com.avaje.ebean.OrderBy Maven / Gradle / Ivy
package com.avaje.ebean;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Represents an Order By for a Query.
*
* Is a ordered list of OrderBy.Property objects each specifying a property and
* whether it is ascending or descending order.
*
*
* Typically you will not construct an OrderBy yourself but use one that exists
* on the Query object.
*
*/
public final class OrderBy implements Serializable {
private static final long serialVersionUID = 9157089257745730539L;
private transient Query query;
private final List list;
/**
* Create an empty OrderBy with no associated query.
*/
public OrderBy() {
this.list = new ArrayList(3);
}
private OrderBy(List list) {
this.list = list;
}
/**
* Create an orderBy parsing the order by clause.
*
* The order by clause follows SQL order by clause with comma's between each
* property and optionally "asc" or "desc" to represent ascending or
* descending order respectively.
*
*/
public OrderBy(String orderByClause) {
this(null, orderByClause);
}
/**
* Construct with a given query and order by clause.
*/
public OrderBy(Query query, String orderByClause) {
this.query = query;
this.list = new ArrayList(3);
parse(orderByClause);
}
/**
* Reverse the ascending/descending order on all the properties.
*/
public void reverse() {
for (int i = 0; i < list.size(); i++) {
list.get(i).reverse();
}
}
/**
* Add a property with ascending order to this OrderBy.
*/
public Query asc(String propertyName) {
list.add(new Property(propertyName, true));
return query;
}
/**
* Add a property with descending order to this OrderBy.
*/
public Query desc(String propertyName) {
list.add(new Property(propertyName, false));
return query;
}
/**
* Return true if the property is known to be contained in the order by clause.
*/
public boolean containsProperty(String propertyName) {
for (int i = 0; i < list.size(); i++) {
if (propertyName.equals(list.get(i).getProperty())) {
return true;
}
}
return false;
}
/**
* Return a copy of this OrderBy with the path trimmed.
*/
public OrderBy copyWithTrim(String path) {
List newList = new ArrayList(list.size());
for (int i = 0; i < list.size(); i++) {
newList.add(list.get(i).copyWithTrim(path));
}
return new OrderBy(newList);
}
/**
* Return the properties for this OrderBy.
*/
public List getProperties() {
// not returning an Immutable list at this point
return list;
}
/**
* Return true if this OrderBy does not have any properties.
*/
public boolean isEmpty() {
return list.isEmpty();
}
/**
* Return the associated query if there is one.
*/
public Query getQuery() {
return query;
}
/**
* Associate this OrderBy with a query.
*/
public void setQuery(Query query) {
this.query = query;
}
/**
* Return a copy of the OrderBy.
*/
public OrderBy copy() {
OrderBy copy = new OrderBy();
for (int i = 0; i < list.size(); i++) {
copy.add(list.get(i).copy());
}
return copy;
}
/**
* Add a property to the order by.
*/
public void add(Property p) {
list.add(p);
}
public String toString() {
return list.toString();
}
/**
* Returns the OrderBy in string format.
*/
public String toStringFormat() {
if (list.isEmpty()) {
return null;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < list.size(); i++) {
Property property = list.get(i);
if (i > 0) {
sb.append(", ");
}
sb.append(property.toStringFormat());
}
return sb.toString();
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof OrderBy)) {
return false;
}
OrderBy e = (OrderBy) obj;
return e.list.equals(list);
}
/**
* Return a hash value for this OrderBy. This can be to determine logical
* equality for OrderBy clauses.
*/
public int hashCode() {
return list.hashCode();
}
/**
* Clear the orderBy removing any current order by properties.
*
* This is intended to be used when some code creates a query with a
* 'default' order by clause and some other code may clear the 'default'
* order by clause and replace.
*
*/
public void clear() {
list.clear();
}
/**
* A property and its ascending descending order.
*/
public static final class Property implements Serializable {
private static final long serialVersionUID = 1546009780322478077L;
private String property;
private boolean ascending;
public Property(String property, boolean ascending) {
this.property = property;
this.ascending = ascending;
}
/**
* Return a copy of this Property with the path trimmed.
*/
public Property copyWithTrim(String path) {
return new Property(property.substring(path.length() + 1), ascending);
}
public int hashCode() {
int hc = property.hashCode();
hc = hc * 31 + (ascending ? 0 : 1);
return hc;
}
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof Property)) {
return false;
}
Property e = (Property) obj;
return e.ascending == ascending
&& e.property.equals(property);
}
public String toString() {
return toStringFormat();
}
public String toStringFormat() {
if (ascending) {
return property;
} else {
return property + " desc";
}
}
/**
* Reverse the ascending/descending order for this property.
*/
public void reverse() {
this.ascending = !ascending;
}
/**
* Trim off the pathPrefix.
*/
public void trim(String pathPrefix) {
property = property.substring(pathPrefix.length() + 1);
}
/**
* Return a copy of this property.
*/
public Property copy() {
return new Property(property, ascending);
}
/**
* Return the property name.
*/
public String getProperty() {
return property;
}
/**
* Set the property name.
*/
public void setProperty(String property) {
this.property = property;
}
/**
* Return true if the order is ascending.
*/
public boolean isAscending() {
return ascending;
}
/**
* Set to true if the order is ascending.
*/
public void setAscending(boolean ascending) {
this.ascending = ascending;
}
}
private void parse(String orderByClause) {
if (orderByClause == null) {
return;
}
String[] chunks = orderByClause.split(",");
for (int i = 0; i < chunks.length; i++) {
String[] pairs = chunks[i].split(" ");
Property p = parseProperty(pairs);
if (p != null) {
list.add(p);
}
}
}
private Property parseProperty(String[] pairs) {
if (pairs.length == 0) {
return null;
}
ArrayList wordList = new ArrayList(pairs.length);
for (int i = 0; i < pairs.length; i++) {
if (!isEmptyString(pairs[i])) {
wordList.add(pairs[i]);
}
}
if (wordList.isEmpty()) {
return null;
}
if (wordList.size() == 1) {
return new Property(wordList.get(0), true);
}
if (wordList.size() == 2) {
boolean asc = isAscending(wordList.get(1));
return new Property(wordList.get(0), asc);
}
String m = "Expecting a max of 2 words in [" + Arrays.toString(pairs)
+ "] but got " + wordList.size();
throw new RuntimeException(m);
}
private boolean isAscending(String s) {
s = s.toLowerCase();
if (s.startsWith("asc")) {
return true;
}
if (s.startsWith("desc")) {
return false;
}
String m = "Expecting [" + s + "] to be asc or desc?";
throw new RuntimeException(m);
}
private boolean isEmptyString(String s) {
return s == null || s.length() == 0;
}
}
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