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From GitBox <...@apache.org>
Subject [GitHub] mbeckerle commented on a change in pull request #88: Daffodil 1919 separators
Date Tue, 07 Aug 2018 21:43:11 GMT
mbeckerle commented on a change in pull request #88: Daffodil 1919 separators
URL: https://github.com/apache/incubator-daffodil/pull/88#discussion_r208395373
 
 

 ##########
 File path: daffodil-runtime1-unparser/src/main/scala/org/apache/daffodil/processors/unparsers/SeparatedSequenceUnparsers.scala
 ##########
 @@ -0,0 +1,423 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.daffodil.processors.unparsers
+
+import org.apache.daffodil.equality.TypeEqual
+import org.apache.daffodil.exceptions.Assert
+import org.apache.daffodil.processors.{ ElementRuntimeData, SequenceRuntimeData, TermRuntimeData
}
+import org.apache.daffodil.schema.annotation.props.SeparatorSuppressionPolicy
+import org.apache.daffodil.schema.annotation.props.gen.{ SeparatorPosition }
+import org.apache.daffodil.infoset.DIElement
+
+/**
+ * DFDL Spec. section 14.2.3 specifies only a few different behaviors
+ * for separator suppression. Each has an algorithm.
+ */
+sealed trait SeparatorSuppressionAlgorithm extends Serializable {
+
+  /**
+   * Determines if we should suppress a zero length element and
+   * separator.
+   *
+   * Checks if the length is zero if necessary to decide.
+   *
+   * Returns Suppress or IfTrailing when the element is, in fact, zero length,
+   * and the algorithm wants those to be suppressed.
+   * Returns DoNotSuppress otherwise.
+   */
+  def shouldSuppressIfZeroLength(state: UState, infosetElement: DIElement): SeparatorSuppressionAction
+
+  def shouldDoExtraSeparators = false
+
+  def checkArrayPos(state: UState, maxRepeats: Long): Boolean = true
+
+}
+
+object SeparatorSuppressionAlgorithm {
+  type Type = SeparatorSuppressionAlgorithm
+  import SeparatorSuppressionAction._
+
+  object None extends Type {
+    def shouldSuppressIfZeroLength(state: UState, infosetElement: DIElement) = Assert.usageError("not
to be called.")
+  }
+  object FixedOrExpression extends Type {
+    def shouldSuppressIfZeroLength(state: UState, infosetElement: DIElement) = DoNotSuppress
+  }
+
+  class SuppressAnyEmpty(zeroLengthDetector: ZeroLengthDetector) extends Type {
+    def shouldSuppressIfZeroLength(state: UState, infosetElement: DIElement) = {
+      val isZL = zeroLengthDetector.isZeroLength(infosetElement)
+      if (isZL) Suppress
+      else DoNotSuppress
+    }
+  }
+
+  trait CheckArrayPosMixin { self: SeparatorSuppressionAlgorithm =>
+    override def checkArrayPos(state: UState, maxRepeats: Long): Boolean = {
+      state.arrayPos <= maxRepeats
+    }
+  }
+
+  class ImplicitSuppressAnyEmpty(zeroLengthDetector: ZeroLengthDetector)
+    extends SuppressAnyEmpty(zeroLengthDetector)
+    with CheckArrayPosMixin
+
+  object ImplicitNeverOrNotPotentiallyTrailing extends Type
+    with CheckArrayPosMixin {
+    def shouldSuppressIfZeroLength(state: UState, infosetElement: DIElement) = DoNotSuppress
+
+    override def shouldDoExtraSeparators = true
+
+  }
+
+  class ImplicitPotentiallyTrailing(zeroLengthDetector: ZeroLengthDetector) extends Type
+    with CheckArrayPosMixin {
+    def shouldSuppressIfZeroLength(state: UState, infosetElement: DIElement) = {
+      val isZL = zeroLengthDetector.isZeroLength(infosetElement)
+      if (isZL) IfTrailing
+      else DoNotSuppress
+    }
+  }
+}
+
+sealed trait SeparatorSuppressionAction extends Serializable
+object SeparatorSuppressionAction {
+  type Type = SeparatorSuppressionAction
+  case object Suppress extends Type
+  case object DoNotSuppress extends Type
+  case object IfTrailing extends Type
+}
+
+trait Separated { self: SequenceChildUnparser =>
+
+  def sep: Unparser
+  def spos: SeparatorPosition
+  def ssp: SeparatorSuppressionPolicy
+  def ssAlgorithm: SeparatorSuppressionAlgorithm
+
+  val childProcessors = Seq(childUnparser, sep)
+}
+
+class ScalarOrderedSeparatedSequenceChildUnparser(
+  childUnparser: Unparser,
+  srd: SequenceRuntimeData,
+  trd: TermRuntimeData,
+  val sep: Unparser,
+  val spos: SeparatorPosition,
+  val ssp: SeparatorSuppressionPolicy,
+  val ssAlgorithm: SeparatorSuppressionAlgorithm)
+  extends SequenceChildUnparser(childUnparser, srd, trd)
+  with Separated {
+
+  override def unparse(state: UState) = childUnparser.unparse1(state)
+}
+
+class RepOrderedSeparatedSequenceChildUnparser(
+  childUnparser: Unparser,
+  srd: SequenceRuntimeData,
+  erd: ElementRuntimeData,
+  val sep: Unparser,
+  val spos: SeparatorPosition,
+  val ssp: SeparatorSuppressionPolicy, // need for diagnostics perhaps
+  val ssAlgorithm: SeparatorSuppressionAlgorithm)
+  extends RepeatingChildUnparser(childUnparser, srd, erd)
+  with Separated {
+
+  override def checkArrayPos(state: UState) = ssAlgorithm.checkArrayPos(state, maxRepeats(state))
+}
+
+class OrderedSeparatedSequenceUnparser(
+  rd: SequenceRuntimeData,
+  ssp: SeparatorSuppressionPolicy,
+  spos: SeparatorPosition,
+  sep: Unparser,
+  childUnparsersArg: Seq[SequenceChildUnparser])
+  extends OrderedSequenceUnparserBase(rd, childUnparsersArg) {
+
+  private val childUnparsers = childUnparsersArg.asInstanceOf[Seq[SequenceChildUnparser with
Separated]]
+
+  /**
+   * True if requires special treatment in the unparse processing loop, as occurrences
+   * of later sequence children can influence whether possible trailing separators
+   * from earlier sequence children are actually trailing or not.
+   */
+  private type IPT = SeparatorSuppressionAlgorithm.ImplicitPotentiallyTrailing
+
+  private val hasTrailingSeparatorSuppression = {
+    childUnparsers.last.ssAlgorithm.isInstanceOf[IPT]
+  }
+
+  /**
+   * Unparses one occurrence.
+   */
+  protected def unparseOne(
+    unparser: SequenceChildUnparser,
+    trd: TermRuntimeData,
+    state: UState): Unit = {
+
+    if (trd.isRepresented) {
+      if ((spos eq SeparatorPosition.Prefix)) {
+        sep.unparse1(state)
+      } else if ((spos eq SeparatorPosition.Infix) && state.groupPos > 1) {
+        sep.unparse1(state)
+      }
+    }
+
+    unparser.unparse1(state)
+
+    if ((spos eq SeparatorPosition.Postfix) && trd.isRepresented) {
+      sep.unparse1(state)
+    }
+  }
+
+  /**
+   * Unparses a zero-length occurrence, without the separator. This is so that
+   * any statements or other side-effects (discriminators, setVariable, etc.)
+   * will occur.
+   */
+  private def unparseZeroLengthWithoutSeparatorForSideEffect(
+    unparser: SequenceChildUnparser,
+    trd: TermRuntimeData,
+    state: UState): Unit = {
+    //
+    // Unfortunately there's no way to confirm that this produced zero length
+    // because of the possible buffering going on in the unparser.
+    // We'd have to depend on intricate details of the unparser behavior to do this,
+    // and that's unwise from separation-of-concerns perspective.
+    //
+    unparser.unparse1(state)
+  }
+
+  /**
+   * Unparses the separator only.
+   *
+   * Does not deals with infix boundary condition, because
+   * the counting of the potential trailing separators takes
+   * this into account.
+   */
+  private def unparseJustSeparator(state: UState): Unit = {
+    sep.unparse1(state)
+  }
+
+  /**
+   * Returns 1, or 0 if infix separator, and this is the first thing
+   * in the sequence meaning there is no separator for it.
+   *
+   * However, if we're not doing trailing separator suppression, always
+   * returns 0.
+   */
+  private def suppressedTrailingSeparatorIncrement(unparser: SequenceChildUnparser with Separated,
state: UState): Int = {
+    Assert.usage(unparser.trd.isRepresented)
+    val notIPT = !unparser.ssAlgorithm.isInstanceOf[IPT]
+    val result =
+      if (notIPT)
+        0
+      else {
+        val infixAndFirst = (spos eq SeparatorPosition.Infix) && state.groupPos ==
1
+        if (infixAndFirst)
+          0
+        else
+          1
+      }
+    result
+  }
+
+  /**
+   * Unparses an entire sequence, including both scalar and array/optional children.
+   */
+  protected def unparse(state: UState): Unit = {
+
+    state.groupIndexStack.push(1L) // one-based indexing
+
+    var index = 0
+    var doUnparser = false
+    val limit = childUnparsers.length
+
+    var potentialTrailingSeparatorCount: Int = 0
+
+    // This state var just lets us check some important
+    // invariants about potentially trailing, e.g., once
+    // you hit it, it sticks until the end of the group.
+    //
+    var haveSeenPotentiallyTrailingSeparators = false
+
+    while (index < limit) {
+      val childUnparser = childUnparsers(index)
+      val trd = childUnparser.trd
+
+      //
+      // Unparsing an ordered sequence depends on the incoming
+      // stream of infoset events matching up with the order that
+      // they are expected as the unparser recurses through the
+      // child term unparsers.
+      //
+      childUnparser match {
+        case unparser: RepOrderedSeparatedSequenceChildUnparser => {
+          val erd = unparser.erd
+          var numOccurrences = 0
+          val maxReps = unparser.maxRepeats(state)
+          //
+          // The number of occurrances we unparse is always exactly driven
+          // by the number of infoset events for the repeating/optional element.
+          //
+          // For RepUnparser - array/optional case - in all cases we should get a
+          // startArray event. If we don't then
+          // the element must be entirely optional, so we get no events for it
+          // at all.
+          //
+          val ssAlgorithm = unparser.ssAlgorithm
+
+          if (state.inspect) {
+            val ev = state.inspectAccessor
+            val isArray = erd.isArray
+            if (ev.isStart && (isArray || erd.isOptional)) {
+              val eventNQN = ev.node.namedQName
+              if (eventNQN =:= erd.namedQName) {
+
+                //
+                // Note: leaving in some ofthese println, since debugger for unparsing is
so inadequate currently.
+                // This is the only way to figure out what is going on.
+                //
+                // System.err.println("Starting unparse of array/opt %s. Array Index Stack
is: %s".format(
+                //   erd.namedQName, state.arrayIndexStack))
+                //
+
+                // StartArray for this unparser's array element
+                //
+                unparser.startArray(state)
+                while ({
+                  doUnparser = unparser.shouldDoUnparser(unparser, state)
+                  doUnparser
+                }) {
+                  val suppressionAction =
+                    ssAlgorithm.shouldSuppressIfZeroLength(
+                      state,
+                      state.inspectAccessor.asElement)
+                  import SeparatorSuppressionAction._
+                  suppressionAction match {
+                    case DoNotSuppress => {
+                      //
+                      // If there are pending potentially trailing separators,
+                      // then we've just proven that they are NOT actually trailing
+                      // So we output them all.
+                      //
+                      while (potentialTrailingSeparatorCount > 0) {
+                        Assert.invariant(haveSeenPotentiallyTrailingSeparators)
+                        Assert.invariant(ssAlgorithm.isInstanceOf[IPT]) // sticks once we
hit one
+                        unparseJustSeparator(state)
+                        potentialTrailingSeparatorCount -= 1
+                      }
+
+                      if (state.dataProc.isDefined) state.dataProc.get.beforeRepetition(state,
this)
+                      // System.err.println("Starting unparse of occurrence of %s. Array
Index Stack is: %s".format(
+                      //   erd.namedQName, state.arrayIndexStack))
+
+                      unparseOne(unparser, erd, state)
+                      numOccurrences += 1
+
+                      state.moveOverOneArrayIndexOnly()
+                      // System.err.println("Finished unparse of occurrence of %s. Array
Index Stack is: %s".format(
+                      //   erd.namedQName, state.arrayIndexStack))
+
+                      state.moveOverOneGroupIndexOnly() // array elements are always represented.
+
+                      if (state.dataProc.isDefined) state.dataProc.get.afterRepetition(state,
this)
+                    }
+                    case Suppress => {
+                      unparseZeroLengthWithoutSeparatorForSideEffect(unparser, trd, state)
+                      state.moveOverOneArrayIndexOnly()
+                      state.moveOverOneGroupIndexOnly() // array elements are always represented.
+                    }
+                    case IfTrailing => {
+                      Assert.invariant(hasTrailingSeparatorSuppression)
+                      haveSeenPotentiallyTrailingSeparators = true // sticks once we've hit
one.
+                      unparseZeroLengthWithoutSeparatorForSideEffect(unparser, trd, state)
+                      state.moveOverOneArrayIndexOnly()
+                      state.moveOverOneGroupIndexOnly() // array elements are always represented
+                      potentialTrailingSeparatorCount += suppressedTrailingSeparatorIncrement(unparser,
state)
+                    }
+                  }
+                }
+                //
+                // For maxOccurs bounded, and never or not potentially trailing
+                //
+                if (ssAlgorithm.shouldDoExtraSeparators && maxReps > numOccurrences)
{
+                  var numExtraSeps = erd.maxOccurs - numOccurrences
+                  while (numExtraSeps > 0) {
+                    unparseJustSeparator(state)
+                    numExtraSeps -= 1
+                  }
+                }
+                // System.err.println("Finished unparse of array/opt %s. Array Index Stack
is: %s, maxReps %s, numOccurrences %s".format(
+                //   erd.namedQName, state.arrayIndexStack, maxReps, numOccurrences))
+                unparser.checkOccursCount(state, unparser, numOccurrences, maxReps)
+                unparser.endArray(erd, state)
+              } else {
+                //
+                // start array for some other array. Not this one. So we
+                // don't unparse anything here, and we'll go on to the next
+                // sequence child, which hopefully will be a matching array.
+                //
+                Assert.invariant(erd.minOccurs == 0L)
+              }
+
+            } else if (ev.isStart) {
+              Assert.invariant(!ev.erd.isArray && !erd.isOptional)
+              //
+              // start of scalar.
+              // That has to be for a different element later in the sequence
+              // since this one has a RepUnparser (i.e., is NOT scalar)
+              val eventNQN = ev.node.namedQName
+              Assert.invariant(eventNQN != erd.namedQName)
+            } else {
+              //              if (!(ev.isEnd && ev.isComplex))
+              //                Assert.invariantFailed("Expected end of complex. Was " +
ev)
+              // System.err.println("End event: " + ev)
+            }
+          } else {
+            // no event (state.inspect returned false)
+            Assert.invariantFailed("No event for unparsing.")
+          }
+        }
+        //
+        case scalarUnparser => {
 
 Review comment:
   Yes. Will add assertion.

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