wenzelm@38425: /*  Title:      Pure/PIDE/text.scala
wenzelm@34276:     Author:     Fabian Immler, TU Munich
wenzelm@34276:     Author:     Makarius
wenzelm@34276: 
wenzelm@38425: Basic operations on plain text.
wenzelm@34276: */
wenzelm@34276: 
wenzelm@34276: package isabelle
wenzelm@34276: 
wenzelm@34276: 
wenzelm@38425: object Text
wenzelm@34276: {
wenzelm@38477:   /* offset */
wenzelm@38426: 
wenzelm@38426:   type Offset = Int
wenzelm@38426: 
wenzelm@38477: 
wenzelm@38565:   /* range -- with total quasi-ordering */
wenzelm@38477: 
wenzelm@38426:   sealed case class Range(val start: Offset, val stop: Offset)
wenzelm@38427:   {
wenzelm@38565:     // denotation: {start} Un {i. start < i & i < stop}
wenzelm@38477:     require(start <= stop)
wenzelm@38477: 
wenzelm@38563:     override def toString = "[" + start.toString + ":" + stop.toString + "]"
wenzelm@38563: 
wenzelm@38427:     def map(f: Offset => Offset): Range = Range(f(start), f(stop))
wenzelm@38427:     def +(i: Offset): Range = map(_ + i)
wenzelm@38565:     def contains(i: Offset): Boolean = start == i || start < i && i < stop
wenzelm@38565:     def contains(that: Range): Boolean = this.contains(that.start) && that.stop <= this.stop
wenzelm@38565:     def overlaps(that: Range): Boolean = this.contains(that.start) || that.contains(this.start)
wenzelm@38565:     def compare(that: Range): Int = if (overlaps(that)) 0 else this.start compare that.start
wenzelm@38485: 
wenzelm@38485:     def start_range: Range = Range(start, start)
wenzelm@38485:     def stop_range: Range = Range(stop, stop)
wenzelm@38485: 
wenzelm@38564:     def restrict(that: Range): Range =
wenzelm@38485:       Range(this.start max that.start, this.stop min that.stop)
wenzelm@38427:   }
wenzelm@38426: 
wenzelm@38426: 
wenzelm@38426:   /* editing */
wenzelm@34286: 
wenzelm@38425:   object Edit
wenzelm@38425:   {
wenzelm@38426:     def insert(start: Offset, text: String): Edit = new Edit(true, start, text)
wenzelm@38426:     def remove(start: Offset, text: String): Edit = new Edit(false, start, text)
wenzelm@38425:   }
wenzelm@34286: 
wenzelm@38426:   class Edit(val is_insert: Boolean, val start: Offset, val text: String)
wenzelm@38425:   {
wenzelm@38425:     override def toString =
wenzelm@38425:       (if (is_insert) "Insert(" else "Remove(") + (start, text).toString + ")"
wenzelm@34286: 
wenzelm@34286: 
wenzelm@38425:     /* transform offsets */
wenzelm@34286: 
wenzelm@38426:     private def transform(do_insert: Boolean, i: Offset): Offset =
wenzelm@38426:       if (i < start) i
wenzelm@38426:       else if (is_insert == do_insert) i + text.length
wenzelm@38426:       else (i - text.length) max start
wenzelm@34286: 
wenzelm@38426:     def convert(i: Offset): Offset = transform(true, i)
wenzelm@38426:     def revert(i: Offset): Offset = transform(false, i)
wenzelm@38425: 
wenzelm@34286: 
wenzelm@38425:     /* edit strings */
wenzelm@38425: 
wenzelm@38426:     private def insert(i: Offset, string: String): String =
wenzelm@38426:       string.substring(0, i) + text + string.substring(i)
wenzelm@34276: 
wenzelm@38426:     private def remove(i: Offset, count: Int, string: String): String =
wenzelm@38426:       string.substring(0, i) + string.substring(i + count)
wenzelm@38425: 
wenzelm@38425:     def can_edit(string: String, shift: Int): Boolean =
wenzelm@38425:       shift <= start && start < shift + string.length
wenzelm@38425: 
wenzelm@38425:     def edit(string: String, shift: Int): (Option[Edit], String) =
wenzelm@38425:       if (!can_edit(string, shift)) (Some(this), string)
wenzelm@38425:       else if (is_insert) (None, insert(start - shift, string))
wenzelm@38425:       else {
wenzelm@38426:         val i = start - shift
wenzelm@38426:         val count = text.length min (string.length - i)
wenzelm@38425:         val rest =
wenzelm@38425:           if (count == text.length) None
wenzelm@38425:           else Some(Edit.remove(start, text.substring(count)))
wenzelm@38426:         (rest, remove(i, count, string))
wenzelm@38425:       }
wenzelm@38425:   }
wenzelm@34276: }