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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2006-2011, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.util.parsing.input
/** `Position` is the base trait for objects describing a position in a ``document''.
*
* It provides functionality for:
* - generating a visual representation of this position (`longString`);
* - comparing two positions (`<`).
*
* To use this class for a concrete kind of ``document'', implement the `lineContents` method.
*
* @author Martin Odersky
* @author Adriaan Moors
*/
trait Position {
/** The line number referred to by the position; line numbers start at 1. */
def line: Int
/** The column number referred to by the position; column numbers start at 1. */
def column: Int
/** The contents of the line at this position. (must not contain a new-line character).
*/
protected def lineContents: String
/** Returns a string representation of the `Position`, of the form `line.column`. */
override def toString = ""+line+"."+column
/** Returns a more ``visual'' representation of this position.
* More precisely, the resulting string consists of two lines:
* 1. the line in the document referred to by this position
* 2. a caret indicating the column
*
* Example:
* {{{
* List(this, is, a, line, from, the, document)
* ^
* }}}
*/
def longString = lineContents+"\n"+lineContents.take(column-1).map{x => if (x == '\t') x else ' ' } + "^"
/** Compare this position to another, by first comparing their line numbers,
* and then -- if necessary -- using the columns to break a tie.
*
* @param `that` a `Position` to compare to this `Position`
* @return true if this position's line number or (in case of equal line numbers)
* column is smaller than the corresponding components of `that`
*/
def <(that: Position) = {
this.line < that.line ||
this.line == that.line && this.column < that.column
}
}
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