1 files changed, 123 insertions, 0 deletions
diff --git a/src/dotty/tools/dotc/util/Text.scala b/src/dotty/tools/dotc/util/Text.scala
new file mode 100644
index 000000000..a63f36b83
--- /dev/null
+++ b/src/dotty/tools/dotc/util/Text.scala
@@ -0,0 +1,123 @@
+package dotty.tools.dotc.util
+
+import language.implicitConversions
+
+object Texts {
+
+  class Text {
+
+    protected def indentMargin = 2
+    protected def pageWidth = 80
+
+    def relems: List[Text]
+
+    def isEmpty: Boolean = this match {
+      case Str(s) => s.isEmpty
+      case Fluid(relems) => relems forall (_.isEmpty)
+      case Rigid(relems) => relems.isEmpty
+    }
+
+    def isRigid = isInstanceOf[Rigid]
+
+    def fitsIn(width: Int): Boolean = this match {
+      case Str(s) =>
+        s.length <= width
+      case Fluid(Str(s) :: prevs) =>
+        s.length < width && Fluid(prevs).fitsIn(width - s.length)
+      case Rigid(_) =>
+        false
+    }
+
+    def lastLineWidth: Int = this match {
+      case Str(s) => s.length
+      case _ => relems.head.lastLineWidth
+    }
+
+    def appendToLastLine(that: Text): Text = that match {
+      case Str(s2) =>
+        this match {
+          case Str(s1) => Str(s1 + s2)
+          case Fluid(Str(s1) :: prev) => Fluid(Str(s1 + s2) :: prev)
+        }
+      case Fluid(relems) =>
+        (this /: relems.reverse)(_ appendToLastLine _)
+    }
+
+    private def appendIndented(that: Text)(width: Int): Text =
+      Rigid(that.layout(width - indentMargin).indented :: this.relems)
+
+    private def append(width: Int)(that: Text): Text =
+      if (this.isEmpty) that.layout(width)
+      else if (that.isEmpty) this
+      else if (that.isRigid) appendIndented(that)(width)
+      else if (this.isRigid) Fluid(that.layout(width) :: this.relems)
+      else if (that.fitsIn(width - this.lastLineWidth)) appendToLastLine(that)
+      else appendIndented(that)(width)
+
+    def layout(width: Int): Text = this match {
+      case Str(_) =>
+        this
+      case Fluid(relems) =>
+        ((Str(""): Text) /: relems.reverse)(_.append(width)(_))
+      case Rigid(relems) =>
+        Rigid(relems map (_ layout width))
+    }
+
+    private def indented: Text = this match {
+      case Str(s) => Str((" " * indentMargin) + s)
+      case Fluid(relems) => Fluid(relems map (_.indented))
+      case Rigid(relems) => Rigid(relems map (_.indented))
+    }
+
+    def print(sb: StringBuilder): Unit = this match {
+      case Str(s) =>
+        sb.append(s)
+      case txt: CompoundText =>
+        var follow = false
+        for (elem <- txt.relems.reverse) {
+          if (follow) sb.append("\n")
+          elem.print(sb)
+          follow = true
+        }
+    }
+
+    def show: String =
+      layout(pageWidth).showRaw
+
+    def showRaw: String = {
+      val sb = new StringBuilder
+      print(sb)
+      sb.toString
+    }
+
+    def +++ (that: Text) =
+      if (this.isEmpty) that
+      else if (that.isEmpty) this
+      else Fluid(that :: this :: Nil)
+
+    def over (that: Text) =
+      if (this.isRigid) Rigid(that :: this.relems)
+      else Rigid(that :: this :: Nil)
+  }
+
+  object Text {
+    def apply(xs: Traversable[Text], sep: String): Text = {
+      val ys = xs filterNot (_.isEmpty)
+      if (ys.isEmpty) Str("")
+      else ys reduce (_ +++ sep +++ _)
+    }
+  }
+
+  abstract class CompoundText extends Text {
+    def relems: List[Text]
+  }
+
+  case class Str(s: String) extends Text {
+    override def relems: List[Text] = List(this)
+  }
+
+  case class Rigid(relems: List[Text]) extends CompoundText
+  case class Fluid(relems: List[Text]) extends CompoundText
+
+  implicit def stringToText(s: String): Text = Str(s)
+}
+\ No newline at end of file