Struct MigrationGraph 

pub struct MigrationGraph { /* private fields */ }

Directed acyclic graph of migrations. Edges: dependency → dependent (A → B means B depends on A).

Implementations

impl MigrationGraph

pub fn new() -> Self

pub fn add(&mut self, migration: Migration) -> Result<(), GraphError>

Add a migration to the graph.

pub fn validate_id(id: &str) -> Result<(), GraphError>

Validate that an id is safe as a filename and unambiguous. Only lowercase letters, digits, and underscores are allowed. Called by Migrator before writing any new migration file.

pub fn heads(&self) -> Vec<&str>

Return IDs of all head migrations (those with no dependents).

pub fn next_number(&self) -> u32

Return the next sequential number (1-based) for a new migration. Parses the leading digits of each migration id (e.g. “0003_add_users” → 3). Returns 1 if the graph is empty.

pub fn detect_conflict(&self) -> Result<(), GraphError>

Returns Err if there are multiple heads (conflict).

pub fn validate_acyclic(&self) -> Result<(), GraphError>

Validate that the graph contains no cycles.

pub fn topological_order(&self) -> Result<Vec<&str>, GraphError>

Produce a deterministic topological order of all migration IDs.

pub fn create_merge_migration( &self, id: String, ) -> Result<Migration, GraphError>

Create an empty merge migration that depends on all current heads.

pub fn get(&self, id: &str) -> Option<&Migration>

pub fn resolve_id(&self, input: &str) -> Result<String, GraphError>

Resolves an exact migration id or an unambiguous prefix in graph order.

Exact ids take precedence over prefixes. Ambiguous prefixes return all matching ids in deterministic topological order.

Trait Implementations

impl Debug for MigrationGraph

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

Formats the value using the given formatter.

impl Default for MigrationGraph

fn default() -> MigrationGraph

Returns the “default value” for a type.