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// This module defines the Context type, which carries deadlines, cancellation signals,
// and other request-scoped values across API boundaries and between processes.
// Based off: https://github.com/golang/go/tree/master/src/context
// Last commit: https://github.com/golang/go/commit/52bf14e0e8bdcd73f1ddfb0c4a1d0200097d3ba2
module context
import time
const (
background = EmptyContext(0)
todo = EmptyContext(1)
cancel_context_key = 'context.CancelContext'
// canceled is the error returned by Context.err when the context is canceled.
canceled = error('context canceled')
// deadline_exceeded is the error returned by Context.err when the context's
// deadline passes.
deadline_exceeded = error('context deadline exceeded')
)
pub interface Context {
// deadline returns the time when work done on behalf of this context
// should be canceled. deadline returns none when no deadline is
// set. Successive calls to deadline return the same results.
deadline() ?time.Time
// done returns a channel that's closed when work done on behalf of this
// context should be canceled. done may return nil if this context can
// never be canceled. Successive calls to done return the same value.
// The close of the done channel may happen asynchronously,
// after the cancel function returns.
//
// with_cancel arranges for done to be closed when cancel is called;
// with_deadline arranges for done to be closed when the deadline
// expires; with_timeout arranges for done to be closed when the timeout
// elapses.
done() chan int
// If done is not yet closed, err returns nil.
// If done is closed, err returns a non-nil error explaining why:
// canceled if the context was canceled
// or deadline_exceeded if the context's deadline passed.
// After err returns a non-nil error, successive calls to err return the same error.
err() IError
// Value returns the value associated with this context for key, or nil
// if no value is associated with key. Successive calls to Value with
// the same key returns the same result.
//
// Use context values only for request-scoped data that transits
// processes and API boundaries, not for passing optional parameters to
// functions.
//
// A key identifies a specific value in a Context. Functions that wish
// to store values in Context typically allocate a key in a global
// variable then use that key as the argument to context.with_value and
// Context.Value. A key can be any type that supports equality;
// packages should define keys as an unexported type to avoid
// collisions.
value(key string) ?voidptr
str() string
}
// background returns an empty Context. It is never canceled, has no
// values, and has no deadline. It is typically used by the main function,
// initialization, and tests, and as the top-level Context for incoming
// requests.
pub fn background() Context {
return context.background
}
// todo returns an empty Context. Code should use todo when
// it's unclear which Context to use or it is not yet available (because the
// surrounding function has not yet been extended to accept a Context
// parameter).
pub fn todo() Context {
return context.todo
}
fn context_name(ctx Context) string {
return typeof(ctx)
}
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