/*
 * Copyright 2015-2015 Amazon Technologies, Inc.
 *
 * 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://aws.amazon.com/apache2.0
 *
 * This file 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 com.amazonaws.services.dynamodbv2.xspec;

import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Represents a literal value in building expressions.
 * <p>
 * This object is as immutable (or unmodifiable) as the underlying value given
 * during construction.
 */
class LiteralOperand extends Operand {
    private final Object value;

    /**
     * Represents a null value.
     */
    LiteralOperand() {
        this.value = null;
    }

    /**
     * @param value
     *            must be a supported type by the DynamoDB Document API.
     */
    LiteralOperand(Object value) {
        this.value = value;
    }

    /**
     * Must be a set of String, Number, or byte[].
     */
    LiteralOperand(Set<?> value) {
        this.value = value;
    }

    /**
     * Must be a list of supported types by the DynamoDB Document API.
     */
    LiteralOperand(List<?> value) {
        this.value = value;
    }

    /**
     * Each value of the map must be a supported type by the DynamoDB Document
     * API.
     */
    LiteralOperand(Map<String, ?> value) {
        this.value = value;
    }

    LiteralOperand(boolean value) {
        this.value = value;
    }

    @Override
    final String asSubstituted(SubstitutionContext context) {
        return context.valueTokenFor(value);
    }

    @Override
    public String toString() {
        return String.valueOf(value);
    }
}
