Package ca.cgjennings.algo

Class TextIndex

  • All Implemented Interfaces:
    java.lang.Iterable<java.lang.String>
    public class TextIndex
extends java.lang.Object
implements java.lang.Iterable<java.lang.String>
    A searchable reverse index of the words contained in a set of documents. Each document is represented by a string (such as a URL) that identifies it. Given a query, the index returns the set of IDs whose documents match the query. A TextIndex is not constructed directly; the index data is generated as a separate step and stored in a file, and the TextIndex instance is created from that file.
    Since:
    3.0
    Author:
    Chris Jennings

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  TextIndex.And
      A query that matches only documents that match both of two child queries.
      static class  TextIndex.Atom
      An atom is a query that matches all documents that contain a specified one-word search term.
      static class  TextIndex.Not
      A query that matches every document except the documents matched by its child query.
      static class  TextIndex.Or
      A query that matches any documents that match either of two child queries.
      static class  TextIndex.Query
      A Query represents a query expression to be matched against a text index.
      static class  TextIndex.QueryParser
      A parser that converts a plain text query string into a query.
      static interface  TextIndex.Result
      A Result captures the result of a query.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.util.Iterator<java.lang.String> iterator()
      An iterator over the index words.
      static TextIndex read​(java.io.File file)
      Creates a text index from the specified file.
      static TextIndex read​(java.io.InputStream in)
      Creates a text index from a stream.
      static TextIndex read​(java.net.URL url)
      Creates a text index from the file at the specified URL.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

      • Methods inherited from interface java.lang.Iterable

        forEach, spliterator

    • Method Detail

      • read

        public static TextIndex read​(java.io.File file)
                      throws java.io.IOException
        Creates a text index from the specified file.
        Parameters:
        file - the previously written text index
        Returns:
        an index generated from the stored index data
        Throws:
        java.io.IOException - if an I/O error occurs while reading the index

      • read

        public static TextIndex read​(java.net.URL url)
                      throws java.io.IOException
        Creates a text index from the file at the specified URL.
        Parameters:
        url - the location of the previously written text index
        Returns:
        an index generated from the stored index data
        Throws:
        java.io.IOException - if an I/O error occurs while reading the index

      • read

        public static TextIndex read​(java.io.InputStream in)
                      throws java.io.IOException
        Creates a text index from a stream.
        Parameters:
        in - a stream containing the previously written text index
        Returns:
        an index generated from the stored index data
        Throws:
        java.io.IOException - if an I/O error occurs while reading the index

      • iterator

        public java.util.Iterator<java.lang.String> iterator()
        An iterator over the index words.
        Specified by:
        iterator in interface java.lang.Iterable<java.lang.String>
        Returns:
        word iterator