#141 - Added model to build ALPS documents.

Added the necessary abstractions to build an ALPS [0] document.

[0] http://alps.io

src/main/java/org/springframework/hateoas/alps/Alps.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * 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 org.springframework.hateoas.alps;
+
+import java.util.List;
+
+import lombok.Value;
+import lombok.experimental.Builder;
+
+import org.springframework.hateoas.alps.Descriptor.DescriptorBuilder;
+import org.springframework.hateoas.alps.Doc.DocBuilder;
+import org.springframework.hateoas.alps.Ext.ExtBuilder;
+
+/**
+ * An ALPS document.
+ * 
+ * @author Oliver Gierke
+ * @since 0.15
+ * @see http://alps.io
+ * @see http://alps.io/spec/#prop-alps
+ */
+@Value
+@Builder(builderMethodName = "alps")
+public class Alps {
+
+	private final String version = "1.0";
+	private final Doc doc;
+	private final List<Descriptor> descriptors;
+
+	/**
+	 * Returns a new {@link DescriptorBuilder}.
+	 * 
+	 * @return
+	 */
+	public static DescriptorBuilder descriptor() {
+		return Descriptor.builder();
+	}
+
+	/**
+	 * Returns a new {@link DocBuilder}.
+	 * 
+	 * @return
+	 */
+	public static DocBuilder doc() {
+		return Doc.builder();
+	}
+
+	/**
+	 * Retruns a new {@link ExtBuilder}.
+	 * 
+	 * @return
+	 */
+	public static ExtBuilder ext() {
+		return Ext.builder();
+	}
+}

src/main/java/org/springframework/hateoas/alps/Descriptor.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * 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 org.springframework.hateoas.alps;
+
+import java.util.List;
+
+import lombok.Value;
+import lombok.experimental.Builder;
+
+/**
+ * A value object for an ALPS descriptor.
+ * 
+ * @author Oliver Gierke
+ * @since 0.15
+ * @see http://alps.io/spec/#prop-descriptor
+ */
+@Value
+@Builder
+public class Descriptor {
+
+	private final String id, href, name;
+	private final Doc doc;
+	private final Type type;
+	private final Ext ext;
+	private final String rt;
+	private final List<Descriptor> descriptors;
+}

src/main/java/org/springframework/hateoas/alps/Doc.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * 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 org.springframework.hateoas.alps;
+
+import lombok.AllArgsConstructor;
+import lombok.Value;
+import lombok.experimental.Builder;
+
+import org.springframework.util.Assert;
+
+/**
+ * A value object for an ALPS doc element.
+ * 
+ * @author Oliver Gierke
+ * @since 0.15
+ * @see http://alps.io/spec/#prop-doc
+ */
+@Value
+@Builder
+@AllArgsConstructor
+public class Doc {
+
+	private final String href, value;
+	private final Format format;
+
+	/**
+	 * Creates a new {@link Doc} instance with the given value and {@link Format}.
+	 * 
+	 * @param value must not be {@literal null} or empty.
+	 * @param format must not be {@literal null}.
+	 */
+	public Doc(String value, Format format) {
+
+		Assert.hasText(value, "Value must not be null or empty!");
+		Assert.notNull(format, "Format must not be null!");
+
+		this.href = null;
+		this.value = value;
+		this.format = format;
+	}
+}

src/main/java/org/springframework/hateoas/alps/Ext.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * 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 org.springframework.hateoas.alps;
+
+import lombok.Value;
+import lombok.experimental.Builder;
+
+/**
+ * A value object for an ALPS ext element.
+ * 
+ * @author Oliver Gierke
+ * @since 0.15
+ * @see http://alps.io/spec/#prop-ext
+ */
+@Value
+@Builder
+public class Ext {
+
+	private final String href;
+	private final String value;
+}

src/main/java/org/springframework/hateoas/alps/Format.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * 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 org.springframework.hateoas.alps;
+
+import java.util.Locale;
+
+/**
+ * Enum for all ALPS doc formats.
+ * 
+ * @author Oliver Gierke
+ * @since 0.15
+ * @see http://alps.io/spec/#prop-format
+ */
+public enum Format {
+
+	TEXT, HTML, ASCIIDOC;
+
+	/*
+	 * (non-Javadoc)
+	 * @see java.lang.Enum#toString()
+	 */
+	public String toString() {
+		return name().toLowerCase(Locale.US);
+	}
+}

src/main/java/org/springframework/hateoas/alps/Type.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * 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 org.springframework.hateoas.alps;
+
+import java.util.Locale;
+
+/**
+ * An enum for ALPS descriptor types
+ * 
+ * @author Oliver Gierke
+ * @since 0.15
+ * @see http://alps.io/spec/#prop-type
+ */
+public enum Type {
+
+	SEMANTIC, SAFE, IDEMPOTENT, UNSAFE;
+
+	/*
+	 * (non-Javadoc)
+	 * @see java.lang.Enum#toString()
+	 */
+	public String toString() {
+		return name().toLowerCase(Locale.US);
+	}
+}