1 files changed, 93 insertions, 0 deletions
diff --git a/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Label.java b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Label.java
new file mode 100644
index 0000000..33664dd
--- /dev/null
+++ b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Label.java
@@ -0,0 +1,93 @@
+package eu.mulk.quarkus.googlecloud.jsonlogging;
+
+import java.util.Objects;
+
+/**
+ * A label usable to tag a log message.
+ *
+ * <p>Instances of {@link Label} can be passed as log parameters to the {@code *f} family of logging
+ * functions on {@link org.jboss.logging.Logger}.
+ *
+ * <p><strong>Example:</strong>
+ *
+ * <pre>{@code
+ * logger.logf("Request rejected: unauthorized.", Label.of("requestId", "123"));
+ * }</pre>
+ *
+ * Result:
+ *
+ * <pre>{@code
+ * {
+ *   "textPayload": "Request rejected: unauthorized.",
+ *   "labels": {
+ *     "requestId": "123"
+ *   }
+ * }
+ * }</pre>
+ *
+ * @see KeyValueParameter
+ * @see StructuredParameter
+ */
+public final class Label {
+
+  private final String key;
+  private final String value;
+
+  private Label(String key, String value) {
+    this.key = key;
+    this.value = value;
+  }
+
+  /**
+   * Constructs a {@link Label} from a key (i.e. name) and a value.
+   *
+   * <p>It is often useful for the key to be a {@link String} constant that is shared by multiple
+   * parts of the program.
+   *
+   * @param key the key (name) of the label.
+   * @param value the value of the label.
+   * @return the newly constructed {@link Label}, ready to be passed to a logging function.
+   */
+  public static Label of(String key, String value) {
+    return new Label(key, value);
+  }
+
+  /**
+   * The name of the label.
+   *
+   * <p>It is often useful for this to be a {@link String} constant that is shared by multiple parts
+   * of the program.
+   *
+   * @return the name of the label.
+   */
+  public String key() {
+    return key;
+  }
+
+  /**
+   * The value of the label.
+   *
+   * @return the value of the label.
+   */
+  public String value() {
+    return value;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (obj == this) return true;
+    if (obj == null || obj.getClass() != this.getClass()) return false;
+    var that = (Label) obj;
+    return Objects.equals(this.key, that.key) && Objects.equals(this.value, that.value);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(key, value);
+  }
+
+  @Override
+  public String toString() {
+    return "Label[" + "key=" + key + ", " + "value=" + value + ']';
+  }
+}