Map function by name

src/main/java/jnr/ffi/annotations/NativeName.java

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+package jnr.ffi.annotations;
+
+import java.lang.annotation.*;
+
+/**
+ * Use if you want to have different names for JNR interface method and native library method.
+ * <b/>
+ * For mapping to work, use {@link jnr.ffi.mapper.NativeNameFunctionMapper}
+ */
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface NativeName {
+    String value();
+}

src/main/java/jnr/ffi/mapper/NativeNameFunctionMapper.java

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+package jnr.ffi.mapper;
+
+import jnr.ffi.annotations.NativeName;
+
+import java.lang.annotation.Annotation;
+import java.util.Collection;
+
+/**
+ * Uses {@link NativeName} annotation to map JNR interface method and native library method with different names.
+ * Example:
+ * <pre>
+ * {@code
+ * LibC libc = LibraryLoader.create(LibC.class).mapper(new NativeNameFunctionMapper()).load("lib");
+ * }
+ * </pre>
+ */
+public class NativeNameFunctionMapper implements FunctionMapper {
+    @Override
+    public String mapFunctionName(String functionName, Context context) {
+        Collection<Annotation> annotations = context.getAnnotations();
+        for (Annotation annotation : annotations) {
+            if (annotation instanceof NativeName) {
+                return ((NativeName) annotation).value();
+            }
+        }
+        return functionName;
+    }
+}

src/test/java/jnr/ffi/mapper/NativeNameFunctionMapperTest.java

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+package jnr.ffi.mapper;
+
+import jnr.ffi.LibraryLoader;
+import jnr.ffi.annotations.NativeName;
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.util.Random;
+
+/**
+ * Created by Andrew
+ * on 01.07.2017.
+ */
+public class NativeNameFunctionMapperTest {
+    static Lib lib;
+
+    @BeforeClass
+    public static void setUpClass()
+            throws Exception {
+        lib = LibraryLoader.create(Lib.class)
+                           .mapper(new NativeNameFunctionMapper())
+                           .load("test");
+    }
+
+    @Test
+    public void testSameFunctionResult()
+            throws Exception {
+        Random random = new Random();
+        for (int i = 0; i < 100; i++) {
+            int randomInt = random.nextInt();
+            Assert.assertEquals(lib.ret_int32_t(randomInt), lib.returnInt(randomInt));
+        }
+    }
+
+    public static interface Lib {
+        public int ret_int32_t(int value);
+
+        @NativeName("ret_int32_t")
+        public int returnInt(int value);
+    }
+}