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This module provides the implementation of MQTT binding traits for Smithy.
/*
* Copyright 2019 Amazon.com, Inc. or its affiliates. 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.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 software.amazon.smithy.mqtt.traits;
import static java.lang.String.format;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
/**
* Represents a parsed MQTT topic.
*/
public final class Topic {
private static final Pattern LABEL_PATTERN = Pattern.compile("^[a-zA-Z0-9_]+$");
private final String topic;
private final List levels;
private Topic(String topic, List levels) {
this.topic = topic;
this.levels = Collections.unmodifiableList(levels);
}
/**
* Parses an MQTT topic and labels.
*
* @param topic Topic to parse.
* @return Returns the parsed topic.
* @throws TopicSyntaxException if the topic is malformed.
*/
public static Topic parse(String topic) {
List levels = new ArrayList<>();
Set labels = new HashSet<>();
for (String level : topic.split("/")) {
if (level.contains("#") || level.contains("+")) {
throw new TopicSyntaxException(format(
"Wildcard levels are not allowed in MQTT topics. Found `%s` in `%s`", level, topic));
} else if (level.startsWith("{") && level.endsWith("}")) {
String label = level.substring(1, level.length() - 1);
if (!LABEL_PATTERN.matcher(label).matches()) {
throw new TopicSyntaxException(format(
"Invalid topic label name `%s` found in `%s`", label, topic));
} else if (labels.contains(label)) {
throw new TopicSyntaxException(format("Duplicate topic label `%s` found in `%s`", label, topic));
}
labels.add(label);
levels.add(new Level(label, true));
} else if (level.contains("{") || level.contains("}")) {
throw new TopicSyntaxException(format(
"Topic labels must span an entire level. Found `%s` in `%s`", level, topic));
} else {
levels.add(new Level(level, false));
}
}
return new Topic(topic, levels);
}
/**
* Gets all of the hierarchical levels of the topic.
*
* @return Returns the topic levels.
*/
public List getLevels() {
return levels;
}
/**
* Gets all of the label levels in the topic.
*
* @return Returns the label levels.
*/
public List getLabels() {
return levels.stream()
.filter(Level::isLabel)
.collect(Collectors.toList());
}
/**
* Returns true if the topic contains the given label string.
*
* @param label Label to check for.
* @return Returns true if the label exists in the topic.
*/
public boolean hasLabel(String label) {
for (Level level : levels) {
if (level.isLabel && level.value.equals(label)) {
return true;
}
}
return false;
}
/**
* Determines if this topic conflicts with another topic.
*
* @param other Topic to check against.
* @return Returns true if there is a conflict.
*/
public boolean conflictsWith(Topic other) {
int minSize = Math.min(levels.size(), other.levels.size());
for (int i = 0; i < minSize; i++) {
Level thisLevel = levels.get(i);
Level otherLevel = other.levels.get(i);
// Both are static levels with different values.
if (!thisLevel.isLabel() && !otherLevel.isLabel()
&& !thisLevel.getContent().equals(otherLevel.getContent())) {
return false;
} else if (thisLevel.isLabel() != otherLevel.isLabel()) {
// One is static and the other is not, so there is not a
// conflict. One is more specific than the other.
return false;
}
}
// At this point, the two patterns are identical. If the segment
// length is different, then one pattern is more specific than the
// other, disambiguating them.
return levels.size() == other.levels.size();
}
@Override
public String toString() {
return topic;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
} else if (!(o instanceof Topic)) {
return false;
}
return topic.equals(((Topic) o).topic);
}
@Override
public int hashCode() {
return topic.hashCode();
}
/**
* Represents a level in a topic.
*/
public static final class Level {
private String value;
private boolean isLabel;
/**
* @param value The value of the topic.
* @param isLabel True if the value is a label.
*/
public Level(String value, boolean isLabel) {
this.isLabel = isLabel;
this.value = value;
}
/**
* @param value The value of the topic.
*/
public Level(String value) {
this(value, false);
}
/**
* Gets the content of the topic.
*
* Label levels do not contain the wrapping "{" and "}"
* characters.
*
* @return Returns the level value text.
*/
public String getContent() {
return value;
}
/**
* Check if the level is a label.
*
* @return Returns true if the level is a label.
*/
public boolean isLabel() {
return isLabel;
}
@Override
public String toString() {
return isLabel ? ("{" + value + "}") : value;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
} else if (!(o instanceof Level)) {
return false;
}
Level level = (Level) o;
return isLabel == level.isLabel && value.equals(level.value);
}
@Override
public int hashCode() {
return Objects.hash(isLabel, value);
}
}
}