tuned signature;

--- a/src/Pure/General/symbol.scala	Sat Oct 01 16:07:05 2022 +0200
+++ b/src/Pure/General/symbol.scala	Sat Oct 01 20:10:56 2022 +0200
@@ -211,7 +211,7 @@
     case class File(name: String) extends Name
 
     def apply(text: CharSequence): Text_Chunk =
-      new Text_Chunk(Text.Range(0, text.length), Index(text))
+      new Text_Chunk(Text.Range.length(text), Index(text))
   }
 
   final class Text_Chunk private(val range: Text.Range, private val index: Index) {

--- a/src/Pure/PIDE/document.scala	Sat Oct 01 16:07:05 2022 +0200
+++ b/src/Pure/PIDE/document.scala	Sat Oct 01 20:10:56 2022 +0200
@@ -611,7 +611,7 @@
             val xml =
               if (Bytes(text) == bytes) {
                 val markup = command.init_markups(Command.Markup_Index.blob(blob))
-                markup.to_XML(Text.Range(0, text.length), text, elements)
+                markup.to_XML(Text.Range.length(text), text, elements)
               }
               else Nil
             blob -> xml
@@ -1161,7 +1161,7 @@
         } yield tree).toList
       }
       else {
-        Text.Range(0, node.source.length).try_restrict(range) match {
+        Text.Range.length(node.source).try_restrict(range) match {
           case None => Nil
           case Some(node_range) =>
             val markup =

--- a/src/Pure/PIDE/text.scala	Sat Oct 01 16:07:05 2022 +0200
+++ b/src/Pure/PIDE/text.scala	Sat Oct 01 20:10:56 2022 +0200
@@ -22,7 +22,9 @@
 
   object Range {
     def apply(start: Offset): Range = Range(start, start)
+    def length(text: CharSequence): Range = Range(0, text.length)
 
+    val zero: Range = apply(0)
     val full: Range = apply(0, Integer.MAX_VALUE / 2)
     val offside: Range = apply(-1)
 
@@ -108,7 +110,7 @@
   ) {
     def is_empty: Boolean = ranges.isEmpty
     def range: Range =
-      if (is_empty) Range(0)
+      if (is_empty) Range.zero
       else Range(ranges.head.start, ranges.last.stop)
 
     override def hashCode: Int = ranges.hashCode