core: Add TypeLiterals utility class.

2 files changed, 167 insertions, 0 deletions

diff --git a/sangria-core/src/main/java/com/tavianator/sangria/core/TypeLiterals.java b/sangria-core/src/main/java/com/tavianator/sangria/core/TypeLiterals.java
new file mode 100644
index 0000000..833f70d
--- /dev/null
+++ b/sangria-core/src/main/java/com/tavianator/sangria/core/TypeLiterals.java
@@ -0,0 +1,87 @@
+/****************************************************************************
+ * Sangria                                                                  *
+ * Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com>             *
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ * http://www.apache.org/licenses/LICENSE-2.0                               *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ****************************************************************************/
+
+package com.tavianator.sangria.core;
+
+import java.util.*;
+
+import com.google.inject.Provider;
+import com.google.inject.TypeLiteral;
+import com.google.inject.util.Types;
+
+/**
+ * Static utility functions for working with {@link TypeLiteral}s.
+ *
+ * @author Tavian Barnes (tavianator@tavianator.com)
+ * @version 1.1
+ * @since 1.1
+ */
+public class TypeLiterals {
+    private TypeLiterals() {
+        // Not for instantiating
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> TypeLiteral<List<T>> listOf(Class<T> type) {
+        return (TypeLiteral<List<T>>)TypeLiteral.get(Types.listOf(type));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> TypeLiteral<List<T>> listOf(TypeLiteral<T> type) {
+        return (TypeLiteral<List<T>>)TypeLiteral.get(Types.listOf(type.getType()));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> TypeLiteral<Set<T>> setOf(Class<T> type) {
+        return (TypeLiteral<Set<T>>)TypeLiteral.get(Types.setOf(type));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> TypeLiteral<Set<T>> setOf(TypeLiteral<T> type) {
+        return (TypeLiteral<Set<T>>)TypeLiteral.get(Types.setOf(type.getType()));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <K, V> TypeLiteral<Map<K, V>> mapOf(Class<K> keyType, Class<V> valueType) {
+        return (TypeLiteral<Map<K, V>>)TypeLiteral.get(Types.mapOf(keyType, valueType));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <K, V> TypeLiteral<Map<K, V>> mapOf(Class<K> keyType, TypeLiteral<V> valueType) {
+        return (TypeLiteral<Map<K, V>>)TypeLiteral.get(Types.mapOf(keyType, valueType.getType()));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <K, V> TypeLiteral<Map<K, V>> mapOf(TypeLiteral<K> keyType, Class<V> valueType) {
+        return (TypeLiteral<Map<K, V>>)TypeLiteral.get(Types.mapOf(keyType.getType(), valueType));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <K, V> TypeLiteral<Map<K, V>> mapOf(TypeLiteral<K> keyType, TypeLiteral<V> valueType) {
+        return (TypeLiteral<Map<K, V>>)TypeLiteral.get(Types.mapOf(keyType.getType(), valueType.getType()));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> TypeLiteral<Provider<T>> providerOf(Class<T> type) {
+        return (TypeLiteral<Provider<T>>)TypeLiteral.get(Types.providerOf(type));
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> TypeLiteral<Provider<T>> providerOf(TypeLiteral<T> type) {
+        return (TypeLiteral<Provider<T>>)TypeLiteral.get(Types.providerOf(type.getType()));
+    }
+}
diff --git a/sangria-core/src/test/java/com/tavianator/sangria/core/TypeLiteralsTest.java b/sangria-core/src/test/java/com/tavianator/sangria/core/TypeLiteralsTest.java
new file mode 100644
index 0000000..93dea77
--- /dev/null
+++ b/sangria-core/src/test/java/com/tavianator/sangria/core/TypeLiteralsTest.java
@@ -0,0 +1,80 @@
+/****************************************************************************
+ * Sangria                                                                  *
+ * Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com>             *
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ * http://www.apache.org/licenses/LICENSE-2.0                               *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ****************************************************************************/
+
+package com.tavianator.sangria.core;
+
+import java.util.*;
+
+import com.google.inject.Provider;
+import com.google.inject.TypeLiteral;
+import org.hamcrest.Matcher;
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Tests for {@link TypeLiterals}.
+ *
+ * @author Tavian Barnes (tavianator@tavianator.com)
+ * @version 1.1
+ * @since 1.1
+ */
+public class TypeLiteralsTest {
+    @Test
+    public void testListOf() {
+        assertThat(TypeLiterals.listOf(String.class),
+                equalTo(new TypeLiteral<List<String>>() { }));
+        assertThat(TypeLiterals.listOf(new TypeLiteral<Class<?>>() { }),
+                equalTo(new TypeLiteral<List<Class<?>>>() { }));
+    }
+
+    @Test
+    public void testSetOf() {
+        assertThat(TypeLiterals.setOf(String.class),
+                equalTo(new TypeLiteral<Set<String>>() { }));
+        assertThat(TypeLiterals.setOf(new TypeLiteral<Class<?>>() { }),
+                equalTo(new TypeLiteral<Set<Class<?>>>() { }));
+    }
+
+    @Test
+    public void testMapOf() {
+        assertThat(TypeLiterals.mapOf(String.class, String.class),
+                equalTo(new TypeLiteral<Map<String, String>>() { }));
+        assertThat(TypeLiterals.mapOf(String.class, new TypeLiteral<Class<?>>() { }),
+                equalTo(new TypeLiteral<Map<String, Class<?>>>() { }));
+        assertThat(TypeLiterals.mapOf(new TypeLiteral<Class<?>>() { }, String.class),
+                equalTo(new TypeLiteral<Map<Class<?>, String>>() { }));
+        assertThat(TypeLiterals.mapOf(new TypeLiteral<Class<?>>() { }, new TypeLiteral<Class<?>>() { }),
+                equalTo(new TypeLiteral<Map<Class<?>, Class<?>>>() { }));
+    }
+
+    @Test
+    public void testProviderOf() {
+        assertThat(TypeLiterals.providerOf(String.class),
+                equalTo(new TypeLiteral<Provider<String>>() { }));
+        assertThat(TypeLiterals.providerOf(new TypeLiteral<Class<?>>() { }),
+                equalTo(new TypeLiteral<Provider<Class<?>>>() { }));
+    }
+
+    /**
+     * Needed to avoid compilation error to to inferred type being anonymous class.
+     */
+    private static <T> Matcher<TypeLiteral<T>> equalTo(TypeLiteral<T> type) {
+        return Matchers.equalTo(type);
+    }
+}