Add CustomColorConverter, re #10

Author: safris

src/main/java/org/libj/logging/CustomColorConverter.java

@@ -0,0 +1,178 @@
+/* Copyright (c) 2025 LibJ
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * You should have received a copy of The MIT License (MIT) along with this
+ * program. If not, see <http://opensource.org/licenses/MIT/>.
+ */
+
+package org.libj.logging;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.Context;
+import ch.qos.logback.core.pattern.CompositeConverter;
+
+/**
+ * A {@link CompositeConverter} that allows for the conversion of a log pattern to be displayed in colors configurable via
+ * {@code <variable>} tags.
+ * <p>
+ * Example:
+ *
+ * <pre>
+ * &lt;variable scope="context" name="cc:com.example.foo" value="[38;5;21m"/>
+ * &lt;variable scope="context" name="cc:com.example.bar" value="[38;5;219m"/>
+ * &lt;conversionRule conversionWord="customColor" converterClass="org.libj.logging.CustomColorConverter"/>
+ * &lt;appender>
+ *   &lt;encoder>
+ *      &lt;pattern>%date{yyyy-MM-dd HH:mm:ss.SSS} %customColor(%logger){loggerName,cc} %color(%level %msg%n)&lt;/pattern>
+ *   &lt;/encoder>
+ * &lt;/appender>
+ * </pre>
+ * <p>
+ * In the provided example, two options are specified:
+ * <ol>
+ * <li>loggerName: The event property to match. Can be one of {level, loggerName, marker, message, threadName}.</li>
+ * <li>cc: The variable prefix to be referenced when parsing defined variables.</li>
+ * </ol>
+ * <p>
+ * The following two variables are also defined:
+ * <ol>
+ * <li>cc:com.example.foo: The key with "cc:" prefix to be matched resulting in the color specified as the value when matching
+ * "com.example.foo" as the "loggerName".</li>
+ * <li>cc:com.example.bar: The key with "cc:" prefix to be matched resulting in the color specified as the value when matching
+ * "com.example.bar" as the "loggerName"</li>
+ * </ol>
+ */
+public class CustomColorConverter extends CompositeConverter<ILoggingEvent> {
+  private static final String esc = String.valueOf((char)0x1b);
+
+  private final ArrayList<String> keys = new ArrayList<>();
+  private final ArrayList<String> values = new ArrayList<>();
+
+  private enum Property {
+    LEVEL("level") {
+      @Override
+      String getValue(final ILoggingEvent event) {
+        return event.getLevel().toString();
+      }
+    },
+    LOGGER_NAME("loggerName") {
+      @Override
+      String getValue(final ILoggingEvent event) {
+        return event.getLoggerName();
+      }
+    },
+    MARKER("marker") {
+      @Override
+      String getValue(final ILoggingEvent event) {
+        return event.getMarker().toString();
+      }
+    },
+    MESSAGE("message") {
+      @Override
+      String getValue(final ILoggingEvent event) {
+        return event.getMessage();
+      }
+    },
+    THREAD_NAME("threadName") {
+      @Override
+      String getValue(final ILoggingEvent event) {
+        return event.getThreadName();
+      }
+    };
+
+    private final String name;
+
+    private Property(final String name) {
+      this.name = name;
+    }
+
+    abstract String getValue(ILoggingEvent event);
+
+    @Override
+    public String toString() {
+      return name;
+    }
+
+    private static Property fromString(final String s) {
+      for (final Property property : values()) // [A]
+        if (property.name.equals(s))
+          return property;
+
+      return null;
+    }
+  }
+
+  private Property property;
+
+  @Override
+  public void start() {
+    final Context context = getContext();
+    if (context == null)
+      return;
+
+    final List<String> optionList = super.getOptionList();
+    if (optionList == null || optionList.size() != 2) {
+      addError("Options {<EVENT_PROPERTY>,<VARIABLE_PREFIX>} are not specified for conversionRule with class " + getClass().getName());
+      return;
+    }
+
+    final String propertyName = optionList.get(0);
+    this.property = Property.fromString(propertyName);
+    if (this.property == null) {
+      addError("EVENT_PROPERTY (" + propertyName + ") does not match: " + Arrays.toString(Property.values()));
+      return;
+    }
+
+    final String prefix = optionList.get(1) + ":";
+    final int len = prefix.length();
+    for (final Map.Entry<String,String> entry : context.getCopyOfPropertyMap().entrySet()) {
+      if (entry.getKey().startsWith(prefix)) {
+        final String key = entry.getKey().substring(len);
+        keys.add(key);
+        values.add(entry.getValue());
+      }
+    }
+
+    super.start();
+  }
+
+  private String match(final ILoggingEvent event) {
+    final String loggerName = event.getLoggerName();
+    final int length = loggerName.length();
+    for (int i = 0, i$ = keys.size(); i < i$; ++i) { // [RA]
+      final String key = keys.get(i);
+      final int len = key.length();
+      final String value = values.get(i);
+      if (len == length) {
+        if (loggerName.equals(value))
+          return value;
+      }
+      else if (len < length) {
+        if (loggerName.startsWith(key) && loggerName.charAt(len) == '.')
+          return value;
+      }
+    }
+
+    return null;
+  }
+
+  @Override
+  protected String transform(final ILoggingEvent event, final String in) {
+    final String value = match(event);
+    return value != null ? esc + value + in + esc + "[0m" : in;
+  }
+}