[
https://issues.apache.org/jira/browse/GROOVY-9159?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Daniel Sun updated GROOVY-9159:
-------------------------------
Description:
h2. *Ⅰ. Background*
In order to make querying different types of data sources convenient, we need a
unified querying interface, i.e. GINQ
h2. *Ⅱ. Solution*
h3. *Basic rationale*
*Groovy User* ==_writes GINQ code_==> *Parrot Parser* ==generates AST==> *GINQ
Transformation* ==_transforms AST to {{Queryable}} method invocations_==>
*Bytecode Writer*
h3. *transforms AST to {{Queryable}} method invocations will be designed for
different cases*
# target objects are all collections
{{Queryable}} method invocations are implemented by Java 8+ stream method
invocations
# target objects are all DB related objects
{{Queryable}} method invocations are implemented by *JOOQ* method invocations(
[https://github.com/jOOQ/jOOQ] ) as a {{GINQ provider}} in a seperate
sub-project(e.g. {{groovy-linq-jooq}}). _Note: *JOOQ* is licensed under *APL2*
too_( [https://github.com/jOOQ/jOOQ/blob/master/LICENSE] )
# target objects are XML, CSV, etc. related objects, or even mixed types of
objects
We can treate the case as a special sub-case of case 1
h3. *Interfaces & implementations*
* {{Queryable}}
[https://github.com/danielsun1106/groovy-linq/blob/master/src/main/java/groovy/linq/Queryable.java]
* {{QueryableCollection}}
[https://github.com/danielsun1106/groovy-linq/blob/master/src/main/java/groovy/linq/QueryableCollection.java]
h3. *Note:*
{color:#d04437}1. The exact syntax might be altered before introduction,
currently working on the general principle.{color}
2.GINQ will reuse most of standard SQL syntax, which can make the learning
curve smooth and avoid infringing the patent of Microsoft.
3. All GINQ related keywords are real keywords, e.g. {{from}}, {{where}},
{{select}}, which is the approach applied by C#. In order to avoid breaking
existing source code as possible as we can, we should add the new keywords to
identifiers.
4. In order to support type inference better, {{select}} clause is placed at
the end of GINQ expression.
5. {{select P1, P2 ... Pn}} is a simplifed syntax of {{select Tuple.tuple(P1,
P2 ... Pn)}} and will create a {{List}} of {{Tuple}} sub-class instances when
and only when {{n >= 2}}
h2. *Ⅲ. EBNF*
h3. TBD
h2. *Ⅳ. Examples*
h3. 1. Filtering
{code:java}
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
}
def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
age: 10), new Person(name: 'Alice', age: 22)]
{code}
h4. 1.1
{code:java}
def result =
from persons p
where p.age > 15 && p.age <= 35
select p.name
assert ['Daniel', 'Alice'] == result
{code}
{code:java}
// interface
from(persons).where(p -> p.age > 15 && p.age <= 35).select(p -> p.name).toList()
{code}
{code:java}
// collection implementation
persons.stream().filter(p -> p.age > 15 && p.age <= 35).map(p ->
p.name).collect(Collectors.toList())
{code}
h4. 1.2
{code:java}
def result =
from persons p
where p.age > 15 && p.age <= 35
select p
assert [new Person(name: 'Daniel', age: 35), new Person(name: 'Alice', age:
22)] == result
{code}
{code:java}
// interface
from(persons).where(p -> p.age > 15 && p.age <= 35).select(p -> p).toList()
{code}
{code:java}
// collection implementation
persons.stream().filter(p -> p.age > 15 && p.age <=
35).collect(Collectors.toList())
{code}
h4. 1.3
{code:java}
def numbers = [1, 2, 3]
def result =
from numbers t
where t <= 2
select t
assert [1, 2] == result
{code}
{code:java}
// interface
from(numbers).where(t -> t <= 2).select(t -> t).toList()
{code}
{code:java}
// collection implementation
numbers.stream().filter(t -> t <= 2).collect(Collectors.toList())
{code}
h3. 2. Joining
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
City city
}
@groovy.transform.EqualsAndHashCode
class City {
String name
}
def persons = [new Person(name: 'Daniel', age: 35, city: new City(name:
'Shanghai')), new Person(name: 'Peter', age: 10, city: new City(name:
'Beijing')), new Person(name: 'Alice', age: 22, city: new City(name:
'Hangzhou'))]
def cities = [new City(name: 'Shanghai'), new City(name: 'Beijing'), new
City(name: 'Guangzhou')]
{code}
h4. 2.1
{code:java}
// inner join
def result =
from persons p
innerjoin cities c on p.city.name == c.name
select p.name, c.name
assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing')] == result
{code}
{code:java}
// interface
from(persons).innerJoin(from(cities), (p, c) -> p.city.name ==
c.name).select((p, c) -> tuple(p.name, c.name)).toList()
{code}
{code:java}
// collection implementation
persons.stream()
.flatMap(p -> cities.stream().filter(c -> p.city.name == c.name).map(c
-> tuple(p.name, c.name)))
.collect(Collectors.toList())
{code}
h4. 2.2
{code:java}
def result =
from persons p
innerjoin cities c on p.city == c
select p.name
assert ['Daniel', 'Peter'] == result
{code}
{code:java}
// interface
from(persons).innerJoin(from(cities), (p, c) -> p.city == c).select((p, c) ->
p.name).toList()
{code}
{code:java}
// collection implementation
persons.stream()
.flatMap(p -> cities.stream().filter(c -> p.city == c).map(c -> p.name))
.collect(Collectors.toList())
{code}
h4. 2.3
{code:java}
// left outer join
def result =
from persons p
leftjoin cities c on p.city.name == c.name // same with left outer join
select p.name, c.name
assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing'), tuple('Alice',
null)] == result
{code}
{code:java}
// interface
from(persons).leftjoin(from(cities), (p, c) -> p.city.name ==
c.name).select((p, c) -> tuple(p.name, c.name)).toList()
{code}
{code:java}
// collection implementation
persons.stream()
.flatMap(p ->
cities.stream()
.map(c -> p.city.name == c.name ? c : GinqConstant.NULL)
.reduce(new LinkedList(), (r, e) -> {
int size = r.size()
if (0 == size) {
r.add(e)
return r
}
int lastIndex = size - 1
Object lastElement = r.get(lastIndex)
if (GinqConstant.NULL != e) {
if (GinqConstant.NULL == lastElement) {
r.set(lastIndex, e)
} else {
r.add(e)
}
}
return r
}).stream()
.map(c -> Tuple.tuple(p.name, GinqConstant.NULL == c ?
GinqConstant.NULL : c.name)))
.collect(Collectors.toList())
{code}
h4. 2.4
{code:java}
// right outer join
def result =
from persons p
rightjoin cities c on p.city.name == c.name // same with right outer
join
select p.name, c.name
assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing'), tuple(null,
'Guangzhou')] == result
{code}
h3. 3. Projection
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
}
def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
age: 10), new Person(name: 'Alice', age: 22)]
{code}
h4. 3.1
{code:java}
def result =
from persons p
select p.name
assert ['Daniel', 'Peter', 'Alice'] == result
{code}
h4. 3.2
{code:java}
def result =
from persons p
select p.name, p.age
assert [tuple('Daniel', 35), tuple('Peter', 10), tuple('Alice', 22)] == result
{code}
h4. 3.3
{code:java}
def result =
from persons p
select [name: p.name, age: p.age]
assert [ [name: 'Daniel', age: 35], [name: 'Peter', age: 10], [name: 'Alice',
age: 22] ] == result
{code}
h4. 3.4
{code:java}
def result =
from persons p
select new Person(name: p.name, age: p.age)
assert persons == result
{code}
h4. 3.5
{code:java}
def result =
from persons p
select p
assert persons == result
{code}
h3. 4. Grouping
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
String gender
}
def persons = [new Person(name: 'Daniel', age: 35, gender: 'Male'), new
Person(name: 'Peter', age: 10, gender: 'Male'), new Person(name: 'Alice', age:
22, gender: 'Female')]
{code}
h4. 4.1
{code:java}
def result =
from persons p
groupby p.gender
select p.gender, max(p.age)
assert [tuple('Male', 35), tuple('Female', 22)] == result
{code}
h3. 5. Having
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
String gender
}
def persons = [new Person(name: 'Daniel', age: 35, gender: 'Male'), new
Person(name: 'Peter', age: 10, gender: 'Male'), new Person(name: 'Alice', age:
22, gender: 'Female')]
{code}
h4. 5.1
{code:java}
def result =
from persons p
groupby p.gender
having p.gender == 'Male'
select p.gender, max(p.age)
assert [tuple('Male', 35)] == result
{code}
h3. 6. Sorting
{code:java}
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
}
def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
age: 10), new Person(name: 'Alice', age: 22)]
{code}
h4. 6.1
{code:java}
def result =
from persons p
orderby p.age
select p.name
assert ['Peter', 'Alice', 'Daniel'] == result
{code}
h4. 6.2
{code:java}
def result =
from persons p
orderby p.age desc
select p.name
assert ['Daniel', 'Alice', 'Peter'] == result
{code}
h3. 7. Pagination
{code:java}
def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
{code}
h4. 7.1
{code:java}
def result =
from numbers n
limit 2, 5
select n
assert [2, 3, 4, 5, 6] == result
{code}
h4. 7.2
{code:java}
def result =
from numbers n
limit 5
select n
assert [0, 1, 2, 3, 4] == result
{code}
h3. 8. Nested Queries
{code:java}
def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
{code}
h4. 8.1
{code:java}
def result =
from (
from numbers n
where n <= 5
select n
) v
limit 2, 5
select v
assert [2, 3, 4, 5] == result
{code}
h3. 9. WITH-Clause
{code:java}
def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
{code}
h4. 9.1
{code:java}
def result =
with v as (
from numbers n
where n <= 5
select n
)
from v
limit 2, 5
select v
assert [2, 3, 4, 5] == result
{code}
h3. 10. Union
{code:java}
def numbers1 = [0, 1, 2]
def numbers2 = [2, 3, 4]
{code}
h4. 10.1
{code:java}
def result =
from numbers1 n
select n
unionall
from numbers2 n
select n
assert [0, 1, 2, 2, 3, 4] == result
{code}
h4. 10.2
{code:java}
def result =
from numbers1 n
select n
union
from numbers2 n
select n
assert [0, 1, 2, 3, 4] == result
{code}
was:
h2. *Ⅰ. Background*
In order to make querying different types of data sources convenient, we need a
unified querying interface, i.e. GINQ
h2. *Ⅱ. Solution*
h3. *Basic rationale*
*Groovy User* ==_writes GINQ code_==> *Parrot Parser* ==generates AST==> *GINQ
Transformation* ==_transforms AST to {{Queryable}} method invocations_==>
*Bytecode Writer*
h3. *transforms AST to {{Queryable}} method invocations will be designed for
different cases*
# target objects are all collections
{{Queryable}} method invocations are implemented by Java 8+ stream method
invocations
# target objects are all DB related objects
{{Queryable}} method invocations are implemented by *JOOQ* method invocations(
[https://github.com/jOOQ/jOOQ] ) as a {{GINQ provider}} in a seperate
sub-project(e.g. {{groovy-linq-jooq}}). _Note: *JOOQ* is licensed under *APL2*
too_( [https://github.com/jOOQ/jOOQ/blob/master/LICENSE] )
# target objects are XML, CSV, etc. related objects, or even mixed types of
objects
We can treate the case as a special sub-case of case 1
h3. *Interfaces & implementations*
* {{Queryable}}
[https://github.com/danielsun1106/groovy-linq/blob/master/src/main/java/groovy/linq/Queryable.java]
* {{QueryableCollection}}
[https://github.com/danielsun1106/groovy-linq/blob/master/src/main/java/groovy/linq/QueryableCollection.java]
h3. *Note:*
{color:#d04437}1. The exact syntax might be altered before introduction,
currently working on the general principle.{color}
2.GINQ will reuse most of standard SQL syntax, which can make the learning
curve smooth and avoid infringing the patent of Microsoft.
3. All GINQ related keywords are real keywords, e.g. {{from}}, {{where}},
{{select}}, which is the approach applied by C#. In order to avoid breaking
existing source code as possible as we can, we should add the new keywords to
identifiers.
4. In order to support type inference better, {{select}} clause is placed at
the end of GINQ expression.
5. {{select P1, P2 ... Pn}} is a simplifed syntax of {{select Tuple.tuple(P1,
P2 ... Pn)}} and will create a {{List}} of {{Tuple}} sub-class instances when
and only when {{n >= 2}}
h2. *Ⅲ. EBNF*
h3. TBD
h2. *Ⅳ. Examples*
h3. 1. Filtering
{code:java}
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
}
def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
age: 10), new Person(name: 'Alice', age: 22)]
{code}
h4. 1.1
{code:java}
def result =
from persons p
where p.age > 15 && p.age <= 35
select p.name
assert ['Daniel', 'Alice'] == result
{code}
{code:java}
// interface
from(persons).where(p -> p.age > 15 && p.age <= 35).select(p -> p.name).toList()
{code}
{code:java}
// collection implementation
persons.stream().filter(p -> p.age > 15 && p.age <= 35).map(p ->
p.name).collect(Collectors.toList())
{code}
h4. 1.2
{code:java}
def result =
from persons p
where p.age > 15 && p.age <= 35
select p
assert [new Person(name: 'Daniel', age: 35), new Person(name: 'Alice', age:
22)] == result
{code}
{code:java}
// interface
from(persons).where(p -> p.age > 15 && p.age <= 35).select(p -> p).toList()
{code}
{code:java}
// collection implementation
persons.stream().filter(p -> p.age > 15 && p.age <=
35).collect(Collectors.toList())
{code}
h4. 1.3
{code:java}
def numbers = [1, 2, 3]
def result =
from numbers t
where t <= 2
select t
assert [1, 2] == result
{code}
{code:java}
// interface
from(numbers).where(t -> t <= 2).select(t -> t).toList()
{code}
{code:java}
// collection implementation
numbers.stream().filter(t -> t <= 2).collect(Collectors.toList())
{code}
h3. 2. Joining
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
City city
}
@groovy.transform.EqualsAndHashCode
class City {
String name
}
def persons = [new Person(name: 'Daniel', age: 35, city: new City(name:
'Shanghai')), new Person(name: 'Peter', age: 10, city: new City(name:
'Beijing')), new Person(name: 'Alice', age: 22, city: new City(name:
'Hangzhou'))]
def cities = [new City(name: 'Shanghai'), new City(name: 'Beijing'), new
City(name: 'Guangzhou')]
{code}
h4. 2.1
{code:java}
// inner join
def result =
from persons p
innerjoin cities c on p.city.name == c.name
select p.name, c.name
assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing')] == result
{code}
{code:java}
// interface
from(persons).innerJoin(from(cities), (p, c) -> p.city.name ==
c.name).select((p, c) -> tuple(p.name, c.name)).toList()
{code}
{code:java}
// collection implementation
persons.stream()
.flatMap(p -> cities.stream().filter(c -> p.city.name == c.name).map(c
-> tuple(p.name, c.name)))
.collect(Collectors.toList())
{code}
h4. 2.2
{code:java}
def result =
from persons p, cities c
where p.city.name == c.name
select p.name, c.name
assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing')] == result
{code}
{code:java}
// interface
from(persons).innerJoin(from(cities), (p, c) -> p.city.name ==
c.name).select((p, c) -> tuple(p.name, c.name)).toList()
{code}
{code:java}
// collection implementation
persons.stream()
.flatMap(p -> cities.stream().filter(c -> p.city.name == c.name).map(c
-> tuple(p.name, c.name)))
.collect(Collectors.toList())
{code}
h4. 2.3
{code:java}
def result =
from persons p, cities c
where p.city == c
select p.name
assert ['Daniel', 'Peter'] == result
{code}
{code:java}
// interface
from(persons).innerJoin(from(cities), (p, c) -> p.city == c).select((p, c) ->
p.name).toList()
{code}
{code:java}
// collection implementation
persons.stream()
.flatMap(p -> cities.stream().filter(c -> p.city == c).map(c -> p.name))
.collect(Collectors.toList())
{code}
h4. 2.4
{code:java}
// left outer join
def result =
from persons p
leftjoin cities c on p.city.name == c.name // same with left outer join
select p.name, c.name
assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing'), tuple('Alice',
null)] == result
{code}
{code:java}
// interface
from(persons).leftjoin(from(cities), (p, c) -> p.city.name ==
c.name).select((p, c) -> tuple(p.name, c.name)).toList()
{code}
{code:java}
// collection implementation
persons.stream()
.flatMap(p ->
cities.stream()
.map(c -> p.city.name == c.name ? c : GinqConstant.NULL)
.reduce(new LinkedList(), (r, e) -> {
int size = r.size()
if (0 == size) {
r.add(e)
return r
}
int lastIndex = size - 1
Object lastElement = r.get(lastIndex)
if (GinqConstant.NULL != e) {
if (GinqConstant.NULL == lastElement) {
r.set(lastIndex, e)
} else {
r.add(e)
}
}
return r
}).stream()
.map(c -> Tuple.tuple(p.name, GinqConstant.NULL == c ?
GinqConstant.NULL : c.name)))
.collect(Collectors.toList())
{code}
h4. 2.5
{code:java}
// right outer join
def result =
from persons p
rightjoin cities c on p.city.name == c.name // same with right outer
join
select p.name, c.name
assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing'), tuple(null,
'Guangzhou')] == result
{code}
h3. 3. Projection
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
}
def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
age: 10), new Person(name: 'Alice', age: 22)]
{code}
h4. 3.1
{code:java}
def result =
from persons p
select p.name
assert ['Daniel', 'Peter', 'Alice'] == result
{code}
h4. 3.2
{code:java}
def result =
from persons p
select p.name, p.age
assert [tuple('Daniel', 35), tuple('Peter', 10), tuple('Alice', 22)] == result
{code}
h4. 3.3
{code:java}
def result =
from persons p
select [name: p.name, age: p.age]
assert [ [name: 'Daniel', age: 35], [name: 'Peter', age: 10], [name: 'Alice',
age: 22] ] == result
{code}
h4. 3.4
{code:java}
def result =
from persons p
select new Person(name: p.name, age: p.age)
assert persons == result
{code}
h4. 3.5
{code:java}
def result =
from persons p
select p
assert persons == result
{code}
h3. 4. Grouping
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
String gender
}
def persons = [new Person(name: 'Daniel', age: 35, gender: 'Male'), new
Person(name: 'Peter', age: 10, gender: 'Male'), new Person(name: 'Alice', age:
22, gender: 'Female')]
{code}
h4. 4.1
{code:java}
def result =
from persons p
groupby p.gender
select p.gender, max(p.age)
assert [tuple('Male', 35), tuple('Female', 22)] == result
{code}
h3. 5. Having
{code:java}
import static groovy.lang.Tuple.*
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
String gender
}
def persons = [new Person(name: 'Daniel', age: 35, gender: 'Male'), new
Person(name: 'Peter', age: 10, gender: 'Male'), new Person(name: 'Alice', age:
22, gender: 'Female')]
{code}
h4. 5.1
{code:java}
def result =
from persons p
groupby p.gender
having p.gender == 'Male'
select p.gender, max(p.age)
assert [tuple('Male', 35)] == result
{code}
h3. 6. Sorting
{code:java}
@groovy.transform.EqualsAndHashCode
class Person {
String name
int age
}
def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
age: 10), new Person(name: 'Alice', age: 22)]
{code}
h4. 6.1
{code:java}
def result =
from persons p
orderby p.age
select p.name
assert ['Peter', 'Alice', 'Daniel'] == result
{code}
h4. 6.2
{code:java}
def result =
from persons p
orderby p.age desc
select p.name
assert ['Daniel', 'Alice', 'Peter'] == result
{code}
h3. 7. Pagination
{code:java}
def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
{code}
h4. 7.1
{code:java}
def result =
from numbers n
limit 2, 5
select n
assert [2, 3, 4, 5, 6] == result
{code}
h4. 7.2
{code:java}
def result =
from numbers n
limit 5
select n
assert [0, 1, 2, 3, 4] == result
{code}
h3. 8. Nested Queries
{code:java}
def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
{code}
h4. 8.1
{code:java}
def result =
from (
from numbers n
where n <= 5
select n
) v
limit 2, 5
select v
assert [2, 3, 4, 5] == result
{code}
h3. 9. WITH-Clause
{code:java}
def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
{code}
h4. 9.1
{code:java}
def result =
with v as (
from numbers n
where n <= 5
select n
)
from v
limit 2, 5
select v
assert [2, 3, 4, 5] == result
{code}
h3. 10. Union
{code:java}
def numbers1 = [0, 1, 2]
def numbers2 = [2, 3, 4]
{code}
h4. 10.1
{code:java}
def result =
from numbers1 n
select n
unionall
from numbers2 n
select n
assert [0, 1, 2, 2, 3, 4] == result
{code}
h4. 10.2
{code:java}
def result =
from numbers1 n
select n
union
from numbers2 n
select n
assert [0, 1, 2, 3, 4] == result
{code}
> [GEP] Support LINQ, aka GINQ
> ----------------------------
>
> Key: GROOVY-9159
> URL: https://issues.apache.org/jira/browse/GROOVY-9159
> Project: Groovy
> Issue Type: New Feature
> Reporter: Daniel Sun
> Priority: Major
> Labels: features
> Fix For: 4.x
>
>
> h2. *Ⅰ. Background*
> In order to make querying different types of data sources convenient, we need
> a unified querying interface, i.e. GINQ
> h2. *Ⅱ. Solution*
> h3. *Basic rationale*
> *Groovy User* ==_writes GINQ code_==> *Parrot Parser* ==generates AST==>
> *GINQ Transformation* ==_transforms AST to {{Queryable}} method
> invocations_==> *Bytecode Writer*
> h3. *transforms AST to {{Queryable}} method invocations will be designed for
> different cases*
> # target objects are all collections
> {{Queryable}} method invocations are implemented by Java 8+ stream method
> invocations
> # target objects are all DB related objects
> {{Queryable}} method invocations are implemented by *JOOQ* method
> invocations( [https://github.com/jOOQ/jOOQ] ) as a {{GINQ provider}} in a
> seperate sub-project(e.g. {{groovy-linq-jooq}}). _Note: *JOOQ* is licensed
> under *APL2* too_( [https://github.com/jOOQ/jOOQ/blob/master/LICENSE] )
> # target objects are XML, CSV, etc. related objects, or even mixed types of
> objects
> We can treate the case as a special sub-case of case 1
> h3. *Interfaces & implementations*
> * {{Queryable}}
>
> [https://github.com/danielsun1106/groovy-linq/blob/master/src/main/java/groovy/linq/Queryable.java]
> * {{QueryableCollection}}
>
> [https://github.com/danielsun1106/groovy-linq/blob/master/src/main/java/groovy/linq/QueryableCollection.java]
> h3. *Note:*
> {color:#d04437}1. The exact syntax might be altered before introduction,
> currently working on the general principle.{color}
> 2.GINQ will reuse most of standard SQL syntax, which can make the learning
> curve smooth and avoid infringing the patent of Microsoft.
> 3. All GINQ related keywords are real keywords, e.g. {{from}}, {{where}},
> {{select}}, which is the approach applied by C#. In order to avoid breaking
> existing source code as possible as we can, we should add the new keywords to
> identifiers.
> 4. In order to support type inference better, {{select}} clause is placed at
> the end of GINQ expression.
> 5. {{select P1, P2 ... Pn}} is a simplifed syntax of {{select
> Tuple.tuple(P1, P2 ... Pn)}} and will create a {{List}} of {{Tuple}}
> sub-class instances when and only when {{n >= 2}}
> h2. *Ⅲ. EBNF*
> h3. TBD
> h2. *Ⅳ. Examples*
> h3. 1. Filtering
> {code:java}
> @groovy.transform.EqualsAndHashCode
> class Person {
> String name
> int age
> }
> def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
> age: 10), new Person(name: 'Alice', age: 22)]
> {code}
> h4. 1.1
> {code:java}
> def result =
> from persons p
> where p.age > 15 && p.age <= 35
> select p.name
> assert ['Daniel', 'Alice'] == result
> {code}
> {code:java}
> // interface
> from(persons).where(p -> p.age > 15 && p.age <= 35).select(p ->
> p.name).toList()
> {code}
> {code:java}
> // collection implementation
> persons.stream().filter(p -> p.age > 15 && p.age <= 35).map(p ->
> p.name).collect(Collectors.toList())
> {code}
> h4. 1.2
> {code:java}
> def result =
> from persons p
> where p.age > 15 && p.age <= 35
> select p
> assert [new Person(name: 'Daniel', age: 35), new Person(name: 'Alice', age:
> 22)] == result
> {code}
> {code:java}
> // interface
> from(persons).where(p -> p.age > 15 && p.age <= 35).select(p -> p).toList()
> {code}
> {code:java}
> // collection implementation
> persons.stream().filter(p -> p.age > 15 && p.age <=
> 35).collect(Collectors.toList())
> {code}
> h4. 1.3
> {code:java}
> def numbers = [1, 2, 3]
> def result =
> from numbers t
> where t <= 2
> select t
> assert [1, 2] == result
> {code}
> {code:java}
> // interface
> from(numbers).where(t -> t <= 2).select(t -> t).toList()
> {code}
> {code:java}
> // collection implementation
> numbers.stream().filter(t -> t <= 2).collect(Collectors.toList())
> {code}
> h3. 2. Joining
> {code:java}
> import static groovy.lang.Tuple.*
> @groovy.transform.EqualsAndHashCode
> class Person {
> String name
> int age
> City city
> }
> @groovy.transform.EqualsAndHashCode
> class City {
> String name
> }
> def persons = [new Person(name: 'Daniel', age: 35, city: new City(name:
> 'Shanghai')), new Person(name: 'Peter', age: 10, city: new City(name:
> 'Beijing')), new Person(name: 'Alice', age: 22, city: new City(name:
> 'Hangzhou'))]
> def cities = [new City(name: 'Shanghai'), new City(name: 'Beijing'), new
> City(name: 'Guangzhou')]
> {code}
> h4. 2.1
> {code:java}
> // inner join
> def result =
> from persons p
> innerjoin cities c on p.city.name == c.name
> select p.name, c.name
> assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing')] == result
> {code}
> {code:java}
> // interface
> from(persons).innerJoin(from(cities), (p, c) -> p.city.name ==
> c.name).select((p, c) -> tuple(p.name, c.name)).toList()
> {code}
> {code:java}
> // collection implementation
> persons.stream()
> .flatMap(p -> cities.stream().filter(c -> p.city.name == c.name).map(c
> -> tuple(p.name, c.name)))
> .collect(Collectors.toList())
> {code}
> h4. 2.2
> {code:java}
> def result =
> from persons p
> innerjoin cities c on p.city == c
> select p.name
> assert ['Daniel', 'Peter'] == result
> {code}
> {code:java}
> // interface
> from(persons).innerJoin(from(cities), (p, c) -> p.city == c).select((p, c) ->
> p.name).toList()
> {code}
> {code:java}
> // collection implementation
> persons.stream()
> .flatMap(p -> cities.stream().filter(c -> p.city == c).map(c -> p.name))
> .collect(Collectors.toList())
> {code}
> h4. 2.3
> {code:java}
> // left outer join
> def result =
> from persons p
> leftjoin cities c on p.city.name == c.name // same with left outer join
> select p.name, c.name
> assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing'),
> tuple('Alice', null)] == result
> {code}
> {code:java}
> // interface
> from(persons).leftjoin(from(cities), (p, c) -> p.city.name ==
> c.name).select((p, c) -> tuple(p.name, c.name)).toList()
> {code}
> {code:java}
> // collection implementation
> persons.stream()
> .flatMap(p ->
> cities.stream()
> .map(c -> p.city.name == c.name ? c : GinqConstant.NULL)
> .reduce(new LinkedList(), (r, e) -> {
> int size = r.size()
> if (0 == size) {
> r.add(e)
> return r
> }
>
> int lastIndex = size - 1
> Object lastElement = r.get(lastIndex)
>
> if (GinqConstant.NULL != e) {
> if (GinqConstant.NULL == lastElement) {
> r.set(lastIndex, e)
> } else {
> r.add(e)
> }
> }
>
> return r
> }).stream()
> .map(c -> Tuple.tuple(p.name, GinqConstant.NULL == c ?
> GinqConstant.NULL : c.name)))
> .collect(Collectors.toList())
> {code}
> h4. 2.4
> {code:java}
> // right outer join
> def result =
> from persons p
> rightjoin cities c on p.city.name == c.name // same with right outer
> join
> select p.name, c.name
> assert [tuple('Daniel', 'Shanghai'), tuple('Peter', 'Beijing'), tuple(null,
> 'Guangzhou')] == result
> {code}
> h3. 3. Projection
> {code:java}
> import static groovy.lang.Tuple.*
> @groovy.transform.EqualsAndHashCode
> class Person {
> String name
> int age
> }
> def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
> age: 10), new Person(name: 'Alice', age: 22)]
> {code}
> h4. 3.1
> {code:java}
> def result =
> from persons p
> select p.name
> assert ['Daniel', 'Peter', 'Alice'] == result
> {code}
> h4. 3.2
> {code:java}
> def result =
> from persons p
> select p.name, p.age
> assert [tuple('Daniel', 35), tuple('Peter', 10), tuple('Alice', 22)] == result
> {code}
> h4. 3.3
> {code:java}
> def result =
> from persons p
> select [name: p.name, age: p.age]
> assert [ [name: 'Daniel', age: 35], [name: 'Peter', age: 10], [name: 'Alice',
> age: 22] ] == result
> {code}
> h4. 3.4
> {code:java}
> def result =
> from persons p
> select new Person(name: p.name, age: p.age)
> assert persons == result
> {code}
> h4. 3.5
> {code:java}
> def result =
> from persons p
> select p
> assert persons == result
> {code}
> h3. 4. Grouping
> {code:java}
> import static groovy.lang.Tuple.*
> @groovy.transform.EqualsAndHashCode
> class Person {
> String name
> int age
> String gender
> }
> def persons = [new Person(name: 'Daniel', age: 35, gender: 'Male'), new
> Person(name: 'Peter', age: 10, gender: 'Male'), new Person(name: 'Alice',
> age: 22, gender: 'Female')]
> {code}
> h4. 4.1
> {code:java}
> def result =
> from persons p
> groupby p.gender
> select p.gender, max(p.age)
> assert [tuple('Male', 35), tuple('Female', 22)] == result
> {code}
> h3. 5. Having
> {code:java}
> import static groovy.lang.Tuple.*
> @groovy.transform.EqualsAndHashCode
> class Person {
> String name
> int age
> String gender
> }
> def persons = [new Person(name: 'Daniel', age: 35, gender: 'Male'), new
> Person(name: 'Peter', age: 10, gender: 'Male'), new Person(name: 'Alice',
> age: 22, gender: 'Female')]
> {code}
> h4. 5.1
> {code:java}
> def result =
> from persons p
> groupby p.gender
> having p.gender == 'Male'
> select p.gender, max(p.age)
> assert [tuple('Male', 35)] == result
> {code}
> h3. 6. Sorting
> {code:java}
> @groovy.transform.EqualsAndHashCode
> class Person {
> String name
> int age
> }
> def persons = [new Person(name: 'Daniel', age: 35), new Person(name: 'Peter',
> age: 10), new Person(name: 'Alice', age: 22)]
> {code}
> h4. 6.1
> {code:java}
> def result =
> from persons p
> orderby p.age
> select p.name
> assert ['Peter', 'Alice', 'Daniel'] == result
> {code}
> h4. 6.2
> {code:java}
> def result =
> from persons p
> orderby p.age desc
> select p.name
> assert ['Daniel', 'Alice', 'Peter'] == result
> {code}
> h3. 7. Pagination
> {code:java}
> def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
> {code}
> h4. 7.1
> {code:java}
> def result =
> from numbers n
> limit 2, 5
> select n
> assert [2, 3, 4, 5, 6] == result
> {code}
> h4. 7.2
> {code:java}
> def result =
> from numbers n
> limit 5
> select n
> assert [0, 1, 2, 3, 4] == result
> {code}
> h3. 8. Nested Queries
> {code:java}
> def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
> {code}
> h4. 8.1
> {code:java}
> def result =
> from (
> from numbers n
> where n <= 5
> select n
> ) v
> limit 2, 5
> select v
> assert [2, 3, 4, 5] == result
> {code}
> h3. 9. WITH-Clause
> {code:java}
> def numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
> {code}
> h4. 9.1
> {code:java}
> def result =
> with v as (
> from numbers n
> where n <= 5
> select n
> )
> from v
> limit 2, 5
> select v
> assert [2, 3, 4, 5] == result
> {code}
> h3. 10. Union
> {code:java}
> def numbers1 = [0, 1, 2]
> def numbers2 = [2, 3, 4]
> {code}
> h4. 10.1
> {code:java}
> def result =
> from numbers1 n
> select n
> unionall
> from numbers2 n
> select n
> assert [0, 1, 2, 2, 3, 4] == result
> {code}
> h4. 10.2
> {code:java}
> def result =
> from numbers1 n
> select n
> union
> from numbers2 n
> select n
>
> assert [0, 1, 2, 3, 4] == result
> {code}
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
