plain input/output prompt strategy w/o chat templates (#1346)

* plain input/output prompt strategy w/o chat templates

* disable duplicate code check

* make sure to add an eos/eot token to the end of the output so it will stop

* multi turn segement support and test

src/axolotl/prompt_strategies/input_output.py

@@ -0,0 +1,54 @@
+"""Module for plain input/output prompt pairs"""
+from typing import Generator, Tuple
+
+from axolotl.prompt_tokenizers import PromptTokenizingStrategy
+from axolotl.prompters import IGNORE_TOKEN_ID, Prompter
+
+
+class RawInputOutputStrategy(PromptTokenizingStrategy):
+    """Prompt Strategy class for input/output pairs"""
+
+    def __init__(self, *args, eos_token=None, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.eos_token = eos_token
+        if not eos_token:
+            self.eos_token = self.tokenizer.eos_token
+
+    def tokenize_prompt(self, prompt):
+        # pylint: disable=duplicate-code
+        input_ids = []
+        labels = []
+        for label, text in self.prompter.build_prompt(prompt["segments"]):
+            tokenized_output = self.tokenizer(
+                text, add_special_tokens=False, return_tensors=None
+            )["input_ids"]
+            input_ids += tokenized_output
+            if label or self.train_on_inputs:
+                labels += tokenized_output
+            else:
+                labels += [IGNORE_TOKEN_ID] * len(tokenized_output)
+
+        tokenized_prompt = {
+            "input_ids": input_ids,
+            "labels": labels,
+            "attention_mask": [1] * len(input_ids),
+        }
+
+        return tokenized_prompt
+
+
+class RawInputOutputPrompter(Prompter):
+    """prompter for raw i/o data"""
+
+    def build_prompt(self, source) -> Generator[Tuple[bool, str], None, None]:
+        for segment in source:
+            yield segment["label"], segment["text"]
+
+
+def load(tokenizer, cfg):
+    return RawInputOutputStrategy(
+        RawInputOutputPrompter(),
+        tokenizer,
+        cfg.train_on_inputs,
+        cfg.sequence_len,
+    )