edu.stanford.nlp.ling.Label.java Source code

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Here is the source code for edu.stanford.nlp.ling.Label.java

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package edu.stanford.nlp.ling;

/**
 * Something that implements the <code>Label</code> interface can act as a
 * constituent, node, or word label with linguistic attributes.
 * A <code>Label</code> is required to have a "primary" <code>String</code>
 * <code>value()</code> (although this may be null).  This is referred to as
 * its <code>value</code>.
 * <p>
 * Implementations of Label split into two groups with
 * respect to equality. Classes that extend ValueLabel define equality
 * solely in terms of String equality of its value (secondary facets may be
 * present but are ignored for purposes of equality), and have equals and
 * compareTo defined across all subclasses of ValueLabel. This behavior
 * should not be changed. Other classes that implement Label define equality only
 * with their own type and require all fields of the type to be equal.
 * <p>
 * A subclass that extends another Label class <i>should</i> override
 * the definition of <code>labelFactory()</code>, since the contract for
 * this method is that it should return a factory for labels of the
 * exact same object type.
    
 * @author Christopher Manning
 */
public interface Label {

    /**
     * Return a String representation of just the "main" value of this label.
     *
     * @return the "value" of the label
     */
    public String value();

    /**
     * Set the value for the label (if one is stored).
     *
     * @param value - the value for the label
     */
    public void setValue(String value);

    /**
     * Return a String representation of the label.  For a multipart label,
     * this will return all parts.  The <code>toString()</code> method
     * causes a label to spill its guts.  It should always return an
     * empty string rather than <code>null</code> if there is no value.
     *
     * @return a text representation of the full label contents
     */
    public String toString();

    /**
     * Set the contents of this label to this <code>String</code>
     * representing the
     * complete contents of the label.  A class implementing label may
     * throw an <code>UnsupportedOperationException</code> for this
     * method (only).  Typically, this method would do
     * some appropriate decoding of the string in a way that sets
     * multiple fields in an inverse of the <code>toString()</code>
     * method.
     *
     * @param labelStr the String that translates into the content of the
     *                 label
     */
    public void setFromString(String labelStr);

    /**
     * Returns a factory that makes labels of the exact same type as this one.
     * May return <code>null</code> if no appropriate factory is known.
     *
     * @return the LabelFactory for this kind of label
     */
    public LabelFactory labelFactory();

}