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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.document;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
/**
* This class represents a path into a document, that can be used to iterate through the document and extract the field
* values you're interested in.
*
* @author Thomas Gundersen
*/
public class FieldPath implements Iterable<FieldPathEntry> {
private final List<FieldPathEntry> list;
/**
* Constructs an empty path.
*/
public FieldPath() {
list = Collections.emptyList();
}
/**
* Constructs a path containing the entries of the specified path, in the order they are returned by that path's
* iterator.
*
* @param path The path whose entries are to be placed into this path.
* @throws NullPointerException If the specified path is null.
*/
public FieldPath(FieldPath path) {
this(path.list);
}
public FieldPath(List<FieldPathEntry> path) {
list = Collections.unmodifiableList(path);
}
public int size() { return list.size(); }
public FieldPathEntry get(int index) { return list.get(index); }
public boolean isEmpty() { return list.isEmpty(); }
public Iterator<FieldPathEntry> iterator() { return list.iterator(); }
public List<FieldPathEntry> getList() { return list; }
/**
* Compares this field path with the given field path, returns true if the field path starts with the other.
*
* @param other The field path to compare with.
* @return Returns true if this field path starts with the other field path, otherwise false
*/
public boolean startsWith(FieldPath other) {
if (other.size() > size()) {
return false;
}
for (int i = 0; i < other.size(); i++) {
if (!other.get(i).equals(get(i))) {
return false;
}
}
return true;
}
/**
* @return Returns the datatype we can expect this field path to return.
*/
public DataType getResultingDataType() {
if (isEmpty()) {
return null;
}
return get(size() - 1).getResultingDataType();
}
/**
* Convenience method to build a field path from a path string. This is a simple proxy for {@link
* DataType#buildFieldPath(String)}.
*
* @param fieldType The data type of the value to build a path for.
* @param fieldPath The path string to parse.
* @return The corresponding field path object.
*/
public static FieldPath newInstance(DataType fieldType, String fieldPath) {
return fieldType.buildFieldPath(fieldPath);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
FieldPath that = (FieldPath) o;
return list.equals(that.list);
}
@Override
public int hashCode() {
return list.hashCode();
}
@Override
public String toString() {
StringBuilder out = new StringBuilder();
DataType prevType = null;
for (FieldPathEntry entry : this) {
FieldPathEntry.Type type = entry.getType();
switch (type) {
case STRUCT_FIELD:
if (out.length() > 0) {
out.append(".");
}
Field field = entry.getFieldRef();
out.append(field.getName());
prevType = field.getDataType();
break;
case ARRAY_INDEX:
out.append("[").append(entry.getLookupIndex()).append("]");
break;
case MAP_KEY:
out.append("{").append(entry.getLookupKey()).append("}");
break;
case MAP_ALL_KEYS:
out.append(".key");
break;
case MAP_ALL_VALUES:
out.append(".value");
break;
case VARIABLE:
if (prevType instanceof ArrayDataType) {
out.append("[$").append(entry.getVariableName()).append("]");
} else if (prevType instanceof WeightedSetDataType || prevType instanceof MapDataType) {
out.append("{$").append(entry.getVariableName()).append("}");
} else {
out.append("$").append(entry.getVariableName());
}
}
}
return out.toString();
}
}
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