com.qulice.checkstyle.DiamondOperatorCheck Maven / Gradle / Ivy
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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 if possible to use Diamond operator in generic instances creation.
*
* @since 0.17
*/
public final class DiamondOperatorCheck extends AbstractCheck {
@Override
public int[] getDefaultTokens() {
return new int[]{TokenTypes.VARIABLE_DEF};
}
@Override
public int[] getAcceptableTokens() {
return this.getDefaultTokens();
}
@Override
public int[] getRequiredTokens() {
return this.getDefaultTokens();
}
@Override
public void visitToken(final DetailAST node) {
final DetailAST generic = DiamondOperatorCheck
.findFirstChildNodeOfType(
node.findFirstToken(TokenTypes.TYPE), TokenTypes.TYPE_ARGUMENTS
);
final DetailAST assign = node.findFirstToken(TokenTypes.ASSIGN);
final DetailAST instance;
if (assign == null || generic == null) {
instance = null;
} else {
instance = assign.getFirstChild().getFirstChild();
}
if (instance != null && instance.getType() == TokenTypes.LITERAL_NEW
&& DiamondOperatorCheck.isNotObjectBlock(instance)
&& DiamondOperatorCheck.isNotArray(instance)) {
final DetailAST type =
DiamondOperatorCheck.findFirstChildNodeOfType(
instance, TokenTypes.TYPE_ARGUMENTS
);
if (generic.equalsTree(type)) {
log(type, "Use diamond operator");
}
}
}
/**
* Checks if node is not array.
*
* @param node Node
* @return True if not array
*/
private static boolean isNotArray(final DetailAST node) {
return node.findFirstToken(TokenTypes.ARRAY_DECLARATOR) == null;
}
/**
* Checks if node is object block.
*
* @param node Node
* @return True if not object block
*/
private static boolean isNotObjectBlock(final DetailAST node) {
return node.getLastChild().getType() != TokenTypes.OBJBLOCK;
}
/**
* Returns the first child node of a specified type.
*
* @param node AST subtree to process.
* @param type Type of token
* @return Child node of specified type
*/
private static DetailAST findFirstChildNodeOfType(
final DetailAST node, final int type
) {
DetailAST result = node.findFirstToken(type);
if (result == null) {
final DetailAST child = node.getFirstChild();
if (child != null) {
result = DiamondOperatorCheck
.findFirstChildNodeOfType(child, type);
}
}
return result;
}
}