Struct DependencyGraph 

pub struct DependencyGraph { /* private fields */ }

A directed acyclic graph representing task dependencies.

Edges go from a task to the tasks it depends on (its blocked_by set). For example, if task B is blocked by task A, we store B -> {A}.

Implementations

impl DependencyGraph

pub fn from_tasks(tasks: &[TaskFile]) -> Self

Build a dependency graph from a slice of tasks.

pub fn would_create_cycle(&self, task_id: &str, depends_on: &str) -> bool

Check whether adding an edge task_id -> depends_on would create a cycle.

Uses BFS starting from depends_on, following existing dependency edges. If we can reach task_id from depends_on, adding this edge would create a cycle.

pub fn add_dependency(&mut self, task_id: &str, depends_on: &str) -> Result<()>

Add a dependency edge: task_id is now blocked by depends_on.

Returns an error if this would create a cycle.

pub fn get_blocked_by(&self, task_id: &str) -> Vec<String>

Get the list of task IDs that task_id is blocked by.

pub fn get_blocks(&self, task_id: &str) -> Vec<String>

Get the list of task IDs that task_id blocks.

pub fn is_ready(&self, task_id: &str, tasks: &[TaskFile]) -> bool

Check whether a task is ready to run (all its dependencies are completed or deleted).

pub fn to_mermaid(&self, tasks: &[TaskFile]) -> String

Export the dependency graph as a Mermaid diagram.

Nodes are colored by status:

• Pending: light gray
• InProgress: light blue
• Completed: light green
• Deleted: light pink

Edges represent blocked_by relationships: dep --> task.

pub fn to_dot(&self, tasks: &[TaskFile]) -> String

Export the dependency graph as a Graphviz DOT diagram.

Same information as to_mermaid but in DOT syntax.

pub fn critical_path(&self, tasks: &[TaskFile]) -> Vec<String>

Compute the critical path (longest dependency chain) through the graph.

Uses topological sort + dynamic programming: longest[node] = max(longest[dep] + 1) for each dependency.

Deleted tasks are excluded from the computation. Returns task IDs in dependency-first order (root → leaf).

pub fn to_terminal(&self, tasks: &[TaskFile]) -> String

Render the DAG as a terminal-friendly Unicode diagram with ANSI colors.

Groups tasks by topological level (phase) and draws connectors. Status is shown with colored symbols:

• ○ Pending (gray), ◉ InProgress (blue), ● Completed (green), ✗ Deleted (red)

Task DAG ─────────────────────────────────

  Phase 0
  ├── ● #1  CC: Concurrency analysis
  ├── ● #2  Codex: Security audit
  └── ● #3  Gemini: API design review
       │
       ▼
  Phase 1
  ├── ◉ #4  Codex: Fix proposals        ← #1, #2
  └── ○ #5  Gemini: Refactoring         ← #2, #3
       │
       ▼
  Phase 2
  └── ○ #6  CC: Final synthesis         ← #4, #5

pub fn to_terminal_plain(&self, tasks: &[TaskFile]) -> String

Render the DAG as a plain-text terminal diagram (no ANSI colors).

Identical layout to to_terminal but without escape sequences, suitable for logging or file output.

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

Compute a topological ordering of the tasks (Kahn’s algorithm).

Returns task IDs in an order where dependencies come before dependents. Returns an error if the graph contains a cycle.

Trait Implementations

impl Clone for DependencyGraph

fn clone(&self) -> DependencyGraph

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DependencyGraph

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

Formats the value using the given formatter.