Struct StateGraph 

pub struct StateGraph<S: State> { /* private fields */ }

Declarative graph definition with typed nodes and edges.

Build a graph using the fluent API, then call compile() to validate and freeze it into a CompiledGraph for execution.

Example

use pe_graph::{StateGraph, START, END};

let graph = StateGraph::new()
    .add_node("prepare", prepare_node)
    .add_node("chat", chat_node)
    .add_edge(START, "prepare")
    .add_edge("prepare", "chat")
    .add_edge("chat", END)
    .compile()?;

Implementations

impl<S: State> StateGraph<S>

pub fn new() -> Self

Create an empty graph definition.

pub fn add_node( self, name: impl Into<String>, node: impl NodeFn<S> + 'static, ) -> Self

Add a named node to the graph.

Reserved names (START, END) are rejected at compile() time, not here — so the builder stays infallible and chainable.

pub fn add_edge(self, from: impl Into<String>, to: impl Into<String>) -> Self

Add a fixed edge: from always transitions to to after completing.

Use START for the first node, END for terminal nodes.

pub fn add_conditional_edge( self, from: impl Into<String>, router: impl Fn(&S) -> Vec<String> + Send + Sync + 'static, ) -> Self

Add a conditional edge: router reads state and returns next node names.

Return vec![END.to_string()] to terminate. Return multiple names for parallel execution in the next superstep.

pub fn compile(self) -> Result<CompiledGraph<S>, PeError>

Validate the graph structure and freeze it into a CompiledGraph.

Validation checks:

• START has at least one outgoing edge
• All fixed edge targets/sources exist as node names (or START/END)
• No conditional edges from START
• All nodes are reachable from START

Trait Implementations

impl<S: State> Default for StateGraph<S>

fn default() -> Self

Returns the “default value” for a type.