feat: support reference ranges in AnswerBuilder (e.g. [1-3])

haystack/components/builders/answer_builder.py

@@ -241,10 +241,26 @@ def _extract_answer_string(reply: str, pattern: str | None = None) -> str:
             return match.group(1)
         return ""
 
+    @staticmethod
+    def _expand_range_references(reply: str) -> list[int]:
+        """
+        Expand range references like [1-3] into individual 1-based indices [1, 2, 3].
+
+        :param reply: The Generator output string.
+        :returns: List of 1-based indices expanded from range references.
+        """
+        expanded = []
+        for match in re.finditer(r"\[(\d+)-(\d+)\]", reply):
+            start, end = int(match.group(1)), int(match.group(2))
+            if start <= end:
+                expanded.extend(range(start, end + 1))
+        return expanded
+
     @staticmethod
     def _extract_reference_idxs(reply: str, reference_pattern: str) -> set[int]:
-        document_idxs = re.findall(reference_pattern, reply)
-        return {int(idx) - 1 for idx in document_idxs}
+        individual = {int(idx) - 1 for idx in re.findall(reference_pattern, reply)}
+        range_refs = {idx - 1 for idx in AnswerBuilder._expand_range_references(reply)}
+        return individual | range_refs
 
     @staticmethod
     def _check_num_groups_in_regex(pattern: str) -> None:

releasenotes/notes/answer-builder-range-references.yaml

@@ -0,0 +1,5 @@
+---
+enhancements:
+  - |
+    ``AnswerBuilder`` now supports range references (e.g. ``[1-3]``) in Generator
+    outputs, automatically expanding them into individual document references.

test/components/builders/test_answer_builder.py

@@ -418,3 +418,23 @@ def test_conversation_history_with_last_message_only_true(self):
         assert "all_messages" in answers[0].meta
         assert answers[0].meta["all_messages"] == replies
         assert len(answers[0].meta["all_messages"]) == 1
+
+    def test_run_with_range_reference_pattern(self):
+        builder = AnswerBuilder(reference_pattern=r"\[(\d+)\]")
+        replies = ["Paris [1-2] and Rome [3]."]
+        documents = [
+            Document(content="Paris is the capital of France."),
+            Document(content="Berlin is the capital of Germany."),
+            Document(content="Rome is the capital of Italy."),
+        ]
+        result = builder.run(query="Capitals?", replies=replies, documents=documents)
+        referenced = [d for d in result["answers"][0].documents if d.meta.get("referenced")]
+        assert {d.meta["source_index"] for d in referenced} == {1, 2, 3}
+
+    def test_run_with_invalid_range_ignored(self):
+        builder = AnswerBuilder(reference_pattern=r"\[(\d+)\]")
+        replies = ["Answer [3-1] and [1]."]
+        documents = [Document(content="Doc 1"), Document(content="Doc 2"), Document(content="Doc 3")]
+        result = builder.run(query="Q?", replies=replies, documents=documents)
+        referenced = [d for d in result["answers"][0].documents if d.meta.get("referenced")]
+        assert {d.meta["source_index"] for d in referenced} == {1}