DOCUMENTATION

Sema - Statement & Execution Control Flow

The src/sema/check/ module separates out complex execution checks based on statement structure. Statement assertions validate execution boundaries rather than direct types, throwing explicitly descriptive errors on illegal structures.

Control Flow (check_control_flow.rs)

Loop Safety

• Maintains a strict loop_depth integer integer tracker.
• Entering a while or for loop dynamically pushes loop_depth += 1.
• The parser itself maps break and continue, but the semantic checker validates whether they are utilized legally (in check_stmt.rs). If the semantic loop_depth reads 0, dedicated variants fire: BreakOutsideLoop ("[S106] Break statement outside of loop") and ContinueOutsideLoop ("[S107] Continue statement outside of loop").

Specialized for Iteration Extrapolation

XCX automatically extrapolates internal type abstractions when iterating:

• Iterating a natively defined Array(Type::T) resolves the inner binding variables to type T.
• Iterating a Table maps internal scope access.
• Iterating a <Fiber> forces validation across the internal yielded states, blocking attempts to iterate None/Void fibers explicitly with CannotIterateOverVoidFiber.

Fiber & Yield Safety (check_fiber.rs)

XCX isolates and strictly bounds yield functionality exclusively inside declared @fiber definitions.

• check_fiber_def() configures the internal tracking state fiber_context and overrides is_fiber_context = true. It validates function closures and verifies trailing return consistency.
• Yield Security: check_yield_stmt_with_target actively audits if is_fiber_context is true before resolving. Yield returns throw errors if escaping the explicit <Fiber> bound state.
• D401 Safety Guard: A raw database operation (DatabaseOpKind::Remove) must be filtered with an explicit .where() before it is yielded, assigned, passed as an argument, or returned from a typed fiber - the guard fires at all five sites (yield, assignment, expression statement, argument passing, typed-fiber return).

Declaration & Variable Binding (check_decl.rs & check_assign.rs)

• Asserts bounds explicitly. If Symbols.has(&name_str) executes securely up the immediate active scope frame on assignments, it permits overwrite. If the assignment tracks symbols.is_const(&name), it panics at ConstReassignment.
• check_var_decl allows dynamic implicit binding. If the syntax does not declare a strict type, the assignment value natively cascades backward and assigns the AST's mapped variable binding type dynamically based on right-side evaluation.

Network Initialization (check_net_stmt.rs)

The serve: keyword is audited in check_net_stmt.rs and check_decl.rs:

• Port/host/workers expressions are generically type-checked; no dedicated Int-port / String-host assertion exists.
• Route parameters are traversed via ExprKind::Tuple and ExprKind::ArrayLiteral (plus Binary right sides); identifiers are cross-checked against the functions map and the symbol table (with "*"/"_" exempt). There is no lambda-state validation.