harn_parser/typechecker/
exits.rs

1//! Free helpers for "does this statement / block definitely exit?" analysis.
2//!
3//! Used both by `harn-lint` (publicly) and the type checker's flow narrowing
4//! logic (via the same-named methods on `TypeChecker`, which delegate here).
5
6use crate::ast::*;
7
8/// Check whether a single statement definitely exits (return/throw/break/continue
9/// or an if/else where both branches exit).
10pub fn stmt_definitely_exits(stmt: &SNode) -> bool {
11    match &stmt.node {
12        Node::ReturnStmt { .. } | Node::ThrowStmt { .. } | Node::BreakStmt | Node::ContinueStmt => {
13            true
14        }
15        Node::IfElse {
16            then_body,
17            else_body: Some(else_body),
18            ..
19        } => block_definitely_exits(then_body) && block_definitely_exits(else_body),
20        _ => false,
21    }
22}
23
24/// Check whether a block definitely exits (contains a terminating statement).
25pub fn block_definitely_exits(stmts: &[SNode]) -> bool {
26    stmts.iter().any(stmt_definitely_exits)
27}
harn_parser/typechecker/exits.rs

harn_parser/typechecker/
exits.rs
