colorsyntaxvisitor.cs

微软系列丛书<<C#2005从入门到精通>>

namespace Tokenizer
{
    using System;
	using System.Windows.Forms;
	using System.Drawing;

    sealed class ColorSyntaxVisitor : ITokenVisitor
    {
        public ColorSyntaxVisitor(RichTextBox rtb)
        {
            this.target = rtb;
            this.target.Clear();
            this.index = 0;
        }

        private void Write(string token, Color color)
        {
            target.AppendText(token);
            target.Select(this.index, this.index + token.Length);
            this.index += token.Length;
            target.SelectionColor = color;
        }

        void ITokenVisitor.VisitComment(string token)
        {
            Write(token, Color.Black);
        }

        void ITokenVisitor.VisitIdentifier(string token)
        {
            Write(token, Color.Black);
        }

        void ITokenVisitor.VisitKeyword(string token)
        {
            Write(token, Color.Blue);
        }

        void ITokenVisitor.VisitOperator(string token)
        {
            Write(token, Color.Black);
        }

        void ITokenVisitor.VisitPunctuator(string token)
        {
            Write(token, Color.Black);
        }

        void ITokenVisitor.VisitStringLiteral(string token)
        {
            Write(token, Color.Green);
        }

        void ITokenVisitor.VisitWhitespace(string token)
        {
            Write(token, Color.Black);
        }

        private readonly RichTextBox target;
		private int index;        
    }
}