ob_start() — internals

ob_start() — internals

Where it lives

• Signature: src/builtins/io/ob_start.rs
• Lowering: src/codegen/lower_inst/builtins/output_buffering.rs:44 (lower_ob_start)
• Function symbol: lower_ob_start()

Lowering notes

• Lowers ob_start([$callback[, $chunk_size[, $flags]]]) to __rt_ob_start_ex.
• Resolves the handler triple (invocation stub, env word, display name) from
• the callback operand: null selects the default handler; a Callable
• descriptor is retained and invoked through __rt_ob_invoke_descriptor; a
• runtime string dispatches through the shared callable descriptor cases (a
• miss raises PHP’s invalid-callback warning and returns false); a boxed
• Mixed value unboxes to one of those shapes at run time.

Runtime helpers

The following runtime helpers are referenced:

• __rt_ob_invoke_descriptor
• __rt_ob_start_ex

Signature summary

function ob_start(mixed $callback = null, int $chunk_size = 0, int $flags = 112): bool

What the type checker enforces

• Arity: takes 0–3 arguments (3 optional).

Eval interpreter (magician)

• Declaration: crates/elephc-magician/src/interpreter/builtins/core/ob_start.rs (eval_builtin!)
• Dispatch hooks: direct, values

Cross-references

• User reference for ob_start()