(new OperandEvaluator(evaluators));
             evaluators.Add(new IfEvaluator(evaluators));
+            evaluators.Add(new GotoEvaluator());
 
             var scriptEvaluator = new ScriptEvaluator(evaluators);
 

diff --git a/EOBot/Interpreter/BotTokenParser.cs b/EOBot/Interpreter/BotTokenParser.cs
@@ -86,7 +86,7 @@ public BotToken GetNextToken()
             if (char.IsLetter(inputChar))
             {
                 var identifier = inputChar.ToString();
-                while (char.IsLetterOrDigit((char)_inputStream.Peek()))
+                while (char.IsLetterOrDigit(Peek()) || Peek() == '_')
                     identifier += Read();
 
                 var type = Keywords.Contains(identifier)

diff --git a/EOBot/Interpreter/States/ExpressionEvaluator.cs b/EOBot/Interpreter/States/ExpressionEvaluator.cs
@@ -44,22 +44,29 @@ public bool Evaluate(ProgramState input)
             {
                 // an expression can be a function call
                 if (_evaluators.OfType<FunctionEvaluator>().Single().Evaluate(input))
-                    return true;
-
-                if (!_evaluators.OfType<OperandEvaluator>().Single().Evaluate(input))
-                    return false;
-
-                // expression_tail is optional
-                if (!_evaluators.OfType<ExpressionTailEvaluator>().Single().Evaluate(input))
                 {
-                    if (input.OperationStack.Count == 0)
+                    // there may or may not be an expression tail after a function call
+                    if (!_evaluators.OfType<ExpressionTailEvaluator>().Single().Evaluate(input))
+                        return true;
+                }
+                else
+                {
+
+                    if (!_evaluators.OfType<OperandEvaluator>().Single().Evaluate(input))
                         return false;
 
-                    // convert to variable token (resolve identifier) so consumer of expression result can use it
-                    var singleOperand = GetOperand(input);
-                    input.OperationStack.Push(singleOperand);
+                    // expression_tail is optional
+                    if (!_evaluators.OfType<ExpressionTailEvaluator>().Single().Evaluate(input))
+                    {
+                        if (input.OperationStack.Count == 0)
+                            return false;
 
-                    return true;
+                        // convert to variable token (resolve identifier) so consumer of expression result can use it
+                        var singleOperand = GetOperand(input);
+                        input.OperationStack.Push(singleOperand);
+
+                        return true;
+                    }
                 }
             }
 

diff --git a/EOBot/Interpreter/States/GotoEvaluator.cs b/EOBot/Interpreter/States/GotoEvaluator.cs
@@ -0,0 +1,23 @@
+using EOBot.Interpreter.Extensions;
+
+namespace EOBot.Interpreter.States
+{
+    public class GotoEvaluator : IScriptEvaluator
+    {
+        public bool Evaluate(ProgramState input)
+        {
+            // ensure we have the right keyword before advancing the program
+            var current = input.Current();
+            if (current.TokenType != BotTokenType.Keyword || current.TokenValue != "goto")
+                return false;
+
+            input.Expect(BotTokenType.Keyword);
+
+            if (!input.Match(BotTokenType.Identifier))
+                return false;
+
+            var label = input.OperationStack.Pop().TokenValue;
+            return input.Goto(input.Labels[label]);
+        }
+    }
+}
diff --git a/EOBot/Interpreter/States/IfEvaluator.cs b/EOBot/Interpreter/States/IfEvaluator.cs
@@ -37,6 +37,10 @@ public bool Evaluate(ProgramState input)
                 if ((input.Expect(BotTokenType.LBrace) && !_evaluators.OfType<StatementListEvaluator>().Single().Evaluate(input)) ||
                     !_evaluators.OfType<StatementEvaluator>().Single().Evaluate(input))
                     return false;
+
+                // hack: put the \n token back since StatementList/Statement will have consumed it
+                if (input.Program[input.ExecutionIndex - 1].TokenType == BotTokenType.NewLine)
+                    input.Goto(input.ExecutionIndex - 1);
             }
             else if (input.Expect(BotTokenType.LBrace))
             {

diff --git a/EOBot/Interpreter/States/KeywordEvaluator.cs b/EOBot/Interpreter/States/KeywordEvaluator.cs
@@ -14,9 +14,9 @@ public KeywordEvaluator(IEnumerable<IScriptEvaluator> evaluators)
 
         public bool Evaluate(ProgramState input)
         {
-            return Evaluate<IfEvaluator>(input);
+            return Evaluate<IfEvaluator>(input)
                     //|| Evaluate<WhileEvaluator>(input)
-                    //|| Evaluate<GotoEvaluator>(input);
+                    || Evaluate<GotoEvaluator>(input);
         }
 
         private bool Evaluate<T>(ProgramState input)

diff --git a/EOBot/Interpreter/States/LabelEvaluator.cs b/EOBot/Interpreter/States/LabelEvaluator.cs
@@ -1,27 +1,10 @@
-using EOBot.Interpreter.Variables;
-
-namespace EOBot.Interpreter.States
+namespace EOBot.Interpreter.States
 {
     public class LabelEvaluator : IScriptEvaluator
     {
         public bool Evaluate(ProgramState input)
         {
-            if (!input.MatchPair(BotTokenType.Identifier, BotTokenType.Colon))
-                return false;
-
-            if (input.OperationStack.Count < 2)
-                return false;
-
-            // pop the colon
-            input.OperationStack.Pop();
-
-            var labelToken = input.OperationStack.Pop();
-            if (labelToken.TokenType != BotTokenType.Identifier)
-                return false;
-
-            input.Labels.Add(new LabelIdentifier(labelToken.TokenValue), input.ExecutionIndex);
-
-            return true;
+            return input.ExpectPair(BotTokenType.Identifier, BotTokenType.Colon);
         }
     }
-}
+}
diff --git a/EOBot/Interpreter/States/ProgramState.cs b/EOBot/Interpreter/States/ProgramState.cs
@@ -1,5 +1,7 @@
 using EOBot.Interpreter.Variables;
+using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace EOBot.Interpreter.States
 {
@@ -11,7 +13,7 @@ public class ProgramState
 
         public Dictionary<string, (bool ReadOnly, IIdentifiable Identifiable)> SymbolTable { get; }
 
-        public Dictionary<LabelIdentifier, int> Labels { get; }
+        public Dictionary<string, int> Labels { get; }
 
         public int ExecutionIndex { get; private set; }
 
@@ -20,10 +22,27 @@ public ProgramState(IReadOnlyList<BotToken> program)
             OperationStack = new Stack<BotToken>();
             Program = program;
             SymbolTable = new Dictionary<string, (bool ReadOnly, IIdentifiable Identifiable)>();
-            Labels = new Dictionary<LabelIdentifier, int>();
+            Labels = Program
+                .Select((token, ndx) => (token, ndx))
+                .Where(x => x.token.TokenType == BotTokenType.Identifier && Program[x.ndx + 1].TokenType == BotTokenType.Colon)
+                .ToDictionary(x => x.token.TokenValue, y => y.ndx + 2);
             ExecutionIndex = 0;
         }
 
+        public void SkipToken()
+        {
+            ExecutionIndex++;
+        }
+
+        public bool Goto(int executionIndex)
+        {
+            if (executionIndex >= Program.Count)
+                return false;
+
+            ExecutionIndex = executionIndex;
+            return true;
+        }
+
         /// <summary>
         /// Check for a token at the program's execution index. If it is the expected type, increment execution index.
         /// </summary>
@@ -41,11 +60,6 @@ public bool Expect(BotTokenType tokenType)
             return false;
         }
 
-        internal void SkipToken()
-        {
-            ExecutionIndex++;
-        }
-
         /// <summary>
         /// Check for a token at the program's execution index. If it is the expected type, push it onto the operation stack and increment execution index.
         /// </summary>
@@ -64,10 +78,25 @@ public bool Match(BotTokenType tokenType)
             return false;
         }
 
+        public bool ExpectPair(BotTokenType first, BotTokenType second)
+        {
+            if (ExecutionIndex >= Program.Count - 1)
+                return false;
+
+            if (Program[ExecutionIndex].TokenType == first &&
+                Program[ExecutionIndex + 1].TokenType == second)
+            {
+                ExecutionIndex += 2;
+                return true;
+            }
+
+            return false;
+        }
+
         /// <summary>
         /// Matches a pair of tokens in order at the program's execution index.
         /// </summary>
-        internal bool MatchPair(BotTokenType first, BotTokenType second)
+        public bool MatchPair(BotTokenType first, BotTokenType second)
         {
             if (ExecutionIndex >= Program.Count - 1)
                 return false;

diff --git a/EOBot/Interpreter/Variables/LabelIdentifier.cs b/EOBot/Interpreter/Variables/LabelIdentifier.cs