Class ScyllaCSRGraph.Builder

Fluent builder for constructing ScyllaCSRGraph instances incrementally, without requiring an intermediate mutable graph.

Inheritance
object
ScyllaCSRGraph.Builder
Inherited Members
Namespace: Scylla.Core.Structures
Assembly: ScyllaCore.dll
Syntax
public sealed class ScyllaCSRGraph.Builder
Remarks

Nodes must be registered with AddNode(int, ScyllaGraphNodeFlags) before edges referencing them can be added via AddEdge(int, int, float). Attempting to add an edge whose source or target node has not been added will throw InvalidOperationException.

When Undirected() is configured, each call to AddEdge(int, int, float) automatically stores both the forward and reverse edge entries so that the resulting graph correctly exposes neighbors from either endpoint. Self-loop edges (fromID == toID) are only stored once even in undirected mode.

The builder is not thread-safe. All calls must originate from a single thread.

Calling Build() does not reset the builder; however the builder state should be considered consumed after Build() is called because subsequent mutations would not affect the already-constructed graph. 

var graph = ScyllaCSRGraph.CreateBuilder()
    .Undirected()
    .Weighted()
    .AddNode(0)
    .AddNode(1)
    .AddNode(2)
    .AddEdge(0, 1, 1.5f)
    .AddEdge(1, 2, 2.0f)
    .Build();

Methods

AddEdge(int, int, float)

Adds an edge between two previously registered nodes. For undirected graphs, a reverse edge entry is also stored automatically so that neighbor queries from either endpoint return the connection. Self-loop edges (fromID == toID) are permitted and stored once even in undirected mode. Duplicate edges between the same pair of nodes are allowed and stored as-is.

Declaration
public ScyllaCSRGraph.Builder AddEdge(int fromID, int toID, float weight = 1)
Parameters
Type Name Description
int fromID

ID of the source node. Must have been previously registered via AddNode(int, ScyllaGraphNodeFlags).
int toID

ID of the target node. Must have been previously registered via AddNode(int, ScyllaGraphNodeFlags).
float weight

Edge weight. Defaults to 1.0f. Ignored (forced to 1.0f) when the graph is configured as unweighted via Unweighted().
Returns
Type Description
ScyllaCSRGraph.Builder

This builder instance for method chaining.
Exceptions
Type Condition
InvalidOperationException

Thrown when fromID or toID has not been registered with AddNode(int, ScyllaGraphNodeFlags).

AddNode(int, ScyllaGraphNodeFlags)

Registers a new node with the specified ID and optional flags.

Declaration
public ScyllaCSRGraph.Builder AddNode(int nodeID, ScyllaGraphNodeFlags flags = ScyllaGraphNodeFlags.Walkable)
Parameters
Type Name Description
int nodeID

A unique integer identifier for the node. Node IDs do not need to be contiguous or start at zero, but must be unique within the builder.
ScyllaGraphNodeFlags flags

Bitpacked property flags for this node. Defaults to Walkable.
Returns
Type Description
ScyllaCSRGraph.Builder

This builder instance for method chaining.
Exceptions
Type Condition
InvalidOperationException

Thrown when a node with nodeID has already been added.

Build()

Compiles all registered nodes and edges into an immutable ScyllaCSRGraph in CSR format.

Declaration
public ScyllaCSRGraph Build()
Returns
Type Description
ScyllaCSRGraph

A new, fully-initialized ScyllaCSRGraph containing all nodes and edges registered with this builder.
Remarks

During the build process:

  • All edge endpoints are validated; any edge referencing an unregistered node throws InvalidOperationException.
  • Nodes are sorted by ID on a working copy of the builder list, leaving the builder's own node order unchanged.
  • Edges are sorted first by source node index (ascending), then by target node ID (ascending) within each source group.
  • Prefix-sum offsets are computed from the sorted edge list to produce the final CSR layout.
  • For undirected graphs, the logical EdgeCount is calculated as (storedEdgeCount - selfLoopCount) / 2 + selfLoopCount because non-self-loop edges are stored twice.
Exceptions
Type Condition
InvalidOperationException

Thrown if any edge in the builder references a node ID that was not registered via AddNode(int, ScyllaGraphNodeFlags). Under normal usage this cannot occur because AddEdge(int, int, float) already validates endpoints; this second validation is a defensive guard against direct manipulation of builder state.

Directed()

Configures the graph as directed, meaning edges have a specific source->target direction and only the direction they were added is stored. This is the default.

Declaration
public ScyllaCSRGraph.Builder Directed()
Returns
Type Description
ScyllaCSRGraph.Builder

This builder instance for method chaining.

Undirected()

Configures the graph as undirected, meaning each edge added via AddEdge(int, int, float) is automatically stored in both directions so that neighbor queries from either endpoint return the connection. Self-loop edges are only stored once.

Declaration
public ScyllaCSRGraph.Builder Undirected()
Returns
Type Description
ScyllaCSRGraph.Builder

This builder instance for method chaining.

Unweighted()

Configures the graph as unweighted (the default). All edge weights are normalized to 1.0f regardless of the value passed to AddEdge(int, int, float). The Weighted flag will not be set on the resulting graph.

Declaration
public ScyllaCSRGraph.Builder Unweighted()
Returns
Type Description
ScyllaCSRGraph.Builder

This builder instance for method chaining.

Weighted()

Configures the graph as weighted, preserving the weight parameter passed to AddEdge(int, int, float).

Declaration
public ScyllaCSRGraph.Builder Weighted()
Returns
Type Description
ScyllaCSRGraph.Builder

This builder instance for method chaining.

Extension Methods