[Shogi] Make core singlefile (#1273)

pgx/_src/games/shogi.py

@@ -16,26 +16,281 @@
 from typing import NamedTuple
 from functools import partial
 
+import numpy as np
 import jax
+from jax import Array
 import jax.numpy as jnp
 
-from pgx._src.shogi_utils import (
-    AROUND_IX,
-    BETWEEN_IX,
-    CAN_MOVE,
-    CAN_MOVE_ANY,
-    INIT_PIECE_BOARD,
-    LEGAL_FROM_IDX,
-    NEIGHBOUR_IX,
-)
-from pgx._src.struct import dataclass
-from pgx._src.types import Array
 
 MAX_TERMINATION_STEPS = 512  # From AZ paper
 
 TRUE = jnp.bool_(True)
 FALSE = jnp.bool_(False)
 
+
+EMPTY = -1  # 空白
+PAWN = 0  # 歩
+LANCE = 1  # 香
+KNIGHT = 2  # 桂
+SILVER = 3  # 銀
+BISHOP = 4  # 角
+ROOK = 5  # 飛
+GOLD = 6  # 金
+KING = 7  # 玉
+PRO_PAWN = 8  # と
+PRO_LANCE = 9  # 成香
+PRO_KNIGHT = 10  # 成桂
+PRO_SILVER = 11  # 成銀
+HORSE = 12  # 馬
+DRAGON = 13  # 龍
+
+
+# fmt: off
+INIT_PIECE_BOARD = jnp.int32([[15, -1, 14, -1, -1, -1, 0, -1, 1],  # noqa: E241
+                              [16, 18, 14, -1, -1, -1, 0,  5, 2],  # noqa: E241
+                              [17, -1, 14, -1, -1, -1, 0, -1, 3],  # noqa: E241
+                              [20, -1, 14, -1, -1, -1, 0, -1, 6],  # noqa: E241
+                              [21, -1, 14, -1, -1, -1, 0, -1, 7],  # noqa: E241
+                              [20, -1, 14, -1, -1, -1, 0, -1, 6],  # noqa: E241
+                              [17, -1, 14, -1, -1, -1, 0, -1, 3],  # noqa: E241
+                              [16, 19, 14, -1, -1, -1, 0,  4, 2],  # noqa: E241
+                              [15, -1, 14, -1, -1, -1, 0, -1, 1]]).flatten()  # noqa: E241
+# fmt: on
+
+
+# Can <piece,14> reach from <from,81> to <to,81> ignoring pieces on board?
+def can_move_to(piece, from_, to):
+    """Can <piece> move from <from_> to <to>?"""
+    if from_ == to:
+        return False
+    x0, y0 = from_ // 9, from_ % 9
+    x1, y1 = to // 9, to % 9
+    dx = x1 - x0
+    dy = y1 - y0
+    if piece == PAWN:
+        if dx == 0 and dy == -1:
+            return True
+        else:
+            return False
+    elif piece == LANCE:
+        if dx == 0 and dy < 0:
+            return True
+        else:
+            return False
+    elif piece == KNIGHT:
+        if dx in (-1, 1) and dy == -2:
+            return True
+        else:
+            return False
+    elif piece == SILVER:
+        if dx in (-1, 0, 1) and dy == -1:
+            return True
+        elif dx in (-1, 1) and dy == 1:
+            return True
+        else:
+            return False
+    elif piece == BISHOP:
+        if dx == dy or dx == -dy:
+            return True
+        else:
+            return False
+    elif piece == ROOK:
+        if dx == 0 or dy == 0:
+            return True
+        else:
+            return False
+    if piece in (GOLD, PRO_PAWN, PRO_LANCE, PRO_KNIGHT, PRO_SILVER):
+        if dx in (-1, 0, 1) and dy in (0, -1):
+            return True
+        elif dx == 0 and dy == 1:
+            return True
+        else:
+            return False
+    elif piece == KING:
+        if abs(dx) <= 1 and abs(dy) <= 1:
+            return True
+        else:
+            return False
+    elif piece == HORSE:
+        if abs(dx) <= 1 and abs(dy) <= 1:
+            return True
+        elif dx == dy or dx == -dy:
+            return True
+        else:
+            return False
+    elif piece == DRAGON:
+        if abs(dx) <= 1 and abs(dy) <= 1:
+            return True
+        if dx == 0 or dy == 0:
+            return True
+        else:
+            return False
+    else:
+        assert False
+
+
+def is_on_the_way(piece, from_, to, point):
+    if to == point:
+        return False
+    if piece not in (LANCE, BISHOP, ROOK, HORSE, DRAGON):
+        return False
+    if not can_move_to(piece, from_, to):
+        return False
+    if not can_move_to(piece, from_, point):
+        return False
+
+    x0, y0 = from_ // 9, from_ % 9
+    x1, y1 = to // 9, to % 9
+    x2, y2 = point // 9, point % 9
+    dx1, dy1 = x1 - x0, y1 - y0
+    dx2, dy2 = x2 - x0, y2 - y0
+
+    def sign(d):
+        if d == 0:
+            return 0
+        return d > 0
+
+    if (sign(dx1) != sign(dx2)) or (sign(dy1) != sign(dy2)):
+        return False
+
+    return abs(dx2) <= abs(dx1) and abs(dy2) <= abs(dy1)
+
+
+CAN_MOVE = np.zeros((14, 81, 81), dtype=jnp.bool_)
+for piece in range(14):
+    for from_ in range(81):
+        for to in range(81):
+            CAN_MOVE[piece, from_, to] = can_move_to(piece, from_, to)
+
+assert CAN_MOVE.sum() == 8228
+CAN_MOVE = jnp.array(CAN_MOVE)
+
+
+# When <lance/bishop/rook/horse/dragon,5> moves from <from,81> to <to,81>,
+# is <point,81> on the way between two points?
+BETWEEN = np.zeros((5, 81, 81, 81), dtype=np.bool_)
+for i, piece in enumerate((LANCE, BISHOP, ROOK, HORSE, DRAGON)):
+    for from_ in range(81):
+        for to in range(81):
+            for p in range(81):
+                BETWEEN[i, from_, to, p] = is_on_the_way(piece, from_, to, p)
+
+BETWEEN = jnp.array(BETWEEN)
+assert BETWEEN.sum() == 10564
+
+
+# Give <dir,10> and <to,81>, return the legal <from> idx
+# E.g. LEGAL_FROM_IDX[Up, to=19] = [20, 21, ..., -1] (filled by -1)
+# Used for computing dlshogi action
+#
+#  dir, to, from
+#  (10, 81, 81)
+#
+#  0 Up
+#  1 Up left
+#  2 Up right
+#  3 Left
+#  4 Right
+#  5 Down
+#  6 Down left
+#  7 Down right
+#  8 Up2 left
+#  9 Up2 right
+
+LEGAL_FROM_IDX = -np.ones((10, 81, 8), dtype=jnp.int32)  # type: ignore
+
+for dir_ in range(10):
+    for to in range(81):
+        x, y = to // 9, to % 9
+        if dir_ == 0:  # Up
+            dx, dy = 0, +1
+        elif dir_ == 1:  # Up left
+            dx, dy = -1, +1
+        elif dir_ == 2:  # Up right
+            dx, dy = +1, +1
+        elif dir_ == 3:  # Left
+            dx, dy = -1, 0
+        elif dir_ == 4:  # Right
+            dx, dy = +1, 0
+        elif dir_ == 5:  # Down
+            dx, dy = 0, -1
+        elif dir_ == 6:  # Down left
+            dx, dy = -1, -1
+        elif dir_ == 7:  # Down right
+            dx, dy = +1, -1
+        elif dir_ == 8:  # Up2 left
+            dx, dy = -1, +2
+        elif dir_ == 9:  # Up2 right
+            dx, dy = +1, +2
+        for i in range(8):
+            x += dx
+            y += dy
+            if x < 0 or 8 < x or y < 0 or 8 < y:
+                break
+            LEGAL_FROM_IDX[dir_, to, i] = x * 9 + y
+            if dir_ == 8 or dir_ == 9:
+                break
+
+LEGAL_FROM_IDX = jnp.array(LEGAL_FROM_IDX)  # type: ignore
+
+
+@jax.jit
+@jax.vmap
+def can_move_any_ix(from_):
+    return jnp.nonzero(
+        (CAN_MOVE[:, from_, :] | CAN_MOVE[:, :, from_]).any(axis=0),
+        size=36,
+        fill_value=-1,
+    )[0]
+
+
+@jax.jit
+@jax.vmap
+def neighbour_ix(from_):
+    return jnp.nonzero(
+        (CAN_MOVE[7, from_, :] | CAN_MOVE[2, :, from_]),
+        size=10,
+        fill_value=-1,
+    )[0]
+
+
+NEIGHBOUR_IX = neighbour_ix(jnp.arange(81))
+
+
+def between_ix(p, from_, to):
+    return jnp.nonzero(BETWEEN[p, from_, to], size=8, fill_value=-1)[0]
+
+
+BETWEEN_IX = jax.jit(
+    jax.vmap(
+        jax.vmap(jax.vmap(between_ix, (None, None, 0)), (None, 0, None)),
+        (0, None, None),
+    )
+)(jnp.arange(5), jnp.arange(81), jnp.arange(81))
+
+
+CAN_MOVE_ANY = can_move_any_ix(jnp.arange(81))  # (81, 36)
+
+
+def _around(c):
+    x, y = c // 9, c % 9
+    dx = jnp.int32([-1, -1, 0, +1, +1, +1, 0, -1])
+    dy = jnp.int32([0, -1, -1, -1, 0, +1, +1, +1])
+
+    def f(i):
+        new_x, new_y = x + dx[i], y + dy[i]
+        return jax.lax.select(
+            (new_x < 0) | (new_x >= 9) | (new_y < 0) | (new_y >= 9),
+            -1,
+            new_x * 9 + new_y,
+        )
+
+    return jax.vmap(f)(jnp.arange(8))
+
+
+AROUND_IX = jax.vmap(_around)(jnp.arange(81))
+
+
 EMPTY = jnp.int32(-1)  # 空白
 PAWN = jnp.int32(0)  # 歩
 LANCE = jnp.int32(1)  # 香
@@ -94,8 +349,7 @@ def legal_action_mask(self, state: GameState) -> Array:
         return _legal_action_mask(state)
 
 
-@dataclass
-class Action:
+class Action(NamedTuple):
     is_drop: Array
     piece: Array
     to: Array