Evaluate all non-binding expressions

This commit is contained in:
Brandon Dyck 2023-07-06 02:29:04 -06:00
parent b1607eebc6
commit f9df52b5f9

View File

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