Avoid creating child ExpansionInfos for each container during evaluation.

Author: tgregg

src/main/java/com/amazon/ion/impl/IonReaderContinuableCoreBinary.java

@@ -1652,7 +1652,7 @@ private void addVoidExpression() {
         }
 
         @Override
-        protected void readParameter(Macro.Parameter parameter, long parameterPresence, boolean isTrailing) {
+        protected void readParameter(Macro.Parameter parameter, long parameterPresence) {
             switch (parameter.getCardinality()) {
                 case ZeroOrOne:
                     if (parameterPresence == PresenceBitmap.EXPRESSION) {

src/main/java/com/amazon/ion/impl/LazyEExpressionArgsReader.java

@@ -2,8 +2,6 @@
 // SPDX-License-Identifier: Apache-2.0
 package com.amazon.ion.impl;
 
-import com.amazon.ion.IonCursor;
-import com.amazon.ion.IonException;
 import com.amazon.ion.IonType;
 import com.amazon.ion.MacroAwareIonWriter;
 import com.amazon.ion.SymbolToken;
@@ -19,9 +17,7 @@
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 
 /**
  * An {@link LazyEExpressionArgsReader} reads an E-Expression from a {@link ReaderAdapter}, constructs
@@ -139,9 +135,8 @@ private Marker getMarker(int index) {
      * Reads a single parameter to a macro invocation.
      * @param parameter information about the parameter from the macro signature.
      * @param parameterPresence the presence bits dedicated to this parameter (unused in text).
-     * @param isTrailing true if this parameter is the last one in the signature; otherwise, false (unused in binary).
      */
-    protected abstract void readParameter(Macro.Parameter parameter, long parameterPresence, boolean isTrailing);
+    protected abstract void readParameter(Macro.Parameter parameter, long parameterPresence);
 
     /**
      * Reads the macro's address and attempts to resolve that address to a Macro from the macro table.
@@ -231,7 +226,7 @@ protected void readValueAsExpression(boolean isImplicitRest) {
         }
     }
 
-    private int collectAndFlattenComplexEExpression(int numberOfParameters, ExpressionTape.Core macroBodyTape, List<Macro.Parameter> signature, PresenceBitmap presenceBitmap, int markerPoolStartIndex) {
+    private int collectAndFlattenComplexEExpression(ExpressionTape.Core macroBodyTape, List<Macro.Parameter> signature, PresenceBitmap presenceBitmap, int markerPoolStartIndex) {
         // TODO drop expression groups? No longer needed after the variables are resolved. Further simplifies the evaluator. Might miss validation? Also, would need to distribute field names over the elements of the group.
         int macroBodyTapeIndex = 0;
         int numberOfVariables = macroBodyTape.getNumberOfVariables();
@@ -250,8 +245,7 @@ private int collectAndFlattenComplexEExpression(int numberOfParameters, Expressi
                     int startIndexInTape = expressionTape.size();
                     readParameter(
                         signature.get(invocationOrdinal),
-                        presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(invocationOrdinal),
-                        invocationOrdinal == (numberOfParameters - 1)
+                        presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(invocationOrdinal)
                     );
                     Marker marker = getMarker(markerPoolStartIndex + invocationOrdinal);
                     marker.typeId = null;
@@ -264,8 +258,7 @@ private int collectAndFlattenComplexEExpression(int numberOfParameters, Expressi
                     expressionTape = expressionTapeScratch;
                     readParameter(
                         signature.get(invocationOrdinal),
-                        presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(invocationOrdinal),
-                        invocationOrdinal == (numberOfParameters - 1)
+                        presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(invocationOrdinal)
                     );
                     expressionTape = expressionTapeOrdered;
                     Marker marker = getMarker(markerPoolStartIndex + invocationOrdinal);
@@ -293,7 +286,7 @@ private int collectAndFlattenComplexEExpression(int numberOfParameters, Expressi
         return macroBodyTapeIndex;
     }
 
-    private int collectAndFlattenSimpleEExpression(int numberOfParameters, ExpressionTape.Core macroBodyTape, List<Macro.Parameter> signature, PresenceBitmap presenceBitmap) {
+    private int collectAndFlattenSimpleEExpression(ExpressionTape.Core macroBodyTape, List<Macro.Parameter> signature, PresenceBitmap presenceBitmap) {
         // TODO drop expression groups? No longer needed after the variables are resolved. Further simplifies the evaluator. Might miss validation? Also, would need to distribute field names over the elements of the group.
         int macroBodyTapeIndex = 0;
         int numberOfVariables = macroBodyTape.getNumberOfVariables();
@@ -304,8 +297,7 @@ private int collectAndFlattenSimpleEExpression(int numberOfParameters, Expressio
             // variable in the signature. This means it can be copied into the tape without using scratch space.
             readParameter(
                 signature.get(i),
-                presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(i),
-                i == (numberOfParameters - 1)
+                presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(i)
             );
         }
         return macroBodyTapeIndex;
@@ -324,9 +316,9 @@ private ExpressionTape collectAndFlattenUserEExpressionArgs(boolean isTopLevel,
                 return constantTape;
             }
         } else if (macro.isSimple()) {
-            macroBodyTapeIndex = collectAndFlattenSimpleEExpression(numberOfParameters, macroBodyTape, signature, presenceBitmap);
+            macroBodyTapeIndex = collectAndFlattenSimpleEExpression(macroBodyTape, signature, presenceBitmap);
         } else {
-            macroBodyTapeIndex = collectAndFlattenComplexEExpression(numberOfParameters, macroBodyTape, signature, presenceBitmap, markerPoolIndex + 1);
+            macroBodyTapeIndex = collectAndFlattenComplexEExpression(macroBodyTape, signature, presenceBitmap, markerPoolIndex + 1);
         }
         // Copy everything after the last parameter.
         expressionTape.copyFromRange(macroBodyTape, macroBodyTapeIndex, macroBodyTape.size());
@@ -341,8 +333,7 @@ private void collectVerbatimEExpressionArgs(Macro macro, List<Macro.Parameter> s
         for (int i = 0; i < numberOfParameters; i++) {
             readParameter(
                 signature.get(i),
-                presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(i),
-                i == (numberOfParameters - 1)
+                presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(i)
             );
         }
         stepOutOfEExpression();

src/main/java/com/amazon/ion/impl/macro/LazyMacroEvaluator.kt

@@ -523,7 +523,7 @@ class LazyMacroEvaluator : IonReader {
             expressionTape = arguments
             sideEffectExpander = getExpander(EMPTY, sideEffects)
             sideEffectExpander!!.keepAlive = true
-            currentExpander = null
+            currentExpander = getExpander(STREAM, expressionTape)
             currentFieldName = fieldName
             currentAnnotations = null
             eExpressionIndex = -1;
@@ -533,20 +533,15 @@ class LazyMacroEvaluator : IonReader {
     /**
      * A container in the macro evaluator's [containerStack].
      */
-    private data class ContainerInfo(var type: Type = Type.Uninitialized, private var _expansion: ExpansionInfo? = null) {
+    private data class ContainerInfo(var type: Type = Type.Uninitialized) {
         enum class Type { TopLevel, List, Sexp, Struct, Uninitialized }
 
         fun close() {
-            _expansion?.close()
-            _expansion = null
             currentFieldName = null
             container = null
             type = Type.Uninitialized
         }
 
-        var expansion: ExpansionInfo
-            get() = _expansion!!
-            set(value) { _expansion = value }
         @JvmField var currentFieldName: SymbolToken? = null
         @JvmField var container: IonType? = null
     }
@@ -594,11 +589,6 @@ class LazyMacroEvaluator : IonReader {
 
         var parentExpansion: ExpansionInfo? = null
 
-        /**
-         * Gets the [ExpansionInfo] at the top of the stack of [childExpansion]s.
-         */
-        fun top(): ExpansionInfo = childExpansion?.top() ?: this
-
         /**
          * Returns an expansion for the given variable.
          */
@@ -734,8 +724,6 @@ class LazyMacroEvaluator : IonReader {
         session.reset(fieldName, encodingExpressions)
         val ci = containerStack.push { _ -> }
         ci.type = ContainerInfo.Type.TopLevel
-
-        ci.expansion = session.getExpander(STREAM, session.expressionTape)
     }
 
     override fun next(): IonType? {
@@ -779,8 +767,7 @@ class LazyMacroEvaluator : IonReader {
         if (containerStack.size() <= 1) throw IonException("Nothing to step out of.")
         val popped = containerStack.pop()
         val currentContainer = containerStack.peek()
-        session.currentExpander = currentContainer.expansion.top()
-        popped.expansion.tape!!.advanceToAfterEndContainer()
+        session.expressionTape!!.advanceToAfterEndContainer()
         popped.close()
         session.currentFieldName = currentContainer.currentFieldName
         currentValueType = null // Must call `next()` to get the next value
@@ -804,11 +791,6 @@ class LazyMacroEvaluator : IonReader {
                 IonType.STRUCT -> ContainerInfo.Type.Struct
                 else -> unreachable()
             }
-            // TODO can this expander be eliminated?
-            ci.expansion = session.getExpander(
-                expansionKind = STREAM,
-                tape = session.expressionTape
-            )
             ci.currentFieldName = null
             currentExpr = null
             session.currentFieldName = null