55 lines
1.6 KiB
Nim
55 lines
1.6 KiB
Nim
# SPDX-FileCopyrightText: ☭ 2021 Emery Hemingway
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# SPDX-License-Identifier: Unlicense
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import std/[hashes, tables]
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import preserves
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import ./actors, ./patterns, ./protocols/dataspace
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from ./protocols/protocol import Handle
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type
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Observe = dataspace.Observe[Ref]
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Turn = actors.Turn
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type
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DuringProc* = proc (turn: var Turn; a: Assertion; h: Handle): TurnAction {.gcsafe.}
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DuringActionKind = enum null, dead, act
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DuringAction = object
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case kind: DuringActionKind
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of null, dead: discard
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of act:
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action: TurnAction
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DuringEntity {.final.}= ref object of Entity
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cb: DuringProc
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assertionMap: Table[Handle, DuringAction]
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method publish(de: DuringEntity; turn: var Turn; a: Assertion; h: Handle) =
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let action = de.cb(turn, a, h)
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# assert(not action.isNil "should have put in a no-op action")
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let g = de.assertionMap.getOrDefault h
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case g.kind
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of null:
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de.assertionMap[h] = DuringAction(kind: act, action: action)
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of dead:
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de.assertionMap.del h
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freshen(turn, action)
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of act:
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raiseAssert("during: duplicate handle in publish: " & $h)
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method retract(de: DuringEntity; turn: var Turn; h: Handle) =
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let g = de.assertionMap.getOrDefault h
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case g.kind
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of null:
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de.assertionMap[h] = DuringAction(kind: dead)
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of dead:
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raiseAssert("during: duplicate handle in retract: " & $h)
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of act:
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de.assertionMap.del h
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if not g.action.isNil:
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g.action(turn)
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proc during*(cb: DuringProc): DuringEntity = DuringEntity(cb: cb)
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proc observe*(turn: var Turn; ds: Ref; pat: Pattern; e: Entity): Handle =
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publish(turn, ds, Observe(pattern: pat, observer: embed newRef(turn, e)))
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