Struct ChangeDetector 

pub struct ChangeDetector {
    pub module_hashes: FxHashMap<ModuleId, [u8; 32]>,
}

Tracks module content hashes for change detection.

Stores BLAKE3 hashes of file contents to detect modifications between builds. This is used to determine if a cached module graph is still valid or if re-analysis is required.

Fields

module_hashes: FxHashMap<ModuleId, [u8; 32]>

BLAKE3 hashes of module file contents, indexed by ModuleId.

Implementations

impl ChangeDetector

pub fn new() -> Self

Create a new empty change detector.

pub fn from_graph(graph: &ModuleGraph) -> Result<Self>

Create a change detector from an existing module graph.

Computes BLAKE3 hashes for all modules in the graph by reading their file contents from disk.

Errors

Returns an error if:

• Any module file cannot be read
• Module path is invalid

Note: Errors are non-fatal for incremental caching - if we can’t hash a file, we should fall back to a full rebuild.

pub fn detect_changes( &self, current_files: &[(ModuleId, [u8; 32])], ) -> ChangeSet

Detect changes between the cached state and current files.

Compares the stored hashes against the current file contents to determine which modules have been modified, added, or removed.

Arguments

• current_files - List of (ModuleId, content_hash) pairs for current state

Returns

A ChangeSet containing all detected changes. Note that this does NOT include transitive dependents - use compute_affected for that.

pub fn compute_affected( &self, changed: &HashSet<ModuleId>, graph: &ModuleGraph, ) -> HashSet<ModuleId>

Compute the transitive closure of affected modules.

Given a set of directly changed modules, compute all modules that transitively depend on those changes using the dependency graph.

Algorithm

1. Start with the set of directly changed modules
2. For each changed module, find all its dependents (reverse edges)
3. Recursively traverse dependents until no new modules are found

Arguments

• changed - Set of directly changed module IDs
• graph - The module graph containing dependency information

Returns

A set containing all changed modules plus their transitive dependents.

Trait Implementations

impl Clone for ChangeDetector

fn clone(&self) -> ChangeDetector

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ChangeDetector

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

Formats the value using the given formatter.

impl Default for ChangeDetector

fn default() -> Self

Returns the “default value” for a type.