make Node.toString stack safe

shared/src/main/scala/scala/xml/Utility.scala

@@ -9,6 +9,7 @@
 package scala
 package xml
 
+import scala.annotation.tailrec
 import scala.collection.mutable
 import scala.language.implicitConversions
 import scala.collection.Seq
@@ -187,9 +188,7 @@ object Utility extends AnyRef with parsing.TokenTests {
  decodeEntities: Boolean = true,
  preserveWhitespace: Boolean = false,
  minimizeTags: Boolean = false): StringBuilder =
- {
  serialize(x, pscope, sb, stripComments, decodeEntities, preserveWhitespace, if (minimizeTags) MinimizeMode.Always else MinimizeMode.Never)
- }
 
  /**
  * Serialize an XML Node to a StringBuilder.
@@ -206,35 +205,67 @@ object Utility extends AnyRef with parsing.TokenTests {
  stripComments: Boolean = false,
  decodeEntities: Boolean = true,
  preserveWhitespace: Boolean = false,
- minimizeTags: MinimizeMode.Value = MinimizeMode.Default): StringBuilder =
- {
- x match {
- case c: Comment => if (!stripComments) c buildString sb; sb
- case s: SpecialNode => s buildString sb
- case g: Group =>
- for (c <- g.nodes) serialize(c, g.scope, sb, stripComments, decodeEntities, preserveWhitespace, minimizeTags); sb
- case el: Elem =>
- // print tag with namespace declarations
- sb.append('<')
- el.nameToString(sb)
- if (el.attributes ne null) el.attributes.buildString(sb)
- el.scope.buildString(sb, pscope)
- if (el.child.isEmpty &&
- (minimizeTags == MinimizeMode.Always ||
- (minimizeTags == MinimizeMode.Default && el.minimizeEmpty))) {
- // no children, so use short form: <xyz .../>
- sb.append("/>")
- } else {
- // children, so use long form: <xyz ...>...</xyz>
- sb.append('>')
- sequenceToXML(el.child, el.scope, sb, stripComments, decodeEntities, preserveWhitespace, minimizeTags)
- sb.append("</")
- el.nameToString(sb)
- sb.append('>')
- }
- case _ => throw new IllegalArgumentException("Don't know how to serialize a " + x.getClass.getName)
- }
+ minimizeTags: MinimizeMode.Value = MinimizeMode.Default
+ ): StringBuilder = {
+ serializeImpl(List(x), pscope, false, stripComments, minimizeTags, sb)
+ sb
+ }
+
+ private def serializeImpl(
+ ns: Seq[Node],
+ pscope: NamespaceBinding,
+ spaced: Boolean,
+ stripComments: Boolean,
+ minimizeTags: MinimizeMode.Value,
+ sb: StringBuilder
+ ): Unit = {
+ @tailrec def ser(nss: List[Seq[Node]], pscopes: List[NamespaceBinding], spaced: List[Boolean], toClose: List[Node]): Unit = nss match {
+ case List(ns) if ns.isEmpty =>
+ case ns :: rests if ns.isEmpty =>
+ if (toClose.head != null) {
+ sb.append("</")
+ toClose.head.nameToString(sb)
+ sb.append('>')
+ }
+ ser(rests, pscopes.tail, spaced.tail, toClose.tail)
+ case ns1 :: r =>
+ val (n, ns) = (ns1.head, ns1.tail)
+ def sp(): Unit = if (ns.nonEmpty && spaced.head) sb.append(' ')
+ n match {
+ case c: Comment =>
+ if (!stripComments) {
+ c.buildString(sb)
+ sp()
+ }
+ ser(ns :: r, pscopes, spaced, toClose)
+ case s: SpecialNode =>
+ s.buildString(sb)
+ sp()
+ ser(ns :: r, pscopes, spaced, toClose)
+ case g: Group =>
+ ser(g.nodes :: ns :: r, g.scope :: pscopes, false :: spaced, null :: toClose)
+ case e: Elem =>
+ sb.append('<')
+ e.nameToString(sb)
+ if (e.attributes.ne(null)) e.attributes.buildString(sb)
+ e.scope.buildString(sb, pscopes.head)
+ if (e.child.isEmpty &&
+ (minimizeTags == MinimizeMode.Always ||
+ (minimizeTags == MinimizeMode.Default && e.minimizeEmpty))) {
+ // no children, so use short form: <xyz .../>
+ sb.append("/>")
+ sp()
+ ser(ns :: r, pscopes, spaced, toClose)
+ } else {
+ sb.append('>')
+ val csp = e.child.forall(isAtomAndNotText)
+ ser(e.child :: ns :: r, e.scope :: pscopes, csp :: spaced, e :: toClose)
+ }
+ case n => throw new IllegalArgumentException("Don't know how to serialize a " + n.getClass.getName)
+ }
  }
+ ser(List(ns), List(pscope), List(spaced), Nil)
+ }
 
  def sequenceToXML(
  children: Seq[Node],
@@ -243,20 +274,11 @@ object Utility extends AnyRef with parsing.TokenTests {
  stripComments: Boolean = false,
  decodeEntities: Boolean = true,
  preserveWhitespace: Boolean = false,
- minimizeTags: MinimizeMode.Value = MinimizeMode.Default): Unit =
- {
- if (children.isEmpty) return
- else if (children forall isAtomAndNotText) { // add space
- val it = children.iterator
- val f = it.next()
- serialize(f, pscope, sb, stripComments, decodeEntities, preserveWhitespace, minimizeTags)
- while (it.hasNext) {
- val x = it.next()
- sb.append(' ')
- serialize(x, pscope, sb, stripComments, decodeEntities, preserveWhitespace, minimizeTags)
- }
- } else children foreach { serialize(_, pscope, sb, stripComments, decodeEntities, preserveWhitespace, minimizeTags) }
- }
+ minimizeTags: MinimizeMode.Value = MinimizeMode.Default
+ ): Unit = if (children.nonEmpty) {
+ val spaced = children.forall(isAtomAndNotText)
+ serializeImpl(children, pscope, spaced, stripComments, minimizeTags, sb)
+ }
 
  /**
  * Returns prefix of qualified name if any.

shared/src/test/scala/scala/xml/UtilityTest.scala

@@ -217,4 +217,10 @@ class UtilityTest {
  val x = <div>{Text(" My name ")}{Text(" is ")}{Text(" Harry ")}</div>
  assertEquals(<div>My name is Harry</div>, Utility.trim(x))
  }
+
+ @Test
+ def toStringStackSafe(): Unit = {
+ val xml = (1 to 5000).foldRight(<x/>) { case (_, n) => <x>{n}</x> }
+ xml.toString
+ }
 }