#656 Prohibit empty line at the start and at the end of javadoc

qulice-checkstyle/src/main/java/com/qulice/checkstyle/JavadocEmptyLineCheck.java

@@ -0,0 +1,136 @@
+/**
+ * Copyright (c) 2011-2016, Qulice.com
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met: 1) Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer. 2) Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution. 3) Neither the name of the Qulice.com nor
+ * the names of its contributors may be used to endorse or promote
+ * products derived from this software without specific prior written
+ * permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
+ * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.qulice.checkstyle;
+
+import com.puppycrawl.tools.checkstyle.api.Check;
+import com.puppycrawl.tools.checkstyle.api.DetailAST;
+import com.puppycrawl.tools.checkstyle.api.TokenTypes;
+
+/**
+ * Check for empty line at the start and at the end of javadoc.
+ * @author Denys Skalenko (d.skalenko@gmail.com)
+ * @version $Id$
+ * @since 0.17
+ */
+public final class JavadocEmptyLineCheck extends Check {
+
+    @Override
+    public int[] getDefaultTokens() {
+        return new int[] {
+            TokenTypes.CLASS_DEF,
+            TokenTypes.INTERFACE_DEF,
+            TokenTypes.VARIABLE_DEF,
+            TokenTypes.CTOR_DEF,
+            TokenTypes.METHOD_DEF,
+        };
+    }
+
+    @Override
+    public void visitToken(final DetailAST ast) {
+        final String[] lines = this.getLines();
+        final int start = ast.getLineNo();
+        final int cstart =
+            JavadocEmptyLineCheck.findCommentStart(lines, start) + 1;
+        if (JavadocEmptyLineCheck.isNodeHasJavaDoc(ast, cstart)) {
+            if (JavadocEmptyLineCheck.isJavadocLineEmpty(lines[cstart])) {
+                this.log(cstart + 1, "Empty javadoc line at the beginning");
+            }
+            final int cend =
+                JavadocEmptyLineCheck.findCommentEnd(lines, start) - 1;
+            if (JavadocEmptyLineCheck.isJavadocLineEmpty(lines[cend])) {
+                this.log(cend + 1, "Empty javadoc line at the end");
+            }
+        }
+    }
+
+    /**
+     * Check if javadoc Line Empty.
+     * @param line Java doc line
+     * @return Is Javadoc Line Empty
+     */
+    private static boolean isJavadocLineEmpty(final String line) {
+        return null != line && "*".equals(line.trim());
+    }
+
+    /**
+     * Check if node has java doc.
+     * @param node Node to be checked for Java docs.
+     * @param start Line number where comment starts.
+     * @return Is node has java doc
+     */
+    private static boolean isNodeHasJavaDoc(final DetailAST node,
+        final int start) {
+        int cprevious = 0;
+        final DetailAST previous = node.getPreviousSibling();
+        if (null != previous) {
+            cprevious = previous.getLineNo();
+        }
+        return start > cprevious;
+    }
+
+    /**
+     * Find javadoc starting comment.
+     * @param lines List of lines to check.
+     * @param start Start searching from this line number.
+     * @return Line number with found starting comment or -1 otherwise.
+     */
+    private static int findCommentStart(final String[] lines, final int start) {
+        return JavadocEmptyLineCheck.findTrimmedTextUp(lines, start, "/**");
+    }
+
+    /**
+     * Find javadoc ending comment.
+     * @param lines List of lines to check.
+     * @param start Start searching from this line number.
+     * @return Line number with found ending comment, or -1 if it wasn't found.
+     */
+    private static int findCommentEnd(final String[] lines, final int start) {
+        return JavadocEmptyLineCheck.findTrimmedTextUp(lines, start, "*/");
+    }
+
+    /**
+     * Find a text in lines, by going up.
+     * @param lines List of lines to check.
+     * @param start Start searching from this line number.
+     * @param text Text to find.
+     * @return Line number with found text, or -1 if it wasn't found.
+     */
+    private static int findTrimmedTextUp(final String[] lines,
+        final int start, final String text) {
+        int found = -1;
+        for (int pos = start - 1; pos >= 0; pos -= 1) {
+            if (lines[pos].trim().equals(text)) {
+                found = pos;
+                break;
+            }
+        }
+        return found;
+    }
+}

qulice-checkstyle/src/test/resources/com/qulice/checkstyle/ChecksTest/JavadocEmptyLineCheck/Invalid.java

@@ -0,0 +1,72 @@
+/**
+ *
+ * This is not a real Java class. It won't be compiled ever. It is used
+ * only as a text resource in integration.ChecksIT.
+ */
+public final class Invalid {
+
+
+	private int x = 0;
+
+	/**
+	 *
+	 * empty javadoc line at the beginning
+	 */
+	private int y = 0;
+
+	/**
+	 * empty javadoc line at the end
+	 *
+	 */
+	private int z = 0;
+
+	/**
+	 *
+	 * empty javadoc line at the beginning
+	 */
+	public Invalid() {}
+
+	/**
+	 * empty javadoc line at the end
+	 *
+	 */
+	public void method() {
+	}
+
+	/**
+	 *
+	 * empty javadoc line at the beginning
+	 */
+	public void method2() {
+	}
+
+	/**
+	 *
+	 * empty javadoc line at the beginning
+	 */
+	public void method3() {
+	}
+
+	public void method4() {
+	}
+}
+/**
+ * This is not a real Java class. It won't be compiled ever. It is used
+ * only as a text resource in integration.ChecksIT.
+ *
+ */
+interface I1 {
+	public void method3() {
+	}
+
+	/**
+	 *
+	 * Integer variable.
+	 */
+	private int x = 0;
+
+}
+
+interface I2 {
+
+}

qulice-checkstyle/src/test/resources/com/qulice/checkstyle/ChecksTest/JavadocEmptyLineCheck/Valid.java

@@ -0,0 +1,63 @@
+/**
+ * This is not a real Java class. It won't be compiled ever. It is used
+ * only as a text resource in integration.ChecksIT.
+ */
+public final class Valid {
+
+
+	private int x = 0;
+
+	/**
+	 * empty javadoc line at the beginning
+	 */
+	private int y = 0;
+
+	/**
+	 * empty javadoc line at the end
+	 */
+	private int z = 0;
+
+	/**
+	 * empty javadoc line at the beginning
+	 */
+	public Valid() {}
+
+	/**
+	 * empty javadoc line at the end
+	 */
+	public void method() {
+	}
+
+	/**
+	 * empty javadoc line at the beginning
+	 */
+	public void method2() {
+	}
+
+	/**
+	 * empty javadoc line at the beginning
+	 */
+	public void method3() {
+	}
+
+	public void method4() {
+	}
+}
+/**
+ * This is not a real Java class. It won't be compiled ever. It is used
+ * only as a text resource in integration.ChecksIT.
+ */
+interface I1 {
+	public void method3() {
+	}
+
+	/**
+	 * Integer variable.
+	 */
+	private int x = 0;
+
+}
+
+interface I2 {
+
+}

qulice-checkstyle/src/test/resources/com/qulice/checkstyle/ChecksTest/JavadocEmptyLineCheck/config.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+		"-//Puppy Crawl//DTD Check Configuration 1.2//EN"
+		"http://www.puppycrawl.com/dtds/configuration_1_2.dtd">
+<!--
+ * This is not a real Checkstyle config. It is used
+ * only as a text resource in integration.ChecksIT.
+ -->
+<module name="Checker">
+	<module name="TreeWalker">
+		<module name="com.qulice.checkstyle.JavadocEmptyLineCheck"/>
+	</module>
+</module>

qulice-checkstyle/src/test/resources/com/qulice/checkstyle/ChecksTest/JavadocEmptyLineCheck/violations.txt

@@ -0,0 +1,9 @@
+2:Empty javadoc line at the beginning
+12:Empty javadoc line at the beginning
+19:Empty javadoc line at the end
+24:Empty javadoc line at the beginning
+31:Empty javadoc line at the end
+37:Empty javadoc line at the beginning
+44:Empty javadoc line at the beginning
+56:Empty javadoc line at the end
+63:Empty javadoc line at the beginning