| /******************************************************************************* |
| * 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.sling.scripting.sightly.compiler.util; |
| |
| import java.util.AbstractMap; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Stack; |
| |
| /** |
| * Tracks information related to HTL variables, at different levels of the compiler. |
| */ |
| public final class VariableTracker<T> { |
| |
| private final Map<String, Stack<T>> variableData = new HashMap<>(); |
| private final Stack<String> declarationStack = new Stack<>(); |
| |
| /** |
| * Checks if the variable identified by {@code name} is tracked by this tracker or not. |
| * |
| * @param name the name of the variable |
| * @return {@code true} if the variable is declared, {@code false} otherwise |
| */ |
| public boolean isDeclared(String name) { |
| name = name.toLowerCase(); |
| Stack<T> dataStack = variableData.get(name); |
| return dataStack != null; |
| } |
| |
| /** |
| * Pushes a variable to this tracker. Call this method whenever a variable is declared. |
| * |
| * @param name the name of the variable |
| * @param data the data associated with the variable |
| */ |
| public void pushVariable(String name, T data) { |
| name = name.toLowerCase(); |
| Stack<T> dataStack = variableData.get(name); |
| if (dataStack == null) { |
| dataStack = new Stack<>(); |
| variableData.put(name, dataStack); |
| } |
| dataStack.push(data); |
| declarationStack.push(name); |
| } |
| |
| /** |
| * Pops a variable from this tracker. Call this method whenever a variable goes out of scope. |
| * |
| * @return the name of the popped variable |
| * @throws java.util.NoSuchElementException if there are no declared variables in the scope |
| */ |
| public String popVariable() { |
| String variable = declarationStack.pop(); |
| Stack<T> dataStack = variableData.get(variable); |
| assert dataStack != null; |
| dataStack.pop(); |
| if (dataStack.isEmpty()) { |
| variableData.remove(variable); |
| } |
| return variable; |
| } |
| |
| /** |
| * Peeks at the top of the declaration stack. |
| * |
| * @return the most recently declared variable and its associated data |
| * @throws java.util.NoSuchElementException if there are no variables in scope |
| */ |
| public Map.Entry<String, T> peek() { |
| String variable = declarationStack.peek(); |
| Stack<T> dataStack = variableData.get(variable); |
| assert dataStack != null; |
| T data = dataStack.peek(); |
| return new AbstractMap.SimpleImmutableEntry<>(variable, data); |
| } |
| |
| /** |
| * Checks if the declaration stack is empty. |
| * |
| * @return {@code true} if the stack is empty, {@code false} otherwise |
| */ |
| public boolean isEmpty() { |
| return declarationStack.isEmpty(); |
| } |
| |
| /** |
| * Get the data associated with the given variable. |
| * |
| * @param name the name of the variable |
| * @return the associated data or {@code null} if that variable is not in scope |
| */ |
| public T get(String name) { |
| name = name.toLowerCase(); |
| Stack<T> dataStack = variableData.get(name); |
| if (dataStack == null) { |
| return null; |
| } |
| assert !dataStack.isEmpty(); |
| return dataStack.peek(); |
| } |
| |
| /** |
| * Check whether a variable was declared and is visible in the current scope. |
| * |
| * @param name the name of the variable |
| * @return {@code true} if the variable is visible in the current scope, {@code false} otherwise |
| */ |
| public boolean isInScope(String name) { |
| name = name.toLowerCase(); |
| return variableData.get(name) != null; |
| } |
| |
| /** |
| * Get an immutable view of all the data items associated with the specified variable. |
| * |
| * @param name the name of the variable |
| * @return a list of all the data associated with this variable name. If the variable is not declared in the current scope then that |
| * list will be empty. Otherwise it will contain all the data associated for the current scope starting with the data associated at |
| * the topmost scope and ending with the most recently associated data |
| */ |
| public List<T> getAll(String name) { |
| name = name.toLowerCase(); |
| Stack<T> dataStack = variableData.get(name); |
| if (dataStack == null) { |
| return Collections.emptyList(); |
| } |
| return Collections.unmodifiableList(dataStack); |
| } |
| |
| /** |
| * Get how many times a variable was declared in the current scope. |
| * |
| * @param name the name of the variable |
| * @return the number of declarations for a variable in the current scope |
| */ |
| public int getOccurrenceCount(String name) { |
| name = name.toLowerCase(); |
| Stack<T> dataStack = variableData.get(name); |
| if (dataStack == null) { |
| return 0; |
| } |
| return dataStack.size(); |
| } |
| } |