| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF 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. |
| */ |
| |
| package org.apache.druid.math.expr; |
| |
| import org.apache.commons.lang.StringEscapeUtils; |
| import org.apache.druid.java.util.common.StringUtils; |
| |
| import javax.annotation.Nullable; |
| import java.util.Objects; |
| |
| /** |
| * This {@link Expr} node is used to represent a variable in the expression language. At evaluation time, the string |
| * identifier will be used to retrieve the runtime value for the variable from {@link Expr.ObjectBinding}. |
| * {@link IdentifierExpr} are terminal nodes of an expression tree, and have no children {@link Expr}. |
| */ |
| class IdentifierExpr implements Expr |
| { |
| private final String identifier; |
| private final String binding; |
| |
| /** |
| * Construct a identifier expression for a {@link LambdaExpr}, where the {@link #identifier} is equal to |
| * {@link #binding} |
| */ |
| IdentifierExpr(String value) |
| { |
| this.identifier = value; |
| this.binding = value; |
| } |
| |
| /** |
| * Construct a normal identifier expression, where {@link #binding} is the key to fetch the backing value from |
| * {@link Expr.ObjectBinding} and the {@link #identifier} is a unique string that identifies this usage of the |
| * binding. |
| */ |
| IdentifierExpr(String identifier, String binding) |
| { |
| this.identifier = identifier; |
| this.binding = binding; |
| } |
| |
| @Override |
| public String toString() |
| { |
| return binding; |
| } |
| |
| /** |
| * Unique identifier for the binding |
| */ |
| @Nullable |
| public String getIdentifier() |
| { |
| return identifier; |
| } |
| |
| /** |
| * Value binding, key to retrieve value from {@link Expr.ObjectBinding#get(String)} |
| */ |
| @Nullable |
| public String getBinding() |
| { |
| return binding; |
| } |
| |
| @Nullable |
| @Override |
| public String getIdentifierIfIdentifier() |
| { |
| return identifier; |
| } |
| |
| @Nullable |
| @Override |
| public String getBindingIfIdentifier() |
| { |
| return binding; |
| } |
| |
| @Nullable |
| @Override |
| public IdentifierExpr getIdentifierExprIfIdentifierExpr() |
| { |
| return this; |
| } |
| |
| @Override |
| public BindingDetails analyzeInputs() |
| { |
| return new BindingDetails(this); |
| } |
| |
| @Override |
| public ExprEval eval(ObjectBinding bindings) |
| { |
| return ExprEval.bestEffortOf(bindings.get(binding)); |
| } |
| |
| @Override |
| public String stringify() |
| { |
| // escape as java strings since identifiers are wrapped in double quotes |
| return StringUtils.format("\"%s\"", StringEscapeUtils.escapeJava(binding)); |
| } |
| |
| @Override |
| public void visit(Visitor visitor) |
| { |
| visitor.visit(this); |
| } |
| |
| @Override |
| public Expr visit(Shuttle shuttle) |
| { |
| return shuttle.visit(this); |
| } |
| |
| @Override |
| public boolean equals(Object o) |
| { |
| if (this == o) { |
| return true; |
| } |
| if (o == null || getClass() != o.getClass()) { |
| return false; |
| } |
| IdentifierExpr that = (IdentifierExpr) o; |
| return Objects.equals(identifier, that.identifier); |
| } |
| |
| @Override |
| public int hashCode() |
| { |
| return Objects.hash(identifier); |
| } |
| } |