////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2017 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.coding;
import java.util.HashSet;
import java.util.Locale;
import java.util.Objects;
import java.util.Set;
import java.util.regex.Pattern;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.Scope;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CheckUtils;
import com.puppycrawl.tools.checkstyle.utils.ScopeUtils;
/**
* Checks that a local variable or a parameter does not shadow
* a field that is defined in the same class.
*
* <p>An example of how to configure the check is:
* <pre>
* <module name="HiddenField"/>
* </pre>
*
* <p>An example of how to configure the check so that it checks variables but not
* parameters is:
* <pre>
* <module name="HiddenField">
* <property name="tokens" value="VARIABLE_DEF"/>
* </module>
* </pre>
*
* <p>An example of how to configure the check so that it ignores the parameter of
* a setter method is:
* <pre>
* <module name="HiddenField">
* <property name="ignoreSetter" value="true"/>
* </module>
* </pre>
*
* <p>A method is recognized as a setter if it is in the following form
* <pre>
* ${returnType} set${Name}(${anyType} ${name}) { ... }
* </pre>
* where ${anyType} is any primitive type, class or interface name;
* ${name} is name of the variable that is being set and ${Name} its
* capitalized form that appears in the method name. By default it is expected
* that setter returns void, i.e. ${returnType} is 'void'. For example
* <pre>
* void setTime(long time) { ... }
* </pre>
* Any other return types will not let method match a setter pattern. However,
* by setting <em>setterCanReturnItsClass</em> property to <em>true</em>
* definition of a setter is expanded, so that setter return type can also be
* a class in which setter is declared. For example
* <pre>
* class PageBuilder {
* PageBuilder setName(String name) { ... }
* }
* </pre>
* Such methods are known as chain-setters and a common when Builder-pattern
* is used. Property <em>setterCanReturnItsClass</em> has effect only if
* <em>ignoreSetter</em> is set to true.
*
* <p>An example of how to configure the check so that it ignores the parameter
* of either a setter that returns void or a chain-setter.
* <pre>
* <module name="HiddenField">
* <property name="ignoreSetter" value="true"/>
* <property name="setterCanReturnItsClass" value="true"/>
* </module>
* </pre>
*
* <p>An example of how to configure the check so that it ignores constructor
* parameters is:
* <pre>
* <module name="HiddenField">
* <property name="ignoreConstructorParameter" value="true"/>
* </module>
* </pre>
*
* <p>An example of how to configure the check so that it ignores variables and parameters
* named 'test':
* <pre>
* <module name="HiddenField">
* <property name="ignoreFormat" value="^test$"/>
* </module>
* </pre>
*
* <pre>
* {@code
* class SomeClass
* {
* private List<String> test;
*
* private void addTest(List<String> test) // no violation
* {
* this.test.addAll(test);
* }
*
* private void foo()
* {
* final List<String> test = new ArrayList<>(); // no violation
* ...
* }
* }
* }
* </pre>
*
* @author Dmitri Priimak
*/
public class HiddenFieldCheck
extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "hidden.field";
/** Stack of sets of field names,
* one for each class of a set of nested classes.
*/
private FieldFrame frame;
/** Pattern for names of variables and parameters to ignore. */
private Pattern ignoreFormat;
/** Controls whether to check the parameter of a property setter method. */
private boolean ignoreSetter;
/**
* If ignoreSetter is set to true then this variable controls what
* the setter method can return By default setter must return void.
* However, is this variable is set to true then setter can also
* return class in which is declared.
*/
private boolean setterCanReturnItsClass;
/** Controls whether to check the parameter of a constructor. */
private boolean ignoreConstructorParameter;
/** Controls whether to check the parameter of abstract methods. */
private boolean ignoreAbstractMethods;
@Override
public int[] getDefaultTokens() {
return getAcceptableTokens();
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.VARIABLE_DEF,
TokenTypes.PARAMETER_DEF,
TokenTypes.CLASS_DEF,
TokenTypes.ENUM_DEF,
TokenTypes.ENUM_CONSTANT_DEF,
TokenTypes.LAMBDA,
};
}
@Override
public int[] getRequiredTokens() {
return new int[] {
TokenTypes.CLASS_DEF,
TokenTypes.ENUM_DEF,
TokenTypes.ENUM_CONSTANT_DEF,
};
}
@Override
public void beginTree(DetailAST rootAST) {
frame = new FieldFrame(null, true, null);
}
@Override
public void visitToken(DetailAST ast) {
final int type = ast.getType();
switch (type) {
case TokenTypes.VARIABLE_DEF:
case TokenTypes.PARAMETER_DEF:
processVariable(ast);
break;
case TokenTypes.LAMBDA:
processLambda(ast);
break;
default:
visitOtherTokens(ast, type);
}
}
/**
* Process a lambda token.
* Checks whether a lambda parameter shadows a field.
* Note, that when parameter of lambda expression is untyped,
* ANTLR parses the parameter as an identifier.
* @param ast the lambda token.
*/
private void processLambda(DetailAST ast) {
final DetailAST firstChild = ast.getFirstChild();
if (firstChild.getType() == TokenTypes.IDENT) {
final String untypedLambdaParameterName = firstChild.getText();
if (isStaticOrInstanceField(firstChild, untypedLambdaParameterName)) {
log(firstChild, MSG_KEY, untypedLambdaParameterName);
}
}
else {
// Type of lambda parameter is not omitted.
processVariable(ast);
}
}
/**
* Called to process tokens other than {@link TokenTypes#VARIABLE_DEF}
* and {@link TokenTypes#PARAMETER_DEF}.
*
* @param ast token to process
* @param type type of the token
*/
private void visitOtherTokens(DetailAST ast, int type) {
//A more thorough check of enum constant class bodies is
//possible (checking for hidden fields against the enum
//class body in addition to enum constant class bodies)
//but not attempted as it seems out of the scope of this
//check.
final DetailAST typeMods = ast.findFirstToken(TokenTypes.MODIFIERS);
final boolean isStaticInnerType =
typeMods != null
&& typeMods.branchContains(TokenTypes.LITERAL_STATIC);
final String frameName;
if (type == TokenTypes.CLASS_DEF || type == TokenTypes.ENUM_DEF) {
frameName = ast.findFirstToken(TokenTypes.IDENT).getText();
}
else {
frameName = null;
}
final FieldFrame newFrame = new FieldFrame(frame, isStaticInnerType, frameName);
//add fields to container
final DetailAST objBlock = ast.findFirstToken(TokenTypes.OBJBLOCK);
// enum constants may not have bodies
if (objBlock != null) {
DetailAST child = objBlock.getFirstChild();
while (child != null) {
if (child.getType() == TokenTypes.VARIABLE_DEF) {
final String name =
child.findFirstToken(TokenTypes.IDENT).getText();
final DetailAST mods =
child.findFirstToken(TokenTypes.MODIFIERS);
if (mods.branchContains(TokenTypes.LITERAL_STATIC)) {
newFrame.addStaticField(name);
}
else {
newFrame.addInstanceField(name);
}
}
child = child.getNextSibling();
}
}
// push container
frame = newFrame;
}
@Override
public void leaveToken(DetailAST ast) {
if (ast.getType() == TokenTypes.CLASS_DEF
|| ast.getType() == TokenTypes.ENUM_DEF
|| ast.getType() == TokenTypes.ENUM_CONSTANT_DEF) {
//pop
frame = frame.getParent();
}
}
/**
* Process a variable token.
* Check whether a local variable or parameter shadows a field.
* Store a field for later comparison with local variables and parameters.
* @param ast the variable token.
*/
private void processVariable(DetailAST ast) {
if (!ScopeUtils.isInInterfaceOrAnnotationBlock(ast)
&& !CheckUtils.isReceiverParameter(ast)
&& (ScopeUtils.isLocalVariableDef(ast)
|| ast.getType() == TokenTypes.PARAMETER_DEF)) {
// local variable or parameter. Does it shadow a field?
final DetailAST nameAST = ast.findFirstToken(TokenTypes.IDENT);
final String name = nameAST.getText();
if ((isStaticFieldHiddenFromAnonymousClass(ast, name)
|| isStaticOrInstanceField(ast, name))
&& !isMatchingRegexp(name)
&& !isIgnoredParam(ast, name)) {
log(nameAST, MSG_KEY, name);
}
}
}
/**
* Checks whether a static field is hidden from closure.
* @param nameAST local variable or parameter.
* @param name field name.
* @return true if static field is hidden from closure.
*/
private boolean isStaticFieldHiddenFromAnonymousClass(DetailAST nameAST, String name) {
return isInStatic(nameAST)
&& frame.containsStaticField(name);
}
/**
* Checks whether method or constructor parameter is ignored.
* @param ast the parameter token.
* @param name the parameter name.
* @return true if parameter is ignored.
*/
private boolean isIgnoredParam(DetailAST ast, String name) {
return isIgnoredSetterParam(ast, name)
|| isIgnoredConstructorParam(ast)
|| isIgnoredParamOfAbstractMethod(ast);
}
/**
* Check for static or instance field.
* @param ast token
* @param name identifier of token
* @return true if static or instance field
*/
private boolean isStaticOrInstanceField(DetailAST ast, String name) {
return frame.containsStaticField(name)
|| !isInStatic(ast) && frame.containsInstanceField(name);
}
/**
* Check name by regExp.
* @param name string value to check
* @return true is regexp is matching
*/
private boolean isMatchingRegexp(String name) {
return ignoreFormat != null && ignoreFormat.matcher(name).find();
}
/**
* Determines whether an AST node is in a static method or static
* initializer.
* @param ast the node to check.
* @return true if ast is in a static method or a static block;
*/
private static boolean isInStatic(DetailAST ast) {
DetailAST parent = ast.getParent();
boolean inStatic = false;
while (parent != null && !inStatic) {
if (parent.getType() == TokenTypes.STATIC_INIT) {
inStatic = true;
}
else if (parent.getType() == TokenTypes.METHOD_DEF
&& !ScopeUtils.isInScope(parent, Scope.ANONINNER)
|| parent.getType() == TokenTypes.VARIABLE_DEF) {
final DetailAST mods =
parent.findFirstToken(TokenTypes.MODIFIERS);
inStatic = mods.branchContains(TokenTypes.LITERAL_STATIC);
break;
}
else {
parent = parent.getParent();
}
}
return inStatic;
}
/**
* Decides whether to ignore an AST node that is the parameter of a
* setter method, where the property setter method for field 'xyz' has
* name 'setXyz', one parameter named 'xyz', and return type void
* (default behavior) or return type is name of the class in which
* such method is declared (allowed only if
* {@link #setSetterCanReturnItsClass(boolean)} is called with
* value <em>true</em>)
*
* @param ast the AST to check.
* @param name the name of ast.
* @return true if ast should be ignored because check property
* ignoreSetter is true and ast is the parameter of a setter method.
*/
private boolean isIgnoredSetterParam(DetailAST ast, String name) {
if (ignoreSetter && ast.getType() == TokenTypes.PARAMETER_DEF) {
final DetailAST parametersAST = ast.getParent();
final DetailAST methodAST = parametersAST.getParent();
if (parametersAST.getChildCount() == 1
&& methodAST.getType() == TokenTypes.METHOD_DEF
&& isSetterMethod(methodAST, name)) {
return true;
}
}
return false;
}
/**
* Determine if a specific method identified by methodAST and a single
* variable name aName is a setter. This recognition partially depends
* on mSetterCanReturnItsClass property.
*
* @param aMethodAST AST corresponding to a method call
* @param aName name of single parameter of this method.
* @return true of false indicating of method is a setter or not.
*/
private boolean isSetterMethod(DetailAST aMethodAST, String aName) {
final String methodName =
aMethodAST.findFirstToken(TokenTypes.IDENT).getText();
boolean isSetterMethod = false;
if (("set" + capitalize(aName)).equals(methodName)) {
// method name did match set${Name}(${anyType} ${aName})
// where ${Name} is capitalized version of ${aName}
// therefore this method is potentially a setter
final DetailAST typeAST = aMethodAST.findFirstToken(TokenTypes.TYPE);
final String returnType = typeAST.getFirstChild().getText();
if (typeAST.branchContains(TokenTypes.LITERAL_VOID)
|| setterCanReturnItsClass && frame.isEmbeddedIn(returnType)) {
// this method has signature
//
// void set${Name}(${anyType} ${name})
//
// and therefore considered to be a setter
//
// or
//
// return type is not void, but it is the same as the class
// where method is declared and and mSetterCanReturnItsClass
// is set to true
isSetterMethod = true;
}
}
return isSetterMethod;
}
/**
* Capitalizes a given property name the way we expect to see it in
* a setter name.
* @param name a property name
* @return capitalized property name
*/
private static String capitalize(final String name) {
String setterName = name;
// we should not capitalize the first character if the second
// one is a capital one, since according to JavaBeans spec
// setXYzz() is a setter for XYzz property, not for xYzz one.
if (name.length() == 1 || !Character.isUpperCase(name.charAt(1))) {
setterName = name.substring(0, 1).toUpperCase(Locale.ENGLISH) + name.substring(1);
}
return setterName;
}
/**
* Decides whether to ignore an AST node that is the parameter of a
* constructor.
* @param ast the AST to check.
* @return true if ast should be ignored because check property
* ignoreConstructorParameter is true and ast is a constructor parameter.
*/
private boolean isIgnoredConstructorParam(DetailAST ast) {
boolean result = false;
if (ignoreConstructorParameter
&& ast.getType() == TokenTypes.PARAMETER_DEF) {
final DetailAST parametersAST = ast.getParent();
final DetailAST constructorAST = parametersAST.getParent();
result = constructorAST.getType() == TokenTypes.CTOR_DEF;
}
return result;
}
/**
* Decides whether to ignore an AST node that is the parameter of an
* abstract method.
* @param ast the AST to check.
* @return true if ast should be ignored because check property
* ignoreAbstractMethods is true and ast is a parameter of abstract methods.
*/
private boolean isIgnoredParamOfAbstractMethod(DetailAST ast) {
boolean result = false;
if (ignoreAbstractMethods
&& ast.getType() == TokenTypes.PARAMETER_DEF) {
final DetailAST method = ast.getParent().getParent();
if (method.getType() == TokenTypes.METHOD_DEF) {
final DetailAST mods = method.findFirstToken(TokenTypes.MODIFIERS);
result = mods.branchContains(TokenTypes.ABSTRACT);
}
}
return result;
}
/**
* Set the ignore format for the specified regular expression.
* @param pattern a pattern.
*/
public void setIgnoreFormat(Pattern pattern) {
ignoreFormat = pattern;
}
/**
* Set whether to ignore the parameter of a property setter method.
* @param ignoreSetter decide whether to ignore the parameter of
* a property setter method.
*/
public void setIgnoreSetter(boolean ignoreSetter) {
this.ignoreSetter = ignoreSetter;
}
/**
* Controls if setter can return only void (default behavior) or it
* can also return class in which it is declared.
*
* @param aSetterCanReturnItsClass if true then setter can return
* either void or class in which it is declared. If false then
* in order to be recognized as setter method (otherwise
* already recognized as a setter) must return void. Later is
* the default behavior.
*/
public void setSetterCanReturnItsClass(
boolean aSetterCanReturnItsClass) {
setterCanReturnItsClass = aSetterCanReturnItsClass;
}
/**
* Set whether to ignore constructor parameters.
* @param ignoreConstructorParameter decide whether to ignore
* constructor parameters.
*/
public void setIgnoreConstructorParameter(
boolean ignoreConstructorParameter) {
this.ignoreConstructorParameter = ignoreConstructorParameter;
}
/**
* Set whether to ignore parameters of abstract methods.
* @param ignoreAbstractMethods decide whether to ignore
* parameters of abstract methods.
*/
public void setIgnoreAbstractMethods(
boolean ignoreAbstractMethods) {
this.ignoreAbstractMethods = ignoreAbstractMethods;
}
/**
* Holds the names of static and instance fields of a type.
* @author Rick Giles
*/
private static class FieldFrame {
/** Name of the frame, such name of the class or enum declaration. */
private final String frameName;
/** Is this a static inner type. */
private final boolean staticType;
/** Parent frame. */
private final FieldFrame parent;
/** Set of instance field names. */
private final Set<String> instanceFields = new HashSet<>();
/** Set of static field names. */
private final Set<String> staticFields = new HashSet<>();
/**
* Creates new frame.
* @param parent parent frame.
* @param staticType is this a static inner type (class or enum).
* @param frameName name associated with the frame, which can be a
*/
FieldFrame(FieldFrame parent, boolean staticType, String frameName) {
this.parent = parent;
this.staticType = staticType;
this.frameName = frameName;
}
/**
* Adds an instance field to this FieldFrame.
* @param field the name of the instance field.
*/
public void addInstanceField(String field) {
instanceFields.add(field);
}
/**
* Adds a static field to this FieldFrame.
* @param field the name of the instance field.
*/
public void addStaticField(String field) {
staticFields.add(field);
}
/**
* Determines whether this FieldFrame contains an instance field.
* @param field the field to check.
* @return true if this FieldFrame contains instance field field.
*/
public boolean containsInstanceField(String field) {
return instanceFields.contains(field)
|| parent != null
&& !staticType
&& parent.containsInstanceField(field);
}
/**
* Determines whether this FieldFrame contains a static field.
* @param field the field to check.
* @return true if this FieldFrame contains static field field.
*/
public boolean containsStaticField(String field) {
return staticFields.contains(field)
|| parent != null
&& parent.containsStaticField(field);
}
/**
* Getter for parent frame.
* @return parent frame.
*/
public FieldFrame getParent() {
return parent;
}
/**
* Check if current frame is embedded in class or enum with
* specific name.
*
* @param classOrEnumName name of class or enum that we are looking
* for in the chain of field frames.
*
* @return true if current frame is embedded in class or enum
* with name classOrNameName
*/
private boolean isEmbeddedIn(String classOrEnumName) {
FieldFrame currentFrame = this;
while (currentFrame != null) {
if (Objects.equals(currentFrame.frameName, classOrEnumName)) {
return true;
}
currentFrame = currentFrame.parent;
}
return false;
}
}
}