fix(JSONAdapter): Braces inside output not properly escaped by parser

dspy/adapters/json_adapter.py

@@ -5,12 +5,12 @@
 import json_repair
 import litellm
 import pydantic
-import regex
 from pydantic.fields import FieldInfo
 
 from dspy.adapters.chat_adapter import ChatAdapter, FieldInfoWithName
 from dspy.adapters.types.tool import ToolCalls
 from dspy.adapters.utils import (
+    _extract_first_json_object,
     format_field_value,
     get_annotation_name,
     parse_value,
@@ -151,10 +151,9 @@ def format_assistant_message_content(
         return self.format_field_with_value(fields_with_values, role="assistant")
 
     def parse(self, signature: type[Signature], completion: str) -> dict[str, Any]:
-        pattern = r"\{(?:[^{}]|(?R))*\}"
-        match = regex.search(pattern, completion, regex.DOTALL)
-        if match:
-            completion = match.group(0)
+        extracted_object = _extract_first_json_object(completion)
+        if extracted_object:
+            completion = extracted_object
         fields = json_repair.loads(completion)
 
         if not isinstance(fields, dict):

dspy/adapters/utils.py

@@ -280,3 +280,42 @@ def _quoted_string_for_literal_type_annotation(s: str) -> str:
     else:
         # Neither => enclose in single quotes
         return f"'{s}'"
+
+def _extract_first_json_object(text: str) -> str | None:
+    """Return the first balanced JSON object found in text or None if absent."""
+
+    in_string = False
+    escape = False
+    depth = 0
+    start_idx: int | None = None
+    seen_lbrace = False
+
+    for idx, char in enumerate(text):
+        if seen_lbrace and in_string:
+            if escape:
+                escape = False
+            elif char == "\\":
+                escape = True
+            elif char == '"':
+                in_string = False
+            continue
+
+        if seen_lbrace and char == '"':
+            in_string = True
+            continue
+
+        if char == "{":
+            if depth == 0:
+                start_idx = idx
+                seen_lbrace = True
+            depth += 1
+            continue
+
+        if char == "}":
+            if depth == 0 or start_idx is None:
+                continue
+            depth -= 1
+            if depth == 0:
+                return text[start_idx : idx + 1]
+
+    return None

tests/adapters/test_adapter_utils.py

@@ -5,7 +5,7 @@
 import pytest
 from pydantic import BaseModel
 
-from dspy.adapters.utils import parse_value
+from dspy.adapters.utils import _extract_first_json_object, parse_value
 
 
 class Profile(BaseModel):
@@ -105,3 +105,43 @@ def test_parse_value_json_repair():
     malformed = "not json or literal"
     with pytest.raises(Exception):
         parse_value(malformed, dict)
+
+
+@pytest.mark.parametrize(
+    "text,expected",
+    [
+        # JSON at the start of text
+        ('{"name": "John", "age": 30} and some trailing text', '{"name": "John", "age": 30}'),
+        # JSON in the middle of text
+        ('Here is your result: {"status": "success", "data": [1, 2, 3]} done', '{"status": "success", "data": [1, 2, 3]}'),
+        # JSON at the end of text
+        ('The answer is {"result": 42}', '{"result": 42}'),
+        # Nested JSON objects
+        ('Response: {"outer": {"inner": {"deep": "value"}}, "count": 5}', '{"outer": {"inner": {"deep": "value"}}, "count": 5}'),
+        # JSON with braces inside string values
+        ('{"message": "Use {placeholders} like {this}", "valid": true}', '{"message": "Use {placeholders} like {this}", "valid": true}'),
+        # JSON with escaped quotes in strings
+        ('{"quote": "She said \\"hello\\" to me"}', '{"quote": "She said \\"hello\\" to me"}'),
+        # No JSON present
+        ("This is just plain text without any JSON", None),
+        # Empty JSON object
+        ("Here is an empty object: {}", "{}"),
+        # Unbalanced braces (no valid JSON)
+        ("This has { an opening but no closing", None),
+        # Multiple JSON objects - should extract only the first
+        ('{"first": 1} and then {"second": 2}', '{"first": 1}'),
+        # JSON with newlines
+        ("""Here is the result:
+    {
+        "name": "Alice",
+        "scores": [95, 87, 92]
+    }
+    End of message""", """{
+        "name": "Alice",
+        "scores": [95, 87, 92]
+    }"""),
+    ],
+)
+def test_extract_first_json_object(text, expected):
+    result = _extract_first_json_object(text)
+    assert result == expected

tests/adapters/test_json_adapter.py

@@ -239,6 +239,41 @@ def test_json_adapter_parse_raise_error_on_mismatch_fields():
     )
 
 
+def test_json_adapter_parse_handles_braces_inside_string_values():
+    class CodeIssue(pydantic.BaseModel):
+        issue_type: str
+        severity_level: str
+        problem_code_snippet: str
+
+    class CodeReview(dspy.Signature):
+        reasoning: str = dspy.OutputField(desc="Short chain-of-thought analysis")
+        issue_list: list[CodeIssue] = dspy.OutputField(desc="Detected issues")
+
+    adapter = dspy.JSONAdapter()
+    completion = (
+        "Here is the review output you asked for:\n\n"
+        "{\n"
+        '  "reasoning": "Inspecting the conditional reveals an unmatched brace.",\n'
+        '  "issue_list": [\n'
+        "    {\n"
+        '      "issue_type": "style",\n'
+        '      "severity_level": "fatal",\n'
+        '      "problem_code_snippet": "if (user) {"\n'
+        "    }\n"
+        "  ]\n"
+        "}\n"
+    )
+
+    result = adapter.parse(CodeReview, completion)
+
+    assert result["reasoning"] == "Inspecting the conditional reveals an unmatched brace."
+    assert len(result["issue_list"]) == 1
+    issue = result["issue_list"][0]
+    assert issue.issue_type == "style"
+    assert issue.severity_level == "fatal"
+    assert issue.problem_code_snippet == "if (user) {"
+
+
 def test_json_adapter_formats_image():
     # Test basic image formatting
     image = dspy.Image(url="https://example.com/image.jpg")