1 files changed, 339 insertions, 0 deletions
diff --git a/gson/src/main/java/org/onap/policy/common/gson/internal/Adapter.java b/gson/src/main/java/org/onap/policy/common/gson/internal/Adapter.java
new file mode 100644
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+++ b/gson/src/main/java/org/onap/policy/common/gson/internal/Adapter.java
@@ -0,0 +1,339 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.TypeAdapter;
+import com.google.gson.reflect.TypeToken;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Type;
+import java.util.function.Supplier;
+import java.util.regex.Pattern;
+import org.onap.policy.common.gson.annotation.GsonJsonProperty;
+
+/**
+ * Super class of adapters used to serialize and de-serialize an item.
+ */
+public class Adapter {
+
+    /**
+     * Pattern to match valid identifiers.
+     */
+    private static final Pattern VALID_NAME_PAT = Pattern.compile("[a-zA-Z_]\\w*");
+
+    /**
+     * Name of the property within the json structure containing the item.
+     */
+    private final String propName;
+
+    /**
+     * Gson object that will provide the type converter.
+     */
+    private final Gson gson;
+
+    /**
+     * Converter used when reading.
+     */
+    private final ConvInfo reader;
+
+    /**
+     * Converter used when writing, allocated lazily, once an actual type is determined.
+     */
+    private volatile ConvInfo writer = null;
+
+    /**
+     * Name of the item being lifted - used when throwing exceptions.
+     */
+    private final String fullName;
+
+    /**
+     * Constructs the object.
+     *
+     * @param gson Gson object providing type adapters
+     * @param field field used to access the item from within an object
+     */
+    public Adapter(Gson gson, Field field) {
+        this.propName = detmPropName(field);
+        this.reader = new ConvInfo(TypeToken.get(field.getGenericType()));
+        this.gson = gson;
+        this.fullName = getQualifiedName(field);
+
+        field.setAccessible(true);
+    }
+
+    /**
+     * Constructs the object.
+     *
+     * @param gson Gson object providing type adapters
+     * @param accessor method used to access the item from within an object
+     * @param forGetter {@code true} if the name is for a "getter" method, {@code false}
+     *        if for a "setter"
+     * @param valueType the class of value on which this operates
+     */
+    public Adapter(Gson gson, Method accessor, boolean forGetter, Type valueType) {
+        this.propName = (forGetter ? detmGetterPropName(accessor) : detmSetterPropName(accessor));
+        this.reader = new ConvInfo(TypeToken.get(valueType));
+        this.gson = gson;
+        this.fullName = getQualifiedName(accessor);
+
+        accessor.setAccessible(true);
+    }
+
+    /**
+     * Converts an object to a json tree.
+     *
+     * @param object the object to be converted
+     * @return a json tree representing the object
+     */
+    @SuppressWarnings("unchecked")
+    public JsonElement toJsonTree(Object object) {
+        // always use a converter for the specific subclass
+        Class<? extends Object> clazz = object.getClass();
+
+        if (writer == null) {
+            // race condition here, but it's ok to overwrite a previous value
+            writer = new ConvInfo(TypeToken.get(clazz));
+        }
+
+        ConvInfo wtr = writer;
+        TypeAdapter<Object> conv =
+                        (TypeAdapter<Object>) (wtr.clazz == clazz ? wtr.getConverter() : gson.getAdapter(clazz));
+
+        return conv.toJsonTree(object);
+    }
+
+    /**
+     * Converts a json tree to an object.
+     *
+     * @param tree the tree to be converted
+     * @return the object represented by the tree
+     */
+    public Object fromJsonTree(JsonElement tree) {
+        return reader.getConverter().fromJsonTree(tree);
+    }
+
+    public final String getPropName() {
+        return propName;
+    }
+
+    public final String getFullName() {
+        return fullName;
+    }
+
+    /**
+     * Makes an error message, appending the item's full name to the message prefix.
+     *
+     * @param prefix the message prefix
+     * @return the error message
+     */
+    public String makeError(String prefix) {
+        return (prefix + fullName);
+    }
+
+    /**
+     * Determines if the field is managed by the walker.
+     *
+     * @param field the field to examine
+     * @return {@code true} if the field is managed by the walker, {@code false} otherwise
+     */
+    public static boolean isManaged(Field field) {
+        return VALID_NAME_PAT.matcher(field.getName()).matches();
+    }
+
+    /**
+     * Determines if the method is managed by the walker.
+     *
+     * @param method the method to examine
+     * @return {@code true} if the method is managed by the walker, {@code false}
+     *         otherwise
+     */
+    public static boolean isManaged(Method method) {
+        return VALID_NAME_PAT.matcher(method.getName()).matches();
+    }
+
+    /**
+     * Determines the property name of an item within the json structure.
+     *
+     * @param field the item within the object
+     * @return the json property name for the item or {@code null} if the name is invalid
+     */
+    public static String detmPropName(Field field) {
+        // use the serialized name, if specified
+        GsonJsonProperty prop = field.getAnnotation(GsonJsonProperty.class);
+        if (prop != null && !prop.value().isEmpty()) {
+            return prop.value();
+        }
+
+        // no name provided - use it as is
+        return (isManaged(field) ? field.getName() : null);
+    }
+
+    /**
+     * Determines the property name of an item, within the json structure, associated with
+     * a "get" method.
+     *
+     * @param method method to be invoked to get the item within the object
+     * @return the json property name for the item, or {@code null} if the method name is
+     *         not valid
+     */
+    public static String detmGetterPropName(Method method) {
+
+        return detmPropNameCommon(method, () -> {
+
+            if (!isManaged(method)) {
+                return null;
+            }
+
+            String name = method.getName();
+
+            if (name.startsWith("get")) {
+                return name.substring(3);
+
+            } else if (name.startsWith("is")) {
+                Class<?> treturn = method.getReturnType();
+
+                if (treturn == boolean.class || treturn == Boolean.class) {
+                    return name.substring(2);
+                }
+            }
+
+            // not a valid name for a "getter" method
+            return null;
+        });
+    }
+
+    /**
+     * Determines the property name of an item, within the json structure, associated with
+     * a "set" method.
+     *
+     * @param method method to be invoked to set the item within the object
+     * @return the json property name for the item, or {@code null} if the method name is
+     *         not valid
+     */
+    public static String detmSetterPropName(Method method) {
+
+        return detmPropNameCommon(method, () -> {
+
+            if (!isManaged(method)) {
+                return null;
+            }
+
+            String name = method.getName();
+
+            if (name.startsWith("set")) {
+                return name.substring(3);
+            }
+
+            // not a valid name for a "setter" method
+            return null;
+        });
+    }
+
+    /**
+     * Determines the property name of an item within the json structure.
+     *
+     * @param method method to be invoked to get/set the item within the object
+     * @param extractor function to extract the name directly from the method name
+     * @return the json property name for the item, or {@code null} if the method name is
+     *         not valid
+     */
+    private static String detmPropNameCommon(Method method, Supplier<String> extractor) {
+
+        // use the property name, if specified
+        GsonJsonProperty propName = method.getAnnotation(GsonJsonProperty.class);
+        if (propName != null && !propName.value().isEmpty()) {
+            return propName.value();
+        }
+
+        // no name provided - must compute it from the method name
+        String name = extractor.get();
+
+        if (name == null || name.isEmpty()) {
+            // nothing left after stripping the prefix - invalid name
+            return null;
+        }
+
+        // translate the first letter to lower-case
+        return name.substring(0, 1).toLowerCase() + name.substring(1);
+    }
+
+    /**
+     * Gets the fully qualified name of a field.
+     *
+     * @param field field whose name is desired
+     * @return the field fully qualified name
+     */
+    public static String getQualifiedName(Field field) {
+        return (field.getDeclaringClass().getName() + "." + field.getName());
+    }
+
+    /**
+     * Gets the fully qualified name of a method.
+     *
+     * @param method method whose name is desired
+     * @return the method's fully qualified name
+     */
+    public static String getQualifiedName(Method method) {
+        return (method.getDeclaringClass().getName() + "." + method.getName());
+    }
+
+    /**
+     * Converter info.
+     */
+    private class ConvInfo {
+
+        /**
+         * Type on which the converter works.
+         */
+        private TypeToken<?> type;
+
+        /**
+         * Class of object on which the converter works.
+         */
+        private Class<?> clazz;
+
+        /**
+         * Converter to use, initialized lazily.
+         */
+        private volatile TypeAdapter<?> conv = null;
+
+        /**
+         * Constructs the object.
+         *
+         * @param type type of object to be converted
+         */
+        public ConvInfo(TypeToken<?> type) {
+            this.type = type;
+            this.clazz = type.getRawType();
+        }
+
+        public final TypeAdapter<?> getConverter() {
+            if (conv == null) {
+                // race condition here, but it's ok to overwrite a previous value
+                this.conv = gson.getAdapter(type);
+            }
+
+            return conv;
+        }
+    }
+}