src/main/java/org/apache/sling/scripting/sightly/java/compiler/impl/VariableAnalyzer.java

/*******************************************************************************
 * 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.java.compiler.impl;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;

import org.apache.sling.commons.compiler.source.JavaEscapeHelper;
import org.apache.sling.scripting.sightly.compiler.util.VariableTracker;
import org.apache.sling.scripting.sightly.java.compiler.SightlyJavaCompilerException;

/**
 * Data structure used in the analysis of variables
 * during the compilation process
 */
public class VariableAnalyzer {

    private final VariableTracker<VariableDescriptor> tracker = new VariableTracker<>();
    private final List<VariableDescriptor> variables = new ArrayList<>();
    private final HashMap<String, VariableDescriptor> dynamicVariables = new HashMap<>();
    private final HashMap<String, VariableDescriptor> staticVariables = new HashMap<>();
    private static final String DYNAMIC_PREFIX = "_dynamic_";
    private static final String GLOBAL_PREFIX = "_global_";

    /**
     * Mark the declaration of a variable in the Java code
     * @param originalName the original name of the variable
     * @param type the variable's type
     * @return - a variable descriptor uniquely assigned to this variable
     */
    public VariableDescriptor declareVariable(String originalName, Type type) {
        originalName = originalName.toLowerCase();
        VariableDescriptor descriptor =
                new VariableDescriptor(originalName, JavaEscapeHelper.getJavaIdentifier(originalName), type, VariableScope.SCOPED);
        tracker.pushVariable(originalName, descriptor);
        variables.add(descriptor);
        return descriptor;
    }

    /**
     * Declare a global variable. Redundant declarations are ignored
     * @param originalName the original name of the variable
     * @return a variable descriptor
     */
    public VariableDescriptor declareGlobal(String originalName) {
        originalName = originalName.toLowerCase();
        VariableDescriptor descriptor = staticVariables.get(originalName);
        if (descriptor == null) {
            String assignedName = findGlobalName(originalName);
            descriptor = new VariableDescriptor(originalName, assignedName, Type.UNKNOWN, VariableScope.GLOBAL);
            variables.add(descriptor);
            staticVariables.put(originalName, descriptor);
        }
        return descriptor;
    }

    /**
     * Mark this variable as a template
     * @param originalName the original name of the variable
     * @return a variable descriptor
     */
    public VariableDescriptor declareTemplate(String originalName) {
        originalName = originalName.toLowerCase();
        VariableDescriptor descriptor = dynamicDescriptor(originalName);
        descriptor.markAsTemplate();
        return descriptor;
    }

    /**
     * Mark the end of a variable scope
     */
    public VariableDescriptor endVariable() {
        VariableDescriptor descriptor = tracker.peek().getValue();
        tracker.popVariable();
        return descriptor;
    }

    /**
     * Get a the descriptor for the given variable
     * @param name the original lowerName of the variable
     * @return the variable descriptor. If the variable is not in scope,
     * then a dynamic variable descriptor is provided
     */
    public VariableDescriptor descriptor(String name) {
        String lowerName = name.toLowerCase();
        VariableDescriptor descriptor = tracker.get(lowerName);
        if (descriptor == null) {
            descriptor = staticVariables.get(lowerName);
        }
        if (descriptor == null) {
            descriptor = dynamicDescriptor(lowerName);
        }
        return descriptor;
    }

    /**
     * Get the collection of all the variables encountered so far
     * @return an unmodifiable list of all the variables tracked by this analyzer
     */
    public Collection<VariableDescriptor> allVariables() {
        return Collections.unmodifiableList(variables);
    }

    /**
     * Shortcut method that returns the assigned name for the given
     * variable
     * @param original the original variable name
     * @return the assigned name for this compilation process
     */
    public String assignedName(String original) {
        return descriptor(original).getAssignedName();
    }

    private VariableDescriptor dynamicDescriptor(String original) {
        VariableDescriptor descriptor = dynamicVariables.get(original);
        if (descriptor == null) {
            String dynamicName = findDynamicName(validName(original));
            descriptor = new VariableDescriptor(original, dynamicName, Type.UNKNOWN, VariableScope.DYNAMIC);
            dynamicVariables.put(original, descriptor);
            variables.add(descriptor);
        }
        return descriptor;
    }

    private String findDynamicName(String original) {
        return DYNAMIC_PREFIX + JavaEscapeHelper.getJavaIdentifier(original);
    }

    private String findGlobalName(String original) {
        return GLOBAL_PREFIX + JavaEscapeHelper.getJavaIdentifier(original);
    }

    private String validName(String name) {
        if (name == null || name.contains("-")) {
            throw new SightlyJavaCompilerException("Unsupported identifier name: " + name);
        }
        return name.toLowerCase();
    }
}