Documentation
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Overview ¶
Package leavemap provides an O(1) leave-value lookup table indexed by a per-tile bitmask. As tiles are played and unplayed during move generation, the bitmask is updated with a single AND/OR and the leave value is read directly from a fixed-size array.
The structure mirrors MAGPIE's LeaveMap (src/ent/leave_map.h) and supports both update conventions in a single type:
Regular methods (AddLetter / TakeLetter) flip bits in ASCENDING order: the n'th copy of a letter sets / clears the bit at position base+n. This matches the convention used by macondo's normal recursiveGen / populateLeaveMap path.
Complement methods (ComplementAddLetter / ComplementTakeLetter) flip bits in DESCENDING order using a precomputed reversed-bit table. They are the inverse of "moving a tile from the played subset back into the leave," and are used by the WMP move generator's nonplaythrough subrack enumeration where the iteration counter naturally goes 0..numthis-1 but the bits need to be touched highest-first for consistency with the leave-map populator.
Both modes share the same letterBaseIndex layout, so a single LeaveMap instance can be populated by one mode and consumed by the other as long as the convention pair is consistent.
Index ¶
- Constants
- type LeaveMap
- func (lm *LeaveMap) AddLetter(ml tilemapping.MachineLetter, numberOnRack int)
- func (lm *LeaveMap) ComplementAddLetter(ml tilemapping.MachineLetter, numberOnRack int)
- func (lm *LeaveMap) ComplementTakeLetter(ml tilemapping.MachineLetter, numberOnRack int)
- func (lm *LeaveMap) CurrentValue() float64
- func (lm *LeaveMap) Init(rack *tilemapping.Rack)
- func (lm *LeaveMap) SetCurrentIndex(idx int)
- func (lm *LeaveMap) SetCurrentValue(value float64)
- func (lm *LeaveMap) TakeLetter(ml tilemapping.MachineLetter, numberOnRack int)
Constants ¶
const MaxRackSize = 7
MaxRackSize is the largest rack the leave map will index. With 7 tiles per rack the bitmask fits in 7 bits and the values array has 128 entries. Matches game.RackTileLimit; duplicated here so this package has no dependency on macondo/game.
const MaxValues = 1 << MaxRackSize
MaxValues is the size of the values array (2^MaxRackSize).
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type LeaveMap ¶
type LeaveMap struct {
// Values holds the leave value for every reachable bitmask.
Values [MaxValues]float64
// LetterBaseIndex maps a MachineLetter to the base bit position
// of its tiles in the bitmask. Each letter occupies count
// consecutive bits starting at base.
LetterBaseIndex [tilemapping.MaxAlphabetSize + 1]int
// ReversedLetterBitMap is a precomputed table used by the
// complement update mode. The j'th-from-bottom occupied bit of a
// letter (j = 0..count-1) maps to the bit at the OPPOSITE end of
// that letter's slot, so iterating j ascending touches bits
// descending.
ReversedLetterBitMap [MaxRackSize]int
// CurrentIndex is the current bitmask. With Initialized=true and
// no plays, all TotalTiles low bits are set.
CurrentIndex int
// TotalTiles is the number of tiles initially on the rack.
TotalTiles int
// Initialized is true after a successful Init call.
Initialized bool
}
LeaveMap stores per-subset leave values keyed by a tile-bitmask.
Field exposure: callers (in particular existing macondo movegen code and leave_map_test.go) read and write Values, CurrentIndex, TotalTiles, and Initialized directly. The methods are the preferred API; the fields are exported for backward compatibility with the pre-package macondo/movegen.leaveMap layout.
func (*LeaveMap) AddLetter ¶
func (lm *LeaveMap) AddLetter(ml tilemapping.MachineLetter, numberOnRack int)
AddLetter sets the bit for the (numberOnRack)'th copy of letter ml in the bitmask, in ASCENDING order: bit at LetterBaseIndex[ml] + numberOnRack. This is the regular update mode used by macondo's normal recursiveGen / populateLeaveMap path. numberOnRack is the count BEFORE the add (i.e., the new copy goes into slot numberOnRack). Mirrors leave_map_add_letter.
func (*LeaveMap) ComplementAddLetter ¶
func (lm *LeaveMap) ComplementAddLetter(ml tilemapping.MachineLetter, numberOnRack int)
ComplementAddLetter clears the bit for letter ml in the bitmask using the REVERSED-bit table. Used by the WMP move generator's nonplaythrough subrack enumeration where the caller passes a 0..n-1 iteration counter but expects bits to be touched highest-first. Mirrors leave_map_complement_add_letter.
func (*LeaveMap) ComplementTakeLetter ¶
func (lm *LeaveMap) ComplementTakeLetter(ml tilemapping.MachineLetter, numberOnRack int)
ComplementTakeLetter sets the same bit that ComplementAddLetter would clear, restoring the leave on the way out of an enumeration. Mirrors leave_map_complement_take_letter.
func (*LeaveMap) CurrentValue ¶
CurrentValue returns the value at the current index. Mirrors leave_map_get_current_value.
func (*LeaveMap) Init ¶
func (lm *LeaveMap) Init(rack *tilemapping.Rack)
Init assigns each tile in rack a unique bit position and sets CurrentIndex to all-bits-set (full rack = empty leave). Mirrors MAGPIE's leave_map_init.
Init clears LetterBaseIndex and ReversedLetterBitMap before (re-)populating them so the same LeaveMap can be reused across multiple racks. If the rack has more than MaxRackSize tiles or is empty, Initialized is left false.
func (*LeaveMap) SetCurrentIndex ¶
SetCurrentIndex overwrites the current bitmask. Mirrors leave_map_set_current_index.
func (*LeaveMap) SetCurrentValue ¶
SetCurrentValue stores value at the current index. Mirrors leave_map_set_current_value.
func (*LeaveMap) TakeLetter ¶
func (lm *LeaveMap) TakeLetter(ml tilemapping.MachineLetter, numberOnRack int)
TakeLetter clears the bit for the (numberOnRack)'th copy of letter ml. numberOnRack is the count AFTER the take. Mirrors leave_map_take_letter.
Source Files