BracketsStructureCheck.java

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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 node/closing brackets to be the last symbols on the line.
 *
 * <p>This is how a correct bracket structure should look like:
 *
 * <pre>
 * String text = String.format(
 *   "some text: %s",
 *   new Foo().with(
 *     "abc",
 *     "foo"
 *   )
 * );
 * </pre>
 *
 * <p>The motivation for such formatting is simple - we want to see the entire
 * block as fast as possible. When you look at a block of code you should be
 * able to see where it starts and where it ends. In exactly the same way
 * we organize curled brackets.
 *
 * <p>In other words, when you open a bracket and can't close it at the same
 * line - you should leave it as the last symbol at this line.
 *
 * @since 0.3
 */
public final class BracketsStructureCheck extends AbstractCheck {

    @Override
    public int[] getDefaultTokens() {
        return new int[] {
            TokenTypes.LITERAL_NEW,
            TokenTypes.METHOD_CALL,
        };
    }

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

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

    @Override
    public void visitToken(final DetailAST ast) {
        if (ast.getType() == TokenTypes.METHOD_CALL
            || ast.getType() == TokenTypes.LITERAL_NEW) {
            this.checkParams(ast);
        } else {
            final DetailAST brackets = ast.findFirstToken(TokenTypes.LPAREN);
            if (brackets != null) {
                this.checkParams(brackets);
            }
        }
    }

    /**
     * Checks params statement to satisfy the rule.
     * @param node Tree node, containing method call statement.
     */
    private void checkParams(final DetailAST node) {
        final DetailAST closing = node.findFirstToken(TokenTypes.RPAREN);
        if (closing != null) {
            this.checkLines(node, node.getLineNo(), closing.getLineNo());
        }
    }

    /**
     * Checks params statement to satisfy the rule.
     * @param node Tree node, containing method call statement.
     * @param start First line
     * @param end Final line
     */
    private void checkLines(final DetailAST node, final int start,
        final int end) {
        if (start != end) {
            final DetailAST elist = node.findFirstToken(TokenTypes.ELIST);
            final int pline = elist.getLineNo();
            if (pline == start) {
                this.log(pline, "Parameters should start on a new line");
            }
            this.checkExpressionList(elist, end);
        }
    }

    /**
     * Checks expression list if closing bracket is on new line.
     * @param elist Tree node, containing expression list
     * @param end Final line
     */
    private void checkExpressionList(final DetailAST elist, final int end) {
        if (elist.getChildCount() > 0) {
            final DetailAST last = elist.getLastChild();
            final int lline = last.getLineNo();
            if (lline == end) {
                this.log(lline, "Closing bracket should be on a new line");
            }
        }
    }

}