Struct DependencyGraph 

pub struct DependencyGraph { /* private fields */ }

Dependency graph for federation @requires directives

Represents dependencies between fields based on @requires directives. Used to detect cycles and determine resolution order.

Implementations

impl DependencyGraph

pub fn build(metadata: &FederationMetadata) -> Result<Self, String>

Build a dependency graph from federation metadata

Scans all types and fields for @requires directives and constructs a directed graph where edges represent dependencies.

Errors

Returns error if graph construction fails (should not happen in normal operation).

pub fn node_count(&self) -> usize

Get the number of nodes in the graph

pub fn has_node(&self, node_id: &str) -> bool

Check if a node exists in the graph

pub fn detect_cycles(&self) -> Vec<Vec<String>>

Detect cycles in the dependency graph using DFS

Returns a vector of cycles, where each cycle is a vector of node IDs that form a circular dependency.

pub fn topological_sort(&self) -> Result<Vec<String>, String>

Perform topological sort using Kahn’s algorithm

Errors

Returns error if cycles are detected in the graph.