jlibs.nblr.codegen.RuleMethod Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jlibs-nblr Show documentation
Non-Blocking Language Recognition
There is a newer version: 3.0.1
/**
 * Copyright 2015 Santhosh Kumar Tekuri
 *
 * The JLibs authors license 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 jlibs.nblr.codegen;

import jlibs.core.annotation.processing.Printer;
import jlibs.nblr.codegen.java.SyntaxClass;
import jlibs.nblr.rules.Node;
import jlibs.nblr.rules.Rule;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;

import static jlibs.core.annotation.processing.Printer.MINUS;
import static jlibs.core.annotation.processing.Printer.PLUS;

/**
 * @author Santhosh Kumar T
 */
public class RuleMethod{
    public final SyntaxClass syntaxClass;
    public final Rule rule;
    public final List states = new ArrayList();

    public RuleMethod(SyntaxClass syntaxClass, Rule rule){
        this.syntaxClass = syntaxClass;
        this.rule = rule;

        ArrayList statesVisited = new ArrayList();
        LinkedHashSet statesPending = new LinkedHashSet();
        statesPending.add(rule.node);

        while(!statesPending.isEmpty()){
            List list = new ArrayList(statesPending);
            Node pendingNode = list.get(list.size()-1);
            statesPending.remove(pendingNode);
            statesVisited.add(pendingNode);
            State state = new State(this, pendingNode);
            states.add(state);
            state.computeNextStates(statesVisited, statesPending);
            if(statesPending.isEmpty()){
                for(Node node: rule.nodes()){
                    if(node.name!=null && !node.name.equals(Node.DYNAMIC_STRING_MATCH)){
                        if(!statesVisited.contains(node))
                            statesPending.add(node);
                    }
                }
            }
        }

        int i = -1;
        for(State state: states){
            ++i;
            state.fromNode.stateID = SyntaxClass.DEBUGGABLE ? state.fromNode.id : i;
        }
    }

    public boolean deleteEmptySwitches(){
        boolean changed = false;
        for(State state: states){
            if(state.decisions.size()==1){
                Decision decision = state.decisions.get(0);
                if(decision.isEmpty()){
                    decision.collapse();
                    changed = true;
                }
            }
        }
        return changed;
    }

    public int maxLookAhead(){
        int maxLookAhead = 0;
        for(State state: states)
            maxLookAhead = Math.max(maxLookAhead, state.maxLookAhead());
        return maxLookAhead;
    }

    public boolean readCodePoint(){
        for(State state: states){
            if(state.readCodePoint())
                return true;
        }
        return false;
    }

    public boolean requiresWhile(){
        for(int i=0; i