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https://github.com/trigersoft/jaque
Lets Java 8 Lambdas to be represented as objects in the form of expression trees at runtime
https://github.com/trigersoft/jaque
expression-tree fluent-interface java java-8 lambda linq
Last synced: about 1 month ago
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Lets Java 8 Lambdas to be represented as objects in the form of expression trees at runtime
- Host: GitHub
- URL: https://github.com/trigersoft/jaque
- Owner: TrigerSoft
- License: gpl-2.0
- Created: 2014-09-21T21:48:51.000Z (about 10 years ago)
- Default Branch: master
- Last Pushed: 2023-11-10T22:13:38.000Z (about 1 year ago)
- Last Synced: 2024-09-29T23:04:33.453Z (about 2 months ago)
- Topics: expression-tree, fluent-interface, java, java-8, lambda, linq
- Homepage:
- Size: 133 KB
- Stars: 162
- Watchers: 16
- Forks: 24
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
[](http://isitmaintained.com/project/TrigerSoft/jaque "Average time to resolve an issue")
[](https://search.maven.org/search?q=g:%22com.trigersoft%22%20AND%20a:%22jaque%22)
The project is discontinued, but inspired a [strong successor](https://github.com/streamx-co/ExTree).
# JAva QUEry
This library enables Java 8 Lambdas to be represented as objects in the form of expression trees at runtime:
```java
void method(Predicate p) {
LambdaExpression> parsed = LambdaExpression.parse(p);
//Use parsed Expression Tree...
}
```
making it possible to create type-safe fluent interfaces, i.e. instead of:
```java
Customer obj = ...
obj.property("name").eq("John")
```
one can write
```java
method(obj -> obj.getName() == "John")
```
in type-safe, refactoring friendly manner. And then the library developer will be able to parse the produced Lambda to the corresponding Expression Tree for analysis.
---
For example, [JPA Criteria API](http://docs.oracle.com/javaee/6/tutorial/doc/gjivm.html) could benefit a lot from using JaQue, e.g.:
```java
//instead of this:
Root pet = cq.from(Pet.class);
Join owner = pet.join(Pet_.owners);
//it could be this:
Join owner = pet.join(Pet::getOwners);
//and instead of this:
query.where(pet.get(Pet_.color).isNull());
query.where(builder.equal(pet.get(Pet_.name), "Fido")
.and(builder.equal(pet.get(Pet_.color), "brown")));
//it could be this:
query.where(pet -> pet.getColor() == null);
query.where(pet -> (pet.getName() == "Fido") && (pet.getColor() == "brown"));
```
If you are looking for an oportunity to start an open source project, implementing the above should be very beneficial for a very large developer comminuty. Should you start this or any other open source project based on JaQue, I'll be happy to [assist you](mailto://[email protected]).
#### How to write fluent interface with JaQue?
- Suppose you want to reference some class property
```java
public class Fluent {
// this interface is required to make the lambda Serializable, which removes a need for
// jdk.internal.lambda.dumpProxyClasses system property. See below.
public static interface Property extends Function, Serializable {
}
public Fluent property(Property propertyRef) {
LambdaExpression> parsed = LambdaExpression
.parse(propertyRef);
Expression body = parsed.getBody();
Expression methodCall = body;
// remove casts
while (methodCall instanceof UnaryExpression)
methodCall = ((UnaryExpression) methodCall).getFirst();
// checks are omitted for brevity
Member member = ((MemberExpression) ((InvocationExpression) methodCall)
.getTarget()).getMember();
// use member
...
return this;
}
}
```
- Now your users will be able to write
```java
Fluent f = new Fluent();
f.property(Customer::getName);
```
> Make the lambda Serializable, as shown in example above. If the lambda is not serializable, the [jdk.internal.lambda.dumpProxyClasses](https://bugs.openjdk.java.net/browse/JDK-8023524) system property must be set and point to an existing writable directory to give the parser access to the lambda byte code.
#### Resources
- [Full Docs](http://trigersoft.github.io/jaque) [(noframes)](http://trigersoft.github.io/jaque/overview-summary.html)
- [Maven Artifact](http://search.maven.org/#search%7Cga%7C1%7Ca%3A%22jaque%22)
- [Technical Details](https://github.com/TrigerSoft/jaque/wiki/Technical-Details)
- [Quality Assurance and Continuous Integration](https://github.com/TrigerSoft/jaque/wiki/Quality-Assurance)