JavadocLocationCheck.java

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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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package com.qulice.checkstyle;

import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;

/**
 * Checks that there is no empty line between a javadoc and it's subject.
 *
 * <p>You can't have empty lines between javadoc block and
 * a class/method/variable. They should stay together, always.
 *
 * @since 0.3
 */
public final class JavadocLocationCheck extends AbstractCheck {

    @Override
    public int[] getDefaultTokens() {
        return new int[] {
            TokenTypes.CLASS_DEF,
            TokenTypes.INTERFACE_DEF,
            TokenTypes.VARIABLE_DEF,
            TokenTypes.CTOR_DEF,
            TokenTypes.METHOD_DEF,
        };
    }

    @Override
    public int[] getAcceptableTokens() {
        return this.getDefaultTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return this.getDefaultTokens();
    }

    @Override
    public void visitToken(final DetailAST ast) {
        if (JavadocLocationCheck.isField(ast)) {
            final int current = ast.getLineNo();
            final int end = JavadocLocationCheck.findCommentEnd(
                this.getLines(), current
            );
            if (end > JavadocLocationCheck.getCommentMinimum(ast)) {
                this.report(current, end);
            }
        }
    }

    /**
     * Report empty lines between current and end line.
     * @param current Current line
     * @param end Final line
     */
    private void report(final int current, final int end) {
        final int diff = current - end;
        if (diff > 1) {
            for (int pos = 1; pos < diff; pos += 1) {
                this.log(
                    end + pos,
                    "Empty line between javadoc and subject"
                );
            }
        }
    }

    /**
     * Returns mimimum line number of the end of the comment.
     * @param node Node to be checked for Java docs.
     * @return Mimimum line number of the end of the comment.
     */
    private static int getCommentMinimum(final DetailAST node) {
        int minimum = 0;
        final DetailAST parent = node.getParent();
        if (null == parent) {
            if (!JavadocLocationCheck.isFirst(node)) {
                final DetailAST object = node
                    .getPreviousSibling()
                    .findFirstToken(TokenTypes.OBJBLOCK);
                // @checkstyle NestedIfDepth (1 line)
                if (object != null) {
                    minimum = object.getLastChild().getLineNo();
                }
            }
        } else {
            DetailAST previous = node.getPreviousSibling();
            if (null == previous) {
                previous = parent;
            }
            minimum = previous.getLineNo();
        }
        return minimum;
    }

    /**
     * Checks the specified node: is it first element or not.
     * @param node Node to be checked.
     * @return True if there are no any nodes before this one, else -
     *  {@code false}.
     */
    private static boolean isFirst(final DetailAST node) {
        final DetailAST previous = node.getPreviousSibling();
        return null == previous;
    }

    /**
     * Returns {@code TRUE} if a specified node is something that should have
     * a Javadoc, which includes classes, interface, class methods, and
     * class variables.
     * @param node Node to check
     * @return Is it a Javadoc-required entity?
     */
    private static boolean isField(final DetailAST node) {
        boolean yes = true;
        if (TokenTypes.VARIABLE_DEF == node.getType()) {
            yes = TokenTypes.OBJBLOCK == node.getParent().getType();
        }
        return yes;
    }

    /**
     * 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 JavadocLocationCheck.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 + 1;
                break;
            }
        }
        return found;
    }
}