Copyright (c) 2008, http://www.snakeyaml.org
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
/**
 * Copyright (c) 2008, http://www.snakeyaml.org
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.yaml.snakeyaml.resolver;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;

import org.yaml.snakeyaml.nodes.NodeId;
import org.yaml.snakeyaml.nodes.Tag;

Resolver tries to detect a type by content (when the tag is implicit)
/**
 * Resolver tries to detect a type by content (when the tag is implicit)
 */
public class Resolver {
    public static final Pattern BOOL = Pattern
            .compile("^(?:yes|Yes|YES|no|No|NO|true|True|TRUE|false|False|FALSE|on|On|ON|off|Off|OFF)$");

    
The regular expression is taken from the 1.2 specification but '_'s are
added to keep backwards compatibility
/**
     * The regular expression is taken from the 1.2 specification but '_'s are
     * added to keep backwards compatibility
     */
    public static final Pattern FLOAT = Pattern
            .compile("^([-+]?(\\.[0-9]+|[0-9_]+(\\.[0-9_]*)?)([eE][-+]?[0-9]+)?|[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\\.[0-9_]*|[-+]?\\.(?:inf|Inf|INF)|\\.(?:nan|NaN|NAN))$");
    public static final Pattern INT = Pattern
            .compile("^(?:[-+]?0b[0-1_]+|[-+]?0[0-7_]+|[-+]?(?:0|[1-9][0-9_]*)|[-+]?0x[0-9a-fA-F_]+|[-+]?[1-9][0-9_]*(?::[0-5]?[0-9])+)$");
    public static final Pattern MERGE = Pattern.compile("^(?:<<)$");
    public static final Pattern NULL = Pattern.compile("^(?:~|null|Null|NULL| )$");
    public static final Pattern EMPTY = Pattern.compile("^$");
    public static final Pattern TIMESTAMP = Pattern
            .compile("^(?:[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]|[0-9][0-9][0-9][0-9]-[0-9][0-9]?-[0-9][0-9]?(?:[Tt]|[ \t]+)[0-9][0-9]?:[0-9][0-9]:[0-9][0-9](?:\\.[0-9]*)?(?:[ \t]*(?:Z|[-+][0-9][0-9]?(?::[0-9][0-9])?))?)$");
    public static final Pattern VALUE = Pattern.compile("^(?:=)$");
    public static final Pattern YAML = Pattern.compile("^(?:!|&|\\*)$");

    protected Map<Character, List<ResolverTuple>> yamlImplicitResolvers = new HashMap<Character, List<ResolverTuple>>();

    protected void addImplicitResolvers() {
        addImplicitResolver(Tag.BOOL, BOOL, "yYnNtTfFoO");
        /*
         * INT must be before FLOAT because the regular expression for FLOAT
         * matches INT (see issue 130)
         * http://code.google.com/p/snakeyaml/issues/detail?id=130
         */
        addImplicitResolver(Tag.INT, INT, "-+0123456789");
        addImplicitResolver(Tag.FLOAT, FLOAT, "-+0123456789.");
        addImplicitResolver(Tag.MERGE, MERGE, "<");
        addImplicitResolver(Tag.NULL, NULL, "~nN\0");
        addImplicitResolver(Tag.NULL, EMPTY, null);
        addImplicitResolver(Tag.TIMESTAMP, TIMESTAMP, "0123456789");
        // The following implicit resolver is only for documentation
        // purposes.
        // It cannot work
        // because plain scalars cannot start with '!', '&', or '*'.
        addImplicitResolver(Tag.YAML, YAML, "!&*");
    }

    public Resolver() {
        addImplicitResolvers();
    }

    public void addImplicitResolver(Tag tag, Pattern regexp, String first) {
        if (first == null) {
            List<ResolverTuple> curr = yamlImplicitResolvers.get(null);
            if (curr == null) {
                curr = new ArrayList<ResolverTuple>();
                yamlImplicitResolvers.put(null, curr);
            }
            curr.add(new ResolverTuple(tag, regexp));
        } else {
            char[] chrs = first.toCharArray();
            for (int i = 0, j = chrs.length; i < j; i++) {
                Character theC = Character.valueOf(chrs[i]);
                if (theC == 0) {
                    // special case: for null
                    theC = null;
                }
                List<ResolverTuple> curr = yamlImplicitResolvers.get(theC);
                if (curr == null) {
                    curr = new ArrayList<ResolverTuple>();
                    yamlImplicitResolvers.put(theC, curr);
                }
                curr.add(new ResolverTuple(tag, regexp));
            }
        }
    }

    public Tag resolve(NodeId kind, String value, boolean implicit) {
        if (kind == NodeId.scalar && implicit) {
            final List<ResolverTuple> resolvers;
            if (value.length() == 0) {
                resolvers = yamlImplicitResolvers.get('\0');
            } else {
                resolvers = yamlImplicitResolvers.get(value.charAt(0));
            }
            if (resolvers != null) {
                for (ResolverTuple v : resolvers) {
                    Tag tag = v.getTag();
                    Pattern regexp = v.getRegexp();
                    if (regexp.matcher(value).matches()) {
                        return tag;
                    }
                }
            }
            if (yamlImplicitResolvers.containsKey(null)) {
                for (ResolverTuple v : yamlImplicitResolvers.get(null)) {
                    Tag tag = v.getTag();
                    Pattern regexp = v.getRegexp();
                    if (regexp.matcher(value).matches()) {
                        return tag;
                    }
                }
            }
        }
        switch (kind) {
        case scalar:
            return Tag.STR;
        case sequence:
            return Tag.SEQ;
        default:
            return Tag.MAP;
        }
    }
}