com.google.sitebricks.persist.EntityQuery Maven / Gradle / Ivy

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package com.google.sitebricks.persist;

import java.util.List;

/**
 * @author [email protected] (Dhanji R. Prasanna)
 */
public interface EntityQuery {
   Clause where(E field, FieldMatcher matcher);

  public static interface Clause {
     Clause and(E field, FieldMatcher matcher);

    EntityQuery or();

    List list();

    List list(int limit);

    List list(int offset, int limit);

    /**
     * Delete all matching persistent objects from the underlying datastore. Useful
     * for bulk deletions, only datastores that support this natively will work.
     */
     void remove();
  }

  public static class FieldMatcher {
    public final Kind kind;
    public final E low, high;
    public final double threshold;

    protected FieldMatcher(Kind kind, E value) {
      this(kind, value, null, -1.0);
    }

    protected FieldMatcher(Kind kind, E low, E high) {
      this(kind, low, high, -1.0);
    }

    protected FieldMatcher(Kind kind, E low, E high, double threshold) {
      this.kind = kind;
      this.low = low;
      this.high = high;
      this.threshold = threshold;
    }

    public static  FieldMatcher is(T t) {
      return new FieldMatcher(Kind.IS, t);
    }

    public static  FieldMatcher not(T t) {
      return new FieldMatcher(Kind.NOT, t);
    }

    public static FieldMatcher like(String t) {
      return new FieldMatcher(Kind.LIKE, t);
    }

    /**
     * Adds fuzzy query constraint on the given string matched against a fuzziness threshold.
     * For example:
     *      *   similarTo("cafe", 1.0);
     * 
     *
     * May return "cate", "café", "late" etc., depending on the threshold. The threshold is an
     * abstract specifier, which the underlying datastore may choose to incorporate into its
     * algorithm or ignore completely.
     * 
     *   A value of 0 of the threshold indicates an exact match, whereas 1.0 indicates an maximally
     *   expansive, fuzzy match.
     * 
     */
    public static  FieldMatcher similarTo(String t, double threshold) {
      if (threshold > 1.0 || threshold < 0.0)
        throw new IllegalArgumentException("Similarity threshold must be between [0 - 1]");
      return new FieldMatcher(Kind.SIMILAR_TO, t, null, threshold);
    }

    public static  FieldMatcher between(T t1, T t2) {
      return new FieldMatcher(Kind.BETWEEN, t1, t2);
    }

    public static  FieldMatcher above(T t) {
      return new FieldMatcher(Kind.ABOVE, t);
    }

    public static  FieldMatcher below(T t) {
      return new FieldMatcher(Kind.BELOW, t);
    }

    public static  FieldMatcher aboveIncluding(T t) {
      return new FieldMatcher(Kind.ABOVE_INCLUDING, t);
    }

    public static  FieldMatcher belowIncluding(T t) {
      return new FieldMatcher(Kind.BELOW_INCLUDING, t);
    }

    public static enum Kind {
      IS, NOT, LIKE, SIMILAR_TO, ABOVE, BELOW, ABOVE_INCLUDING, BELOW_INCLUDING, BETWEEN,
      CUSTOM,
    }
  }
}