TokenUtil

///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2026 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.utils;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Locale;
import java.util.Map;
import java.util.Optional;
import java.util.ResourceBundle;
import java.util.Set;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;

/**
 * Contains utility methods for tokens.
 *
 */
public final class TokenUtil {

    /** Maps from a token name to value. */
    private static final Map<String, Integer> TOKEN_NAME_TO_VALUE;
    /** Maps from a token value to name. */
    private static final Map<Integer, String> TOKEN_VALUE_TO_NAME;

    /** Array of all token IDs. */
    private static final int[] TOKEN_IDS;

    /** Format for exception message when getting token by given id. */
    private static final String TOKEN_ID_EXCEPTION_FORMAT = "unknown TokenTypes id '%s'";

    /** Format for exception message when getting token by given name. */
    private static final String TOKEN_NAME_EXCEPTION_FORMAT = "unknown TokenTypes value '%s'";

    // initialise the constants
    static {
        TOKEN_NAME_TO_VALUE = nameToValueMapFromPublicIntFields(TokenTypes.class);
        TOKEN_VALUE_TO_NAME = invertMap(TOKEN_NAME_TO_VALUE);
        TOKEN_IDS = TOKEN_NAME_TO_VALUE.values().stream().mapToInt(Integer::intValue).toArray();
    }

    /** Stop instances being created. **/
    private TokenUtil() {
    }

    /**
     * Gets the IDENT token from the given AST node.
     *
     * <p>This method must only be used for AST types where the IDENT token
     * is guaranteed to NEVER be null. The known types are:
     * <ul>
     * <li>{@link TokenTypes#METHOD_DEF}</li>
     * <li>{@link TokenTypes#CLASS_DEF}</li>
     * <li>{@link TokenTypes#VARIABLE_DEF}</li>
     * <li>{@link TokenTypes#PARAMETER_DEF}, <b>but not receiver parameter</b>.</li>
     * <li>{@link TokenTypes#INTERFACE_DEF}</li>
     * <li>{@link TokenTypes#ENUM_DEF}</li>
     * <li>{@link TokenTypes#ANNOTATION_DEF}</li>
     * <li>{@link TokenTypes#RECORD_DEF}</li>
     * <li>{@link TokenTypes#LITERAL_CATCH}</li>
     * </ul>
     *
     * @param ast the AST node.
     * @return the IDENT token (not null).
     */
    public static DetailAST getIdent(DetailAST ast) {
        return NullUtil.notNull(ast.findFirstToken(TokenTypes.IDENT));
    }

    /**
     * Gets the value of a static or instance field of type int or of another primitive type
     * convertible to type int via a widening conversion. Does not throw any checked exceptions.
     *
     * @param field from which the int should be extracted
     * @param object to extract the int value from
     * @return the value of the field converted to type int
     * @throws IllegalStateException if this Field object is enforcing Java language access control
     *         and the underlying field is inaccessible
     * @see Field#getInt(Object)
     */
    public static int getIntFromField(Field field, Object object) {
        try {
            return field.getInt(object);
        }
        catch (final IllegalAccessException exception) {
            throw new IllegalStateException(exception);
        }
    }

    /**
     * Creates a map of 'field name' to 'field value' from all {@code public} {@code int} fields
     * of a class.
     *
     * @param cls source class
     * @return unmodifiable name to value map
     */
    public static Map<String, Integer> nameToValueMapFromPublicIntFields(Class<?> cls) {
        return Arrays.stream(cls.getDeclaredFields())
            .filter(fld -> Modifier.isPublic(fld.getModifiers()) && fld.getType() == Integer.TYPE)
            .collect(Collectors.toUnmodifiableMap(
                Field::getName, fld -> getIntFromField(fld, null))
            );
    }

    /**
     * Inverts a given map by exchanging each entry's key and value.
     *
     * @param map source map
     * @return inverted map
     */
    public static Map<Integer, String> invertMap(Map<String, Integer> map) {
        return map.entrySet().stream()
            .collect(Collectors.toUnmodifiableMap(Map.Entry::getValue, Map.Entry::getKey));
    }

    /**
     * Get total number of TokenTypes.
     *
     * @return total number of TokenTypes.
     */
    public static int getTokenTypesTotalNumber() {
        return TOKEN_IDS.length;
    }

    /**
     * Get all token IDs that are available in TokenTypes.
     *
     * @return array of token IDs
     */
    public static int[] getAllTokenIds() {
        final int[] safeCopy = new int[TOKEN_IDS.length];
        System.arraycopy(TOKEN_IDS, 0, safeCopy, 0, TOKEN_IDS.length);
        return safeCopy;
    }

    /**
     * Returns the name of a token for a given ID.
     *
     * @param id the ID of the token name to get
     * @return a token name
     * @throws IllegalArgumentException when id is not valid
     */
    public static String getTokenName(int id) {
        final String name = TOKEN_VALUE_TO_NAME.get(id);
        if (name == null) {
            throw new IllegalArgumentException(
                String.format(Locale.ROOT, TOKEN_ID_EXCEPTION_FORMAT, id));
        }
        return name;
    }

    /**
     * Returns the ID of a token for a given name.
     *
     * @param name the name of the token ID to get
     * @return a token ID
     * @throws IllegalArgumentException when id is null
     */
    public static int getTokenId(String name) {
        final Integer id = TOKEN_NAME_TO_VALUE.get(name);
        if (id == null) {
            throw new IllegalArgumentException(
                String.format(Locale.ROOT, TOKEN_NAME_EXCEPTION_FORMAT, name));
        }
        return id;
    }

    /**
     * Returns the short description of a token for a given name.
     *
     * @param name the name of the token ID to get
     * @return a short description
     * @throws IllegalArgumentException when name is unknown
     */
    public static String getShortDescription(String name) {
        if (!TOKEN_NAME_TO_VALUE.containsKey(name)) {
            throw new IllegalArgumentException(
                String.format(Locale.ROOT, TOKEN_NAME_EXCEPTION_FORMAT, name));
        }

        final String tokenTypes =
            "com.puppycrawl.tools.checkstyle.api.tokentypes";
        final ResourceBundle bundle = ResourceBundle.getBundle(tokenTypes, Locale.ROOT);
        return bundle.getString(name);
    }

    /**
     * Is argument comment-related type (SINGLE_LINE_COMMENT,
     * BLOCK_COMMENT_BEGIN, BLOCK_COMMENT_END, COMMENT_CONTENT).
     *
     * @param type
     *        token type.
     * @return true if type is comment-related type.
     */
    public static boolean isCommentType(int type) {
        return type == TokenTypes.SINGLE_LINE_COMMENT
                || type == TokenTypes.BLOCK_COMMENT_BEGIN
                || type == TokenTypes.BLOCK_COMMENT_END
                || type == TokenTypes.COMMENT_CONTENT;
    }

    /**
     * Is argument comment-related type name (SINGLE_LINE_COMMENT,
     * BLOCK_COMMENT_BEGIN, BLOCK_COMMENT_END, COMMENT_CONTENT).
     *
     * @param type
     *        token type name.
     * @return true if type is comment-related type name.
     */
    public static boolean isCommentType(String type) {
        return isCommentType(getTokenId(type));
    }

    /**
     * Finds the first {@link Optional} child token of {@link DetailAST} root node
     * which matches the given predicate.
     *
     * @param root root node.
     * @param predicate predicate.
     * @return {@link Optional} of {@link DetailAST} node which matches the predicate.
     */
    public static Optional<DetailAST> findFirstTokenByPredicate(DetailAST root,
                                                                Predicate<DetailAST> predicate) {
        Optional<DetailAST> result = Optional.empty();
        for (DetailAST ast = root.getFirstChild(); ast != null; ast = ast.getNextSibling()) {
            if (predicate.test(ast)) {
                result = Optional.of(ast);
                break;
            }
        }
        return result;
    }

    /**
     * Performs an action for each child of {@link DetailAST} root node
     * which matches the given token type.
     *
     * @param root root node.
     * @param type token type to match.
     * @param action action to perform on the nodes.
     */
    public static void forEachChild(DetailAST root, int type, Consumer<DetailAST> action) {
        for (DetailAST ast = root.getFirstChild(); ast != null; ast = ast.getNextSibling()) {
            if (ast.getType() == type) {
                action.accept(ast);
            }
        }
    }

    /**
     * Determines if two ASTs are on the same line.
     *
     * @param ast1   the first AST
     * @param ast2   the second AST
     *
     * @return true if they are on the same line.
     */
    public static boolean areOnSameLine(DetailAST ast1, DetailAST ast2) {
        return ast1.getLineNo() == ast2.getLineNo();
    }

    /**
     * Is type declaration token type (CLASS_DEF, INTERFACE_DEF,
     * ANNOTATION_DEF, ENUM_DEF, RECORD_DEF).
     *
     * @param type
     *        token type.
     * @return true if type is type declaration token type.
     */
    public static boolean isTypeDeclaration(int type) {
        return type == TokenTypes.CLASS_DEF
                || type == TokenTypes.INTERFACE_DEF
                || type == TokenTypes.ANNOTATION_DEF
                || type == TokenTypes.ENUM_DEF
                || type == TokenTypes.RECORD_DEF;
    }

    /**
     * Determines if the token type belongs to the given types.
     *
     * @param type the Token Type to check
     * @param types the acceptable types
     *
     * @return true if type matches one of the given types.
     */
    public static boolean isOfType(int type, int... types) {
        boolean matching = false;
        for (int tokenType : types) {
            if (tokenType == type) {
                matching = true;
                break;
            }
        }
        return matching;
    }

    /**
     * Determines if the token type belongs to the given types.
     *
     * @param type the Token Type to check
     * @param types the acceptable types
     *
     * @return true if type matches one of the given types.
     */
    public static boolean isOfType(int type, Set<Integer> types) {
        return types.contains(type);
    }

    /**
     * Determines if the AST belongs to the given types.
     *
     * @param ast the AST node to check
     * @param types the acceptable types
     *
     * @return true if type matches one of the given types.
     */
    public static boolean isOfType(DetailAST ast, int... types) {
        return ast != null && isOfType(ast.getType(), types);
    }

    /**
     * Determines if given AST is a root node, i.e. if the type
     * of the token we are checking is {@code COMPILATION_UNIT}.
     *
     * @param ast AST to check
     * @return true if AST is a root node
     */
    public static boolean isRootNode(DetailAST ast) {
        return ast.getType() == TokenTypes.COMPILATION_UNIT;
    }

    /**
     * Checks if a token type is a literal true or false.
     *
     * @param tokenType the TokenType
     * @return true if tokenType is LITERAL_TRUE or LITERAL_FALSE
     */
    public static boolean isBooleanLiteralType(final int tokenType) {
        final boolean isTrue = tokenType == TokenTypes.LITERAL_TRUE;
        final boolean isFalse = tokenType == TokenTypes.LITERAL_FALSE;
        return isTrue || isFalse;
    }

    /**
     * Creates a new {@code BitSet} from array of tokens.
     *
     * @param tokens to initialize the BitSet
     * @return tokens as BitSet
     */
    public static BitSet asBitSet(int... tokens) {
        return IntStream.of(tokens)
                .collect(BitSet::new, BitSet::set, BitSet::or);
    }

    /**
     * Creates a new {@code BitSet} from array of tokens.
     *
     * @param tokens to initialize the BitSet
     * @return tokens as BitSet
     */
    public static BitSet asBitSet(String... tokens) {
        return Arrays.stream(tokens)
                .map(String::trim)
                .filter(Predicate.not(String::isEmpty))
                .mapToInt(TokenUtil::getTokenId)
                .collect(BitSet::new, BitSet::set, BitSet::or);
    }

}