org.graalvm.nativeimage.c.struct.CStruct Maven / Gradle / Ivy
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package org.graalvm.nativeimage.c.struct;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.graalvm.nativeimage.c.CContext;
import org.graalvm.word.PointerBase;
/**
* Denotes Java interface that imports a C struct. The interface must extend {@link PointerBase},
* i.e., it is a word type. There is never a Java class that implements the interface.
*
* Field accesses are done via interface methods that are annotated with {@link CField},
* {@link CFieldAddress}, or {@link CFieldOffset}. All calls of the interface methods are replaced
* with the appropriate memory or address arithmetic operations. Here is an example to define a
* complex number structure:
*
* {@snippet file="org/graalvm/nativeimage/StackValue.java" region="ComplexValue"}
*
* The annotated interface, or an outer class that contains the interface, must be annotated with
* {@link CContext}. Allocate an instances of the {@code struct} either by
* {@link org.graalvm.nativeimage.StackValue#get(java.lang.Class)} or by
* {@link org.graalvm.nativeimage.UnmanagedMemory#malloc(org.graalvm.word.UnsignedWord)}.
*
* To access an array of structs one can define a special {@code addressOf} method:
*
*
* {@snippet file="org/graalvm/nativeimage/StackValue.java" region="IntOrDouble"}
*
* Implementation of such method then allows one to do array arithmetics - e.g. obtain
* pointer to the first element of the array and then access the others:
*
*
* {@snippet file="org/graalvm/nativeimage/StackValue.java" region="acceptIntIntDouble"}
*
* @since 19.0
* @see org.graalvm.nativeimage.StackValue
* @see org.graalvm.nativeimage.UnmanagedMemory
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
public @interface CStruct {
/**
* Specifies the name of the imported C struct type. If no name is provided, the type name is
* used as the struct name.
*
* @since 19.0
*/
String value() default "";
/**
* If marked as incomplete, we will not try to determine the size of the struct.
*
* @since 19.0
*/
boolean isIncomplete() default false;
/**
* Add the C "struct" keyword to the name specified in {@link #value()}.
*
* @since 19.0
*/
boolean addStructKeyword() default false;
}