Merge pull request #3147 from som-snytt/issue/repl-columns

SI-7969 REPL -C columnar output

4 files changed, 126 insertions, 14 deletions

diff --git a/src/repl/scala/tools/nsc/interpreter/ConsoleReaderHelper.scala b/src/repl/scala/tools/nsc/interpreter/ConsoleReaderHelper.scala
index cf03ecb480..d8efcda8b5 100644
--- a/src/repl/scala/tools/nsc/interpreter/ConsoleReaderHelper.scala
+++ b/src/repl/scala/tools/nsc/interpreter/ConsoleReaderHelper.scala
@@ -8,7 +8,9 @@ package interpreter
 
 import jline.console.{ ConsoleReader, CursorBuffer }
 
-trait ConsoleReaderHelper extends ConsoleReader {
+trait ConsoleReaderHelper { _: ConsoleReader with Tabulator =>
+  def isAcross: Boolean
+
   def terminal    = getTerminal()
   def width       = terminal.getWidth()
   def height      = terminal.getHeight()
@@ -16,7 +18,8 @@ trait ConsoleReaderHelper extends ConsoleReader {
   def readOneKey(prompt: String): Int
   def eraseLine(): Unit
 
-  private val marginSize = 3
+  val marginSize = 3
+
   private def morePrompt = "--More--"
   private def emulateMore(): Int = {
     val key = readOneKey(morePrompt)
@@ -38,19 +41,12 @@ trait ConsoleReaderHelper extends ConsoleReader {
   }
 
   override def printColumns(items: JCollection[_ <: CharSequence]): Unit =
-    printColumns(items: List[String])
-
-  def printColumns(items: List[String]): Unit = {
-    if (items forall (_ == ""))
-      return
+    printColumns_(items: List[String])
 
-    val longest    = items map (_.length) max
+  private def printColumns_(items: List[String]): Unit = if (items exists (_ != "")) {
+    val grouped = tabulate(items)
     var linesLeft  = if (isPaginationEnabled()) height - 1 else Int.MaxValue
-    val columnSize = longest + marginSize
-    val padded     = items map ("%-" + columnSize + "s" format _)
-    val groupSize  = 1 max (width / columnSize)   // make sure it doesn't divide to 0
-
-    padded grouped groupSize foreach { xs =>
+    grouped foreach { xs =>
       println(xs.mkString)
       linesLeft -= 1
       if (linesLeft <= 0) {
@@ -61,3 +57,104 @@ trait ConsoleReaderHelper extends ConsoleReader {
     }
   }
 }
+
+trait Tabulator {
+  def isAcross: Boolean
+  def width: Int
+  def marginSize: Int
+
+  protected def fits(items: Seq[String], width: Int): Boolean = (
+    (items map (_.length)).sum + (items.length - 1) * marginSize < width
+  )
+  def tabulate(items: Seq[String]): Seq[Seq[String]] = (
+    if (fits(items, width)) Seq(Seq(items mkString " " * marginSize))
+    else printMultiLineColumns(items)
+  )
+  protected def columnize(ss: Seq[String]): Seq[Seq[String]] = ss map (s => Seq(s))
+  protected def printMultiLineColumns(items: Seq[String]): Seq[Seq[String]] = {
+    import SimpleMath._
+    val longest     = (items map (_.length)).max
+    val columnWidth = longest + marginSize
+    val maxcols = (
+      if (columnWidth >= width) 1
+      else 1 max (width / columnWidth)   // make sure it doesn't divide to 0
+    )
+    val nrows       = items.size /% maxcols
+    val ncols       = items.size /% nrows
+    val groupSize   = ncols
+    val padded      = items map (s"%-${columnWidth}s" format _)
+    val xwise       = isAcross || ncols >= items.length
+    val grouped: Seq[Seq[String]]    =
+      if (groupSize == 1) columnize(items)
+      else if (xwise) (padded grouped groupSize).toSeq
+      else {
+        val h       = 1 max padded.size /% groupSize
+        val cols    = (padded grouped h).toList
+        for (i <- 0 until h) yield
+          for (j <- 0 until groupSize) yield
+            if (i < cols(j).size) cols(j)(i) else ""
+      }
+    grouped
+  }
+}
+
+/** Adjust the column width and number of columns to minimize the row count. */
+trait VariColumnTabulator extends Tabulator {
+  override protected def printMultiLineColumns(items: Seq[String]): Seq[Seq[String]] = {
+    import SimpleMath._
+    val longest  = (items map (_.length)).max
+    val shortest = (items map (_.length)).min
+    val fattest  = longest + marginSize
+    val skinny   = shortest + marginSize
+
+    // given ncols, calculate nrows and a list of column widths, or none if not possible
+    // if ncols > items.size, then columnWidths.size == items.size
+    def layout(ncols: Int): Option[(Int, Seq[Int], Seq[Seq[String]])] = {
+      val nrows = items.size /% ncols
+      val xwise = isAcross || ncols >= items.length
+      def maxima(sss: Seq[Seq[String]]) =
+        (0 until (ncols min items.size)) map (i => (sss map (ss => ss(i).length)).max)
+      def resulting(rows: Seq[Seq[String]]) = {
+        val columnWidths = maxima(rows) map (_ + marginSize)
+        val linelen      = columnWidths.sum
+        if (linelen <= width) Some((nrows, columnWidths, rows))
+        else None
+      }
+      if (ncols == 1) resulting(columnize(items))
+      else if (xwise) resulting((items grouped ncols).toSeq)
+      else {
+        val cols = (items grouped nrows).toList
+        val rows = for (i <- 0 until nrows) yield
+          for (j <- 0 until ncols) yield
+            if (j < cols.size && i < cols(j).size) cols(j)(i) else ""
+        resulting(rows)
+      }
+    }
+
+    if (fattest >= width) {
+      columnize(items)
+    } else {
+      // if every col is widest, we have at least this many cols
+      val mincols = 1 max (width / fattest)
+      // if every other col is skinniest, we have at most this many cols
+      val maxcols = 1 + ((width - fattest) / skinny)
+      val possibles = (mincols to maxcols).map(n => layout(n)).flatten
+      val minrows = (possibles map (_._1)).min
+
+      // select the min ncols that results in minrows
+      val (_, columnWidths, sss) = (possibles find (_._1 == minrows)).get
+
+      // format to column width
+      sss map (ss => ss.zipWithIndex map {
+        case (s, i) => s"%-${columnWidths(i)}s" format s
+      })
+    }
+  }
+}
+
+private[interpreter] object SimpleMath {
+  implicit class DivRem(private val i: Int) extends AnyVal {
+    /** i/n + if (i % n != 0) 1 else 0 */
+    def /%(n: Int): Int = (i + n - 1) / n
+  }
+}
diff --git a/src/repl/scala/tools/nsc/interpreter/JLineReader.scala b/src/repl/scala/tools/nsc/interpreter/JLineReader.scala
index 8b0c6d78fa..b6e834a1ed 100644
--- a/src/repl/scala/tools/nsc/interpreter/JLineReader.scala
+++ b/src/repl/scala/tools/nsc/interpreter/JLineReader.scala
@@ -33,7 +33,11 @@ class JLineReader(_completion: => Completion) extends InteractiveReader {
     }
   }
 
-  class JLineConsoleReader extends ConsoleReader with ConsoleReaderHelper {
+  class JLineConsoleReader extends ConsoleReader with ConsoleReaderHelper with VariColumnTabulator {
+    val isAcross = interpreter.`package`.isAcross
+
+    this setPaginationEnabled interpreter.`package`.isPaged
+
     // ASAP
     this setExpandEvents false
 
diff --git a/src/repl/scala/tools/nsc/interpreter/ReplConfig.scala b/src/repl/scala/tools/nsc/interpreter/ReplConfig.scala
index 3392ea0b5e..046d6ecbfb 100644
--- a/src/repl/scala/tools/nsc/interpreter/ReplConfig.scala
+++ b/src/repl/scala/tools/nsc/interpreter/ReplConfig.scala
@@ -46,4 +46,8 @@ trait ReplConfig {
   def isReplDebug: Boolean = replProps.debug || isReplTrace
   def isReplInfo: Boolean  = replProps.info || isReplDebug
   def isReplPower: Boolean = replProps.power
+
+  private def csv(p: String, v: String) = p split "," contains v
+  def isPaged: Boolean     = replProps.format.isSet && csv(replProps.format.get, "paged")
+  def isAcross: Boolean    = replProps.format.isSet && csv(replProps.format.get, "across")
 }
diff --git a/src/repl/scala/tools/nsc/interpreter/ReplProps.scala b/src/repl/scala/tools/nsc/interpreter/ReplProps.scala
index 2364918494..36e6dbbccc 100644
--- a/src/repl/scala/tools/nsc/interpreter/ReplProps.scala
+++ b/src/repl/scala/tools/nsc/interpreter/ReplProps.scala
@@ -18,6 +18,13 @@ class ReplProps {
   val trace = bool("scala.repl.trace")
   val power = bool("scala.repl.power")
 
+  /** CSV of paged,across to enable pagination or `-x` style
+   *  columns, "across" instead of down the column.  Since
+   *  pagination turns off columnar output, these flags are
+   *  currently mutually exclusive.
+   */
+  val format = Prop[String]("scala.repl.format")
+
   val replAutorunCode = Prop[JFile]("scala.repl.autoruncode")
   val powerInitCode   = Prop[JFile]("scala.repl.power.initcode")
   val powerBanner     = Prop[JFile]("scala.repl.power.banner")