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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2023 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.expr.instruct;
import net.sf.saxon.Controller;
import net.sf.saxon.event.PipelineConfiguration;
import net.sf.saxon.expr.*;
import net.sf.saxon.expr.elab.*;
import net.sf.saxon.expr.parser.*;
import net.sf.saxon.expr.sort.*;
import net.sf.saxon.functions.CurrentGroupCall;
import net.sf.saxon.lib.StringCollator;
import net.sf.saxon.lib.TraceListener;
import net.sf.saxon.om.*;
import net.sf.saxon.pattern.Pattern;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.Err;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.ErrorType;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.SchemaType;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.StringValue;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.function.Supplier;
/**
* Handler for xsl:for-each-group elements in stylesheet. This is a new instruction
* defined in XSLT 2.0
*/
public class ForEachGroup extends Instruction
implements SortKeyEvaluator, ContextSwitchingExpression {
public static final int GROUP_BY = 0;
public static final int GROUP_ADJACENT = 1;
public static final int GROUP_STARTING = 2;
public static final int GROUP_ENDING = 3;
public static final int GROUP_BREAKING_WHEN = 4;
private final byte algorithm;
private StringCollator collator; // collation used for the grouping comparisons
private AtomicComparer[] sortComparators = null; // comparators used for sorting the groups
private ItemEvaluator[] sortKeyEvaluators = null;
private boolean composite = false;
private boolean inFork = false;
private final Operand selectOp;
private final Operand actionOp;
private final Operand keyOp;
private Operand collationOp;
private Operand sortKeysOp;
/**
* Create a for-each-group instruction
* @param select the select expression (selects the population to be grouped)
* @param action the body of the for-each-group (applied to each group in turn)
* @param algorithm one of group-by, group-adjacent, group-starting-with, group-ending-with
* @param key expression to evaluate the grouping key
* @param collator user for comparing strings
* @param collationNameExpression expression that yields the name of the collation to be used
* @param sortKeys list of xsl:sort keys for sorting the groups. May be null.
*/
public ForEachGroup(Expression select,
Expression action,
byte algorithm,
Expression key,
StringCollator collator,
Expression collationNameExpression,
SortKeyDefinitionList sortKeys) {
selectOp = new Operand(this, select, OperandRole.FOCUS_CONTROLLING_SELECT);
actionOp = new Operand(this, action, OperandRole.FOCUS_CONTROLLED_ACTION);
OperandRole keyRole = (algorithm == GROUP_ENDING || algorithm == GROUP_STARTING) ? OperandRole.PATTERN : OperandRole.NEW_FOCUS_ATOMIC;
keyOp = new Operand(this, key, keyRole);
if (collationNameExpression != null) {
collationOp = new Operand(this, collationNameExpression, OperandRole.SINGLE_ATOMIC);
}
if (sortKeys != null) {
sortKeysOp = new Operand(this, sortKeys, OperandRole.SINGLE_ATOMIC);
}
this.algorithm = algorithm;
this.collator = collator;
for (Operand o : operands()) {
adoptChildExpression(o.getChildExpression());
}
}
/**
* Get the name of this instruction for diagnostic and tracing purposes
*
* @return the name of the instruction
*/
@Override
public int getInstructionNameCode() {
return StandardNames.XSL_FOR_EACH_GROUP;
}
@Override
public Iterable operands() {
return operandSparseList(selectOp, actionOp, keyOp, collationOp, sortKeysOp);
}
/**
* Get the select expression
*
* @return the select expression
*/
@Override
public Expression getSelectExpression() {
return selectOp.getChildExpression();
}
/**
* Get the action expression (the content of the for-each-group)
*
* @return the body of the xsl:for-each-group instruction
*/
@Override
public Expression getActionExpression() {
return actionOp.getChildExpression();
}
/**
* Get the grouping algorithm (one of group-by, group-adjacent, group-starting-with, group-ending-with)
*
* @return one of group-by, group-adjacent, group-starting-with, group-ending-with
*/
public byte getAlgorithm() {
return algorithm;
}
/**
* Get the grouping key expression expression (the group-by or group-adjacent expression, or a
* PatternSponsor containing the group-starting-with or group-ending-with expression)
*
* @return the expression used to calculate grouping keys
*/
public Expression getGroupingKey() {
return keyOp.getChildExpression();
}
/**
* Get the sort keys defined at the for-each-group level, that is, the keys for sorting the groups
*
* @return the definitions of the sort keys defined as children of the xsl:for-each-group element,
* or null if there are no sort keys
*/
public SortKeyDefinitionList getSortKeyDefinitions() {
return sortKeysOp == null ? null : (SortKeyDefinitionList)sortKeysOp.getChildExpression();
}
/**
* Get the statically-allocated sort key comparators for sorting at the group level, if known
*
* @return the comparators used for comparing sort key values, one entry in the array for each
* nested xsl:sort element
*/
public AtomicComparer[] getSortKeyComparators() {
return sortComparators;
}
/**
* Get the statically-determined collator, or null if the collation was not determined statically
*
* @return the collation, if known statically, or null if not
*/
/*@Nullable*/
public StringCollator getCollation() {
return collator;
}
/**
* Get the static base URI of the instruction
*
* @return the static base URI if known, or null otherwise
*/
/*@Nullable*/
public URI getBaseURI() {
try {
return getRetainedStaticContext().getStaticBaseUri();
} catch (XPathException err) {
return null;
}
}
public boolean isComposite() {
return composite;
}
public void setComposite(boolean composite) {
this.composite = composite;
}
public boolean isInFork() {
return inFork;
}
public void setIsInFork(boolean inFork) {
this.inFork = inFork;
}
/**
* Ask whether common subexpressions found in the operands of this expression can
* be extracted and evaluated outside the expression itself. The result is irrelevant
* in the case of operands evaluated with a different focus, which will never be
* extracted in this way, even if they have no focus dependency.
*
* @return false for this kind of expression
*/
@Override
public boolean allowExtractingCommonSubexpressions() {
return false;
}
/*@NotNull*/
@Override
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
selectOp.typeCheck(visitor, contextInfo);
if (collationOp != null) {
collationOp.typeCheck(visitor, contextInfo);
}
ItemType selectedItemType = getSelectExpression().getItemType();
if (selectedItemType == ErrorType.getInstance()) {
return Literal.makeEmptySequence();
}
fixupGroupReferences(this, this, selectedItemType, false);
ContextItemStaticInfo cit = visitor.getConfiguration().makeContextItemStaticInfo(selectedItemType, false);
cit.setContextSettingExpression(getSelectExpression());
actionOp.typeCheck(visitor, cit);
keyOp.typeCheck(visitor, cit);
if (Literal.isEmptySequence(getSelectExpression())) {
return getSelectExpression();
}
if (Literal.isEmptySequence(getActionExpression())) {
return getActionExpression();
}
if (getSortKeyDefinitions() != null) {
boolean allFixed = true;
for (SortKeyDefinition sk : getSortKeyDefinitions()) {
Expression sortKey = sk.getSortKey();
sortKey = sortKey.typeCheck(visitor, cit);
if (sk.isBackwardsCompatible()) {
sortKey = FirstItemExpression.makeFirstItemExpression(sortKey);
} else {
Supplier role =
() -> new RoleDiagnostic(RoleDiagnostic.INSTRUCTION, "xsl:sort/select", 0, "XTTE1020");
sortKey = CardinalityChecker.makeCardinalityChecker(sortKey, StaticProperty.ALLOWS_ZERO_OR_ONE, role);
}
sk.setSortKey(sortKey, true);
sk.typeCheck(visitor, contextInfo);
if (sk.isFixed()) {
AtomicComparer comp = sk.makeComparator(
visitor.getStaticContext().makeEarlyEvaluationContext());
sk.setFinalComparator(comp);
} else {
allFixed = false;
}
}
if (allFixed) {
sortComparators = new AtomicComparer[getSortKeyDefinitions().size()];
for (int i = 0; i < getSortKeyDefinitions().size(); i++) {
sortComparators[i] = getSortKeyDefinitions().getSortKeyDefinition(i).getFinalComparator();
}
}
}
return this;
}
private static void fixupGroupReferences(Expression exp, ForEachGroup feg, ItemType selectedItemType, boolean isInLoop) {
if (exp == null) {
// no action
} else if (exp instanceof CurrentGroupCall) {
((CurrentGroupCall) exp).setControllingInstruction(feg, selectedItemType, isInLoop);
} else if (exp instanceof ForEachGroup) {
// a current-group() reference to the outer for-each-group can occur in the select expression
// or in the AVTs of a contained xsl:sort
ForEachGroup feg2 = (ForEachGroup)exp;
if (feg2 == feg) {
fixupGroupReferences(feg2.getActionExpression(), feg, selectedItemType, false);
} else {
fixupGroupReferences(feg2.getSelectExpression(), feg, selectedItemType, isInLoop);
fixupGroupReferences(feg2.getGroupingKey(), feg, selectedItemType, isInLoop);
if (feg2.getSortKeyDefinitions() != null) {
for (SortKeyDefinition skd : feg2.getSortKeyDefinitions()) {
fixupGroupReferences(skd.getOrder(), feg, selectedItemType, isInLoop);
fixupGroupReferences(skd.getCaseOrder(), feg, selectedItemType, isInLoop);
fixupGroupReferences(skd.getDataTypeExpression(), feg, selectedItemType, isInLoop);
fixupGroupReferences(skd.getLanguage(), feg, selectedItemType, isInLoop);
fixupGroupReferences(skd.getCollationNameExpression(), feg, selectedItemType, isInLoop);
fixupGroupReferences(skd.getOrder(), feg, selectedItemType, isInLoop);
}
}
}
} else {
for (Operand o : exp.operands()) {
fixupGroupReferences(o.getChildExpression(), feg, selectedItemType, isInLoop || o.isHigherOrder());
}
}
}
/*@NotNull*/
@Override
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException {
selectOp.optimize(visitor, contextItemType);
ItemType selectedItemType = getSelectExpression().getItemType();
ContextItemStaticInfo sit = visitor.getConfiguration().makeContextItemStaticInfo(selectedItemType, false);
sit.setContextSettingExpression(getSelectExpression());
actionOp.optimize(visitor, sit);
keyOp.optimize(visitor, sit);
if (Literal.isEmptySequence(getSelectExpression())) {
return getSelectExpression();
}
if (Literal.isEmptySequence(getActionExpression())) {
return getActionExpression();
}
// Optimize the sort key definitions
if (getSortKeyDefinitions() != null) {
for (SortKeyDefinition skd : getSortKeyDefinitions()) {
Expression sortKey = skd.getSortKey();
sortKey = sortKey.optimize(visitor, sit);
skd.setSortKey(sortKey, true);
}
}
if (collationOp != null) {
collationOp.optimize(visitor, contextItemType);
}
if (collator == null && (getCollationNameExpression() instanceof StringLiteral)) {
String collation = ((StringLiteral) getCollationNameExpression()).stringify();
URI collationURI;
try {
collationURI = new URI(collation);
if (!collationURI.isAbsolute()) {
collationURI = getStaticBaseURI().resolve(collationURI);
final String collationNameString = collationURI.toString();
setCollationNameExpression(new StringLiteral(collationNameString));
collator = visitor.getConfiguration().getCollation(collationNameString);
if (collator == null) {
XPathException err = new XPathException("Unknown collation " + Err.wrap(collationURI.toString(), Err.URI));
err.setErrorCode("XTDE1110");
err.setLocation(getLocation());
throw err;
}
}
} catch (URISyntaxException err) {
XPathException e = new XPathException("Collation name '" + getCollationNameExpression() + "' is not a valid URI");
e.setErrorCode("XTDE1110");
e.setLocation(getLocation());
throw e;
}
}
return this;
}
/**
* Copy an expression. This makes a deep copy.
*
* @return the copy of the original expression
* @param rebindings a mutable list of (old binding, new binding) pairs
* that is used to update the bindings held in any
* local variable references that are copied.
*/
/*@NotNull*/
@Override
public Expression copy(RebindingMap rebindings) {
SortKeyDefinition[] newKeyDef = null;
if (getSortKeyDefinitions() != null) {
newKeyDef = new SortKeyDefinition[getSortKeyDefinitions().size()];
for (int i = 0; i < getSortKeyDefinitions().size(); i++) {
newKeyDef[i] = getSortKeyDefinitions().getSortKeyDefinition(i).copy(rebindings);
}
}
ForEachGroup feg = new ForEachGroup(
getSelectExpression().copy(rebindings),
getActionExpression().copy(rebindings),
algorithm,
getGroupingKey().copy(rebindings),
collator,
getCollationNameExpression().copy(rebindings),
newKeyDef == null ? null : new SortKeyDefinitionList(newKeyDef));
ExpressionTool.copyLocationInfo(this, feg);
feg.setComposite(isComposite());
fixupGroupReferences(feg, feg, getSelectExpression().getItemType(), false);
return feg;
}
/**
* Get the item type of the items returned by evaluating this instruction
*
* @return the static item type of the instruction
*/
/*@NotNull*/
@Override
public ItemType getItemType() {
return getActionExpression().getItemType();
}
/**
* Compute the dependencies of an expression, as the union of the
* dependencies of its subexpressions. (This is overridden for path expressions
* and filter expressions, where the dependencies of a subexpression are not all
* propogated). This method should be called only once, to compute the dependencies;
* after that, getDependencies should be used.
*
* @return the depencies, as a bit-mask
*/
@Override
public int computeDependencies() {
// some of the dependencies in the "action" part and in the grouping and sort keys aren't relevant,
// because they don't depend on values set outside the for-each-group expression
int dependencies = 0;
dependencies |= getSelectExpression().getDependencies();
dependencies |= getGroupingKey().getDependencies() & ~StaticProperty.DEPENDS_ON_FOCUS;
dependencies |= getActionExpression().getDependencies()
& ~(StaticProperty.DEPENDS_ON_FOCUS | StaticProperty.DEPENDS_ON_CURRENT_GROUP);
if (getSortKeyDefinitions() != null) {
for (SortKeyDefinition skd : getSortKeyDefinitions()) {
dependencies |= skd.getSortKey().getDependencies() & ~StaticProperty.DEPENDS_ON_FOCUS;
Expression e = skd.getCaseOrder();
if (e != null && !(e instanceof Literal)) {
dependencies |= e.getDependencies();
}
e = skd.getDataTypeExpression();
if (e != null && !(e instanceof Literal)) {
dependencies |= e.getDependencies();
}
e = skd.getLanguage();
if (e != null && !(e instanceof Literal)) {
dependencies |= e.getDependencies();
}
}
}
if (getCollationNameExpression() != null) {
dependencies |= getCollationNameExpression().getDependencies();
}
return dependencies;
}
/**
* Get the static properties of this expression (other than its type). The result is
* bit-signficant. These properties are used for optimizations. In general, if
* property bit is set, it is true, but if it is unset, the value is unknown.
*
* @return a set of flags indicating static properties of this expression
*/
@Override
protected int computeSpecialProperties() {
int p = super.computeSpecialProperties();
p |= getActionExpression().getSpecialProperties() & StaticProperty.ALL_NODES_UNTYPED;
return p;
}
/**
* Determine whether this instruction creates new nodes.
* This implementation returns true if the "action" creates new nodes.
* (Nodes created by the condition can't contribute to the result).
*/
@Override
public final boolean mayCreateNewNodes() {
int props = getActionExpression().getSpecialProperties();
return (props & StaticProperty.NO_NODES_NEWLY_CREATED) == 0;
}
/**
* Get the (partial) name of a class that supports streaming of this kind of expression
*
* @return the partial name of a class that can be instantiated to provide streaming support in Saxon-EE,
* or null if there is no such class
*/
@Override
public String getStreamerName() {
return "ForEachGroup";
}
/**
* Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited
* by an expression in a source tree.
* The default implementation of this method assumes that an expression does no navigation other than
* the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the
* same context as the containing expression. The method must be overridden for any expression
* where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression,
* and RootExpression (because they perform navigation), and for the doc(), document(), and collection()
* functions because they create a new navigation root. Implementations also exist for PathExpression and
* FilterExpression because they have subexpressions that are evaluated in a different context from the
* calling expression.
*
* @param pathMap the PathMap to which the expression should be added
* @param pathMapNodeSet the set of nodes within the path map
* @return the pathMapNode representing the focus established by this expression, in the case where this
* expression is the first operand of a path expression or filter expression. For an expression that does
* navigation, it represents the end of the arc in the path map that describes the navigation route. For other
* expressions, it is the same as the input pathMapNode.
*/
@Override
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) {
PathMap.PathMapNodeSet target = getSelectExpression().addToPathMap(pathMap, pathMapNodeSet);
if (getCollationNameExpression() != null) {
getCollationNameExpression().addToPathMap(pathMap, pathMapNodeSet);
}
if (getSortKeyDefinitions() != null) {
for (SortKeyDefinition skd : getSortKeyDefinitions()) {
skd.getSortKey().addToPathMap(pathMap, target);
SortExpression.addSortKeyDetailsToPathMap(pathMap, pathMapNodeSet, skd);
}
}
return getActionExpression().addToPathMap(pathMap, target);
}
/**
* Check that any elements and attributes constructed or returned by this expression are acceptable
* in the content model of a given complex type. It's always OK to say yes, since the check will be
* repeated at run-time. The process of checking element and attribute constructors against the content
* model of a complex type also registers the type of content expected of those constructors, so the
* static validation can continue recursively.
*/
@Override
public void checkPermittedContents(SchemaType parentType, boolean whole) throws XPathException {
getActionExpression().checkPermittedContents(parentType, false);
}
/**
* Get the expression which, on evaluation, yields the name of the collation to be used
*
* @return the expression that returns the collation name
*/
public Expression getCollationNameExpression() {
return collationOp == null ? null : collationOp.getChildExpression();
}
/**
* Get (and if necessary, create) the comparator used for comparing grouping key values
*
* @param context XPath dynamic context
* @return a StringCollator suitable for comparing the values of grouping keys
* @throws XPathException if a failure occurs evaluating the expression that determines the collation name
*/
private StringCollator getCollator(XPathContext context) throws XPathException {
if (getCollationNameExpression() != null) {
StringValue collationValue = (StringValue) getCollationNameExpression().evaluateItem(context);
assert collationValue != null;
String cname = collationValue.getStringValue();
try {
return context.getConfiguration().getCollation(cname, getStaticBaseURIString(), "FOCH0002");
} catch (XPathException e) {
e.setLocation(getLocation());
throw e;
}
} else {
// Fallback - this shouldn't happen
return CodepointCollator.getInstance();
}
}
public GroupIterator getGroupIterator(PullEvaluator selectPull, XPathContext context) throws XPathException {
// get an iterator over the groups in "order of first appearance"
GroupIterator groupIterator;
switch (algorithm) {
case GROUP_BY: {
StringCollator coll = collator;
if (coll==null) {
// The collation is determined at run-time
coll = getCollator(context);
}
XPathContext c2 = context.newMinorContext();
FocusIterator population = c2.trackFocus(selectPull.iterate(context));
groupIterator = new GroupByIterator(population, getGroupingKey(), c2, coll, composite);
break;
}
case GROUP_ADJACENT: {
StringCollator coll = collator;
if (coll==null) {
// The collation is determined at run-time
coll = getCollator(context);
}
groupIterator = new GroupAdjacentIterator(selectPull, getGroupingKey(), context, coll, composite);
break;
}
case GROUP_STARTING:
groupIterator = new GroupStartingIterator(selectPull, (Pattern) getGroupingKey(), context);
break;
case GROUP_ENDING:
groupIterator = new GroupEndingIterator(selectPull, (Pattern) getGroupingKey(), context);
break;
case GROUP_BREAKING_WHEN:
FunctionItem breakWhen = (FunctionItem)getGroupingKey().evaluateItem(context);
groupIterator = new GroupBreakingIterator(selectPull, breakWhen, context);
break;
default:
throw new AssertionError("Unknown grouping algorithm");
}
// now iterate over the leading nodes of the groups
if (getSortKeyDefinitions() != null) {
AtomicComparer[] comps = sortComparators;
XPathContext xpc = context.newMinorContext();
if (comps == null) {
comps = new AtomicComparer[getSortKeyDefinitions().size()];
for (int s = 0; s < getSortKeyDefinitions().size(); s++) {
comps[s] = getSortKeyDefinitions().getSortKeyDefinition(s).makeComparator(xpc);
}
}
makeSortKeyEvaluators();
groupIterator = new SortedGroupIterator(xpc, groupIterator, this, comps);
}
return groupIterator;
}
private void makeSortKeyEvaluators() {
if (sortKeyEvaluators == null && getSortKeyDefinitions() != null) {
sortKeyEvaluators = new ItemEvaluator[getSortKeyDefinitions().size()];
for (int s = 0; s < getSortKeyDefinitions().size(); s++) {
sortKeyEvaluators[s] = getSortKeyDefinitions().getSortKeyDefinition(s)
.getSortKey().makeElaborator().elaborateForItem();
}
}
}
/**
* Return an Iterator to iterate over the values of a sequence. The value of every
* expression can be regarded as a sequence, so this method is supported for all
* expressions. This default implementation relies on the process() method: it
* "pushes" the results of the instruction to a sequence in memory, and then
* iterates over this in-memory sequence.
* In principle instructions should implement a pipelined iterate() method that
* avoids the overhead of intermediate storage.
*
* @param context supplies the context for evaluation
* @return a SequenceIterator that can be used to iterate over the result
* of the expression
* @throws XPathException if any dynamic error occurs evaluating the
* expression
*/
/*@NotNull*/
@Override
public SequenceIterator iterate(XPathContext context) throws XPathException {
return makeElaborator().elaborateForPull().iterate(context);
}
/**
* Callback for evaluating the sort keys
*
* @param n the requested index
* @param c the XPath context
* @return the evaluated sort key
* @throws XPathException if any error occurs
*/
@Override
public AtomicValue evaluateSortKey(int n, XPathContext c) throws XPathException {
return (AtomicValue) sortKeyEvaluators[n].eval(c);
}
public SortKeyDefinitionList getSortKeyDefinitionList() {
if (sortKeysOp == null) {
return null;
}
return (SortKeyDefinitionList) sortKeysOp.getChildExpression();
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
@Override
public void export(ExpressionPresenter out) throws XPathException {
out.startElement("forEachGroup", this);
out.emitAttribute("algorithm", getAlgorithmName(algorithm));
String flags = "";
if (composite) {
flags = "c";
}
if (isInFork()) {
flags += "k";
}
if (!flags.isEmpty()) {
out.emitAttribute("flags", flags);
}
out.setChildRole("select");
getSelectExpression().export(out);
out.setChildRole(algorithm == GROUP_BY || algorithm == GROUP_ADJACENT || algorithm == GROUP_BREAKING_WHEN
? "key" : "match");
getGroupingKey().export(out);
if (getSortKeyDefinitions() != null) {
out.setChildRole("sort");
getSortKeyDefinitionList().export(out);
}
if (getCollationNameExpression() != null) {
out.setChildRole("collation");
getCollationNameExpression().export(out);
}
out.setChildRole("content");
getActionExpression().export(out);
out.endElement();
}
private static String getAlgorithmName(byte algorithm) {
switch (algorithm) {
case GROUP_BY:
return "by";
case GROUP_ADJACENT:
return "adjacent";
case GROUP_STARTING:
return "starting";
case GROUP_ENDING:
return "ending";
case GROUP_BREAKING_WHEN:
return "breaking";
default:
return "** unknown algorithm **";
}
}
public void setSelect(Expression select) {
selectOp.setChildExpression(select);
}
public void setAction(Expression action) {
actionOp.setChildExpression(action);
}
public void setKey(Expression key) {
keyOp.setChildExpression(key);
}
public void setCollationNameExpression(Expression collationNameExpression) {
if (collationOp == null) {
collationOp = new Operand(this, collationNameExpression, OperandRole.SINGLE_ATOMIC);
} else {
collationOp.setChildExpression(collationNameExpression);
}
}
/**
* Make an elaborator for this expression
*
* @return an appropriate {@link Elaborator}
*/
@Override
public Elaborator getElaborator() {
return new ForEachGroupElaborator();
}
public static class ForEachGroupElaborator extends PushElaborator {
private PullEvaluator getGroupIteratorProvider() {
// get an iterator over the groups in "order of first appearance"
ForEachGroup expr = (ForEachGroup)getExpression();
Expression select = expr.getSelectExpression();
PullEvaluator selectPull = select.makeElaborator().elaborateForPull();
int algorithm = expr.getAlgorithm();
switch (algorithm) {
case GROUP_BY: {
return context -> {
StringCollator coll = expr.collator;
if (coll == null) {
// The collation is determined at run-time
coll = expr.getCollator(context);
}
XPathContext c2 = context.newMinorContext();
FocusIterator population = c2.trackFocus(selectPull.iterate(context));
return new GroupByIterator(population, expr.getGroupingKey(), c2, coll, expr.composite);
};
}
case GROUP_ADJACENT: {
return context -> {
StringCollator coll = expr.collator;
if (coll == null) {
// The collation is determined at run-time
coll = expr.getCollator(context);
}
return new GroupAdjacentIterator(selectPull, expr.getGroupingKey(), context, coll, expr.composite);
};
}
case GROUP_STARTING:
return context -> new GroupStartingIterator(selectPull, (Pattern) expr.getGroupingKey(), context);
case GROUP_ENDING:
return context -> new GroupEndingIterator(selectPull, (Pattern) expr.getGroupingKey(), context);
case GROUP_BREAKING_WHEN:
return context -> {
FunctionItem breakWhen = (FunctionItem) expr.getGroupingKey().evaluateItem(context);
return new GroupBreakingIterator(selectPull, breakWhen, context);
};
default:
throw new AssertionError("Unknown grouping algorithm");
}
}
private PullEvaluator getSortedGroupIteratorProvider() {
// now iterate over the leading nodes of the groups
ForEachGroup expr = (ForEachGroup) getExpression();
if (expr.getSortKeyDefinitions() != null) {
final AtomicComparer[] comps = expr.sortComparators == null
? new AtomicComparer[expr.getSortKeyDefinitions().size()]
: expr.sortComparators;
PullEvaluator grouper = getGroupIteratorProvider();
return context -> {
XPathContext xpc = context.newMinorContext();
if (comps[0] == null) {
for (int s = 0; s < expr.getSortKeyDefinitions().size(); s++) {
comps[s] = expr.getSortKeyDefinitions().getSortKeyDefinition(s).makeComparator(xpc);
}
}
return new SortedGroupIterator(xpc, (GroupIterator) grouper.iterate(xpc), expr, comps);
};
} else {
return getGroupIteratorProvider();
}
}
@Override
public PushEvaluator elaborateForPush() {
ForEachGroup expr = (ForEachGroup)getExpression();
expr.makeSortKeyEvaluators();
PullEvaluator grouper = getSortedGroupIteratorProvider();
PushEvaluator action = expr.getActionExpression().makeElaborator().elaborateForPush();
return (output, context) -> {
Controller controller = context.getController();
assert controller != null;
PipelineConfiguration pipe = output.getPipelineConfiguration();
GroupIterator groupIterator = (GroupIterator)grouper.iterate(context);
XPathContextMajor c2 = context.newContext();
c2.setOrigin(expr);
FocusIterator focusIterator = c2.trackFocus(groupIterator);
c2.setCurrentGroupIterator(groupIterator);
c2.setCurrentTemplateRule(null);
pipe.setXPathContext(c2);
if (controller.isTracing()) {
TraceListener listener = controller.getTraceListener();
assert listener != null;
Item item;
while ((item = focusIterator.next()) != null) {
listener.startCurrentItem(item);
TailCall tc = action.processLeavingTail(output, c2);
Expression.dispatchTailCall(tc);
listener.endCurrentItem(item);
}
} else {
while (focusIterator.next() != null) {
TailCall tc = action.processLeavingTail(output, c2);
Expression.dispatchTailCall(tc);
}
}
pipe.setXPathContext(context);
return null;
};
}
@Override
public PullEvaluator elaborateForPull() {
ForEachGroup expr = (ForEachGroup) getExpression();
expr.makeSortKeyEvaluators();
PullEvaluator grouper = getSortedGroupIteratorProvider();
PullEvaluator action = expr.getActionExpression().makeElaborator().elaborateForPull();
return context -> {
GroupIterator master = (GroupIterator)grouper.iterate(context);
XPathContextMajor c2 = context.newContext();
c2.setOrigin(expr);
c2.trackFocus(master);
c2.setCurrentGroupIterator(master);
c2.setCurrentTemplateRule(null);
return new ContextMappingIterator(cxt -> action.iterate(cxt), c2);
};
}
}
}