freemarker-core/src/main/java/org/apache/freemarker/core/_Debug.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.freemarker.core;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by Én on 2/26/2017.
 */
public final class _Debug {

    private _Debug() {
        //
    }


    public static void insertDebugBreak(Template t, int line) {
        ASTElement te = findTemplateElement(t.getRootASTNode(), line);
        if (te == null) {
            return;
        }
        ASTElement parent = te.getParent();
        ASTDebugBreak db = new ASTDebugBreak(te);
        // TODO: Ensure there always is a parent by making sure
        // that the root element in the template is always a ASTImplicitParent
        // Also make sure it doesn't conflict with anyone's code.
        parent.setChildAt(indexOfChild(parent, te), db);
    }

    public static void removeDebugBreak(Template t, int line) {
        ASTElement te = findTemplateElement(t.getRootASTNode(), line);
        if (te == null) {
            return;
        }
        ASTDebugBreak db = null;
        while (te != null) {
            if (te instanceof ASTDebugBreak) {
                db = (ASTDebugBreak) te;
                break;
            }
            te = te.getParent();
        }
        if (db == null) {
            return;
        }
        ASTElement parent = db.getParent();
        parent.setChildAt(indexOfChild(parent, db), db.fastGetChild(0));
    }
    
    private static final int indexOfChild(ASTElement parent, ASTElement node) {
        for (int i = 0; i < parent.getChildCount(); i++) {
            if (parent.getChild(i) == node) {
                return i;
            }
        }
        return -1;
    }

    private static ASTElement findTemplateElement(ASTElement te, int line) {
        if (te.getBeginLine() > line || te.getEndLine() < line) {
            return null;
        }
        // Find the narrowest match
        List<ASTElement> childMatches = new ArrayList<>();
        for (ASTElement child : te.getChildren()) {
            ASTElement childmatch = findTemplateElement(child, line);
            if (childmatch != null) {
                childMatches.add(childmatch);
            }
        }
        //find a match that exactly matches the begin/end line
        ASTElement bestMatch = null;
        for (int i = 0; i < childMatches.size(); i++) {
            ASTElement e = childMatches.get(i);

            if ( bestMatch == null ) {
                bestMatch = e;
            }

            if ( e.getBeginLine() == line && e.getEndLine() > line ) {
                bestMatch = e;
            }

            if ( e.getBeginLine() == e.getEndLine() && e.getBeginLine() == line) {
                bestMatch = e;
                break;
            }
        }
        if ( bestMatch != null) {
            return bestMatch;
        }
        // If no child provides narrower match, return this
        return te;
    }

    public static void removeDebugBreaks(Template t) {
        removeDebugBreaks(t.getRootASTNode());
    }

    private static void removeDebugBreaks(ASTElement te) {
        int count = te.getChildCount();
        for (int i = 0; i < count; ++i) {
            ASTElement child = te.fastGetChild(i);
            while (child instanceof ASTDebugBreak) {
                ASTElement dbchild = child.fastGetChild(0);
                te.setChildAt(i, dbchild);
                child = dbchild;
            }
            removeDebugBreaks(child);
        }
    }
}