Restructure and document exceptions

Author: marksparkza

CHANGELOG.rst

@@ -1,6 +1,31 @@
 Changelog
 =========
 
+v0.11.0 (2023-06-03)
+--------------------
+Breaking changes:
+
+* ``RelativeJSONPointerError`` superseded by ``RelativeJSONPointerMalformedError``
+  and ``RelativeJSONPointerReferenceError``
+
+Deprecations:
+
+* Exception classes dropped from the top-level package API
+* ``jschon.exceptions`` module renamed to ``jschon.exc``
+
+Documentation:
+
+* Exception classes documented
+* Custom keyword example refactored to raise exception in constructor
+
+Miscellaneous:
+
+* ``JschonError`` base exception class introduced
+* ``JSONPointerError`` partitioned into ``JSONPointerMalformedError``,
+  ``JSONPointerReferenceError``, ``RelativeJSONPointerMalformedError``
+  and ``RelativeJSONPointerReferenceError``
+
+
 v0.10.3 (2023-05-21)
 --------------------
 Bug Fixes:

docs/api.rst

@@ -8,39 +8,32 @@ Catalog
 .. autofunction:: jschon.create_catalog
 
 * :class:`~jschon.catalog.Catalog`
-* :class:`~jschon.exceptions.CatalogError`
 * :class:`~jschon.catalog.LocalSource`
 * :class:`~jschon.catalog.RemoteSource`
 
 JSON
 ^^^^
 * :class:`~jschon.json.JSON`
 * :class:`~jschon.json.JSONCompatible`
-* :class:`~jschon.exceptions.JSONError`
 
 JSON Patch
 ^^^^^^^^^^
 * :class:`~jschon.jsonpatch.JSONPatch`
-* :class:`~jschon.exceptions.JSONPatchError`
 * :class:`~jschon.jsonpatch.JSONPatchOperation`
 
 JSON Pointer
 ^^^^^^^^^^^^
 * :class:`~jschon.jsonpointer.JSONPointer`
-* :class:`~jschon.exceptions.JSONPointerError`
 * :class:`~jschon.jsonpointer.RelativeJSONPointer`
-* :class:`~jschon.exceptions.RelativeJSONPointerError`
 
 JSON Schema
 ^^^^^^^^^^^
 * :class:`~jschon.jsonschema.JSONSchema`
-* :class:`~jschon.exceptions.JSONSchemaError`
 * :class:`~jschon.jsonschema.Result`
 
 URI
 ^^^
 * :class:`~jschon.uri.URI`
-* :class:`~jschon.exceptions.URIError`
 
 Module Reference
 ----------------

docs/reference/exc.rst

@@ -0,0 +1,3 @@
+jschon.exc
+==========
+.. automodule:: jschon.exc

docs/reference/exceptions.rst

@@ -28,22 +28,24 @@ class EnumRefKeyword(Keyword):
     # ignore non-string instances
     instance_types = "string",
 
+    def __init__(self, parentschema: JSONSchema, value: str):
+        super().__init__(parentschema, value)
+
+        # raise an exception during schema construction if a reference is invalid
+        if value not in remote_enum_cache:
+            raise JSONSchemaError(f"Unknown remote enumeration {value}")
+
     def evaluate(self, instance: JSON, result: Result) -> None:
-        # get the keyword's value as it appears in the JSON schema
-        enum_id = self.json.value
-        try:
-            # retrieve the enumeration from the remote enumeration cache
-            enum = remote_enum_cache[enum_id]
-        except KeyError:
-            raise JSONSchemaError(f"Unknown remote enumeration {enum_id}")
-
-        # test the value of the current JSON instance node against the enumeration
-        if instance.data in enum:
+        # the keyword's value is a reference to a remote enumeration
+        enum_ref = self.json.value
+
+        # evaluate the current JSON instance node against the enumeration
+        if instance.data in remote_enum_cache.get(enum_ref):
             # (optionally) on success, annotate the result
-            result.annotate(enum_id)
+            result.annotate(enum_ref)
         else:
             # on failure, mark the result as failed, with an (optional) error message
-            result.fail(f"The instance is not a member of the {enum_id} enumeration")
+            result.fail(f"The instance is not a member of the {enum_ref} enumeration")
 
 
 # initialize the catalog, with JSON Schema 2020-12 vocabulary support

examples/custom_keyword.py

@@ -1,5 +1,5 @@
 from .catalog import Catalog, LocalSource, RemoteSource
-from .exceptions import CatalogError, JSONError, JSONPatchError, JSONPointerError, JSONSchemaError, RelativeJSONPointerError, URIError
+from .exceptions import CatalogError, JSONError, JSONPatchError, JSONPointerError, JSONSchemaError, URIError
 from .json import JSON, JSONCompatible
 from .jsonpatch import JSONPatch, JSONPatchOperation
 from .jsonpointer import JSONPointer, RelativeJSONPointer
@@ -8,28 +8,21 @@
 
 __all__ = [
     'Catalog',
-    'CatalogError',
     'JSON',
     'JSONCompatible',
-    'JSONError',
     'JSONPatch',
-    'JSONPatchError',
     'JSONPatchOperation',
     'JSONPointer',
-    'JSONPointerError',
     'JSONSchema',
-    'JSONSchemaError',
     'LocalSource',
     'RelativeJSONPointer',
-    'RelativeJSONPointerError',
     'RemoteSource',
     'Result',
     'URI',
-    'URIError',
     'create_catalog',
 ]
 
-__version__ = '0.10.3'
+__version__ = '0.11.0'
 
 
 def create_catalog(*versions: str, name: str = 'catalog') -> Catalog:

jschon/__init__.py

@@ -0,0 +1,50 @@
+class JschonError(Exception):
+    """Generic error class."""
+
+
+class CatalogError(JschonError):
+    """An error originating in the :mod:`~jschon.catalog` module."""
+
+
+class JSONError(JschonError):
+    """An error originating in the :class:`~jschon.json` module."""
+
+
+class JSONPatchError(JschonError):
+    """An error originating in the :mod:`~jschon.jsonpatch` module."""
+
+
+class JSONPointerError(JschonError):
+    """An error originating in the :mod:`~jschon.jsonpointer` module."""
+
+
+class JSONPointerMalformedError(JSONPointerError):
+    """Raised for an invalid :class:`~jschon.jsonpointer.JSONPointer`
+    constructor argument."""
+
+
+class JSONPointerReferenceError(JSONPointerError):
+    """Raised when a :class:`~jschon.jsonpointer.JSONPointer`
+    evaluates a non-existent location in a document."""
+
+
+class RelativeJSONPointerMalformedError(JSONPointerError):
+    """Raised for an invalid :class:`~jschon.jsonpointer.RelativeJSONPointer`
+    constructor argument."""
+
+
+class RelativeJSONPointerReferenceError(JSONPointerError):
+    """Raised when a :class:`~jschon.jsonpointer.RelativeJSONPointer`
+    evaluates a non-existent location in a document."""
+
+
+class JSONSchemaError(JschonError):
+    """Raised when an error occurs during construction of a
+    :class:`~jschon.jsonschema.JSONSchema` object. May be raised by
+    :class:`~jschon.vocabulary.Keyword` initializers and reference
+    resolution methods.
+    """
+
+
+class URIError(JschonError):
+    """An error originating in the :mod:`~jschon.uri` module."""

jschon/exc.py

@@ -1,26 +1,2 @@
-class CatalogError(Exception):
-    pass
-
-
-class JSONError(Exception):
-    pass
-
-
-class JSONPatchError(Exception):
-    pass
-
-
-class JSONPointerError(Exception):
-    pass
-
-
-class JSONSchemaError(Exception):
-    pass
-
-
-class RelativeJSONPointerError(Exception):
-    pass
-
-
-class URIError(Exception):
-    pass
+# noinspection PyUnresolvedReferences
+from .exc import *

jschon/exceptions.py

@@ -5,7 +5,12 @@
 import urllib.parse
 from typing import Any, Iterable, Literal, Mapping, Sequence, TYPE_CHECKING, Union, overload
 
-from jschon.exceptions import JSONPointerError, RelativeJSONPointerError
+from jschon.exc import (
+    JSONPointerMalformedError,
+    JSONPointerReferenceError,
+    RelativeJSONPointerMalformedError,
+    RelativeJSONPointerReferenceError,
+)
 
 if TYPE_CHECKING:
     from jschon.json import JSON
@@ -74,16 +79,16 @@ def __new__(cls, *values: Union[str, Iterable[str]]) -> JSONPointer:
 
         :param values: each value may either be an RFC 6901 string, or an iterable
             of unescaped keys
-        :raise JSONPointerError: if a string argument does not conform to the RFC
-            6901 syntax
+        :raise JSONPointerMalformedError: if a string argument does not conform to
+            the RFC 6901 syntax
         """
         self = object.__new__(cls)
         self._keys = []
 
         for value in values:
             if isinstance(value, str):
                 if not JSONPointer._json_pointer_re.fullmatch(value):
-                    raise JSONPointerError(f"'{value}' is not a valid JSON pointer")
+                    raise JSONPointerMalformedError(f"'{value}' is not a valid JSON pointer")
                 self._keys.extend(self.unescape(token) for token in value.split('/')[1:])
 
             elif isinstance(value, JSONPointer):
@@ -179,8 +184,8 @@ def evaluate(self, document: Any) -> Any:
         will always fail.
 
         :param document: any Python object
-        :raise JSONPointerError: if `self` references a non-existent location
-            within `document`
+        :raise JSONPointerReferenceError: if `self` references a non-existent
+            location in `document`
         """
 
         def resolve(value, keys):
@@ -203,7 +208,7 @@ def resolve(value, keys):
             except (KeyError, IndexError):
                 pass
 
-            raise JSONPointerError(f"Path '{self}' not found in document")
+            raise JSONPointerReferenceError(f"Path '{self}' not found in document")
 
         return resolve(document, collections.deque(self._keys))
 
@@ -283,13 +288,13 @@ def __new__(
             a value of 0, which is not allowed by the grammar, is treated as if
             there is no adjustment.
         :param ref: a :class:`JSONPointer` instance, or the literal ``'#'``
-        :raise RelativeJSONPointerError: for any invalid arguments
+        :raise RelativeJSONPointerMalformedError: for any invalid arguments
         """
         self = object.__new__(cls)
 
         if value is not None:
             if not (match := RelativeJSONPointer._regex.fullmatch(value)):
-                raise RelativeJSONPointerError(f"'{value}' is not a valid relative JSON pointer")
+                raise RelativeJSONPointerMalformedError(f"'{value}' is not a valid relative JSON pointer")
 
             up, over, ref = match.group('up', 'over', 'ref')
             self.up = int(up)
@@ -337,25 +342,25 @@ def evaluate(self, document: JSON) -> Union[int, str, JSON]:
         node = document
         for _ in range(self.up):
             if node.parent is None:
-                raise RelativeJSONPointerError('Up too many levels')
+                raise RelativeJSONPointerReferenceError('Up too many levels')
             node = node.parent
 
         if self.over:
             if node.parent is None:
-                raise RelativeJSONPointerError('No containing node for index adjustment')
+                raise RelativeJSONPointerReferenceError('No containing node for index adjustment')
             if node.parent.type != "array":
-                raise RelativeJSONPointerError(f'Index adjustment not valid for type {node.parent.type}')
+                raise RelativeJSONPointerReferenceError(f'Index adjustment not valid for type {node.parent.type}')
             adjusted = int(node.key) + self.over
             if adjusted < 0 or adjusted >= len(node.parent):
-                raise RelativeJSONPointerError(f'Index adjustment out of range')
+                raise RelativeJSONPointerReferenceError(f'Index adjustment out of range')
             node = node.parent[adjusted]
 
         if self.index:
             if node.parent is None:
-                raise RelativeJSONPointerError('No containing node')
+                raise RelativeJSONPointerReferenceError('No containing node')
             return int(node.key) if node.parent.type == "array" else node.key
 
         try:
             return self.path.evaluate(node)
-        except JSONPointerError as e:
-            raise RelativeJSONPointerError from e
+        except JSONPointerReferenceError as e:
+            raise RelativeJSONPointerReferenceError from e

jschon/jsonpointer.py

@@ -6,7 +6,8 @@
 import pytest
 from hypothesis import given, strategies as hs
 
-from jschon import JSON, JSONCompatible, JSONPointer, JSONPointerError, RelativeJSONPointer, RelativeJSONPointerError
+from jschon import JSON, JSONCompatible, JSONPointer, RelativeJSONPointer
+from jschon.exc import JSONPointerReferenceError, RelativeJSONPointerReferenceError
 from jschon.utils import json_loadf
 from tests.strategies import json, jsonpointer, jsonpointer_key, relative_jsonpointer, relative_jsonpointer_regex
 
@@ -85,18 +86,18 @@ def test_evaluate_jsonpointer(value, testkey):
         assert JSONPointer(pointer).evaluate(JSON(value)) == target
 
     if isinstance(value, list):
-        with pytest.raises(JSONPointerError):
+        with pytest.raises(JSONPointerReferenceError):
             JSONPointer(f'/{len(value)}').evaluate(value)
-        with pytest.raises(JSONPointerError):
+        with pytest.raises(JSONPointerReferenceError):
             JSONPointer('/-').evaluate(value)
-        with pytest.raises(JSONPointerError):
+        with pytest.raises(JSONPointerReferenceError):
             JSONPointer('/').evaluate(value)
     elif isinstance(value, dict):
         if testkey not in value:
-            with pytest.raises(JSONPointerError):
+            with pytest.raises(JSONPointerReferenceError):
                 JSONPointer(f'/{jsonpointer_escape(testkey)}').evaluate(value)
     else:
-        with pytest.raises(JSONPointerError):
+        with pytest.raises(JSONPointerReferenceError):
             JSONPointer(f'/{value}').evaluate(value)
 
 
@@ -180,7 +181,7 @@ def test_evaluate_relative_jsonpointer(data, start, ref, result):
     if result == '<data>':
         result = data
     elif result == '<fail>':
-        with pytest.raises(RelativeJSONPointerError):
+        with pytest.raises(RelativeJSONPointerReferenceError):
             ref.evaluate(node)
         return