Evaluate all non-binding expressions
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parent
b1607eebc6
commit
f9df52b5f9
196
Interpreter.cs
196
Interpreter.cs
@ -1,4 +1,5 @@
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using System;
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using System.Collections.Generic;
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using System.Collections.Immutable;
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using AST = Finn.AST;
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@ -27,13 +28,47 @@ public class Interpreter : AST.IExprVisitor<object>
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}
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}
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private class List
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{
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public required ImmutableList<object> Items { get; init; }
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public static List Empty = new List { Items = ImmutableList<object>.Empty };
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public object this[double i]
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{
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get { return Items[(int)i]; }
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}
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public bool IsEmpty
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{
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get { return Items.IsEmpty; }
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}
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public List Add(object item)
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{
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return new List { Items = Items.Add(item) };
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}
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public override string ToString()
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{
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System.IO.StringWriter sw = new System.IO.StringWriter();
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sw.Write("[");
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foreach (var item in this.Items)
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{
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sw.Write($" {item},");
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}
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sw.Write(" ]");
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return sw.ToString();
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}
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}
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private class Record
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{
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public static Record Empty = new Record
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{
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Fields = ImmutableDictionary<string, ImmutableStack<object>>.Empty,
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Fields = ImmutableSortedDictionary<string, ImmutableStack<object>>.Empty,
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};
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public required ImmutableDictionary<string, ImmutableStack<object>> Fields { get; init; }
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public required ImmutableSortedDictionary<string, ImmutableStack<object>> Fields { get; init; }
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public Record Update(string name, object value)
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{
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@ -77,6 +112,21 @@ public class Interpreter : AST.IExprVisitor<object>
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var values = Fields.GetValueOrDefault(name, ImmutableStack<object>.Empty);
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return new Record { Fields = Fields.SetItem(name, values.Push(value)) };
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}
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public override string ToString()
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{
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System.IO.StringWriter sw = new System.IO.StringWriter();
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sw.Write("{");
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foreach ((var label, var values) in this.Fields)
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{
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foreach (var value in values)
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{
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sw.Write($" {label} = {value},");
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}
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}
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sw.Write(" }");
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return sw.ToString();
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}
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}
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private record Variant(string Tag, object? Value)
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@ -120,9 +170,21 @@ public class Interpreter : AST.IExprVisitor<object>
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return expr.accept(this);
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}
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private void checkNumberOperand(Token op, Object operand)
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private List checkListOperand(Token op, Object operand)
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{
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if (operand is double) return;
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if (operand is List l) return l;
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throw new RuntimeError(op, "Operand must be a record.");
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}
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private Record checkRecordOperand(Token op, Object operand)
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{
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if (operand is Record r) return r;
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throw new RuntimeError(op, "Operand must be a record.");
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}
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private double checkNumberOperand(Token op, Object operand)
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{
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if (operand is double d) return d;
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throw new RuntimeError(op, "Operand must be a number.");
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}
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@ -138,6 +200,15 @@ public class Interpreter : AST.IExprVisitor<object>
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throw new RuntimeError(op, "Operands must be strings.");
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}
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private Variant checkBoolOperand(Token op, object operand)
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{
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if (operand is Variant v)
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{
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if (v == Variant.True || v == Variant.False) return v;
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}
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throw new RuntimeError(op, "Operand must be <true,false>.");
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}
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public object visitBinaryExpr(AST.Binary expr)
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{
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var left = evaluate(expr.Left);
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@ -202,7 +273,6 @@ public class Interpreter : AST.IExprVisitor<object>
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public object visitGroupingExpr(AST.Grouping expr)
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{
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return evaluate(expr.Expression);
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throw new System.NotImplementedException();
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}
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public object visitIdentifierExpr(AST.Identifier expr)
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@ -212,12 +282,31 @@ public class Interpreter : AST.IExprVisitor<object>
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public object visitIfExpr(AST.If expr)
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{
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throw new System.NotImplementedException();
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var cond = evaluate(expr.Condition);
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// TODO Maybe I should token info in the AST.
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var vb = checkBoolOperand(new Token(TokenType.If, "if", null, 1), cond);
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if (vb == Variant.True)
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{
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return evaluate(expr.Then);
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}
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else
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{
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return evaluate(expr.Else);
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}
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}
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public object visitIndexerExpr(AST.Indexer expr)
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{
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throw new System.NotImplementedException();
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// TODO use real token
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var tok = new Token(TokenType.LBracket, "[", null, 1);
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var left = checkListOperand(tok, evaluate(expr.Left));
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var index = checkNumberOperand(tok, evaluate(expr.Index));
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try
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{
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var item = left[index];
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return new Variant("some", item);
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}
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catch { return new Variant("nothing", null); }
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}
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public object visitLetExpr(AST.Let expr)
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@ -227,7 +316,20 @@ public class Interpreter : AST.IExprVisitor<object>
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public object visitListExpr(AST.List expr)
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{
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throw new System.NotImplementedException();
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// TODO use real token
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var tok = new Token(TokenType.LBracket, "[", null, 1);
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List l = List.Empty;
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foreach (var itemExpr in expr.Elements)
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{
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var item = evaluate(itemExpr);
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if (!l.IsEmpty)
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{
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try { checkTypesEqual(l[0], item); }
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catch { throw new RuntimeError(tok, "List items must all have same type."); }
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}
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l = l.Add(item);
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}
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return l;
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}
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public object visitLiteralExpr(AST.Literal expr)
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@ -237,17 +339,79 @@ public class Interpreter : AST.IExprVisitor<object>
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public object visitRecordExpr(AST.Record expr)
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{
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throw new System.NotImplementedException();
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// TODO use real token
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Token tok = new Token(TokenType.LBrace, "{", null, 1);
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Record rec = Record.Empty;
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if (expr.Base != null)
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{
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var baseRecValue = evaluate(expr.Base.Value);
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if (baseRecValue is not Record)
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{
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throw new RuntimeError(tok, "Base record must be a record.");
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}
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var baseRec = (Record)baseRecValue;
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// Updates
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HashSet<string> updateLabels = new HashSet<string>();
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foreach (AST.Field update in expr.Base.Updates)
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{
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var label = update.Name.Value;
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if (updateLabels.Contains(label))
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{
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throw new RuntimeError(tok, "Record updates must be to unique fields.");
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}
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updateLabels.Add(label);
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if (update.Value == null) throw new NotImplementedException();
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try
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{
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baseRec = baseRec.Update(label, evaluate(update.Value));
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}
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catch
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{
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throw new RuntimeError(tok, "Field update must have same type as previous value.");
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}
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}
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rec = baseRec;
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}
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// Extensions
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HashSet<string> extLabels = new HashSet<string>();
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foreach (AST.Field extension in expr.Extensions)
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{
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var label = extension.Name.Value;
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if (extLabels.Contains(label))
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{
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throw new RuntimeError(tok, "Record extensions must have unique field names.");
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}
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extLabels.Add(label);
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if (extension.Value == null) throw new NotImplementedException();
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rec = rec.Extend(label, evaluate(extension.Value));
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}
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return rec;
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}
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public object visitSelectorExpr(AST.Selector expr)
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{
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throw new System.NotImplementedException();
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var left = evaluate(expr.Left);
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// TODO Use real token.
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var tok = new Token(TokenType.Period, ".", null, 1);
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var r = checkRecordOperand(tok, left);
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try
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{
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return r.Get(expr.FieldName.Value);
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}
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catch
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{
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throw new RuntimeError(tok, "Operand must have selected field.");
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}
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}
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public object visitSequenceExpr(AST.Sequence expr)
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{
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throw new System.NotImplementedException();
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evaluate(expr.Left);
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return evaluate(expr.Right);
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}
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public object visitUnaryExpr(AST.Unary expr)
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@ -259,18 +423,14 @@ public class Interpreter : AST.IExprVisitor<object>
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checkNumberOperand(expr.Op, right);
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return -(double)right;
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case TokenType.Bang:
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if (right is Variant v)
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{
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if (v == Variant.True)
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if (checkBoolOperand(expr.Op, right) == Variant.True)
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{
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return Variant.False;
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}
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else if (v == Variant.False)
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else
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{
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return Variant.True;
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}
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}
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throw new RuntimeError(expr.Op, "Boolean must be <true, false>");
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default:
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// Unreachable
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throw new Exception($"bad unary op: {expr.Op}");
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@ -279,7 +439,7 @@ public class Interpreter : AST.IExprVisitor<object>
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public object visitVariantExpr(AST.Variant expr)
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{
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throw new System.NotImplementedException();
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return new Variant(expr.Tag.Value, expr.Argument);
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}
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public object visitWhenExpr(AST.When expr)
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