129 lines
2.4 KiB
C#
129 lines
2.4 KiB
C#
using System;
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using System.IO;
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using Finn.AST;
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namespace Finn;
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class ASTPrinter : IVisitor<string>
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{
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public string print(Expr expr)
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{
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return expr.accept(this);
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}
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private string parenthesize(string name, params Expr[] exprs)
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{
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var w = new StringWriter();
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w.Write($"({name}");
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foreach (Expr expr in exprs)
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{
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w.Write(" ");
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w.Write(expr.accept(this));
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}
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w.Write(")");
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return w.ToString();
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}
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public string visitBinaryExpr(Binary expr)
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{
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return parenthesize(expr.Op.lexeme, expr.Left, expr.Right);
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}
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public string visitGroupingExpr(Grouping expr)
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{
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return parenthesize("group", expr.Expression);
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}
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public string visitLiteralExpr(Literal expr)
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{
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return expr.Value.ToString() ?? "";
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}
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private string formatName(Name name)
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{
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if (name.Quoted) return $"@\"{name.Value}\"";
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return name.Value;
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}
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public string visitIdentifierExpr(Identifier expr)
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{
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return formatName(expr.Value);
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}
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public string visitUnaryExpr(Unary expr)
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{
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return parenthesize(expr.Op.lexeme, expr.Right);
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}
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public string visitIfExpr(If expr)
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{
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return parenthesize("if", expr.Condition, expr.Then, expr.Else);
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}
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public string visitSequenceExpr(Sequence expr)
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{
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return parenthesize("seq", expr.Left, expr.Right);
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}
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public string visitSelectorExpr(Selector expr)
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{
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return parenthesize(".", expr.Left, new Identifier { Value = expr.FieldName });
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}
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public string visitListExpr(List expr)
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{
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return parenthesize("list", expr.Elements);
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}
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public string visitVariantExpr(Variant expr)
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{
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if (expr.Argument == null)
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{
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return parenthesize("variant", new Identifier { Value = expr.Tag });
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}
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return parenthesize("variant", new Identifier { Value = expr.Tag }, expr.Argument);
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}
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public string visitRecordExpr(Record expr)
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{
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StringWriter w = new StringWriter();
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w.Write("(record");
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writeFields("extend", expr.Extensions);
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if (expr.Base != null)
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{
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w.Write(" (base ");
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w.Write(print(expr.Base.Value));
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writeFields("update", expr.Base.Updates);
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w.Write(')');
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}
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w.Write(')');
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return w.ToString();
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void writeFields(string header, Field[] fields)
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{
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if (fields.Length != 0)
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{
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w.Write($" ({header}");
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foreach (var field in fields)
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{
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w.Write(' ');
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var name = formatName(field.Name);
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if (field.Value == null)
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{
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w.Write(name);
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}
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else
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{
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w.Write(parenthesize(name, field.Value));
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}
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}
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w.Write(')');
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}
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}
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}
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}
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