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99 lines
2.0 KiB
Markdown
99 lines
2.0 KiB
Markdown
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# %% Fibers %%
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Pocketlang support coroutines via [fibers](https://en.wikipedia.org/wiki/Fiber_(computer_science))
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(light weight threads with cooperative multitask). A fiber object is a wrapper
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around a function, contains the execution state (simply the stack and the
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instruction pointer) for that function, which can be run and once yielded
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resumed.
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```ruby
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import Fiber
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def fn(h, w)
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print(h, w)
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end
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fb = Fiber.new(fn) # Create a fiber.
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Fiber.run(fb, 'hello', 'world') # Run the fiber.
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```
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## %% Yielding %%
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When a function is yielded, it's state will be stored in the fiber it's
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belongs to and will return from the function, to parent fiber it's running
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from (not the caller of the function). And you can pass values between
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fibers when they yield.
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```ruby
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import Fiber
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def fn()
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print('running')
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yield()
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print('resumed')
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end
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fb = Fiber.new(fn)
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Fiber.run(fb) # Prints 'running'.
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print('before resumed')
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Fiber.resume(fb) # Prints 'resumed'.
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```
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Yield from the fiber with a value.
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```ruby
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import Fiber
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def fn()
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print('running')
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yield(42) # Return 42.
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print('resumed')
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end
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fb = Fiber.new(fn)
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val = Fiber.run(fb) # Prints 'running'.
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print(val) # Prints 42.
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Fiber.resume(fb) # Prints 'resumed'.
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```
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Resume the fiber with a value.
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```ruby
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import Fiber
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def fn()
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print('running')
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val = yield() # Resumed value.
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print(val) # Prints 42.
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print('resumed')
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end
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fb = Fiber.new(fn)
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val = Fiber.run(fb) # Prints 'running'.
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Fiber.resume(fb, 42) # Resume with 42, Prints 'resumed'.
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```
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Once a fiber is done execution, trying to resume it will cause a runtime
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error. To check if the fiber is finished check its attribute
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`is_done` and use the attribute `function` to get it's function,
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which could be used to create a new fiber to "re-start" the fiber.
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```ruby
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import Fiber
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Fiber.run(fb = Fiber.new(
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func()
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for i in 0..5 do
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yield(i)
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end
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end))
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while not fb.is_done
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Fiber.resume(fb)
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end
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# Get the function from the fiber.
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fn = Fiber.get_func(fb)
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```
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