IncrementalRecognizer.java

package com.sap.ide.cts.parser.incremental;

import static com.sap.furcas.runtime.textblocks.TbNavigationUtil.getNextInSubTree;
import static com.sap.furcas.runtime.textblocks.TbNavigationUtil.getSubNodeAt;
import static com.sap.furcas.runtime.textblocks.TbNavigationUtil.getSubNodes;
import static com.sap.furcas.runtime.textblocks.TbNavigationUtil.isLastInSubTree;
import static com.sap.furcas.runtime.textblocks.TbNavigationUtil.isToken;
import static com.sap.furcas.runtime.textblocks.modifcation.TbMarkingUtil.isEOS;
import static com.sap.furcas.runtime.textblocks.modifcation.TbMarkingUtil.marked;
import static com.sap.furcas.runtime.textblocks.modifcation.TbVersionUtil.getOtherVersion;

import java.util.List;

import com.sap.furcas.metamodel.FURCAS.textblocks.AbstractToken;
import com.sap.furcas.metamodel.FURCAS.textblocks.Bostoken;
import com.sap.furcas.metamodel.FURCAS.textblocks.DocumentNode;
import com.sap.furcas.metamodel.FURCAS.textblocks.Eostoken;
import com.sap.furcas.metamodel.FURCAS.textblocks.TextBlock;
import com.sap.furcas.metamodel.FURCAS.textblocks.TextblocksFactory;
import com.sap.furcas.metamodel.FURCAS.textblocks.Version;

public abstract class IncrementalRecognizer {

    public static final String EOS = "EOS";
    public static final String BOS = "BOS";
    protected Bostoken bosRef;
    protected Eostoken eosRef;
    protected TextblocksFactory textblocksFactory = TextblocksFactory.eINSTANCE;

    /**
     * As the Beginning of Stream (BOS) token is always the first token in the root textblock this token is used here
     * 
     * @param root
     *            The root textblock of the document to lex
     */
    protected void setBOSFromRoot(TextBlock root) {
        bosRef = (Bostoken) root.getSubNodes().get(0);
    }

    /**
     * As the End of Stream (EOS) token is always the last token in the root textblock this token is used here
     * 
     * @param root
     *            The root textblock of the document to lex
     */
    protected void setEOSFromRoot(TextBlock root) {
        eosRef = (Eostoken) root.getSubNodes().get(root.getSubNodes().size() - 1);
    }

    /**
     * Find the next marked token within or after node.
     */
    protected AbstractToken findNextRegion(DocumentNode node) {
        if (isEOS(node) || (isToken(node) && marked((AbstractToken) node))) {
            return (AbstractToken) node;
        }
        if (node instanceof TextBlock && hasNestedChanges((TextBlock) node, Version.PREVIOUS)) {
            return findNextRegion(getSubNodeAt(((TextBlock) node), 0));
        }
        if (node instanceof TextBlock && ((TextBlock) node).getParent() == null) {
            // node is the parent block and there were no changes detected so
            // return EOS which
            // is always the last token within the Root Textblock
            return eosRef;
        }

        return findNextRegion(nextSubtree(node));
    }

    protected DocumentNode nextSubtree(DocumentNode node) {
        TextBlock parent = node.getParent();
        if (parent == null) {
            // node is the root node so there is no further subtree
            return eosRef;
        }
        if (isLastInSubTree(node)) {
            while (parent.getParent() != null && isLastInSubTree(parent)) {
                // its the last element, so traverse to the next subtree and
                // find the first leaf there
                parent = parent.getParent();
            }
            DocumentNode child = getNextInSubTree(parent);
            return child;
        } else {
            List<? extends DocumentNode> parentSubNodes = getSubNodes(parent);
            return parentSubNodes.get(parentSubNodes.indexOf(node) + 1);
        }
    }

    /**
     * This method should be overridden if a parser uses another token type for eof/oes than -1
     * 
     * @return the token type representing end of stream
     */
    protected static int getEOSTokenType() {
        return -1;
    }

    /**
     * This method should be overridden if a parser uses another token type for bof/bes than -1
     * 
     * @return the token type representing beginning of stream
     */
    protected static int getBOSTokenType() {
        return -2;
    }

    protected static boolean hasNestedChanges(TextBlock node, Version reference) {
        TextBlock otherVersion = getOtherVersion(node, reference);
        if (otherVersion == null) {
            // this means it is a new block which also means that the block is changed
            return true;
        } else {
            return otherVersion.isChildrenChanged();
        }
    }

    protected static boolean wasReLexed(AbstractToken token) {
        // TODO check if this is correct here
        return token.isRelexingNeeded();
    }

}