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Common utilities for Google APIs in Java
/*
* Copyright 2016, Google Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.google.api.pathtemplate;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import javax.annotation.Nullable;
/**
* Class for representing and working with resource names.
*
* A resource name is represented by {@link PathTemplate}, an assignment to variables in the
* template, and an optional endpoint. The {@code ResourceName} class implements the map interface
* (unmodifiable) to work with the variable assignments, and has methods to reproduce the string
* representation of the name, to construct new names, and to dereference names into resources.
*
*
As a resource name essentially represents a match of a path template against a string, it can
* be also used for other purposes than naming resources. However, not all provided methods may make
* sense in all applications.
*
*
Usage examples:
*
*
{@code
* PathTemplate template = PathTemplate.create("shelves/*/books/*");
* TemplatedResourceName resourceName = TemplatedResourceName.create(template, "shelves/s1/books/b1");
* assert resourceName.get("$1").equals("b1");
* assert resourceName.parentName().toString().equals("shelves/s1/books");
* }
*/
public class TemplatedResourceName implements Map {
// ResourceName Resolver
// =====================
/** Represents a resource name resolver which can be registered with this class. */
public interface Resolver {
/** Resolves the resource name into a resource by calling the underlying API. */
T resolve(Class resourceType, TemplatedResourceName name, @Nullable String version);
}
// The registered resource name resolver.
// TODO(wrwg): its a bit spooky to have this static global. Think of ways to
// configure this from the outside instead if programmatically (e.g. java properties).
private static volatile Resolver resourceNameResolver =
new Resolver() {
@Override
public T resolve(Class resourceType, TemplatedResourceName name, String version) {
throw new IllegalStateException(
"No resource name resolver is registered in ResourceName class.");
}
};
/**
* Sets the resource name resolver which is used by the {@link #resolve(Class, String)} method. By
* default, no resolver is registered.
*/
public static void registerResourceNameResolver(Resolver resolver) {
resourceNameResolver = resolver;
}
// ResourceName
// ============
/**
* Creates a new resource name based on given template and path. The path must match the template,
* otherwise null is returned.
*
* @throws ValidationException if the path does not match the template.
*/
public static TemplatedResourceName create(PathTemplate template, String path) {
Map values = template.match(path);
if (values == null) {
throw new ValidationException("path '%s' does not match template '%s'", path, template);
}
return new TemplatedResourceName(template, values, null);
}
/**
* Creates a new resource name from a template and a value assignment for variables.
*
* @throws ValidationException if not all variables in the template are bound.
*/
public static TemplatedResourceName create(PathTemplate template, Map values) {
if (!values.keySet().containsAll(template.vars())) {
Set unbound = Sets.newLinkedHashSet(template.vars());
unbound.removeAll(values.keySet());
throw new ValidationException("unbound variables: %s", unbound);
}
return new TemplatedResourceName(template, values, null);
}
/**
* Creates a new resource name based on given template and path, where the path contains an
* endpoint. If the path does not match, null is returned.
*/
@Nullable
public static TemplatedResourceName createFromFullName(PathTemplate template, String path) {
Map values = template.matchFromFullName(path);
if (values == null) {
return null;
}
return new TemplatedResourceName(template, values, null);
}
private final PathTemplate template;
private final ImmutableMap values;
private final String endpoint;
private volatile String stringRepr;
private TemplatedResourceName(
PathTemplate template, Map values, String endpoint) {
this.template = template;
this.values = ImmutableMap.copyOf(values);
this.endpoint = endpoint;
}
@Override
public String toString() {
if (stringRepr == null) {
stringRepr = template.instantiate(values);
}
return stringRepr;
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof TemplatedResourceName)) {
return false;
}
TemplatedResourceName other = (TemplatedResourceName) obj;
return Objects.equals(template, other.template)
&& Objects.equals(endpoint, other.endpoint)
&& Objects.equals(values, other.values);
}
@Override
public int hashCode() {
return Objects.hash(template, endpoint, values);
}
/** Gets the template associated with this resource name. */
public PathTemplate template() {
return template;
}
/** Checks whether the resource name has an endpoint. */
public boolean hasEndpoint() {
return endpoint != null;
}
/** Returns the endpoint of this resource name, or null if none is defined. */
@Nullable
public String endpoint() {
return endpoint;
}
/** Returns a resource name with specified endpoint. */
public TemplatedResourceName withEndpoint(String endpoint) {
return new TemplatedResourceName(template, values, Preconditions.checkNotNull(endpoint));
}
/**
* Returns the parent resource name. For example, if the name is {@code shelves/s1/books/b1}, the
* parent is {@code shelves/s1/books}.
*/
public TemplatedResourceName parentName() {
PathTemplate parentTemplate = template.parentTemplate();
return new TemplatedResourceName(parentTemplate, values, endpoint);
}
/**
* Returns true of the resource name starts with the parent resource name, i.e. is a child of the
* parent.
*/
public boolean startsWith(TemplatedResourceName parentName) {
// TODO: more efficient implementation.
return toString().startsWith(parentName.toString());
}
/**
* Attempts to resolve a resource name into a resource, by calling the associated API. The
* resource name must have an endpoint. An optional version can be specified to determine in which
* version of the API to call.
*/
public T resolve(Class resourceType, @Nullable String version) {
Preconditions.checkArgument(hasEndpoint(), "Resource name must have an endpoint.");
return resourceNameResolver.resolve(resourceType, this, version);
}
// Map Interface
// =============
@Override
public int size() {
return values.size();
}
@Override
public boolean isEmpty() {
return values.isEmpty();
}
@Override
public boolean containsKey(Object key) {
return values.containsKey(key);
}
@Override
public boolean containsValue(Object value) {
return values.containsValue(value);
}
@Override
public String get(Object key) {
return values.get(key);
}
@Override
@Deprecated
public String put(String key, String value) {
return values.put(key, value);
}
@Override
@Deprecated
public String remove(Object key) {
return values.remove(key);
}
@Override
@Deprecated
public void putAll(Map m) {
values.putAll(m);
}
@Override
@Deprecated
public void clear() {
values.clear();
}
@Override
public Set keySet() {
return values.keySet();
}
@Override
public Collection values() {
return values.values();
}
@Override
public Set> entrySet() {
return values.entrySet();
}
}