Java tutorial
/* * Licensed to CRATE Technology GmbH ("Crate") under one or more contributor * license agreements. See the NOTICE file distributed with this work for * additional information regarding copyright ownership. Crate licenses * this file to you 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. * * However, if you have executed another commercial license agreement * with Crate these terms will supersede the license and you may use the * software solely pursuant to the terms of the relevant commercial agreement. */ package io.crate.sql.tree; import com.google.common.collect.HashMultimap; import com.google.common.collect.Multimap; import java.util.ArrayList; import java.util.List; import java.util.Map; public abstract class Literal extends Expression { @Override public <R, C> R accept(AstVisitor<R, C> visitor, C context) { return visitor.visitLiteral(this, context); } public static Literal fromObject(Object value) { Literal literal = null; if (value == null) { literal = NullLiteral.INSTANCE; } else if (value instanceof String) { literal = new StringLiteral((String) value); } else if (value instanceof Number) { if (value instanceof Float || value instanceof Double) { literal = new DoubleLiteral(value.toString()); } else if (value instanceof Short || value instanceof Integer || value instanceof Long) { literal = new LongLiteral(value.toString()); } } else if (value instanceof Boolean) { literal = (Boolean) value ? BooleanLiteral.TRUE_LITERAL : BooleanLiteral.FALSE_LITERAL; } else if (value instanceof Object[]) { List<Expression> expressions = new ArrayList<>(); for (Object o : (Object[]) value) { expressions.add(fromObject(o)); } literal = new ArrayLiteral(expressions); } else if (value instanceof Map) { Multimap<String, Expression> map = HashMultimap.create(); @SuppressWarnings("unchecked") Map<String, Object> valueMap = (Map<String, Object>) value; for (Map.Entry<String, Object> entry : valueMap.entrySet()) { map.put(entry.getKey(), fromObject(entry.getValue())); } literal = new ObjectLiteral(map); } return literal; } }