gui-cs.Terminal.Gui/UICatalog/Scenarios/SyntaxHighlighting.cs


using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using Terminal.Gui;
using static UICatalog.Scenario;
using Attribute = Terminal.Gui.Attribute;

namespace UICatalog.Scenarios {
	[ScenarioMetadata (Name: "Syntax Highlighting", Description: "Text editor with keyword highlighting")]
	[ScenarioCategory ("Controls")]
	class SyntaxHighlighting : Scenario {

			public override void Setup ()
			{
				Win.Title = this.GetName ();
				Win.Y = 1; // menu
				Win.Height = Dim.Fill (1); // status bar
				Top.LayoutSubviews ();

				var menu = new MenuBar (new MenuBarItem [] {
				new MenuBarItem ("_File", new MenuItem [] {
					new MenuItem ("_Quit", "", () => Quit()),
				})
				});
				Top.Add (menu);

				var textView = new SqlTextView () {
					X = 0,
					Y = 0,
					Width = Dim.Fill (),
					Height = Dim.Fill (1),
				};

				textView.Init();

				textView.Text = "SELECT TOP 100 * \nfrom\n MyDb.dbo.Biochemistry;";
				
				Win.Add (textView);

				var statusBar = new StatusBar (new StatusItem [] {
				new StatusItem(Key.CtrlMask | Key.Q, "~^Q~ Quit", () => Quit()),

			});


				Top.Add (statusBar);
			}


			private void Quit ()
			{
				Application.RequestStop ();
			}

		private class SqlTextView : TextView{

			private HashSet<string> keywords = new HashSet<string>(StringComparer.CurrentCultureIgnoreCase);
			private Attribute blue;
			private Attribute white;


			public void Init()
			{
				keywords.Add("select");
				keywords.Add("distinct");
				keywords.Add("top");
				keywords.Add("from");

				blue = Driver.MakeAttribute (Color.Cyan, Color.Black);
				white = Driver.MakeAttribute (Color.White, Color.Black);
			}

			protected override void ColorNormal ()
			{
				Driver.SetAttribute (white);
			}

			protected override void ColorNormal (List<System.Rune> line, int idx)
			{
				if(IsKeyword(line,idx))
				{
					Driver.SetAttribute (blue);
				}
				else{
					Driver.SetAttribute (white);
				}
			}

			private bool IsKeyword(List<System.Rune> line, int idx)
			{
				var word = IdxToWord(line,idx);
				
				if(string.IsNullOrWhiteSpace(word)){
					return false;
				}

				return keywords.Contains(word,StringComparer.CurrentCultureIgnoreCase);
			}

			private string IdxToWord(List<System.Rune> line, int idx)
			{
				var words = Regex.Split(
					new string(line.Select(r=>(char)r).ToArray()),
					"\b");


				int count = 0;
				string current = null;

				foreach(var word in words)
				{
					current = word;
					count+= word.Length;
					if(count >= idx){
						break;
					}
				}

				return current;
			}
		}
	}
}