001/* 002 * Copyright 2012-2018 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.boot.cli.command.shell; 018 019import java.util.ArrayDeque; 020import java.util.Deque; 021 022/** 023 * Abstraction to manage a stack of prompts. 024 * 025 * @author Phillip Webb 026 */ 027public class ShellPrompts { 028 029 private static final String DEFAULT_PROMPT = "$ "; 030 031 private final Deque<String> prompts = new ArrayDeque<>(); 032 033 /** 034 * Push a new prompt to be used by the shell. 035 * @param prompt the prompt 036 * @see #popPrompt() 037 */ 038 public void pushPrompt(String prompt) { 039 this.prompts.push(prompt); 040 } 041 042 /** 043 * Pop a previously pushed prompt, returning to the previous value. 044 * @see #pushPrompt(String) 045 */ 046 public void popPrompt() { 047 if (!this.prompts.isEmpty()) { 048 this.prompts.pop(); 049 } 050 } 051 052 /** 053 * Returns the current prompt. 054 * @return the current prompt 055 */ 056 public String getPrompt() { 057 return this.prompts.isEmpty() ? DEFAULT_PROMPT : this.prompts.peek(); 058 } 059 060}