[Oberon] Exercise in Text parameter handling.

[peter at easthope.ca]

From:	Andreas Pirklbauer <andreas_pirklbauer at yahoo.com>
Date:	Wed, 14 Mar 2018 19:10:54 +0100
IF v.state > 1 THEN  (*v is a displayed viewer*)
  ELSIF v.state = 1 THEN  (*v is a filler viewer*)
  ELSIF v.state = 0 THEN  (*v is a closed viewer*)
  ELSIF v.state < 0 THEN  (*v is a suspended viewer*)
END

OK, thanks.  My exercise including "Oberon.MarkedViewer().state > 1" 
follows.

For * marked viewers, distinguishing an original style Text viewer 
from a Document viewer is by the order of the two Marked evaluations.  
I have yet to learn how to make the distinction for selected Text.  Is 
a selection in a plain viewer or in a Document viewer?  Necessary if I 
want to open a new viewer of the same style as the original.

Any comments about the exercise are welcome of course.  Likely I've 
missed at least one detail.

Thanks,                        ... Lyall E.

MODULE ParameterHandling IN Oberon;
	IMPORT Documents, Oberon, Texts;
	VAR
		S: Texts.Scanner;
		W: Texts.Writer;
		sel: Texts.Text;
		beg, end, time: LONGINT;
		source: CHAR; (* "t" for all Text in a Text viewer,
									"d" for all Text in a Document viewer,
									"n" for * parameter following command and no marker displayed,
									"s" for for Text selected in a Text viewer,
									"u" for for Text selected in a Document viewer,
									"o" for ^ parameter following command but no selection,
									"f" for a named file and
									"z" for command with no parameter; ParameterHandling.Test ~ . *)
		
	(* ParameterHandling.Test *  (Marked viewer),
		ParameterHandling.Test ^  (Text selection),
		ParameterHandling.Test { <filename> } ~  Named files containing Texts. *)
	PROCEDURE Test*;
	BEGIN
		Texts.OpenScanner(S, Oberon.Par.text, Oberon.Par.pos); Texts.Scan(S);
		IF S.class=Texts.Char THEN
			IF S.c="*"  THEN (* Viewer marked? *)
				IF (Documents.MarkedDoc() # NIL) & (Oberon.MarkedViewer().state > 1) THEN
					source := "d"
				ELSIF (Oberon.MarkedViewer() # NIL) & (Oberon.MarkedViewer().state > 1) THEN
					source := "t"
				ELSE
					source := "n"
				END
			ELSIF S.c="^" THEN (* Text selected? *)
				Oberon.GetSelection(sel, beg, end, time);
				(* Is the Text in an original style Text viewer or in a Document viewer? *)
				IF sel # NIL THEN
					source := "s"
				ELSIF FALSE THEN
					source := "u"
				ELSE
					source := "o"
				END
			END
		ELSIF S.class=Texts.Name THEN (* Existing or new file named. *)
			source := "f"
		ELSE
			source := "z"
		END;
		Texts.WriteString(W, "source = "); Texts.Write(W, source); Texts.WriteLn(W);
		Texts.Append(Oberon.Log, W.buf);
		IF source = "f" THEN
			Texts.WriteString(W, "Filename parameter = "); Texts.WriteString(W, S.s); Texts.WriteLn(W);
			Texts.Append(Oberon.Log, W.buf);
		END
	END Test;
	
BEGIN
	Texts.OpenWriter(W)
END ParameterHandling.

Compiler.Compile * ~
ParameterHandling.Test *
ParameterHandling.Test ^
ParameterHandling.Test Oberon.ParameterHandling.Mod ~

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