| /* |
| * 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.commons.jexl3.internal; |
| |
| import java.util.ArrayDeque; |
| import java.util.Deque; |
| |
| /** |
| * The set of valued symbols defined in a lexical frame. |
| * <p>The symbol identifiers are determined by the functional scope. |
| */ |
| public class LexicalFrame extends LexicalScope { |
| /** |
| * The script frame. |
| */ |
| private final Frame frame; |
| /** |
| * Previous frame. |
| */ |
| protected LexicalFrame previous; |
| /** |
| * The stack of values in the lexical frame. |
| */ |
| private Deque<Object> stack = null; |
| |
| /** |
| * Lexical frame ctor. |
| * |
| * @param scriptf the script frame |
| * @param outerf the previous lexical frame |
| */ |
| public LexicalFrame(final Frame scriptf, final LexicalFrame outerf) { |
| this.previous = outerf; |
| this.frame = scriptf; |
| } |
| |
| /** |
| * Copy ctor. |
| * |
| * @param src the frame to copy |
| */ |
| public LexicalFrame(final LexicalFrame src) { |
| super(src.symbols, src.moreSymbols); |
| frame = src.frame; |
| previous = src.previous; |
| stack = src.stack != null ? new ArrayDeque<>(src.stack) : null; |
| } |
| |
| /** |
| * Define the arguments. |
| * |
| * @return this frame |
| */ |
| public LexicalFrame defineArgs() { |
| if (frame != null) { |
| final int argc = frame.getScope().getArgCount(); |
| for (int a = 0; a < argc; ++a) { |
| super.addSymbol(a); |
| } |
| } |
| return this; |
| } |
| |
| /** |
| * Defines a symbol. |
| * |
| * @param symbol the symbol to define |
| * @param capture whether this redefines a captured symbol |
| * @return true if symbol is defined, false otherwise |
| */ |
| public boolean defineSymbol(final int symbol, final boolean capture) { |
| final boolean declared = addSymbol(symbol); |
| if (declared && capture) { |
| if (stack == null) { |
| stack = new ArrayDeque<>(); |
| } |
| stack.push(symbol); |
| Object value = frame.get(symbol); |
| if (value == null) { |
| value = this; |
| } |
| stack.push(value); |
| } |
| return declared; |
| } |
| |
| /** |
| * Pops back values and lexical frame. |
| * |
| * @return the previous frame |
| */ |
| public LexicalFrame pop() { |
| // undefine all symbols |
| clearSymbols(s -> frame.set(s, Scope.UNDEFINED) ); |
| // restore values of captured symbols that were overwritten |
| if (stack != null) { |
| while (!stack.isEmpty()) { |
| Object value = stack.pop(); |
| if (value == Scope.UNDECLARED) { |
| value = Scope.UNDEFINED; |
| } else if (value == this) { |
| value = null; |
| } |
| final int symbol = (Integer) stack.pop(); |
| frame.set(symbol, value); |
| } |
| } |
| return previous; |
| } |
| |
| } |