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ImportOrderCheck.java
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ImportOrderCheck.java
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////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2016 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.imports;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.beanutils.ConversionException;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.FullIdent;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
/**
* <ul>
* <li>groups imports: ensures that groups of imports come in a specific order
* (e.g., java. comes first, javax. comes second, then everything else)</li>
* <li>adds a separation between groups : ensures that a blank line sit between
* each group</li>
* <li>sorts imports inside each group: ensures that imports within each group
* are in lexicographic order</li>
* <li>sorts according to case: ensures that the comparison between import is
* case sensitive</li>
* <li>groups static imports: ensures that static imports are at the top (or the
* bottom) of all the imports, or above (or under) each group, or are treated
* like non static imports (@see {@link ImportOrderOption}</li>
* </ul>
*
* <pre>
* Properties:
* </pre>
* <table summary="Properties" border="1">
* <tr><th>name</th><th>Description</th><th>type</th><th>default value</th></tr>
* <tr><td>option</td><td>policy on the relative order between regular imports and static
* imports</td><td>{@link ImportOrderOption}</td><td>under</td></tr>
* <tr><td>groups</td><td>list of imports groups (every group identified either by a common
* prefix string, or by a regular expression enclosed in forward slashes (e.g. /regexp/)</td>
* <td>list of strings</td><td>empty list</td></tr>
* <tr><td>ordered</td><td>whether imports within group should be sorted</td>
* <td>Boolean</td><td>true</td></tr>
* <tr><td>separated</td><td>whether imports groups should be separated by, at least,
* one blank line</td><td>Boolean</td><td>false</td></tr>
* <tr><td>caseSensitive</td><td>whether string comparison should be case sensitive or not.
* Case sensitive sorting is in ASCII sort order</td><td>Boolean</td><td>true</td></tr>
* <tr><td>sortStaticImportsAlphabetically</td><td>whether static imports grouped by top or
* bottom option are sorted alphabetically or not</td><td>Boolean</td><td>false</td></tr>
* <tr><td>useContainerOrderingForStatic</td><td>whether to use container ordering
* (Eclipse IDE term) for static imports or not</td><td>Boolean</td><td>false</td></tr>
* </table>
*
* <p>
* Example:
* </p>
* <p>To configure the check so that it matches default Eclipse formatter configuration
* (tested on Kepler, Luna and Mars):</p>
* <ul>
* <li>group of static imports is on the top</li>
* <li>groups of non-static imports: "java" then "javax"
* packages first, then "org" and then all other imports</li>
* <li>imports will be sorted in the groups</li>
* <li>groups are separated by, at least, one blank line</li>
* </ul>
*
* <pre>
* <module name="ImportOrder">
* <property name="groups" value="/^javax?\./,org"/>
* <property name="ordered" value="true"/>
* <property name="separated" value="true"/>
* <property name="option" value="above"/>
* <property name="sortStaticImportsAlphabetically" value="true"/>
* </module>
* </pre>
*
* <p>To configure the check so that it matches default IntelliJ IDEA formatter configuration
* (tested on v14):</p>
* <ul>
* <li>group of static imports is on the bottom</li>
* <li>groups of non-static imports: all imports except of "javax" and
* "java", then "javax" and "java"</li>
* <li>imports will be sorted in the groups</li>
* <li>groups are separated by, at least, one blank line</li>
* </ul>
*
* <p>
* Note: "separated" option is disabled because IDEA default has blank line
* between "java" and static imports, and no blank line between
* "javax" and "java"
* </p>
*
* <pre>
* <module name="ImportOrder">
* <property name="groups" value="*,javax,java"/>
* <property name="ordered" value="true"/>
* <property name="separated" value="false"/>
* <property name="option" value="bottom"/>
* <property name="sortStaticImportsAlphabetically" value="true"/>
* </module>
* </pre>
*
* <p>To configure the check so that it matches default NetBeans formatter configuration
* (tested on v8):</p>
* <ul>
* <li>groups of non-static imports are not defined, all imports will be sorted
* as a one group</li>
* <li>static imports are not separated, they will be sorted along with other imports</li>
* </ul>
*
* <pre>
* <module name="ImportOrder">
* <property name="option" value="inflow"/>
* </module>
* </pre>
*
* <p>
* Group descriptions enclosed in slashes are interpreted as regular
* expressions. If multiple groups match, the one matching a longer
* substring of the imported name will take precedence, with ties
* broken first in favor of earlier matches and finally in favor of
* the first matching group.
* </p>
*
* <p>
* There is always a wildcard group to which everything not in a named group
* belongs. If an import does not match a named group, the group belongs to
* this wildcard group. The wildcard group position can be specified using the
* {@code *} character.
* </p>
*
* <p>Check also has on option making it more flexible:
* <b>sortStaticImportsAlphabetically</b> - sets whether static imports grouped by
* <b>top</b> or <b>bottom</b> option should be sorted alphabetically or
* not, default value is <b>false</b>. It is applied to static imports grouped
* with <b>top</b> or <b>bottom</b> options.<br>
* This option is helping in reconciling of this Check and other tools like
* Eclipse's Organize Imports feature.
* </p>
* <p>
* To configure the Check allows static imports grouped to the <b>top</b>
* being sorted alphabetically:
* </p>
*
* <pre>
* {@code
* import static java.lang.Math.abs;
* import static org.abego.treelayout.Configuration.AlignmentInLevel; // OK, alphabetical order
*
* import org.abego.*;
*
* import java.util.Set;
*
* public class SomeClass { ... }
* }
* </pre>
*
*
* @author Bill Schneider
* @author o_sukhodolsky
* @author David DIDIER
* @author Steve McKay
* @author <a href="mailto:nesterenko-aleksey@list.ru">Aleksey Nesterenko</a>
* @author Andrei Selkin
*/
public class ImportOrderCheck
extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_SEPARATION = "import.separation";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_ORDERING = "import.ordering";
/** The special wildcard that catches all remaining groups. */
private static final String WILDCARD_GROUP_NAME = "*";
/** Empty array of pattern type needed to initialize check. */
private static final Pattern[] EMPTY_PATTERN_ARRAY = new Pattern[0];
/** List of import groups specified by the user. */
private Pattern[] groups = EMPTY_PATTERN_ARRAY;
/** Require imports in group be separated. */
private boolean separated;
/** Require imports in group. */
private boolean ordered = true;
/** Should comparison be case sensitive. */
private boolean caseSensitive = true;
/** Last imported group. */
private int lastGroup;
/** Line number of last import. */
private int lastImportLine;
/** Name of last import. */
private String lastImport;
/** If last import was static. */
private boolean lastImportStatic;
/** Whether there was any imports. */
private boolean beforeFirstImport;
/** Whether static imports should be sorted alphabetically or not. */
private boolean sortStaticImportsAlphabetically;
/** Whether to use container ordering (Eclipse IDE term) for static imports or not. */
private boolean useContainerOrderingForStatic;
/** The policy to enforce. */
private ImportOrderOption option = ImportOrderOption.UNDER;
/**
* Set the option to enforce.
* @param optionStr string to decode option from
* @throws ConversionException if unable to decode
*/
public void setOption(String optionStr) {
try {
option = ImportOrderOption.valueOf(optionStr.trim().toUpperCase(Locale.ENGLISH));
}
catch (IllegalArgumentException iae) {
throw new ConversionException("unable to parse " + optionStr, iae);
}
}
/**
* Sets the list of package groups and the order they should occur in the
* file.
*
* @param packageGroups a comma-separated list of package names/prefixes.
*/
public void setGroups(String... packageGroups) {
groups = new Pattern[packageGroups.length];
for (int i = 0; i < packageGroups.length; i++) {
String pkg = packageGroups[i];
final StringBuilder pkgBuilder = new StringBuilder(pkg);
final Pattern grp;
// if the pkg name is the wildcard, make it match zero chars
// from any name, so it will always be used as last resort.
if (WILDCARD_GROUP_NAME.equals(pkg)) {
// matches any package
grp = Pattern.compile("");
}
else if (CommonUtils.startsWithChar(pkg, '/')) {
if (!CommonUtils.endsWithChar(pkg, '/')) {
throw new IllegalArgumentException("Invalid group");
}
pkg = pkg.substring(1, pkg.length() - 1);
grp = Pattern.compile(pkg);
}
else {
if (!CommonUtils.endsWithChar(pkg, '.')) {
pkgBuilder.append('.');
}
grp = Pattern.compile("^" + Pattern.quote(pkgBuilder.toString()));
}
groups[i] = grp;
}
}
/**
* Sets whether or not imports should be ordered within any one group of
* imports.
*
* @param ordered
* whether lexicographic ordering of imports within a group
* required or not.
*/
public void setOrdered(boolean ordered) {
this.ordered = ordered;
}
/**
* Sets whether or not groups of imports must be separated from one another
* by at least one blank line.
*
* @param separated
* whether groups should be separated by oen blank line.
*/
public void setSeparated(boolean separated) {
this.separated = separated;
}
/**
* Sets whether string comparison should be case sensitive or not.
*
* @param caseSensitive
* whether string comparison should be case sensitive.
*/
public void setCaseSensitive(boolean caseSensitive) {
this.caseSensitive = caseSensitive;
}
/**
* Sets whether static imports (when grouped using 'top' and 'bottom' option)
* are sorted alphabetically or according to the package groupings.
* @param sortAlphabetically true or false.
*/
public void setSortStaticImportsAlphabetically(boolean sortAlphabetically) {
sortStaticImportsAlphabetically = sortAlphabetically;
}
/**
* Sets whether to use container ordering (Eclipse IDE term) for static imports or not.
* @param useContainerOrdering whether to use container ordering for static imports or not.
*/
public void setUseContainerOrderingForStatic(boolean useContainerOrdering) {
useContainerOrderingForStatic = useContainerOrdering;
}
@Override
public int[] getDefaultTokens() {
return getAcceptableTokens();
}
@Override
public int[] getAcceptableTokens() {
return new int[] {TokenTypes.IMPORT, TokenTypes.STATIC_IMPORT};
}
@Override
public int[] getRequiredTokens() {
return new int[] {TokenTypes.IMPORT};
}
@Override
public void beginTree(DetailAST rootAST) {
lastGroup = Integer.MIN_VALUE;
lastImportLine = Integer.MIN_VALUE;
lastImport = "";
lastImportStatic = false;
beforeFirstImport = true;
}
@Override
public void visitToken(DetailAST ast) {
final FullIdent ident;
final boolean isStatic;
if (ast.getType() == TokenTypes.IMPORT) {
ident = FullIdent.createFullIdentBelow(ast);
isStatic = false;
}
else {
ident = FullIdent.createFullIdent(ast.getFirstChild()
.getNextSibling());
isStatic = true;
}
final boolean isStaticAndNotLastImport = isStatic && !lastImportStatic;
final boolean isLastImportAndNonStatic = lastImportStatic && !isStatic;
// using set of IF instead of SWITCH to analyze Enum options to satisfy coverage.
// https://github.com/checkstyle/checkstyle/issues/1387
if (option == ImportOrderOption.TOP) {
if (isLastImportAndNonStatic) {
lastGroup = Integer.MIN_VALUE;
lastImport = "";
}
doVisitToken(ident, isStatic, isStaticAndNotLastImport);
}
else if (option == ImportOrderOption.BOTTOM) {
if (isStaticAndNotLastImport) {
lastGroup = Integer.MIN_VALUE;
lastImport = "";
}
doVisitToken(ident, isStatic, isLastImportAndNonStatic);
}
else if (option == ImportOrderOption.ABOVE) {
// previous non-static but current is static
doVisitToken(ident, isStatic, isStaticAndNotLastImport);
}
else if (option == ImportOrderOption.UNDER) {
doVisitToken(ident, isStatic, isLastImportAndNonStatic);
}
else if (option == ImportOrderOption.INFLOW) {
// "previous" argument is useless here
doVisitToken(ident, isStatic, true);
}
else {
throw new IllegalStateException(
"Unexpected option for static imports: " + option);
}
lastImportLine = ast.findFirstToken(TokenTypes.SEMI).getLineNo();
lastImportStatic = isStatic;
beforeFirstImport = false;
}
/**
* Shares processing...
*
* @param ident the import to process.
* @param isStatic whether the token is static or not.
* @param previous previous non-static but current is static (above), or
* previous static but current is non-static (under).
*/
private void doVisitToken(FullIdent ident, boolean isStatic,
boolean previous) {
final String name = ident.getText();
final int groupIdx = getGroupNumber(name);
final int line = ident.getLineNo();
if (groupIdx == lastGroup
|| !beforeFirstImport && isAlphabeticallySortableStaticImport(isStatic)) {
doVisitTokenInSameGroup(isStatic, previous, name, line);
}
else if (groupIdx > lastGroup) {
if (!beforeFirstImport && separated && line - lastImportLine < 2) {
log(line, MSG_SEPARATION, name);
}
}
else {
log(line, MSG_ORDERING, name);
}
lastGroup = groupIdx;
lastImport = name;
}
/**
* Checks whether static imports grouped by <b>top</b> or <b>bottom</b> option
* are sorted alphabetically or not.
* @param isStatic if current import is static.
* @return true if static imports should be sorted alphabetically.
*/
private boolean isAlphabeticallySortableStaticImport(boolean isStatic) {
return isStatic && sortStaticImportsAlphabetically
&& (option == ImportOrderOption.TOP
|| option == ImportOrderOption.BOTTOM);
}
/**
* Shares processing...
*
* @param isStatic whether the token is static or not.
* @param previous previous non-static but current is static (above), or
* previous static but current is non-static (under).
* @param name the name of the current import.
* @param line the line of the current import.
*/
private void doVisitTokenInSameGroup(boolean isStatic,
boolean previous, String name, int line) {
if (ordered) {
if (option == ImportOrderOption.INFLOW) {
if (isWrongOrder(name, isStatic)) {
log(line, MSG_ORDERING, name);
}
}
else {
final boolean shouldFireError =
// previous non-static but current is static (above)
// or
// previous static but current is non-static (under)
previous
||
// current and previous static or current and
// previous non-static
lastImportStatic == isStatic
&& isWrongOrder(name, isStatic);
if (shouldFireError) {
log(line, MSG_ORDERING, name);
}
}
}
}
/**
* Checks whether import name is in wrong order.
* @param name import name.
* @param isStatic whether it is a static import name.
* @return true if import name is in wrong order.
*/
private boolean isWrongOrder(String name, boolean isStatic) {
final boolean result;
if (isStatic && useContainerOrderingForStatic) {
result = compareContainerOrder(lastImport, name, caseSensitive) > 0;
}
else {
// out of lexicographic order
result = compare(lastImport, name, caseSensitive) > 0;
}
return result;
}
/**
* Compares two import strings.
* We first compare the container of the static import, container being the type enclosing
* the static element being imported. When this returns 0, we compare the qualified
* import name. For e.g. this is what is considered to be container names:
* <p>
* import static HttpConstants.COLON => HttpConstants
* import static HttpHeaders.addHeader => HttpHeaders
* import static HttpHeaders.setHeader => HttpHeaders
* import static HttpHeaders.Names.DATE => HttpHeaders.Names
* </p>
* <p>
* According to this logic, HttpHeaders.Names would come after HttpHeaders.
*
* For more details, see <a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=473629#c3">
* static imports comparison method</a> in Eclipse.
* </p>
*
* @param importName1 first import name.
* @param importName2 second import name.
* @param caseSensitive whether the comparison of fully qualified import names is case
* sensitive.
* @return the value {@code 0} if str1 is equal to str2; a value
* less than {@code 0} if str is less than the str2 (container order
* or lexicographical); and a value greater than {@code 0} if str1 is greater than str2
* (container order or lexicographically).
*/
private static int compareContainerOrder(String importName1, String importName2,
boolean caseSensitive) {
final String container1 = getImportContainer(importName1);
final String container2 = getImportContainer(importName2);
final int compareContainersOrderResult;
if (caseSensitive) {
compareContainersOrderResult = container1.compareTo(container2);
}
else {
compareContainersOrderResult = container1.compareToIgnoreCase(container2);
}
final int result;
if (compareContainersOrderResult == 0) {
result = compare(importName1, importName2, caseSensitive);
}
else {
result = compareContainersOrderResult;
}
return result;
}
/**
* Extracts import container name from fully qualified import name.
* An import container name is the type which encloses the static element being imported.
* For example, HttpConstants, HttpHeaders, HttpHeaders.Names are import container names:
* <p>
* import static HttpConstants.COLON => HttpConstants
* import static HttpHeaders.addHeader => HttpHeaders
* import static HttpHeaders.setHeader => HttpHeaders
* import static HttpHeaders.Names.DATE => HttpHeaders.Names
* </p>
* @param qualifiedImportName fully qualified import name.
* @return import container name.
*/
private static String getImportContainer(String qualifiedImportName) {
final int lastDotIndex = qualifiedImportName.lastIndexOf('.');
return qualifiedImportName.substring(0, lastDotIndex);
}
/**
* Finds out what group the specified import belongs to.
*
* @param name the import name to find.
* @return group number for given import name.
*/
private int getGroupNumber(String name) {
int bestIndex = groups.length;
int bestLength = -1;
int bestPos = 0;
// find out what group this belongs in
// loop over groups and get index
for (int i = 0; i < groups.length; i++) {
final Matcher matcher = groups[i].matcher(name);
while (matcher.find()) {
final int length = matcher.end() - matcher.start();
if (length > bestLength
|| length == bestLength && matcher.start() < bestPos) {
bestIndex = i;
bestLength = length;
bestPos = matcher.start();
}
}
}
return bestIndex;
}
/**
* Compares two strings.
*
* @param string1
* the first string.
* @param string2
* the second string.
* @param caseSensitive
* whether the comparison is case sensitive.
* @return the value {@code 0} if string1 is equal to string2; a value
* less than {@code 0} if string1 is lexicographically less
* than the string2; and a value greater than {@code 0} if
* string1 is lexicographically greater than string2.
*/
private static int compare(String string1, String string2,
boolean caseSensitive) {
final int result;
if (caseSensitive) {
result = string1.compareTo(string2);
}
else {
result = string1.compareToIgnoreCase(string2);
}
return result;
}
}