src/Pure/PIDE/text.scala
author wenzelm
Sun Aug 22 19:33:01 2010 +0200 (2010-08-22)
changeset 38578 1ebc6b76e5ff
parent 38577 4e4d3ea3725a
child 38662 4d4553e09337
permissions -rw-r--r--
misc tuning and simplification;
     1 /*  Title:      Pure/PIDE/text.scala
     2     Author:     Fabian Immler, TU Munich
     3     Author:     Makarius
     4 
     5 Basic operations on plain text.
     6 */
     7 
     8 package isabelle
     9 
    10 
    11 object Text
    12 {
    13   /* offset */
    14 
    15   type Offset = Int
    16 
    17 
    18   /* range -- with total quasi-ordering */
    19 
    20   object Range
    21   {
    22     def apply(start: Offset): Range = Range(start, start)
    23   }
    24 
    25   sealed case class Range(val start: Offset, val stop: Offset)
    26   {
    27     // denotation: {start} Un {i. start < i & i < stop}
    28     require(start <= stop)
    29 
    30     override def toString = "[" + start.toString + ":" + stop.toString + "]"
    31 
    32     def map(f: Offset => Offset): Range = Range(f(start), f(stop))
    33     def +(i: Offset): Range = map(_ + i)
    34     def -(i: Offset): Range = map(_ - i)
    35     def contains(i: Offset): Boolean = start == i || start < i && i < stop
    36     def contains(that: Range): Boolean = this.contains(that.start) && that.stop <= this.stop
    37     def overlaps(that: Range): Boolean = this.contains(that.start) || that.contains(this.start)
    38     def compare(that: Range): Int = if (overlaps(that)) 0 else this.start compare that.start
    39 
    40     def restrict(that: Range): Range =
    41       Range(this.start max that.start, this.stop min that.stop)
    42   }
    43 
    44 
    45   /* information associated with text range */
    46 
    47   case class Info[A](val range: Text.Range, val info: A)
    48   {
    49     def restrict(r: Text.Range): Info[A] = Info(range.restrict(r), info)
    50   }
    51 
    52 
    53   /* editing */
    54 
    55   object Edit
    56   {
    57     def insert(start: Offset, text: String): Edit = new Edit(true, start, text)
    58     def remove(start: Offset, text: String): Edit = new Edit(false, start, text)
    59   }
    60 
    61   class Edit(val is_insert: Boolean, val start: Offset, val text: String)
    62   {
    63     override def toString =
    64       (if (is_insert) "Insert(" else "Remove(") + (start, text).toString + ")"
    65 
    66 
    67     /* transform offsets */
    68 
    69     private def transform(do_insert: Boolean, i: Offset): Offset =
    70       if (i < start) i
    71       else if (is_insert == do_insert) i + text.length
    72       else (i - text.length) max start
    73 
    74     def convert(i: Offset): Offset = transform(true, i)
    75     def revert(i: Offset): Offset = transform(false, i)
    76 
    77 
    78     /* edit strings */
    79 
    80     private def insert(i: Offset, string: String): String =
    81       string.substring(0, i) + text + string.substring(i)
    82 
    83     private def remove(i: Offset, count: Int, string: String): String =
    84       string.substring(0, i) + string.substring(i + count)
    85 
    86     def can_edit(string: String, shift: Int): Boolean =
    87       shift <= start && start < shift + string.length
    88 
    89     def edit(string: String, shift: Int): (Option[Edit], String) =
    90       if (!can_edit(string, shift)) (Some(this), string)
    91       else if (is_insert) (None, insert(start - shift, string))
    92       else {
    93         val i = start - shift
    94         val count = text.length min (string.length - i)
    95         val rest =
    96           if (count == text.length) None
    97           else Some(Edit.remove(start, text.substring(count)))
    98         (rest, remove(i, count, string))
    99       }
   100   }
   101 }