livestatus/src/Filter.h

   1 // +------------------------------------------------------------------+
   2 // |             ____ _               _        __  __ _  __           |
   3 // |            / ___| |__   ___  ___| | __   |  \/  | |/ /           |
   4 // |           | |   | '_ \ / _ \/ __| |/ /   | |\/| | ' /            |
   5 // |           | |___| | | |  __/ (__|   <    | |  | | . \            |
   6 // |            \____|_| |_|\___|\___|_|\_\___|_|  |_|_|\_\           |
   7 // |                                                                  |
   8 // | Copyright Mathias Kettner 2014             mk@mathias-kettner.de |
   9 // +------------------------------------------------------------------+
  10 //
  11 // This file is part of Check_MK.
  12 // The official homepage is at http://mathias-kettner.de/check_mk.
  13 //
  14 // check_mk is free software;  you can redistribute it and/or modify it
  15 // under the  terms of the  GNU General Public License  as published by
  16 // the Free Software Foundation in version 2.  check_mk is  distributed
  17 // in the hope that it will be useful, but WITHOUT ANY WARRANTY;  with-
  18 // out even the implied warranty of  MERCHANTABILITY  or  FITNESS FOR A
  19 // PARTICULAR PURPOSE. See the  GNU General Public License for more de-
  20 // tails. You should have  received  a copy of the  GNU  General Public
  21 // License along with GNU Make; see the file  COPYING.  If  not,  write
  22 // to the Free Software Foundation, Inc., 51 Franklin St,  Fifth Floor,
  23 // Boston, MA 02110-1301 USA.
  24
  25 #ifndef Filter_h
  26 #define Filter_h
  27
  28 #include "config.h"  // IWYU pragma: keep
  29 #include <bitset>
  30 #include <chrono>
  31 #include <cstdint>
  32 #include <functional>
  33 #include <iosfwd>
  34 #include <memory>
  35 #include <optional>
  36 #include <string>
  37 #include <vector>
  38 #include "contact_fwd.h"
  39 class Column;
  40 class Filter;
  41 class Row;
  42
  43 using Filters = std::vector<std::unique_ptr<Filter>>;
  44
  45 /// A propositional formula over column value relations, kept in negation normal
  46 /// form.
  47 class Filter {
  48 public:
  49     enum Kind { row, stats, wait_condition };
  50
  51     explicit Filter(Kind kind) : _kind(kind) {}
  52     virtual ~Filter();
  53     Kind kind() const { return _kind; }
  54     virtual bool accepts(Row row, const contact *auth_user,
  55                          std::chrono::seconds timezone_offset) const = 0;
  56     virtual std::unique_ptr<Filter> partialFilter(
  57         std::function<bool(const Column &)> predicate) const = 0;
  58
  59     // TODO(sp) We might be able to unify all the methods below if we make the
  60     // underlying lattice structure explicit, i.e. provide a set type and
  61     // corresponding meet/join operations. Perhaps we can even get rid of the
  62     // std::optional by making the lattice bounded, i.e. by providing bottom/top
  63     // values.
  64     virtual std::optional<std::string> stringValueRestrictionFor(
  65         const std::string &column_name) const;
  66     virtual std::optional<int32_t> greatestLowerBoundFor(
  67         const std::string &column_name,
  68         std::chrono::seconds timezone_offset) const;
  69     virtual std::optional<int32_t> leastUpperBoundFor(
  70         const std::string &column_name,
  71         std::chrono::seconds timezone_offset) const;
  72     virtual std::optional<std::bitset<32>> valueSetLeastUpperBoundFor(
  73         const std::string &column_name,
  74         std::chrono::seconds timezone_offset) const;
  75
  76     virtual std::unique_ptr<Filter> copy() const = 0;
  77     virtual std::unique_ptr<Filter> negate() const = 0;
  78
  79     /// Checks for a *syntactic* tautology.
  80     virtual bool is_tautology() const = 0;
  81
  82     /// Checks for a *syntactic* contradiction.
  83     virtual bool is_contradiction() const = 0;
  84
  85     /// Combining the returned filters with *or* yields a filter equivalent to
  86     /// the current one.
  87     virtual Filters disjuncts() const = 0;
  88
  89     /// Combining the returned filters with *and* yields a filter equivalent to
  90     /// the current one.
  91     virtual Filters conjuncts() const = 0;
  92
  93     friend std::ostream &operator<<(std::ostream &os, const Filter &filter) {
  94         return filter.print(os);
  95     }
  96
  97 private:
  98     const Kind _kind;
  99     virtual std::ostream &print(std::ostream &os) const = 0;
 100 };
 101
 102 #endif  // Filter_h