| /* |
| * 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.brooklyn.camp.brooklyn.spi.dsl.parse; |
| |
| import java.util.Collection; |
| import java.util.List; |
| |
| import org.apache.brooklyn.util.collections.MutableList; |
| |
| public class DslParser { |
| private final String expression; |
| int index = -1; |
| |
| public DslParser(String expression) { |
| this.expression = expression; |
| } |
| |
| public synchronized Object parse() { |
| if (index>=0) |
| throw new IllegalStateException("Parser can only be used once"); |
| |
| index++; |
| Object result = next(); |
| |
| if (index < expression.length()) |
| throw new IllegalStateException("Unexpected character at position "+index+" in "+expression); |
| |
| return result; |
| } |
| |
| @SuppressWarnings("unchecked") |
| public Object next() { |
| int start = index; |
| |
| skipWhitespace(); |
| if (index >= expression.length()) |
| throw new IllegalStateException("Unexpected end of expression to parse, looking for content since position "+start); |
| |
| if (expression.charAt(index)=='"') { |
| // assume a string |
| int stringStart = index; |
| index++; |
| do { |
| if (index >= expression.length()) |
| throw new IllegalStateException("Unexpected end of expression to parse, looking for close quote since position "+stringStart); |
| char c = expression.charAt(index); |
| if (c=='"') break; |
| if (c=='\\') index++; |
| index++; |
| } while (true); |
| index++; |
| return new QuotedString(expression.substring(stringStart, index)); |
| } |
| |
| // not a string, must be a function (or chain thereof) |
| List<FunctionWithArgs> result = new MutableList<FunctionWithArgs>(); |
| |
| int fnStart = index; |
| do { |
| if (index >= expression.length()) |
| break; |
| char c = expression.charAt(index); |
| if (Character.isJavaIdentifierPart(c)) ; |
| // these chars also permitted |
| else if (".:".indexOf(c)>=0) ; |
| // other things e.g. whitespace, parentheses, etc, skip |
| else break; |
| index++; |
| } while (true); |
| String fn = expression.substring(fnStart, index); |
| if (fn.length()==0) |
| throw new IllegalStateException("Expected a function name at position "+start); |
| skipWhitespace(); |
| |
| if (index < expression.length() && expression.charAt(index)=='(') { |
| // collect arguments |
| int parenStart = index; |
| List<Object> args = new MutableList<Object>(); |
| index ++; |
| do { |
| skipWhitespace(); |
| if (index >= expression.length()) |
| throw new IllegalStateException("Unexpected end of arguments to function '"+fn+"', no close parenthesis matching character at position "+parenStart); |
| char c = expression.charAt(index); |
| if (c==')') break; |
| if (c==',') { |
| if (args.isEmpty()) |
| throw new IllegalStateException("Invalid character at position"+index); |
| index++; |
| } else { |
| if (!args.isEmpty()) |
| throw new IllegalStateException("Expected , before position"+index); |
| } |
| args.add(next()); |
| } while (true); |
| result.add(new FunctionWithArgs(fn, args)); |
| index++; |
| skipWhitespace(); |
| if (index >= expression.length()) |
| return result; |
| char c = expression.charAt(index); |
| if (c=='.') { |
| // chained expression |
| int chainStart = index; |
| index++; |
| Object next = next(); |
| if (next instanceof List) { |
| result.addAll((Collection<? extends FunctionWithArgs>) next); |
| return result; |
| } else { |
| throw new IllegalStateException("Expected functions following position"+chainStart); |
| } |
| } else { |
| // following word not something handled at this level; assume parent will handle (or throw) - e.g. a , or extra ) |
| return result; |
| } |
| } else { |
| // it is just a word; return it with args as null |
| return new FunctionWithArgs(fn, null); |
| } |
| } |
| |
| private void skipWhitespace() { |
| while (index<expression.length() && Character.isWhitespace(expression.charAt(index))) |
| index++; |
| } |
| |
| } |