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package com.legstar.base.visitor;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import com.legstar.base.ConversionException;
import com.legstar.base.FromHostException;
import com.legstar.base.FromHostResult;
import com.legstar.base.context.CobolContext;
import com.legstar.base.type.CobolType;
import com.legstar.base.type.composite.CobolArrayType;
import com.legstar.base.type.composite.CobolChoiceType;
import com.legstar.base.type.composite.CobolComplexType;
import com.legstar.base.type.primitive.CobolPrimitiveType;
/**
* Generic visitor using mainframe data as input and producing some kind of
* output (up to the specialized classes).
*
* Mainframe data is expected as a byte array.
*
*/
public abstract class FromCobolVisitor implements CobolVisitor {
/**
* Host COBOL configuration parameters.
*/
private final CobolContext cobolContext;
/**
* Incoming mainframe data.
*/
private final byte[] hostData;
/**
* Where to start processing in the incoming mainframe data buffer.
*/
private final int start;
/**
* Certain field values might need to be accessed, after they were visited,
* by some other node downstream.
*
* One use case is variable size arrays which dimension is given at runtime
* by a numeric field marked as odoObject.
*
* Another use case is custom code invoked by this visitor that might need
* field values to make decisions. Such fields are marked as customVariable.
*/
private final Map < String, Object > variables;
/**
* There are 2 mechanisms to mark custom variables:
*
*
From within a primitive type description using the customVariable
* property
*
At runtime by specifying the custom variable name in this collection
*
* TODO custom variable names are not namespaced within a structure and
* there is a conflict risk
*/
private final List < String > customVariables;
/**
* By default, this is the strategy for choice alternative selection.
*/
private final FromCobolChoiceStrategy defaultChoiceStrategy;
/**
* Optionally, user might provide a custom strategy for alternative
* selection.
*/
private final FromCobolChoiceStrategy customChoiceStrategy;
/**
* Field being visited. The name identifies this field to its immediate
* parent.
*/
private String curFieldName;
/**
* After the visitor is done visiting, this will contain the last position
* in the incoming mainframe data buffer that was processed.
*/
private int lastPos;
// -----------------------------------------------------------------------------
// Constructors
// -----------------------------------------------------------------------------
public FromCobolVisitor(CobolContext cobolContext, byte[] hostData,
int start) {
this(cobolContext, hostData, start, null);
}
public FromCobolVisitor(CobolContext cobolContext, byte[] hostData,
int start, FromCobolChoiceStrategy customChoiceStrategy) {
this(cobolContext, hostData, start, customChoiceStrategy, null);
}
public FromCobolVisitor(CobolContext cobolContext, byte[] hostData,
int start, FromCobolChoiceStrategy customChoiceStrategy,
List < String > customVariables) {
if (hostData == null) {
throw new IllegalArgumentException("Mainframe data buffer is null");
}
if (start >= hostData.length) {
throw new IllegalArgumentException("Start position " + start
+ " is outside the mainframe data buffer");
}
this.cobolContext = cobolContext;
this.hostData = hostData;
this.start = start;
this.lastPos = start;
this.variables = new HashMap < String, Object >();
this.customVariables = customVariables;
this.customChoiceStrategy = customChoiceStrategy;
this.defaultChoiceStrategy = new DefaultFromCobolChoiceStrategy(
cobolContext);
}
// -----------------------------------------------------------------------------
// Visiting logic available to specific implementations
// -----------------------------------------------------------------------------
/**
* Visit a complex type which visits each of its children in turn.
*
* @param type the complex type to visit
* @param callback a function that is invoked for each child in turn after
* it has been visited
*/
public void visitComplexType(CobolComplexType type,
ComplexTypeChildHandler callback) {
int index = 0;
for (Entry < String, CobolType > child : type.getFields().entrySet()) {
curFieldName = child.getKey();
child.getValue().accept(this);
if (!callback.postVisit(child.getKey(), index, child.getValue())) {
break;
}
index++;
}
}
/**
* Visit an array type which visits each items in turn.
*
* Size of the array might be inferred from an ODOObject visited before this
* array.
*
* @param type the array's item type
* @param callback a function that is invoked for each item in turn after it
* has been visited
*/
public void visitCobolArrayType(CobolArrayType type,
ArrayTypeItemHandler callback) {
for (int i = 0; i < getOccurs(type); i++) {
type.getItemType().accept(this);
if (!callback.postVisit(i, type)) {
break;
}
}
}
/**
* Visit a choice type (COBOL REDEFINES) which determines which alternative
* must be selected.
*
*
* @param type the choice type
* @param callback a function that is invoked after the selected alternative
* has been visited
* @throws ConversionException
*/
public void visitCobolChoiceType(CobolChoiceType type,
ChoiceTypeAlternativeHandler callback) throws ConversionException {
CobolType alternative = null;
// If we have a user provided strategy give it a chance to select a
// alternative
if (customChoiceStrategy != null) {
alternative = customChoiceStrategy.choose(curFieldName, type,
getVariables(), getHostData(), getLastPos());
}
// If user strategy did not succeed, try the default one
if (alternative == null) {
alternative = defaultChoiceStrategy.choose(curFieldName, type,
getVariables(), getHostData(), getLastPos());
}
// All attempts have failed
if (alternative == null) {
throw new FromHostException(
"Unable to select an alternative for choice "
+ curFieldName, getHostData(), getLastPos());
}
// Make sure the strategy is returning a known alternative
String alternativeName = type.getAlternativeName(alternative);
if (alternativeName == null) {
throw new FromHostException(
"Alternative does not correspond to a known alternative for choice "
+ curFieldName, getHostData(), getLastPos());
}
alternative.accept(this);
callback.postVisit(alternativeName,
type.getAlternativeIndex(alternativeName), alternative);
}
/**
* Visit a primitive type performing the actual conversion to a java object.
*
* @param type the primitive type
* @param callback a function that is invoked after the primitive type has
* been visited
* @throws ConversionException
*/
public void visitCobolPrimitiveType(CobolPrimitiveType < ? > type,
PrimitiveTypeHandler callback) throws ConversionException {
FromHostResult < ? > result = type.fromHost(cobolContext,
getHostData(), getLastPos());
this.lastPos += result.getBytesProcessed();
// Keep those values that might be needed later
if (type.isOdoObject() || isCustomVariable(type, curFieldName)) {
putVariable(curFieldName, result.getValue());
}
callback.postVisit(type, result.getValue());
}
// -----------------------------------------------------------------------------
// Notification interfaces
// -----------------------------------------------------------------------------
/**
* Notifies specialized implementations when a complex type child has been
* visited.
*/
public interface ComplexTypeChildHandler {
/**
* Notify caller that a field was visited
*
* @param fieldName the visited field's name
* @param fieldIndex the visited field's name position in its parent
* complex type
* @param child the visited field type
* @return if false, visiting should stop
*/
boolean postVisit(String fieldName, int fieldIndex, CobolType child);
}
/**
* Notifies specialized implementations when an array's item has been
* visited.
*/
public interface ArrayTypeItemHandler {
/**
* Notify caller that an item was visited
*
* @param itemIndex the visited item index in the array
* @param item the visited item type
* @return if false, visiting should stop
*/
boolean postVisit(int itemIndex, CobolType item);
}
/**
* Notifies specialized implementations when an alternative has been
* selected and visited
*/
public interface ChoiceTypeAlternativeHandler {
/**
* Notify caller that an alternative was visited
*
* @param alternativeName the visited alternative field name in the
* choice
* @param alternativeIndex the visited alternative position in the
* choice
* @param alternative the visited alternative type
*/
void postVisit(String alternativeName, int alternativeIndex,
CobolType alternative);
}
/**
* Notifies specialized implementations when a primitive type has been
* visited (and hence its value is known).
*/
public interface PrimitiveTypeHandler {
/**
* Notify caller that a primitive type was visited
*
* @param type the primitive type
* @param value the primitive type value converted from mainframe data
*/
void postVisit(CobolType type, Object value);
}
// -----------------------------------------------------------------------------
// Internal methods
// -----------------------------------------------------------------------------
/**
* Retrieve the size of an array.
*
* For variable size arrays this requires an ODOObject whose value
* determines the size at runtime.
*
* @param type the array type
* @return the actual size of the array
*/
private int getOccurs(CobolArrayType type) {
if (type.isVariableSize()) {
Object odoValue = variables.get(type.getDependingOn());
if (odoValue == null) {
throw new FromHostException("No value available for ODOObject "
+ type.getDependingOn()
+ ". Variable size array cannot be sized",
getHostData(), getLastPos());
} else if (odoValue instanceof Number) {
return ((Number) odoValue).intValue();
} else {
throw new FromHostException("The value " + odoValue.toString()
+ " for ODOObject " + type.getDependingOn()
+ " si not numeric.", getHostData(), getLastPos());
}
} else {
return type.getMaxOccurs();
}
}
// -----------------------------------------------------------------------------
// Getters/Setters
// -----------------------------------------------------------------------------
/**
* Incoming mainframe data.
*
* @return Incoming mainframe data
*/
public byte[] getHostData() {
return hostData;
}
/**
* Where to start processing in the incoming mainframe data buffer.
*
* @return Where to start processing in the incoming mainframe data buffer
*/
public int getStart() {
return start;
}
/**
* After the visitor is done visiting, this will contain the last position
* in the incoming mainframe data buffer that was processed.
*
* @return last position in the incoming mainframe data buffer that was
* processed
*/
public int getLastPos() {
return lastPos;
}
/**
* Specialized implementations might need to advance the last position.
*
* @param lastPos last position in the inciming mainframe byte array
*/
public void setLastPos(int lastPos) {
this.lastPos = lastPos;
}
/**
* Keep track of a variable's value
*
* @param name the variable name
* @param value the variable value
*/
public void putVariable(String name, Object value) {
this.variables.put(name, value);
}
/**
* The set of custom variables and ODOObjects collected while visiting.
*
* @return a map of variable names to their values
*/
public Map < String, Object > getVariables() {
return variables;
}
/**
* A primitive type is a custom variable if it has been marked as so via one
* of the available mechanisms.
*
* @param type the primitive type
* @param name the variable name
* @return true if this is a custom variable
*/
public boolean isCustomVariable(CobolPrimitiveType < ? > type, String name) {
if (type.isCustomVariable()) {
return true;
}
if (customVariables != null && customVariables.contains(name)) {
return true;
}
return false;
}
/**
* Field being visited. The name identifies this field to its immediate
* parent.
*
* @return name of field being visited
*/
public String getCurFieldName() {
return curFieldName;
}
/**
* @param curFieldName name of field being visited
*/
public void setCurFieldName(String curFieldName) {
this.curFieldName = curFieldName;
}
public CobolContext getCobolContext() {
return cobolContext;
}
}
