feat(#3332): fix all the code offences

eo-parser/src/main/java/org/eolang/parser/ParsingErrors.java

@@ -83,6 +83,10 @@ public void syntaxError(
         final String msg,
         final RecognitionException error
     ) {
+        // @checkstyle MethodBodyCommentsCheck (20 lines)
+        // @todo #3332:30min Add more specific error messages.
+        //  Currently we write just "error: no viable alternative at input" for all errors.
+        //  It's better to use {@link #recognizer} to get more specific error messages.
         if (error instanceof NoViableAltException) {
             final Token token = (Token) symbol;
             this.errors.add(

eo-parser/src/main/java/org/eolang/parser/UnderlinedMessage.java

@@ -25,18 +25,54 @@
 
 import java.util.Collections;
 
+/**
+ * Underlined message.
+ * For example, if you have a message "Problem is here" and you want to underline
+ * the word "is", you can create an instance of this class with the following
+ * parameters: origin="Problem is here", from=8, length=2.
+ * The result will be:
+ * {@code
+ * Problem is here
+ *         ^^
+ * }
+ * @since 0.50
+ * @todo #3332:30min Add more decorators for the error message.
+ *  For example, {@link ParsingErrors} currently contains logic related to the message formatting.
+ *  It's better to create a separate class for this purpose.
+ */
 final class UnderlinedMessage {
 
+    /**
+     * The message.
+     */
     private final String origin;
+
+    /**
+     * The position from which to start underlining.
+     */
     private final int from;
+
+    /**
+     * The length of the underline.
+     */
     private final int length;
 
+    /**
+     * Ctor.
+     * @param origin The message.
+     * @param from The position from which to start underlining.
+     * @param length The length of the underline.
+     */
     UnderlinedMessage(final String origin, final int from, final int length) {
         this.origin = origin;
         this.from = from;
         this.length = length;
     }
 
+    /**
+     * Formatted message.
+     * @return The formatted message.
+     */
     String formatted() {
         return String.format(
             "%s\n%s",
@@ -45,23 +81,33 @@ String formatted() {
         );
     }
 
+    /**
+     * Underline.
+     * @return The underlined string.
+     */
     private String underline() {
         final String result;
         if (this.origin.isEmpty() || this.length <= 0 || this.from >= this.origin.length()) {
             result = "";
         } else if (this.from < 0) {
-            result = this.repeat("^", this.origin.length());
+            result = UnderlinedMessage.repeat("^", this.origin.length());
         } else {
             result = String.format(
                 "%s%s",
-                this.repeat(" ", this.from),
-                this.repeat("^", Math.min(this.length, this.origin.length()))
+                UnderlinedMessage.repeat(" ", this.from),
+                UnderlinedMessage.repeat("^", Math.min(this.length, this.origin.length()))
             );
         }
         return result;
     }
 
-    private String repeat(final String symbol, final int n) {
-        return String.join("", Collections.nCopies(n, symbol));
+    /**
+     * Repeat a symbol n times.
+     * @param symbol The symbol.
+     * @param times The number of times to repeat the symbol.
+     * @return The repeated symbol.
+     */
+    private static String repeat(final String symbol, final int times) {
+        return String.join("", Collections.nCopies(times, symbol));
     }
 }

eo-parser/src/test/java/org/eolang/parser/UnderlinedMessageTest.java

@@ -1,3 +1,26 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016-2024 Objectionary.com
+ *
+ * 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.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
 package org.eolang.parser;
 
 import java.util.stream.Stream;
@@ -10,7 +33,9 @@
 /**
  * Test case for {@link UnderlinedMessage}.
  * @since 0.1
+ * @checkstyle ParameterNumberCheck (500 lines)
  */
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 final class UnderlinedMessageTest {
 
     @ParameterizedTest
@@ -47,5 +72,4 @@ static Stream<Arguments> examples() {
             Arguments.of("", 1, 10, "\n")
         );
     }
-
-}
+}