// An extension of strings that is comparable.
// (c) 1996 duane a. bailey
package structure;

public class ComparableString implements Comparable
{
    protected String val;

    public ComparableString(String s)
    // pre: s is non-null
    // post: construct a ComparableString whose initial value is s.
    {
        Assert.pre(s != null, "Initial string is non-null");
        val = s;
    }

    public boolean lessThan(Comparable other)
    // pre: other is non-null
    // post: returns true if this string is less than the other
    //       string, lexically
    {
        Assert.pre(other != null,"Comparison value is non-null.");
        Assert.pre(other instanceof ComparableString,
                   "lessThan expects a ComparableString");
        ComparableString otherString = (ComparableString)other;
        return val.compareTo(otherString.value()) < 0;
    }

    public boolean equals(Object other)
    // pre: other is non-null
    // post: returns true if this string is same as other
    //       string, lexically
    {
        Assert.pre(other != null,"Comparison value is non-null.");
        Assert.pre(other instanceof ComparableString,
                   "equals expects a ComparableString");
        ComparableString otherString = (ComparableString)other;
        return val.compareTo(otherString.value()) == 0;
    }
    
    public int hashCode()
    // pre: returns hash code associated with string.
    {
        return val.hashCode();
    }

    public String value()
    // post: returns the underlying value of the string.
    {
        return val;
    }

    public String toString()
    // post: returns string representation
    {
        return val;
    }
}