69 lines
1.9 KiB
Nim
69 lines
1.9 KiB
Nim
# Copyright 2024 Mattia Giambirtone & All Contributors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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## Position evaluation utilities
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import board
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type
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Score* = int16
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proc getPieceValue(kind: PieceKind): Score =
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## Returns the absolute value of a piece
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case kind:
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of Pawn:
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return Score(100)
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of Bishop:
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return Score(330)
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of Knight:
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return Score(280)
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of Rook:
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return Score(525)
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of Queen:
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return Score(950)
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else:
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discard
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proc getPieceScore(board: Chessboard, square: Square): Score =
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## Returns the value of the piece located at
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## the given square
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return board.getPiece(square).kind.getPieceValue()
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proc evaluateMaterial(board: ChessBoard): Score =
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## Returns the material evaluation of the
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## current position relative to white (positive
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## if in white's favor, negative otherwise)
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var
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whiteScore: Score
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blackScore: Score
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for sq in board.getOccupancyFor(White):
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whiteScore += board.getPieceScore(sq)
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for sq in board.getOccupancyFor(Black):
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blackScore += board.getPieceScore(sq)
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result = whiteScore - blackScore
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if board.position.sideToMove == Black:
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result *= -1
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proc evaluate*(board: Chessboard): Score =
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## Evaluates the current position
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result = board.evaluateMaterial() |