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Scala example source code file (SourceFile.scala)

This example Scala source code file (SourceFile.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

abstractfile, annotation, array, batchsourcefile, boolean, collection, int, io, lf, mutable, position, reflection, scriptsourcefile, sourcefile, string

The SourceFile.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author  Martin Odersky
 */


package scala
package reflect.internal.util

import scala.reflect.io.{ AbstractFile, VirtualFile }
import scala.collection.mutable.ArrayBuffer
import scala.annotation.tailrec
import java.util.regex.Pattern
import java.io.IOException
import scala.reflect.internal.Chars._

/** abstract base class of a source file used in the compiler */
abstract class SourceFile {
  def content: Array[Char]         // normalized, must end in SU
  def file   : AbstractFile
  def isLineBreak(idx: Int): Boolean
  def isEndOfLine(idx: Int): Boolean
  def isSelfContained: Boolean
  def length : Int
  def position(offset: Int): Position = {
    assert(offset < length, file + ": " + offset + " >= " + length)
    Position.offset(this, offset)
  }

  def offsetToLine(offset: Int): Int
  def lineToOffset(index : Int): Int

  /** Map a position to a position in the underlying source file.
   *  For regular source files, simply return the argument.
   */
  def positionInUltimateSource(position: Position) = position
  override def toString() = file.name
  def path = file.path

  def lineToString(index: Int): String = {
    val start = lineToOffset(index)
    var end = start
    while (!isEndOfLine(end) && end <= length) end += 1
    new String(content, start, end - start)
  }

  @tailrec
  final def skipWhitespace(offset: Int): Int =
    if (content(offset).isWhitespace) skipWhitespace(offset + 1) else offset

  def identifier(pos: Position): Option[String] = None
}

/** An object representing a missing source file.
 */
object NoSourceFile extends SourceFile {
  def content                   = Array()
  def file                      = NoFile
  def isLineBreak(idx: Int)     = false
  def isEndOfLine(idx: Int)     = false
  def isSelfContained           = true
  def length                    = -1
  def offsetToLine(offset: Int) = -1
  def lineToOffset(index : Int) = -1
  override def toString = "<no source file>"
}

object NoFile extends VirtualFile("<no file>", "<no file>")

object ScriptSourceFile {
  /** Length of the script header from the given content, if there is one.
   *  The header begins with "#!" or "::#!" and ends with a line starting
   *  with "!#" or "::!#".
   */
  def headerLength(cs: Array[Char]): Int = {
    val headerPattern = Pattern.compile("""((?m)^(::)?!#.*|^.*/env .*)(\r|\n|\r\n)""")
    val headerStarts  = List("#!", "::#!")

    if (headerStarts exists (cs startsWith _)) {
      val matcher = headerPattern matcher cs.mkString
      if (matcher.find) matcher.end
      else throw new IOException("script file does not close its header with !# or ::!#")
    }
    else 0
  }

  def apply(file: AbstractFile, content: Array[Char]) = {
    val underlying = new BatchSourceFile(file, content)
    val headerLen = headerLength(content)
    val stripped = new ScriptSourceFile(underlying, content drop headerLen, headerLen)

    stripped
  }

  def apply(underlying: BatchSourceFile) = {
    val headerLen = headerLength(underlying.content)
    new ScriptSourceFile(underlying, underlying.content drop headerLen, headerLen)
  }
}

class ScriptSourceFile(underlying: BatchSourceFile, content: Array[Char], override val start: Int) extends BatchSourceFile(underlying.file, content) {
  override def isSelfContained = false

  override def positionInUltimateSource(pos: Position) =
    if (!pos.isDefined) super.positionInUltimateSource(pos)
    else pos withSource underlying withShift start
}

/** a file whose contents do not change over time */
class BatchSourceFile(val file : AbstractFile, content0: Array[Char]) extends SourceFile {
  def this(_file: AbstractFile)                 = this(_file, _file.toCharArray)
  def this(sourceName: String, cs: Seq[Char])   = this(new VirtualFile(sourceName), cs.toArray)
  def this(file: AbstractFile, cs: Seq[Char])   = this(file, cs.toArray)

  // If non-whitespace tokens run all the way up to EOF,
  // positions go wrong because the correct end of the last
  // token cannot be used as an index into the char array.
  // The least painful way to address this was to add a
  // newline to the array.
  val content = (
    if (content0.length == 0 || !content0.last.isWhitespace)
      content0 :+ '\n'
    else content0
  )
  val length = content.length
  def start = 0
  def isSelfContained = true

  override def identifier(pos: Position) =
    if (pos.isDefined && pos.source == this && pos.point != -1) {
      def isOK(c: Char) = isIdentifierPart(c) || isOperatorPart(c)
      Some(new String(content drop pos.point takeWhile isOK))
    } else {
      super.identifier(pos)
    }

  private def charAtIsEOL(idx: Int)(p: Char => Boolean) = {
    // don't identify the CR in CR LF as a line break, since LF will do.
    def notCRLF0 = content(idx) != CR || !content.isDefinedAt(idx + 1) || content(idx + 1) != LF

    idx < length && notCRLF0 && p(content(idx))
  }

  def isLineBreak(idx: Int) = charAtIsEOL(idx)(isLineBreakChar)

  /** True if the index is included by an EOL sequence. */
  def isEndOfLine(idx: Int) = (content isDefinedAt idx) && PartialFunction.cond(content(idx)) {
    case CR | LF => true
  }

  /** True if the index is end of an EOL sequence. */
  def isAtEndOfLine(idx: Int) = charAtIsEOL(idx) {
    case CR | LF => true
    case _       => false
  }

  def calculateLineIndices(cs: Array[Char]) = {
    val buf = new ArrayBuffer[Int]
    buf += 0
    for (i <- 0 until cs.length) if (isAtEndOfLine(i)) buf += i + 1
    buf += cs.length // sentinel, so that findLine below works smoother
    buf.toArray
  }
  private lazy val lineIndices: Array[Int] = calculateLineIndices(content)

  def lineToOffset(index : Int): Int = lineIndices(index)

  private var lastLine = 0

  /** Convert offset to line in this source file.
   *  Lines are numbered from 0.
   */
  def offsetToLine(offset: Int): Int = {
    val lines = lineIndices
    def findLine(lo: Int, hi: Int, mid: Int): Int = (
      if (mid < lo || hi < mid) mid // minimal sanity check - as written this easily went into infinite loopyland
      else if (offset < lines(mid)) findLine(lo, mid - 1, (lo + mid - 1) / 2)
      else if (offset >= lines(mid + 1)) findLine(mid + 1, hi, (mid + 1 + hi) / 2)
      else mid
    )
    lastLine = findLine(0, lines.length, lastLine)
    lastLine
  }

  override def equals(that : Any) = that match {
    case that : BatchSourceFile => file.path == that.file.path && start == that.start
    case _ => false
  }
  override def hashCode = file.path.## + start.##
}

Other Scala source code examples

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