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verify.DiffUtil.scala Maven / Gradle / Ivy

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/*
 * 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 verify

import scala.annotation.tailrec
import scala.collection.mutable

// borrowed from https://github.com/lampepfl/dotty/blob/d77c70ce9901ae57719de0f16d100a8d2f9992db/compiler/src/dotty/tools/dotc/util/DiffUtil.scala
object DiffUtil {

  val EOF: String = new String("EOF") // Unique string up to reference

  val ansiColorToken: Char = '\u001b'

  @tailrec private def splitTokens(str: String, acc: List[String]): List[String] =
    if (str == "")
      acc.reverse
    else {
      val head = str.charAt(0)
      val (token, rest) =
        if (head == ansiColorToken) { // ansi color token
          val splitIndex = str.indexOf('m') + 1
          (str.substring(0, splitIndex), str.substring(splitIndex))
        } else if (Character.isAlphabetic(head) || Character.isDigit(head))
          str.span(c => Character.isAlphabetic(c) || Character.isDigit(c) && c != ansiColorToken)
        else if (Character.isMirrored(head) || Character.isWhitespace(head))
          str.splitAt(1)
        else
          str.span { c =>
            !Character.isAlphabetic(c) && !Character.isDigit(c) &&
            !Character.isMirrored(c) && !Character.isWhitespace(c) && c != ansiColorToken
          }
      splitTokens(rest, token :: acc)
    }

  /** @return a tuple of the (found, expected, changedPercentage) diffs as strings */
  def mkColoredTypeDiff(found: String, expected: String): (String, String, Double) = {
    var totalChange = 0
    val foundTokens = splitTokens(found, Nil).toArray
    val expectedTokens = splitTokens(expected, Nil).toArray

    val diffExp = hirschberg(foundTokens, expectedTokens)
    val diffAct = hirschberg(expectedTokens, foundTokens)

    val exp = diffExp.collect {
      case Unmodified(str) => str
      case Inserted(str) =>
        totalChange += str.length
        added(str)
    }.mkString

    val fnd = diffAct.collect {
      case Unmodified(str) => str
      case Inserted(str) =>
        totalChange += str.length
        deleted(str)
    }.mkString

    (fnd, exp, totalChange.toDouble / (expected.length + found.length))
  }

  /**
   * Return a colored diff between the tokens of every line in `expected` and `actual`. Each line of
   * output contains the expected value on the left and the actual value on the right.
   *
   * @param expected The expected lines
   * @param actual   The actual lines
   * @return A string with one element of `expected` and `actual` on each lines, where
   *         differences are highlighted.
   */
  def mkColoredLineDiff(expected: Seq[String], actual: Seq[String]): String = {
    val diffs =
      actual
        .padTo(expected.length, "")
        .zip(expected.padTo(actual.length, ""))
        .map { case (act, exp) =>
          mkColoredLineDiff(exp, act)
        }

    padDiffs(diffs).mkString(System.lineSeparator)
  }

  def padDiffs(diffs: Seq[(String, String)]): Seq[String] = {
    // skip ANSI control sequence
    def textLength(str: String): Int = str.replaceAll("\u001b\\[[\\d;]*[^\\d;]", "").length
    val expectedSize = EOF.length max textLength(diffs.maxBy(diff => textLength(diff._1))._1)
    println(expectedSize)
    diffs map { case (expected, found) =>
      val pad = " " * 0.max(expectedSize - textLength(expected))
      expected + pad + "  |  " + found
    }
  }

  def mkColoredLineDiff(expected: String, actual: String): (String, String) = {
    lazy val diff = {
      val tokens = splitTokens(expected, Nil).toArray
      val lastTokens = splitTokens(actual, Nil).toArray
      hirschberg(lastTokens, tokens)
    }

    val expectedDiff =
      if (expected eq EOF) eof()
      else
        diff.collect {
          case Unmodified(str)  => str
          case Inserted(str)    => added(str)
          case Modified(_, str) => added(str)
          case Deleted(_)       => ""
        }.mkString

    val actualDiff =
      if (actual eq EOF) eof()
      else
        diff.collect {
          case Unmodified(str)  => str
          case Inserted(_)      => ""
          case Modified(str, _) => deleted(str)
          case Deleted(str)     => deleted(str)
        }.mkString

    (expectedDiff, actualDiff)
  }

  def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {
    val tokens = splitTokens(code, Nil).toArray
    val lastTokens = splitTokens(lastCode, Nil).toArray

    val diff = hirschberg(lastTokens, tokens)

    diff.collect {
      case Unmodified(str)                    => str
      case Inserted(str)                      => added(str)
      case Modified(old, str) if printDiffDel => deleted(str) + added(str)
      case Modified(_, str)                   => added(str)
      case Deleted(str) if printDiffDel       => deleted(str)
    }.mkString
  }

  private def added(str: String): String = bgColored(str, Console.GREEN)
  private def deleted(str: String) = bgColored(str, Console.RED)
  private def bgColored(str: String, color: String): String =
    if (str.isEmpty) ""
    else {
      val (spaces, rest) = str.span(_ == '\n')
      if (spaces.isEmpty) {
        val (text, rest2) = str.span(_ != '\n')
        Console.BOLD + color + "[" + text + "]" + Console.RESET + bgColored(rest2, color)
      } else spaces + bgColored(rest, color)
    }
  private def eof() = "\u001B[51m" + "EOF" + Console.RESET

  private sealed trait Patch
  private final case class Unmodified(str: String) extends Patch
  private final case class Modified(original: String, str: String) extends Patch
  private final case class Deleted(str: String) extends Patch
  private final case class Inserted(str: String) extends Patch

  private def hirschberg(a: Array[String], b: Array[String]): Array[Patch] = {
    def build(x: Array[String], y: Array[String], builder: mutable.ArrayBuilder[Patch]): Unit =
      if (x.isEmpty)
        builder += Inserted(y.mkString)
      else if (y.isEmpty)
        builder += Deleted(x.mkString)
      else if (x.length == 1 || y.length == 1)
        needlemanWunsch(x, y, builder)
      else {
        val xlen = x.length
        val xmid = xlen / 2

        val (x1, x2) = x.splitAt(xmid)
        val leftScore = nwScore(x1, y)
        val rightScore = nwScore(x2.reverse, y.reverse)
        val scoreSum = (leftScore zip rightScore.reverse).map { case (left, right) =>
          left + right
        }
        val max = scoreSum.max
        val ymid = scoreSum.indexOf(max)

        val (y1, y2) = y.splitAt(ymid)
        build(x1, y1, builder)
        build(x2, y2, builder)
      }
    val builder = Array.newBuilder[Patch]
    build(a, b, builder)
    builder.result()
  }

  private def nwScore(x: Array[String], y: Array[String]): Array[Int] = {
    def ins(s: String) = -2
    def del(s: String) = -2
    def sub(s1: String, s2: String) = if (s1 == s2) 2 else -1

    val score = Array.fill(x.length + 1, y.length + 1)(0)
    for (j <- 1 to y.length)
      score(0)(j) = score(0)(j - 1) + ins(y(j - 1))
    for (i <- 1 to x.length) {
      score(i)(0) = score(i - 1)(0) + del(x(i - 1))
      for (j <- 1 to y.length) {
        val scoreSub = score(i - 1)(j - 1) + sub(x(i - 1), y(j - 1))
        val scoreDel = score(i - 1)(j) + del(x(i - 1))
        val scoreIns = score(i)(j - 1) + ins(y(j - 1))
        score(i)(j) = scoreSub max scoreDel max scoreIns
      }
    }
    Array.tabulate(y.length + 1)(j => score(x.length)(j))
  }

  private def needlemanWunsch(x: Array[String], y: Array[String], builder: mutable.ArrayBuilder[Patch]): Unit = {
    def similarity(a: String, b: String) = if (a == b) 2 else -1
    val d = 1
    val score = Array.tabulate(x.length + 1, y.length + 1) { (i, j) =>
      if (i == 0) d * j
      else if (j == 0) d * i
      else 0
    }
    for (i <- 1 to x.length)
      for (j <- 1 to y.length) {
        val mtch = score(i - 1)(j - 1) + similarity(x(i - 1), y(j - 1))
        val delete = score(i - 1)(j) + d
        val insert = score(i)(j - 1) + d
        score(i)(j) = mtch max insert max delete
      }

    var alignment = List.empty[Patch]
    var i = x.length
    var j = y.length
    while (i > 0 || j > 0) if (i > 0 && j > 0 && score(i)(j) == score(i - 1)(j - 1) + similarity(x(i - 1), y(j - 1))) {
      val newHead =
        if (x(i - 1) == y(j - 1)) Unmodified(x(i - 1))
        else Modified(x(i - 1), y(j - 1))
      alignment = newHead :: alignment
      i = i - 1
      j = j - 1
    } else if (i > 0 && score(i)(j) == score(i - 1)(j) + d) {
      alignment = Deleted(x(i - 1)) :: alignment
      i = i - 1
    } else {
      alignment = Inserted(y(j - 1)) :: alignment
      j = j - 1
    }
    builder ++= alignment
  }
}




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