scala.io.Position.scala Maven / Gradle / Ivy
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
package io
/** The object Position provides convenience methods to encode
* line and column number in one single integer. The encoded line
* (column) numbers range from 0 to `LINE_MASK` (`COLUMN_MASK`),
* where `0` indicates that the line (column) is undefined and
* `1` represents the first line (column).
*
* Line (Column) numbers greater than `LINE_MASK` (`COLUMN_MASK`) are
* replaced by `LINE_MASK` (`COLUMN_MASK`). Furthermore, if the encoded
* line number is `LINE_MASK`, the column number is always set to 0.
*
* The following properties hold:
*
* the undefined position is 0: `encode(0,0) == 0`
* encodings are non-negative : `encode(line,column) >= 0`
* position order is preserved:
* {{{
* (line1 <= line2) || (line1 == line2 && column1 <= column2)
* }}}
* implies
* {{{
* encode(line1,column1) <= encode(line2,column2)
* }}}
* @author Burak Emir (translated from work by Matthias Zenger and others)
*/
@deprecated("this class will be removed", "2.10.0")
private[scala] abstract class Position {
/** Definable behavior for overflow conditions.
*/
def checkInput(line: Int, column: Int): Unit
/** Number of bits used to encode the line number */
final val LINE_BITS = 20
/** Number of bits used to encode the column number */
final val COLUMN_BITS = 31 - LINE_BITS // no negatives => 31
/** Mask to decode the line number */
final val LINE_MASK = (1 << LINE_BITS) - 1
/** Mask to decode the column number */
final val COLUMN_MASK = (1 << COLUMN_BITS) - 1
/** Encodes a position into a single integer. */
final def encode(line: Int, column: Int): Int = {
checkInput(line, column)
if (line >= LINE_MASK)
LINE_MASK << COLUMN_BITS
else
(line << COLUMN_BITS) | scala.math.min(COLUMN_MASK, column)
}
/** Returns the line number of the encoded position. */
final def line(pos: Int): Int = (pos >> COLUMN_BITS) & LINE_MASK
/** Returns the column number of the encoded position. */
final def column(pos: Int): Int = pos & COLUMN_MASK
/** Returns a string representation of the encoded position. */
def toString(pos: Int): String = line(pos) + ":" + column(pos)
}
private[scala] object Position extends Position {
def checkInput(line: Int, column: Int) {
if (line < 0)
throw new IllegalArgumentException(line + " < 0")
if ((line == 0) && (column != 0))
throw new IllegalArgumentException(line + "," + column + " not allowed")
if (column < 0)
throw new IllegalArgumentException(line + "," + column + " not allowed")
}
}