SQLPredicate.jsh

class SQLPredicate<T> {
    private final Predicate<T> t;
    private final String sql;

    SQLPredicate(Predicate<T> t, String name) {
        this.t = t;
        this.sql = name;
    }
    
    static <T> SQLPredicate<T> of(Predicate<T> t, String sql) {
        return new SQLPredicate<T>(t, sql);
    }
    String getSql() {
        return sql;
    }
    boolean test(T t) {
        return this.t.test(t);
    }
    SQLPredicate<T> and(SQLPredicate<? super T> other) {
        return new SQLPredicate<>((t) -> this.test(t) && other.test(t), "(" + this.sql + " AND " + other.sql + ")");
    }
    SQLPredicate<T> negate() {
        return new SQLPredicate<>((t) -> !this.test(t), "NOT " + this.sql);
    }
    SQLPredicate<T> or(SQLPredicate<? super T> other) {
        return new SQLPredicate<>((t) -> this.test(t) || other.test(t), "(" + this.sql + " OR " + other.sql + ")");
    }
}

    class Entity {
    public String name;
    public String address;
    public Integer year;

    public Entity(String name, String address, Integer year) {
        this.name = name;
        this.address = address;
        this.year = year;
    }
}

SQLPredicate<Entity> hasName = of(e -> e.name != null, "name = :name");
SQLPredicate<Entity> hasAddress = of(e -> e.address != null, "address = :address");
SQLPredicate<Entity> hasYear = of(e -> e.year != null, "year = :year");
SQLPredicate<Entity> hasAll = of(
  e -> e.year != null & e.address != null & e.name != null,
  "year = :year and year = :year and year = :year");
SQLPredicate<Entity> hasNameOrAddress = hasName.or(hasAddress);
SQLPredicate<Entity> hasYearAndHasNameOrAddress = hasYear.and(hasNameOrAddress);
hasYearAndHasNameOrAddress.getSql();
hasYearAndHasNameOrAddress.test(new Entity(null, "addr", 1995));
hasYearAndHasNameOrAddress.test(new Entity(null, "addr", null));