Enum GraphError 

pub enum GraphError {
    EmptyGraph,
    NodeNotFound(usize),
    CycleDetected,
    SubgraphCycle,
    SubgraphNotFound(usize),
    ArenaOom,
    BuilderFailed,
    ExceedsMaxNodes {
        count: usize,
        max: usize,
    },
    ExceedsMaxLevels {
        depth: usize,
        max: usize,
    },
}

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

Examples

use ascii_dag::GraphError;

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

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.

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 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 Diagnostic

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for GraphError

impl StructuralPartialEq for GraphError