A basic implementation of generative grammar in Java

_README.md

The code might be changed and you can browse the master branch of repository here.

Category.java

package com.erayerdin.linglib.syntax.generative;

import java.util.HashMap;

/**
 * A Category for syntactic structure.
 *
 * @author Eray Erdin
 * @see com.erayerdin.linglib.syntax.generative.Phrase
 */
public class Category implements java.io.Serializable {
    public String name;
    protected Character initialChar;

    // Category Library
    public static Category NOUN = new Category("Noun");
    public static Category ADJECTIVE = new Category("Adjective");
    public static Category DETERMINER = new Category("Determiner");
    public static Category VERB = new Category("Verb");
    public static Category ADVERB = new Category("Adverb");
    public static Category INFLECTION = new Category("Inflection");
    public static Category COMPLEMENTIZER = new Category("Complementizer");

    public static HashMap<String, Category> COMMONS = new HashMap<String, Category>(){{
        put("noun", NOUN);
        put("adjective", ADJECTIVE);
        put("determiner", DETERMINER);
        put("verb", VERB);
        put("adverb", ADVERB);
        put("inflection", INFLECTION);
        put("complementizer", COMPLEMENTIZER);
    }};

    public Category(String name) {
        this.name = name;
        this.initialChar = this.name.charAt(0);
    }

    public String toString() {
        return String.format("Category: %s", this.name);
    }
}

Parameter.java

package com.erayerdin.linglib.syntax.generative;

/**
 * A Parameter for generative grammar.
 * Parameter is passed to render function of any
 * Phrase object to linearize a Phrase object
 * to a string.
 *
 * @author Eray Erdin
 * @see com.erayerdin.linglib.syntax.generative.Phrase
 */
public class Parameter implements java.io.Serializable {
    protected boolean complement;
    protected boolean adjunct;
    protected boolean specifier;

    public Parameter(boolean complement, boolean adjunct, boolean specifier) {
        this.complement = complement;
        this.adjunct = adjunct;
        this.specifier = specifier;
    }

    public Parameter(boolean complement, boolean adjunct) {
        this.complement = complement;
        this.adjunct = adjunct;
        this.specifier = false;
    }

    public String toString() {
        java.util.ArrayList<String> places = new java.util.ArrayList<String>();
        places.add("terminal");

        if (this.complement == false)
            places.add(0, "[complement]");
        else
            places.add("[complement]");

        if (this.adjunct == false)
            places.add(0, "[adjunct...]");
        else
            places.add("[adjunct...]");

        if (this.specifier == false)
            places.add(0, "[specifier]");
        else
            places.add("[specifier]");

        String placesString = Phrase.mergeStringArray(places);
        String string = String.format("Parameter: %s", placesString);
        return string;
    }
}

Phrase.java

package com.erayerdin.linglib.syntax.generative;

import java.util.ArrayList;

/**
 * A Phrase in Generative syntax structure.
 *
 * @author Eray Erdin
 * @see com.erayerdin.linglib.syntax.generative.Category
 * @see com.erayerdin.linglib.syntax.generative.Parameter
 */
public class Phrase implements java.io.Serializable {
    private Category category;
    private Phrase complement = null;
    private ArrayList<Phrase> adjunct = new ArrayList<Phrase>();
    private Phrase specifier = null;
    public String value = null;

    public  Phrase(Category category) {
        this.category = category;
    }

    public Phrase(Category category, String value) {
        this.category = category;
        this.value = value;
    }

//    public Phrase(Category category, Phrase complement) {
//        this.category = category;
//        this.complement = complement;
//        this.adjunct = null;
//        this.specifier = null;
//    }

    public String toString() {
        return String.format("Phrase: %s", this.value);
    }

    /**
     * Gets complement object.
     *
     * @return Returns complement Phrase.
     */
    public Phrase getComplement() {
        return this.complement;
    }

    /**
     * Changes complement with given object.
     *
     * @param complement A Phrase object.
     */
    public void extendComplement(Phrase complement) {
        this.complement = complement;
    }

    /**
     * Gets specifier object.
     *
     * @return Returns specifier Phrase.
     */
    public Phrase getSpecifier() {
        return this.specifier;
    }

    /**
     * Changes specifier with given object.
     *
     * @param specifier A Phrase object.
     */
    public void extendSpecifier(Phrase specifier) {
        this.specifier = specifier;
    }

    /**
     * Gets an adjunct with given index.
     *
     * @param index Index of adjunct.
     * @return A Phrase object.
     */
    public Phrase getAdjunct(int index) {
        return this.adjunct.get(index);
    }

    /**
     * Adds adjunct Phrase.
     *
     * @param adjunct A Phrase object.
     */
    public void addAdjunct(Phrase adjunct) {
        this.adjunct.add(adjunct);
    }

    /**
     * Adds adjunct Phrase to given index.
     *
     * @param index Index to be added.
     * @param adjunct A Phrase object.
     */
    public void addAdjunct(int index, Phrase adjunct) {
        this.adjunct.add(index,adjunct);
    }

    /**
     * Removes adjunct in given index.
     *
     * @param index Index to be removed.
     */
    public void removeAdjunct(int index) {
        this.adjunct.remove(index);
    }

    /**
     * Size of adjuncts.
     *
     * @return The size of adjuncts.
     */
    public int sizeAdjunct() {
        return this.adjunct.size();
    }

    /**
     * Gets all adjuncts in ArrayList.
     *
     * @return ArrayList of Phrase objects.
     */
    public ArrayList<Phrase> adjuncts() {
        return this.adjunct;
    }

    /**
     * Joins an Array of String objects with space between.
     *
     * @param stringArray An Array of String objects.
     * @return Joined string of string array.
     */
    public static String mergeStringArray(String[] stringArray) {
        ArrayList<String> newStringArrayList = new ArrayList<String>();

        for (String s : stringArray) {
            if (s != null)
                newStringArrayList.add(s);
        }

        String newString = String.join(" ", newStringArrayList);
        return newString;
    }

    /**
     * Joins an ArrayList of String objects with space between.
     *
     * @param stringArray An ArrayList of String objects.
     * @return Joined string of string ArrayList.
     */
    public static String mergeStringArray(ArrayList<String> stringArrayList) {
        ArrayList<String> newStringArrayList = new ArrayList<String>();

        for (String s : stringArrayList) {
            if (s != null)
                newStringArrayList.add(s);
        }

        String newString = String.join(" ", newStringArrayList);
        return newString;
    }

    /**
     * Renders this Phrase object with all complement, adjunct and specifier objects.
     *
     * @param param A Parameter object.
     * @return A merged string.
     */
    public String render(Parameter param) {
        ArrayList<String> renderArrayList = new ArrayList<String>();
        renderArrayList.add(this.value);

        // Add complement
        if (this.complement != null) {
            if (param.complement == false)
                renderArrayList.add(0, this.complement.render(param));
            else
                renderArrayList.add(this.complement.render(param));
        }

        // Add adjuncts
        if (this.adjunct.size() != 0) {
            // Render all adjuncts
            ArrayList<String> renderAdjunctArrayList = new ArrayList<String>();

            for (Phrase a : this.adjunct) {
                renderAdjunctArrayList.add(
                        a.render(param)
                );
            }

            String renderAdjunctString = Phrase.mergeStringArray(renderAdjunctArrayList);

            if (param.adjunct == false)
                renderArrayList.add(0, renderAdjunctString);
            else
                renderArrayList.add(renderAdjunctString);
        }

        // Add specifier
        if (this.specifier != null) {
            if (param.specifier == false)
                renderArrayList.add(0, this.specifier.render(param));
            else
                renderArrayList.add(this.specifier.render(param));
        }

        String mergeAll = Phrase.mergeStringArray(renderArrayList);

        return mergeAll;
    }
}