Add Completion generation model

outlines/text/sequences/__init__.py

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+from .completion import completion

outlines/text/sequences/completion.py

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+from typing import Optional
+
+import numpy as np
+from numpy.typing import NDArray
+
+from outlines.text.sequences.sequence import Sequence
+
+
+class Completion(Sequence):
+    """Represents a completion generation model.
+
+    `Completion` instances are unconstrained generation models that stop when an EOS token
+    has been found or when the maximum number of tokens has been reached.
+
+    >> import outlines.text as text
+    >> sequence = text.sequence(model)("Say something")
+
+    """
+
+    def __init__(self, model, max_tokens: Optional[int]):
+        super().__init__(model, max_tokens)
+
+    def is_finished(self, token_ids: NDArray[np.int64]) -> NDArray[np.bool_]:
+        """Determine whether the sequences reached maximum length of end with
+        and EOS token.
+
+        In practice, `Sequence`'s `__call__` methods only passed the `token_ids`
+        of the sequences that haven't been marked as finished already, which is
+        why we only need to look for the EOS token in the last element rather
+        than in the whole sequence.
+
+        Parameters
+        ----------
+        token_ids
+            The input sequences.
+
+        """
+        is_finished = np.zeros((token_ids.shape[0],), dtype=np.bool_)
+        is_finished[token_ids[:, -1] == self.model.tokenizer.eos_token_id] = True
+
+        return is_finished
+
+
+def completion(model, max_tokens: Optional[int] = None):
+    return Completion(model, max_tokens)

tests/text/sequences/test_completion.py

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+import numpy as np
+from numpy.testing import assert_array_equal
+
+from outlines.text.sequences.completion import Completion
+
+
+def test_completion_eos():
+    class Tokenizer:
+        eos_token_id = 0
+        pad_token_ids = -1
+
+    class Model:
+        tokenizer = Tokenizer()
+
+    model = Completion(Model(), 10)
+
+    token_ids = np.array([[3, 2]])
+    result = model.is_finished(token_ids)
+    assert_array_equal(result, [False])
+
+    token_ids = np.array([[3, 2, 0]])
+    result = model.is_finished(token_ids)
+    assert_array_equal(result, [True])
+
+    token_ids = np.array([[3, 2, 1], [3, 2, 0]])
+    result = model.is_finished(token_ids)
+    assert_array_equal(result, [False, True])
+
+    token_ids = np.array([[3, 2, 1, 0], [3, 2, 0, -1]])
+    result = model.is_finished(token_ids)
+    assert_array_equal(result, [True, False])