GH-548 Replace complex Messenger with simple logging API (Resolve #540)

Author: dzikoysk

panda-framework/src/main/java/org/panda_lang/language/interpreter/logging/Channel.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2020 Dzikoysk
+ *
+ * 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.panda_lang.language.interpreter.logging;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import static org.panda_lang.utilities.commons.collection.Lists.add;
+
+public class Channel implements Comparable<Channel> {
+
+    private static final Collection<Channel> VALUES = new ArrayList<>();
+
+    public static Channel FATAL = add(VALUES, new Channel("fatal", 6.0));
+    public static Channel ERROR = add(VALUES, new Channel("error", 5.0));
+    public static Channel WARN = add(VALUES, new Channel("warn", 4.0));
+    public static Channel INFO = add(VALUES, new Channel("info", 3.0));
+    public static Channel DEBUG = add(VALUES, new Channel("debug", 2.0));
+    public static Channel TRACE = add(VALUES, new Channel("trace", 1.0));
+
+    private final String channel;
+    private final double priority;
+
+    public Channel(String channel, double priority) {
+        this.channel = channel;
+        this.priority = priority;
+    }
+
+    @Override
+    public int compareTo(@NotNull Channel o) {
+        return Double.compare(priority, o.priority);
+    }
+
+    public double getPriority() {
+        return priority;
+    }
+
+    public String getChannel() {
+        return channel;
+    }
+
+    public static Channel of(String channel) {
+        for (Channel value : VALUES) {
+            if (value.getChannel().equalsIgnoreCase(channel)) {
+                return value;
+            }
+        }
+
+        throw new UnsupportedOperationException(channel + " is not supported by default");
+    }
+
+}

panda-framework/src/main/java/org/panda_lang/language/interpreter/logging/Logger.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2020 Dzikoysk
+ *
+ * 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.panda_lang.language.interpreter.logging;
+
+public interface Logger {
+
+    void log(Channel channel, String message);
+
+    void exception(Throwable throwable);
+
+    default void fatal(String message) {
+        log(Channel.FATAL, message);
+    }
+
+    default void error(String message) {
+        log(Channel.ERROR, message);
+    }
+
+    default void warn(String message) {
+        log(Channel.WARN, message);
+    }
+
+    default void info(String message) {
+        log(Channel.INFO, message);
+    }
+
+    default void debug(String message) {
+        log(Channel.DEBUG, message);
+    }
+
+    default void trace(String message) {
+        log(Channel.TRACE, message);
+    }
+
+}

panda-framework/src/main/java/org/panda_lang/language/interpreter/messenger/LoggerHolder.java renamed to panda-framework/src/main/java/org/panda_lang/language/interpreter/logging/LoggerHolder.java

@@ -14,9 +14,7 @@
  * limitations under the License.
  */
 
-package org.panda_lang.language.interpreter.messenger;
-
-import org.slf4j.Logger;
+package org.panda_lang.language.interpreter.logging;
 
 /**
  * Logger container

panda-framework/src/main/java/org/panda_lang/language/interpreter/messenger/PandaMessengerMessage.java renamed to panda-framework/src/main/java/org/panda_lang/language/interpreter/logging/SystemLogger.java

@@ -14,28 +14,30 @@
  * limitations under the License.
  */
 
-package org.panda_lang.language.interpreter.messenger;
+package org.panda_lang.language.interpreter.logging;
 
-import org.slf4j.event.Level;
+public final class SystemLogger implements Logger {
 
-public final class PandaMessengerMessage implements MessengerMessage {
+    private final Channel threshold;
 
-    private final Level level;
-    private final String message;
+    public SystemLogger() {
+        this(Channel.INFO);
+    }
 
-    public PandaMessengerMessage(Level level, String message) {
-        this.message = message;
-        this.level = level;
+    public SystemLogger(Channel threshold) {
+        this.threshold = threshold;
     }
 
     @Override
-    public String getContent() {
-        return message;
+    public void log(Channel channel, String message) {
+        if (channel.getPriority() >= threshold.getPriority()) {
+            System.out.println(message);
+        }
     }
 
     @Override
-    public Level getLevel() {
-        return level;
+    public void exception(Throwable throwable) {
+        throwable.printStackTrace(System.err);
     }
 
 }