[04/n] Add json_source_map

parse_errors/json_source_map/__init__.py

@@ -0,0 +1,25 @@
+"""Thin wrapper around the json-source-map package that returns our own types."""
+
+from __future__ import annotations
+
+import json_source_map as _ext
+
+from ..source_map import Entry, Location, TSourceMap
+
+
+def calculate(source: str) -> TSourceMap:
+    """Calculate the source map for a JSON document."""
+    return {
+        pointer: Entry(
+            value_start=_loc(e.value_start),
+            value_end=_loc(e.value_end),
+            key_start=_loc(e.key_start) if e.key_start is not None else None,
+            key_end=_loc(e.key_end) if e.key_end is not None else None,
+        )
+        for pointer, e in _ext.calculate(source).items()
+    }
+
+
+def _loc(ext: _ext.Location) -> Location:
+    """Translate to our internal structure."""
+    return Location(line=ext.line, column=ext.column, position=ext.position)

parse_errors/json_source_map/__main__.py

@@ -0,0 +1,7 @@
+if __name__ == "__main__":  # pragma: no cover
+    import sys
+    from . import calculate
+
+    source = open(sys.argv[1]).read()
+    for pointer, entry in calculate(source).items():
+        print(f"{pointer!r:40s} {entry}")

parse_errors/source_map.py

@@ -33,6 +33,7 @@ def detect_format(path: Path) -> str | None:
     """Detect the format of a file based on its extension."""
     suffix = path.suffix.lower()
     return {
+        ".json": "json",
         ".toml": "toml",
         ".yaml": "yaml",
         ".yml": "yaml",
@@ -51,6 +52,12 @@ def build_source_map(source: str | bytes, fmt: str) -> TSourceMap:
         return yaml_source_map.calculate(
             source.decode("utf-8") if isinstance(source, bytes) else source
         )
+    elif fmt == "json":
+        from . import json_source_map
+
+        return json_source_map.calculate(
+            source.decode("utf-8") if isinstance(source, bytes) else source
+        )
     else:
         raise ValueError(f"Unknown format: {fmt!r}")
 

setup.cfg

@@ -16,6 +16,7 @@ setup_requires =
     setuptools >= 65
 include_package_data = true
 install_requires =
+    json-source-map
     pyyaml
     tree-sitter
     tree-sitter-toml

tests/test_parse_context_json.py

@@ -0,0 +1,79 @@
+import pytest
+import msgspec
+
+from parse_errors import ParseContext, ParseError
+
+from ._types import Config, Nested
+
+
+JSON_GOOD = b'{"host": "localhost", "port": 8080}'
+JSON_BAD = b'{"host": "localhost", "port": "not-an-int"}'
+JSON_NESTED_BAD = b'{"server": {"host": "localhost", "port": "not-an-int"}}'
+
+JSON_SOURCE = """\
+{
+  "host": "localhost",
+  "port": "not-an-int"
+}
+"""
+
+JSON_NESTED_SOURCE = """\
+{
+  "server": {
+    "host": "localhost",
+    "port": "not-an-int"
+  }
+}
+"""
+
+
+def test_json_no_error():
+    with ParseContext("config.json", data=JSON_GOOD.decode()):
+        msgspec.json.decode(JSON_GOOD, type=Config)
+
+
+def test_json_non_jsonpath_exception_passes_through():
+    with pytest.raises(ZeroDivisionError):
+        with ParseContext("config.json", data=JSON_SOURCE):
+            raise ZeroDivisionError("oops")
+
+
+def test_json_raises_parse_error():
+    with pytest.raises(ParseError) as exc_info:
+        with ParseContext("config.json", data=JSON_SOURCE):
+            msgspec.json.decode(JSON_SOURCE.encode(), type=Config)
+
+    err = exc_info.value
+    assert err.filename == "config.json"
+    assert err.line == 3
+    assert str(err) == "config.json:3:11: Expected `int`, got `str` - at `$.port`"
+
+
+def test_json_nested_raises_parse_error():
+    with pytest.raises(ParseError) as exc_info:
+        with ParseContext("config.json", data=JSON_NESTED_SOURCE):
+            msgspec.json.decode(JSON_NESTED_SOURCE.encode(), type=Nested)
+
+    err = exc_info.value
+    assert (
+        str(err) == "config.json:4:13: Expected `int`, got `str` - at `$.server.port`"
+    )
+
+
+def test_json_bytes_data():
+    with pytest.raises(ParseError) as exc_info:
+        with ParseContext("config.json", data=JSON_SOURCE.encode()):
+            msgspec.json.decode(JSON_SOURCE.encode(), type=Config)
+
+    assert (
+        str(exc_info.value)
+        == "config.json:3:11: Expected `int`, got `str` - at `$.port`"
+    )
+
+
+def test_json_original_exception_is_cause():
+    with pytest.raises(ParseError) as exc_info:
+        with ParseContext("config.json", data=JSON_SOURCE):
+            msgspec.json.decode(JSON_SOURCE.encode(), type=Config)
+
+    assert isinstance(exc_info.value.__cause__, msgspec.ValidationError)