Add path method for KFunction1

docs/en/jpql-with-kotlin-jdsl/paths.md

@@ -13,6 +13,75 @@ entity(Book::class, "b").path(Book::isbn).path(Isbn::value)
 entity(Book::class, "b")(Book::isbn)(Isbn::value)
 ```
 
+## Java entity
+
+`path()` and `invoke()` take `KProperty1` or `KFuction1` as an argument.
+`KFunction1` is useful when you use Java entity with private property and public getter.
+
+```java
+@Entity
+public class Book {
+    @Id
+    private Long id;
+
+    private String title;
+
+    public String getTitle() {
+        return title;
+    }
+}
+```
+
+```kotlin
+// compile error
+path(Book::title)
+
+// Book.title
+path(Book::getTitle)
+```
+
+Kotlin JDSL follows the following rules to infer property name from getter name.
+
+- If the name starts with `is`, use the name as it is.
+- If the name starts with `get`, remove `get` and change the first letter to lowercase.
+- Otherwise, use the name as it is.
+
+```kotlin
+// Book.isAvailable
+path(Book::isAvailable)
+
+// Book.available
+path(Book::getAvailable)
+```
+
+If you want to use your own rule instead of the above rules, you need to implement `JpqlPropertyIntrospector` and provide it to `RenderContext`.
+
+```kotlin
+class MyIntrospector : JpqlPropertyIntrospector() {
+    override fun introspect(property: KCallable<*>): JpqlPropertyDescription? {
+        if (property is KFunction1<*, *>) {
+            // resolve a name with your own rule
+            val name = ...
+            return MyProperty(name)
+        }
+
+        return null
+    }
+
+    private data class MyProperty(
+        override val name: String,
+    ) : JpqlPropertyDescription
+}
+
+val myModule = object : JpqlRenderModule {
+    override fun setupModule(context: JpqlRenderModule.SetupContext) {
+        context.prependIntrospector(MyIntrospector())
+    }
+}
+
+val myContext = JpqlRenderContext().registerModule(myModule)
+```
+
 ## Expression
 
 `Path` can be used as [`Expression`](expressions.md), such as in a [select clause](statements.md#select-clause) or [predicate](predicates.md).

docs/ko/jpql-with-kotlin-jdsl/paths.md

@@ -13,6 +13,75 @@ entity(Book::class, "b").path(Book::isbn).path(Isbn::value)
 entity(Book::class, "b")(Book::isbn)(Isbn::value)
 ```
 
+## Java entity
+
+`path()` 와 `invoke()`는 `KProperty1` 또는 `KFuction1`를 인자로 받습니다.
+`KFunction1`의 경우, getter만 public인 Java로 선언한 entity를 사용할 때 유용합니다.
+
+```java
+@Entity
+public class Book {
+    @Id
+    private Long id;
+
+    private String title;
+
+    public String getTitle() {
+        return title;
+    }
+}
+```
+
+```kotlin
+// compile error
+path(Book::title)
+
+// Book.title
+path(Book::getTitle)
+```
+
+Kotlin JDSL은 getter 이름에서 프로퍼티 이름을 추론하기 위해 다음 규칙을 따릅니다.
+
+- `is`로 시작하는 경우 이름 그대로 사용합니다.
+- `get`으로 시작하는 경우 `get`을 제거하고 이후 첫 글자를 소문자로 변경합니다.
+- 그 외의 경우, 이름 그대로 사용합니다.
+
+```kotlin
+// Book.isAvailable
+path(Book::isAvailable)
+
+// Book.available
+path(Book::getAvailable)
+```
+
+위 규칙 대신 나만의 규칙을 사용하고 싶다면, `JpqlPropertyIntrospector`를 구현하고 이를 이를 `RenderContext`에 추가해야 합니다.
+
+```kotlin
+class MyIntrospector : JpqlPropertyIntrospector() {
+    override fun introspect(property: KCallable<*>): JpqlPropertyDescription? {
+        if (property is KFunction1<*, *>) {
+            // 나만의 규칙으로 이름을 추론합니다
+            val name = ...
+            return MyProperty(name)
+        }
+
+        return null
+    }
+
+    private data class MyProperty(
+        override val name: String,
+    ) : JpqlPropertyDescription
+}
+
+val myModule = object : JpqlRenderModule {
+    override fun setupModule(context: JpqlRenderModule.SetupContext) {
+        context.prependIntrospector(MyIntrospector())
+    }
+}
+
+val myContext = JpqlRenderContext().registerModule(myModule)
+```
+
 ## Expression
 
 `Path`는 [select clause](statements.md#select-clause) 나 [predicate](predicates.md) 등에서 [`Expression`](expressions.md)으로 사용될 수 있습니다.

dsl/jpql/src/main/kotlin/com/linecorp/kotlinjdsl/dsl/jpql/Jpql.kt

@@ -41,6 +41,7 @@ import java.math.BigDecimal
 import java.math.BigInteger
 import kotlin.internal.Exact
 import kotlin.reflect.KClass
+import kotlin.reflect.KFunction1
 import kotlin.reflect.KProperty1
 
 /**
@@ -194,6 +195,15 @@ open class Jpql : JpqlDsl {
         return Paths.path(property)
     }
 
+    /**
+     * Creates a path expression with the property.
+     * The path starts from the entity which is the owner of the property.
+     */
+    @SinceJdsl("3.1.0")
+    fun <T : Any, V> path(getter: KFunction1<T, @Exact V>): Path<V & Any> {
+        return Paths.path(getter)
+    }
+
     /**
      * Creates a path expression with the entity and property.
      */
@@ -202,6 +212,14 @@ open class Jpql : JpqlDsl {
         return Paths.path(this.toEntity(), property)
     }
 
+    /**
+     * Creates a path expression with the entity and property.
+     */
+    @SinceJdsl("3.1.0")
+    fun <T : Any, V> Entityable<T>.path(getter: KFunction1<T, @Exact V>): Path<V & Any> {
+        return Paths.path(this.toEntity(), getter)
+    }
+
     /**
      * Creates a path expression with the path and property.
      */
@@ -210,6 +228,14 @@ open class Jpql : JpqlDsl {
         return Paths.path(this.toPath(), property)
     }
 
+    /**
+     * Creates a path expression with the path and property.
+     */
+    @SinceJdsl("3.1.0")
+    fun <T : Any, V> Pathable<T>.path(getter: KFunction1<T, @Exact V>): Path<V & Any> {
+        return Paths.path(this.toPath(), getter)
+    }
+
     /**
      * Creates a path expression with the entity and property.
      */
@@ -218,6 +244,14 @@ open class Jpql : JpqlDsl {
         return Paths.path(this.toEntity(), property)
     }
 
+    /**
+     * Creates a path expression with the entity and property.
+     */
+    @SinceJdsl("3.1.0")
+    operator fun <T : Any, V> Entityable<T>.invoke(getter: KFunction1<T, @Exact V>): Path<V & Any> {
+        return Paths.path(this.toEntity(), getter)
+    }
+
     /**
      * Creates a path expression with the path and property.
      */
@@ -226,6 +260,14 @@ open class Jpql : JpqlDsl {
         return Paths.path(this.toPath(), property)
     }
 
+    /**
+     * Creates a path expression with the path and property.
+     */
+    @SinceJdsl("3.1.0")
+    operator fun <T : Any, V> Pathable<T>.invoke(getter: KFunction1<T, @Exact V>): Path<V & Any> {
+        return Paths.path(this.toPath(), getter)
+    }
+
     /**
      * Creates an aliased expression with the alias expression.
      * The aliased expression can be referenced by the alias expression.