Class ScyllaSquareGrid<TCell>

Dense, array-backed square grid that stores one value of type TCell per cell, addressed by SquareCoord (column, row).

Inheritance
object
ScyllaSquareGrid<TCell>
Implements
Inherited Members
Namespace: Scylla.Core.Structures
Assembly: ScyllaCore.dll
Syntax
public sealed class ScyllaSquareGrid<TCell> : IScyllaGrid<SquareCoord, TCell>, IScyllaCollection
Type Parameters
Name Description
TCell

The type of data stored in each grid cell. May be any managed type. For value types the array is zero-initialized; for reference types all slots start as null.
Remarks

All width * height cells are pre-allocated at construction time as a single flat array in row-major order (index = row * width + col), giving O(1) random access with excellent cache locality. The total cell count must not exceed MaxValue; an ArgumentOutOfRangeException is thrown otherwise.

Use a dense grid when the majority of cells will be populated. For grids where only a small fraction of cells are active, prefer ScyllaSparseSquareGrid<TCell> to avoid the memory cost of pre-allocating every cell.

This class is not thread-safe by default. Call AsSynchronized(object) to obtain a ScyllaSquareGrid<TCell>.SynchronizedScyllaSquareGrid wrapper that locks all operations with a shared monitor.

Use CreateBuilder() for a fluent construction API that supports default-value filling and optional synchronization. 

var grid = new ScyllaSquareGrid<int>(10, 10, new SquareGridLayout(1f, 1f));
grid[new SquareCoord(3, 4)] = 42;
var center = grid.GridToWorld(new SquareCoord(3, 4));

Constructors

ScyllaSquareGrid(int, int, SquareGridLayout)

Creates a new dense square grid with the specified dimensions and spatial layout. All cells are initialized to the default value of TCell.

Declaration
public ScyllaSquareGrid(int width, int height, SquareGridLayout layout)
Parameters
Type Name Description
int width

The number of columns. Must be at least 1.
int height

The number of rows. Must be at least 1.
SquareGridLayout layout

The spatial layout that defines cell size and world-space origin. See SquareGridLayout.
Exceptions
Type Condition
ArgumentOutOfRangeException

Thrown when width or height is less than 1, or when the total cell count width * height exceeds MaxValue.

Properties

Capabilities

Gets the feature and capability flags supported by this collection instance.

Declaration
public ScyllaCollectionCapabilities Capabilities { get; }
Property Value
Type Description
ScyllaCollectionCapabilities

A bitfield of ScyllaCollectionCapabilities flags describing which optional operations the concrete instance supports. The value None indicates that only the base contract (Count, IsEmpty, Clear()) is available.
Remarks

Use Capabilities for feature detection in place of type-casting. For example: 

if ((collection.Capabilities & ScyllaCollectionCapabilities.SupportsPeek) != 0)
{
    // safe to call TryPeek through IScyllaCollection<T>
}

Synchronized wrappers cache the capability flags of their inner collection at construction time, so the value returned is stable and does not require synchronization.

See Also

CellCount

Gets the number of populated (logically active) cells in the grid.

Declaration
public int CellCount { get; }
Property Value
Type Description
int

For dense grids, this always equals Count - every cell slot is pre-allocated and considered populated regardless of its stored value. The value is fixed at construction and never changes.

For sparse grids, this equals the number of cells that have been explicitly written via TrySet(TCoord, TCell) and not yet removed. The value may be zero on a freshly created or cleared sparse grid.

See Also
TrySet(TCoord, TCell)

Count

Gets the number of items currently contained in the collection.

Declaration
public int Count { get; }
Property Value
Type Description
int

A non-negative integer representing the current element count. Returns 0 when the collection is empty.
Remarks

On unsynchronized collections, Count is not thread-safe and may return a stale value when accessed concurrently. On synchronized wrappers, reading Count is protected by the internal lock.

Height

Gets the number of rows in this grid.

Declaration
public int Height { get; }
Property Value
Type Description
int

IsEmpty

Always false. A dense grid pre-allocates every cell at construction time and is never considered logically empty, regardless of the cell values.

Declaration
public bool IsEmpty { get; }
Property Value
Type Description
bool

this[SquareCoord]

Gets or sets the cell value at the specified SquareCoord. Delegates to the this[int, int] indexer.

Declaration
public TCell this[SquareCoord coord] { get; set; }
Parameters
Type Name Description
SquareCoord coord

The grid coordinate. Must be within the bounds of this grid.
Property Value
Type Description
TCell
Exceptions
Type Condition
IndexOutOfRangeException

Thrown when coord is out of bounds.

this[int, int]

Gets or sets the cell value at the specified column and row using direct integer indices.

Declaration
public TCell this[int col, int row] { get; set; }
Parameters
Type Name Description
int col

The zero-based column index. Must be in the range [0, Width).
int row

The zero-based row index. Must be in the range [0, Height).
Property Value
Type Description
TCell
Remarks

Bounds are validated using unsigned comparison, so negative indices also throw.

Exceptions
Type Condition
IndexOutOfRangeException

Thrown when col or row is out of bounds.

Layout

Gets the spatial layout used for world-space conversion.

Declaration
public SquareGridLayout Layout { get; }
Property Value
Type Description
SquareGridLayout
See Also

SyncRoot

Gets the synchronization root object used to externally coordinate multi-step operations with this collection.

Declaration
public object SyncRoot { get; }
Property Value
Type Description
object

A non-null object suitable for use with lock when ThreadSafety is Synchronized. Returns null for unsynchronized collections, which do not own a lock.
Remarks

When this collection is a synchronized wrapper, SyncRoot must be non-null and stable for the entire lifetime of the wrapper. All internal operations on the wrapper must lock on this same object. This allows callers to perform atomic multi-step sequences: 

lock (collection.SyncRoot)
{
    if (!collection.IsEmpty)
        typedCollection.TryRemove(out var item);
}

For unsynchronized collections (SyncRoot == null), callers are responsible for supplying and consistently applying their own external synchronization mechanism. A null SyncRoot does not mean the collection is thread-safe; consult ThreadSafety for the authoritative guarantee.

See Also

ThreadSafety

Gets the thread-safety guarantees provided by this collection instance.

Declaration
public ScyllaCollectionThreadSafety ThreadSafety { get; }
Property Value
Type Description
ScyllaCollectionThreadSafety

A ScyllaCollectionThreadSafety value indicating whether the collection is unsynchronized, synchronized via a lock, or safe for lock-free concurrent access. Most core implementations return Unsynchronized. Synchronized wrappers return Synchronized.
Remarks

Always check this property (or SyncRoot) before assuming a collection is safe for concurrent use. Do not rely solely on the absence of a non-null SyncRoot to infer thread safety; use this property as the authoritative source.

See Also

Width

Gets the number of columns in this grid.

Declaration
public int Width { get; }
Property Value
Type Description
int

Methods

AsSynchronized(object)

Creates and returns a thread-safe ScyllaSquareGrid<TCell>.SynchronizedScyllaSquareGrid wrapper around this grid instance.

Declaration
public ScyllaSquareGrid<TCell>.SynchronizedScyllaSquareGrid AsSynchronized(object syncRoot = null)
Parameters
Type Name Description
object syncRoot

An optional external lock object to share. When null, the wrapper creates a new private object as its lock.
Returns
Type Description
ScyllaSquareGrid<TCell>.SynchronizedScyllaSquareGrid

A ScyllaSquareGrid<TCell>.SynchronizedScyllaSquareGrid that wraps this grid and synchronizes all reads and writes.
Remarks

All operations on the returned wrapper are synchronized using a shared lock. Multiple synchronized wrappers sharing the same syncRoot can be used to implement compound atomic operations across two or more grids.

Clear()

Removes all items from the collection and resets it to an empty state.

Declaration
public void Clear()
Remarks

Implementations that store reference-type elements should null out internal slots after clearing to avoid retaining object references and preventing garbage collection. After Clear returns, Count must be 0 and IsEmpty must be true.

On synchronized wrappers this operation is protected by the collection's internal lock. On unsynchronized collections, callers are responsible for external coordination.

Contains(SquareCoord)

Determines whether the specified coordinate is addressable and populated in this grid.

Declaration
public bool Contains(SquareCoord coord)
Parameters
Type Name Description
SquareCoord coord

The coordinate to test.
Returns
Type Description
bool

For dense grids, returns true when coord maps to a valid index within the grid's pre-allocated array - that is, when the coordinate is geometrically within the grid's dimensions, regardless of the stored value.

For sparse grids, returns true only when coord has been explicitly written via TrySet(TCoord, TCell) and not since removed. An in-bounds coordinate that has never been written returns false.

Remarks

This method is equivalent to checking whether TryGet(TCoord, out TCell) would return true for the same coordinate. Use it when you only need the existence check and do not need the value.

See Also
TryGet(TCoord, out TCell)
TrySet(TCoord, TCell)

CreateBuilder()

Creates and returns a new fluent ScyllaSquareGrid<TCell>.Builder for configuring and constructing a ScyllaSquareGrid<TCell> instance.

Declaration
public static ScyllaSquareGrid<TCell>.Builder CreateBuilder()
Returns
Type Description
ScyllaSquareGrid<TCell>.Builder

A fresh ScyllaSquareGrid<TCell>.Builder with default settings (1x1 grid, no layout set).

Fill(TCell)

Fills every cell in this grid with value.

Declaration
public void Fill(TCell value)
Parameters
Type Name Description
TCell value

The value to write into every cell.
Remarks

This is equivalent to writing value to each cell individually but uses Fill<T>(T[], T) for optimal performance. The version counter is incremented, invalidating any active enumerators.

GetEnumerator()

Returns a value-type enumerator that iterates through all cells in row-major order.

Declaration
public ScyllaSquareGrid<TCell>.Enumerator GetEnumerator()
Returns
Type Description
ScyllaSquareGrid<TCell>.Enumerator

An ScyllaSquareGrid<TCell>.Enumerator positioned before the first cell.
Remarks

Because the return type is the concrete value-type ScyllaSquareGrid<TCell>.Enumerator, using this method in a foreach loop on the concrete grid type avoids heap allocation. Modifying the grid while iterating causes the next MoveNext() call to throw InvalidOperationException.

GetNeighborsNonAlloc(SquareCoord, Span<SquareCoord>, SquareAdjacency)

Writes the in-bounds neighbors of coord into buffer.

Declaration
public int GetNeighborsNonAlloc(SquareCoord coord, Span<SquareCoord> buffer, SquareAdjacency adjacency = SquareAdjacency.VonNeumann)
Parameters
Type Name Description
SquareCoord coord

The cell whose neighbors are requested. Does not need to be in bounds.
Span<SquareCoord> buffer

A Span<T> to receive the in-bounds neighbor coordinates. Writing stops when the buffer is full, so provide at least 4 elements for VonNeumann or 8 elements for Moore to guarantee all neighbors are returned.
SquareAdjacency adjacency

The adjacency model to use. Defaults to VonNeumann.
Returns
Type Description
int

The number of neighbor coordinates written into buffer.
Remarks

Only neighbors whose coordinates fall within the grid bounds are written to the buffer. Border cells will yield fewer than 4 (VonNeumann) or 8 (Moore) neighbors.

With VonNeumann the offsets are tested in the order N, E, S, W. With Moore the order is N, NE, E, SE, S, SW, W, NW.

GridToWorld(SquareCoord)

Converts a grid coordinate to the world-space center of the corresponding cell using this grid's Layout.

Declaration
public Vector2 GridToWorld(SquareCoord coord)
Parameters
Type Name Description
SquareCoord coord

The grid coordinate to convert.
Returns
Type Description
Vector2

The world-space UnityEngine.Vector2 at the center of the cell.
See Also

IsInBounds(int, int)

Determines whether the specified column and row fall within this grid's bounds.

Declaration
public bool IsInBounds(int col, int row)
Parameters
Type Name Description
int col

The column index to test.
int row

The row index to test.
Returns
Type Description
bool

true if both col and row are within [0, Width) and [0, Height) respectively; false otherwise.

TryGet(SquareCoord, out TCell)

Attempts to retrieve the value stored at the specified coordinate without throwing on failure.

Declaration
public bool TryGet(SquareCoord coord, out TCell value)
Parameters
Type Name Description
SquareCoord coord

The grid coordinate to look up.
TCell value

When this method returns true, contains the cell value at coord. When this method returns false, contains default(TCell). This parameter is passed uninitialized and is always written before this method returns.
Returns
Type Description
bool

true if coord is within the grid's valid range and a value was successfully read; false if the coordinate is out of bounds (dense grids) or has not been explicitly written (sparse grids).
Remarks

Prefer this method over direct indexer access when the coordinate's validity is not guaranteed, as it avoids the cost of exception handling on out-of-bounds access. For dense grids, "within bounds" means the coordinate maps to a valid flat-array index. For sparse grids, "within bounds" additionally requires that the cell has been set.

See Also
TrySet(TCoord, TCell)
Contains(TCoord)

TrySet(SquareCoord, TCell)

Attempts to store a value at the specified coordinate without throwing on failure.

Declaration
public bool TrySet(SquareCoord coord, TCell value)
Parameters
Type Name Description
SquareCoord coord

The grid coordinate to write to.
TCell value

The value to store at coord.
Returns
Type Description
bool

true if the coordinate is valid and the value was successfully stored; false if the coordinate is out of bounds and no change was made.
Remarks

For dense grids, this writes to the pre-allocated cell at coord and returns false if the coordinate falls outside the grid's dimensions.

For sparse grids, this inserts or updates the entry at coord and returns false only when the grid is bounded and coord falls outside the defined bounds. On unbounded sparse grids this method always returns true.

A successful call increments CellCount on sparse grids when coord is newly written for the first time.

See Also
TryGet(TCoord, out TCell)
Contains(TCoord)

WorldToGrid(Vector2)

Converts a world-space position to the grid coordinate of the cell that contains it, using this grid's Layout.

Declaration
public SquareCoord WorldToGrid(Vector2 worldPos)
Parameters
Type Name Description
Vector2 worldPos

The world-space position to convert.
Returns
Type Description
SquareCoord

The SquareCoord of the cell containing worldPos.
See Also
WorldToGrid(Vector2)

Implements

Extension Methods

See Also

IScyllaGrid<TCoord, TCell>