# HG changeset patch
# User wenzelm
# Date 1263230662 -3600
# Node ID 265075989f01627b64bad4b350a0d89945e50b06
# Parent  f0a6f02ad70594662ae8c56a7aa136de363704b0
simplified Text_Edit -- deflated class hierarchy;

diff -r f0a6f02ad705 -r 265075989f01 src/Pure/Thy/text_edit.scala
--- a/src/Pure/Thy/text_edit.scala	Mon Jan 11 18:23:06 2010 +0100
+++ b/src/Pure/Thy/text_edit.scala	Mon Jan 11 18:24:22 2010 +0100
@@ -8,72 +8,40 @@
 package isabelle
 
 
-sealed abstract class Text_Edit
-{
-  val start: Int
-  def text: String
-  def after(offset: Int): Int
-  def before(offset: Int): Int
-  def can_edit(string_length: Int, shift: Int): Boolean
-  def edit(string: String, shift: Int): (Option[Text_Edit], String)
-}
-
-
-object Text_Edit
+class Text_Edit(val is_insert: Boolean, val start: Int, val text: String)
 {
   /* transform offsets */
 
-  private def after_insert(start: Int, text: String, offset: Int): Int =
-    if (start <= offset) offset + text.length
-    else offset
+  private def transform(do_insert: Boolean, offset: Int): Int =
+    if (offset < start) offset
+    else if (is_insert == do_insert) offset + text.length
+    else (offset - text.length) max start
 
-  private def after_remove(start: Int, text: String, offset: Int): Int =
-    if (start > offset) offset
-    else (offset - text.length) max start
+  def after(offset: Int): Int = transform(true, offset)
+  def before(offset: Int): Int = transform(false, offset)
 
 
   /* edit strings */
 
-  private def insert(index: Int, text: String, string: String): String =
+  private def insert(index: Int, string: String): String =
     string.substring(0, index) + text + string.substring(index)
 
   private def remove(index: Int, count: Int, string: String): String =
     string.substring(0, index) + string.substring(index + count)
 
-
-  /* explicit edits */
-
-  case class Insert(start: Int, text: String) extends Text_Edit
-  {
-    def after(offset: Int): Int = after_insert(start, text, offset)
-    def before(offset: Int): Int = after_remove(start, text, offset)
-
-    def can_edit(string_length: Int, shift: Int): Boolean =
-      shift <= start && start <= shift + string_length
-
-    def edit(string: String, shift: Int): (Option[Insert], String) =
-      if (can_edit(string.length, shift)) (None, insert(start - shift, text, string))
-      else (Some(this), string)
-  }
+  def can_edit(string: String, shift: Int): Boolean =
+    shift <= start && start < shift + string.length
 
-  case class Remove(start: Int, text: String) extends Text_Edit
-  {
-    def after(offset: Int): Int = after_remove(start, text, offset)
-    def before(offset: Int): Int = after_insert(start, text, offset)
-
-    def can_edit(string_length: Int, shift: Int): Boolean =
-      shift <= start && start < shift + string_length
-
-    def edit(string: String, shift: Int): (Option[Remove], String) =
-      if (can_edit(string.length, shift)) {
-        val index = start - shift
-        val count = text.length min (string.length - index)
-        val rest =
-          if (count == text.length) None
-          else Some(Remove(start, text.substring(count)))
-        (rest, remove(index, count, string))
-      }
-      else (Some(this), string)
-  }
+  def edit(string: String, shift: Int): (Option[Text_Edit], String) =
+    if (!can_edit(string, shift)) (Some(this), string)
+    else if (is_insert) (None, insert(start - shift, string))
+    else {
+      val index = start - shift
+      val count = text.length min (string.length - index)
+      val rest =
+        if (count == text.length) None
+        else Some(new Text_Edit(false, start, text.substring(count)))
+      (rest, remove(index, count, string))
+    }
 }