com.puppycrawl.tools.checkstyle.utils

Class XpathUtil

java.lang.Object

com.puppycrawl.tools.checkstyle.utils.XpathUtil

public final class XpathUtil
extends java.lang.Object

Contains utility methods for xpath.

Field Summary

Fields

Modifier and Type	Field and Description
private static java.util.regex.Pattern	CARRIAGE_RETURN_TO_TAG This regexp is used to convert carriage return to carriage-return tag.
private static java.lang.String	DELIMITER Delimiter to separate xpath results.
private static java.util.regex.Pattern	NEWLINE_TO_TAG This regexp is used to convert new line to newline tag.
private static java.util.Set<java.lang.Integer>	TOKEN_TYPES_WITH_TEXT_ATTRIBUTE List of token types which support text attribute.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	XpathUtil() Stop instances being created.

Method Summary

Modifier and Type	Method and Description
static java.util.List<AbstractNode>	createChildren(AbstractNode root, AbstractNode parent, DetailAST firstChild) Iterates siblings of the given node and creates new Xpath-nodes.
static java.lang.String	getTextAttributeValue(DetailAST ast) Returns content of the text attribute of the ast element.
static java.lang.String	printXpathBranch(java.lang.String xpath, java.io.File file) Returns xpath query results on file as string.
static boolean	supportsTextAttribute(DetailAST ast) Checks, if specified node can have @text attribute.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TOKEN_TYPES_WITH_TEXT_ATTRIBUTE

private static final java.util.Set<java.lang.Integer> TOKEN_TYPES_WITH_TEXT_ATTRIBUTE

List of token types which support text attribute. These token types were selected based on analysis that all others do not match required criteria - text attribute of the token must be useful and help to retrieve more precise results. There are three types of AST tokens: 1. Tokens for which the texts are equal to the name of the token. Or in other words, nodes for which the following expression is always true:

     detailAst.getText().equals(TokenUtil.getTokenName(detailAst.getType()))
 

For example:

     //MODIFIERS[@text='MODIFIERS']
     //OBJBLOCK[@text='OBJBLOCK']
 

These tokens do not match required criteria because their texts do not carry any additional information, they do not affect the xpath requests and do not help to get more accurate results. The texts of these nodes are useless. No matter what code you analyze, these texts are always the same. In addition, they make xpath queries more complex, less readable and verbose. 2. Tokens for which the texts differ from token names, but texts are always constant. For example:

     //LITERAL_VOID[@text='void']
     //RCURLY[@text='}']
 

These tokens are not used for the same reasons as were described in the previous part. 3. Tokens for which texts are not constant. The texts of these nodes are closely related to a concrete class, method, variable and so on. For example:

     String greeting = "HelloWorld";
     //STRING_LITERAL[@text='HelloWorld']
 

     int year = 2017;
     //NUM_INT[@text=2017]
 

     int age = 23;
     //NUM_INT[@text=23]
 

As you can see same NUM_INT token type can have different texts, depending on context.

     public class MyClass {}
     //IDENT[@text='MyClass']
 

Only these tokens support text attribute because they make our xpath queries more accurate. These token types are listed below.

NEWLINE_TO_TAG

private static final java.util.regex.Pattern NEWLINE_TO_TAG

This regexp is used to convert new line to newline tag.

CARRIAGE_RETURN_TO_TAG

private static final java.util.regex.Pattern CARRIAGE_RETURN_TO_TAG

This regexp is used to convert carriage return to carriage-return tag.

DELIMITER

private static final java.lang.String DELIMITER

Delimiter to separate xpath results.

Constructor Detail

XpathUtil

private XpathUtil()

Stop instances being created.

Method Detail

createChildren

public static java.util.List<AbstractNode> createChildren(AbstractNode root,
                                                          AbstractNode parent,
                                                          DetailAST firstChild)

Iterates siblings of the given node and creates new Xpath-nodes.

Parameters:

root - the root node

parent - the parent node

firstChild - the first DetailAST

Returns:

children list

supportsTextAttribute

public static boolean supportsTextAttribute(DetailAST ast)

Checks, if specified node can have @text attribute.

Parameters:

ast - DetailAst element

Returns:

true if element supports @text attribute, false otherwise

getTextAttributeValue

public static java.lang.String getTextAttributeValue(DetailAST ast)

Returns content of the text attribute of the ast element.

Parameters:

ast - DetailAst element

Returns:

text attribute of the ast element

printXpathBranch

public static java.lang.String printXpathBranch(java.lang.String xpath,
                                                java.io.File file)
                                         throws CheckstyleException,
                                                java.io.IOException

Returns xpath query results on file as string.

Parameters:

xpath - query to evaluate

file - file to run on

Returns:

all results as string separated by delimiter

Throws:

CheckstyleException - if some parsing error happens

java.io.IOException - if an error occurs