Enum GraphError 

#[non_exhaustive]
pub enum GraphError {
    EmptyGraph,
    NodeNotFound(usize),
    CycleDetected,
    SubgraphCycle,
    SubgraphNotFound(usize),
    ArenaOom,
    BuilderFailed,
    ExceedsMaxNodes {
        count: usize,
        max: usize,
    },
    ExceedsMaxLevels {
        depth: usize,
        max: usize,
    },
    ExceedsMaxExtent {
        extent: usize,
        max: usize,
    },
    RenderPlanOom,
    RenderCanvasTooSmall {
        needed: usize,
        got: usize,
    },
    RenderOutputTooSmall,
    RenderWorkspaceTooSmall {
        needed_bytes: usize,
        got_bytes: usize,
    },
    RenderSinkFailed,
}

Unified error type for all graph and layout operations.

Each variant carries a WDP error code accessible via GraphError::code(), and an actionable hint via GraphError::hint().

WDP Code Mapping

Variant	WDP Code	Meaning
EmptyGraph	E.Graph.Node.001	MISSING — no nodes
NodeNotFound	E.Graph.Node.021	NOT_FOUND — node absent
CycleDetected	E.Graph.Dag.003	INVALID — DAG constraint violated
SubgraphCycle	E.Graph.Subgraph.003	INVALID — nesting cycle
SubgraphNotFound	E.Graph.Subgraph.021	NOT_FOUND — subgraph absent
ArenaOom	E.ArenaLayout.Alloc.026	EXHAUSTED — arena memory
BuilderFailed	E.ArenaLayout.Builder.026	EXHAUSTED — builder alloc
ExceedsMaxNodes	E.ArenaLayout.Node.004	OVERFLOW — index type full
ExceedsMaxLevels	E.ArenaLayout.Level.004	OVERFLOW — too deep
ExceedsMaxExtent	E.ArenaLayout.Extent.004	OVERFLOW — canvas past the coordinate type
RenderPlanOom	E.Render.Plan.026	EXHAUSTED — plan buffer
RenderCanvasTooSmall	E.Render.Canvas.026	EXHAUSTED — band buffer
RenderOutputTooSmall	E.Render.Sink.026	EXHAUSTED — output buffer
RenderWorkspaceTooSmall	E.Render.Workspace.026	EXHAUSTED — composer workspace
RenderSinkFailed	E.Render.Sink.032	FAILED — caller’s writer errored

Examples

use ascii_dag::GraphError;

let err = GraphError::EmptyGraph;
assert_eq!(err.code(), "E.Graph.Node.001");
assert!(!err.hint().is_empty());

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

EmptyGraph

The graph has no nodes.

WDP: E.Graph.Node.001 (MISSING)

NodeNotFound(usize)

A referenced node ID does not exist in the graph.

WDP: E.Graph.Node.021 (NOT_FOUND)

CycleDetected

The graph contains a cycle but acyclicity was required.

WDP: E.Graph.Dag.003 (INVALID)

SubgraphCycle

Subgraph nesting would create a cycle in the hierarchy.

WDP: E.Graph.Subgraph.003 (INVALID)

SubgraphNotFound(usize)

A referenced subgraph ID does not exist.

WDP: E.Graph.Subgraph.021 (NOT_FOUND)

ArenaOom

The arena allocator ran out of memory.

WDP: E.ArenaLayout.Alloc.026 (EXHAUSTED)

Use Graph::estimate_layout_arena_size() to compute the required size.

BuilderFailed

The IR builder failed to allocate output structures.

WDP: E.ArenaLayout.Builder.026 (EXHAUSTED)

ExceedsMaxNodes

The graph has more nodes or edges than the selected index type supports.

WDP: E.ArenaLayout.Node.004 (OVERFLOW)

Fields

count: usize

Actual node or edge count.

max: usize

Maximum supported by the current index type.

ExceedsMaxLevels

The graph’s longest path exceeds the maximum level depth.

WDP: E.ArenaLayout.Level.004 (OVERFLOW)

Fields

depth: usize

Actual depth of the longest path.

max: usize

Maximum supported levels.

ExceedsMaxExtent

The layout’s cross-axis extent — its packed nodes plus the cells port routing opens beside them — exceeds the arena coordinate type.

WDP: E.ArenaLayout.Extent.004 (OVERFLOW)

Fields

extent: usize

The extent the layout needs.

max: usize

Maximum representable by the coordinate type.

RenderPlanOom

The caller-provided render-plan buffer is too small.

WDP: E.Render.Plan.026 (EXHAUSTED)

Use estimate_render_arena_size() to compute the required size.

RenderCanvasTooSmall

The caller-provided band buffer holds fewer than width × band_rows cells.

WDP: E.Render.Canvas.026 (EXHAUSTED)

Fields

needed: usize

Cells required (width × band_rows).

got: usize

Cells provided.

RenderOutputTooSmall

The caller-provided output byte buffer filled up mid-render.

WDP: E.Render.Sink.026 (EXHAUSTED)

RenderWorkspaceTooSmall

A fixed composer workspace cannot hold this scene’s composition. Units are BYTES — explicit in the field names so they can never be confused with the cell counts of RenderCanvasTooSmall.

WDP: E.Render.Workspace.026 (EXHAUSTED)

Fields

needed_bytes: usize

Bytes the composition needs (usize::MAX: the requirement itself overflowed — the scene cannot fit any workspace).

got_bytes: usize

Bytes the workspace holds.

RenderSinkFailed

The caller’s fmt::Write sink reported an error mid-render. The failure originated downstream of the renderer (the writer itself); rendering state is unaffected and the render may be retried with a healthy sink. Previously a writer failure could only surface as a bare fmt::Error with no code.

WDP: E.Render.Sink.032 (FAILED)

Implementations

impl GraphError

pub fn code(&self) -> &'static str

WDP Level 0 error code.

Format: Severity.Component.Primary.Sequence

Every variant maps to a unique code — no two variants share the same Component.Primary.Sequence triple.

pub fn hint(&self) -> &'static str

Actionable hint for resolving this error.

Trait Implementations

impl Clone for GraphError

fn clone(&self) -> GraphError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for GraphError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for GraphError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for GraphError

impl Error for GraphError

Available on crate feature std only.

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<GraphError> for ErrorChain

Available on crate feature alloc only.

fn from(error: GraphError) -> Self

Converts to this type from the input type.

impl PartialEq for GraphError

fn eq(&self, other: &GraphError) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl ProjectedFailure for GraphError

fn cause(&self) -> Option<&Self>

The next cause beneath this failure, if any.

impl StructuralPartialEq for GraphError