alcibiades 0.3.0

A framework for writing chess engines in Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100

//! Defines the `Evaluator` trait.

use uci::SetOption;
use board::Board;
use moves::Move;
use value::*;


/// A trait used to statically evaluate positions.
///
/// An evaluation function is used to heuristically determine the
/// relative value of a position, i.e. the chances of winning. If we
/// could see to the end of the game in every line, the evaluation
/// would only have values of "loss", "draw", and "win". In practice,
/// however, we do not know the exact value of a position, so we must
/// make an approximation. Beginning chess players learn to do this
/// starting with the value of the pieces themselves. Computer
/// evaluation functions also use the value of the material as the
/// most significant aspect and then add other considerations.
///
/// Static evaluation is an evaluation that considers only the static
/// material and positional properties of the current position,
/// without analyzing any tactical variations. Therefore, if the
/// position has pending tactical threats, the static evaluation will
/// be grossly incorrect. To implement your own static evaluator, you
/// must define a type that implements the `Evaluator` trait.
pub trait Evaluator: Clone + SetOption + Send + 'static {
    /// Creates a new instance bound to a given position.
    ///
    /// When a new evaluator is created it is bound to a particular
    /// chess position (given by the `position` parameter), and for
    /// the moment, this is the only position that it can
    /// evaluate. The evaluator then can be re-bound to the next (or
    /// the previous) position in the current line of play by issuing
    /// a pair of calls to the `will_do_move` and `done_move` methods
    /// (or respectively, `will_undo_move` and `undone_move`
    /// methods). Thus, evaluator's state can be kept up-to-date,
    /// following the current line of play.
    fn new(position: &Board) -> Self;

    /// Evaluates the the position to which the evaluator is currently
    /// bound.
    ///
    /// `position` points to the position to which the evaluator is
    /// currently bound.
    ///
    /// The returned value must be between `VALUE_EVAL_MIN` and
    /// `VALUE_EVAL_MAX`.
    fn evaluate(&self, position: &Board) -> Value;

    /// Returns whether the position to which the evaluator is
    /// currently bound is "zugzwangy".
    ///
    /// `position` points to the position to which the evaluator is
    /// currently bound.
    ///
    /// In many endgame positions there is a relatively high
    /// probability of zugzwang occurring. For such positions, this
    /// method returns `true`. This is useful when we want to decide
    /// whether it is safe to try a null move.
    fn is_zugzwangy(&self, position: &Board) -> bool;

    /// Updates evaluator's state to keep up with a move that will be
    /// played.
    ///
    /// `position` points to the position to which the evaluator is
    /// currently bound (that is: before `m` is played).
    ///
    /// `m` is a legal move, or (if not in check) a "null move".
    #[inline]
    #[allow(unused_variables)]
    fn will_do_move(&mut self, position: &Board, m: Move) {}

    /// Updates evaluator's state to keep up with a move that was
    /// played.
    ///
    /// `position` points to the new position to which the evaluator
    /// is bound (that is: after `m` was played).
    #[inline]
    #[allow(unused_variables)]
    fn done_move(&mut self, position: &Board, m: Move) {}

    /// Updates evaluator's state to keep up with a move that will be
    /// taken back.
    ///
    /// `position` points to the position to which the evaluator is
    /// currently bound (that is: before `m` is taken back).
    #[inline]
    #[allow(unused_variables)]
    fn will_undo_move(&mut self, position: &Board, m: Move) {}

    /// Updates evaluator's state in accordance with a move that was
    /// taken back.
    ///
    /// `position` points to the new position to which the evaluator is
    /// bound (that is: after `m` was taken back).
    #[inline]
    #[allow(unused_variables)]
    fn undone_move(&mut self, position: &Board, m: Move) {}
}