Fix escaping in JSON schema patterns (#487)

The escaping logic for patterns in JSON schema got convoluted, and we
introduced inadvertently inconsistencies in the formatting. Namely,
we first *unescaped* all the characters before passing them into
the parser for regular expressions. This unescaped characters later
propagated and mixed with *escaped* characters when the expression was
transpiled for UTF-16.

To solve this mess, we remove the unescaping step at the beginning and
test more thoroughly to specify & observe the expected behavior.

Fixes #485.

README.rst

@@ -138,7 +138,7 @@ Call the generator with the appropriate target:
 .. code-block::
 
     usage: aas-core-codegen [-h] --model_path MODEL_PATH --snippets_dir
-                            SNIPPETS_DIR --output_dir OUTPUT_DIR --target                          
+                            SNIPPETS_DIR --output_dir OUTPUT_DIR --target
                             {csharp,cpp,golang,java,jsonschema,python,typescript,rdf_shacl,xsd,jsonld_context,protobuf}
                             [--version]
 

aas_core_codegen/jsonschema/main.py

@@ -1,7 +1,6 @@
 """Generate JSON schema corresponding to the meta-model."""
 import collections
 import json
-import re
 from typing import (
     TextIO,
     Any,
@@ -141,51 +140,9 @@ def _define_type(
         )
 
 
-# noinspection RegExpSimplifiable
-_ESCAPE_BACKSLASH_X_U_U_RE = re.compile(
-    r"(\\x([a-fA-f0-9]{2})|\\u([a-fA-f0-9]{4})|\\U([a-fA-f0-9]{8}))"
-)
-
-
-def _undo_escaping_backslash_x_u_and_U_in_pattern(pattern: str) -> str:
-    """
-    Undo the escaping of ``\\x??``, ``\\u????`` and ``\\U????????`` in the ``pattern``.
-
-    This is necessary since Greenery does not know how to handle such escape
-    sequences in the patterns and need the verbatim characters.
-    """
-    parts = []  # type: List[str]
-    cursor = None  # type: Optional[int]
-    for mtch in re.finditer(_ESCAPE_BACKSLASH_X_U_U_RE, pattern):
-        if cursor is None:
-            parts.append(pattern[: mtch.start()])
-        else:
-            parts.append(pattern[cursor : mtch.start()])
-
-        substring = mtch.group(0)
-        assert len(substring) > 2
-        assert substring[0] == "\\"
-
-        hex_code = substring[2:]
-        code_point = int(hex_code, base=16)
-        character = chr(code_point)
-        parts.append(character)
-        cursor = mtch.end()
-
-    if cursor is None:
-        parts.append(pattern)
-    else:
-        if cursor < len(pattern):
-            parts.append(pattern[cursor:])
-
-    return "".join(parts)
-
-
 def _fix_pattern_for_utf16(pattern: str) -> str:
     """Fix the pattern for UTF-16-only regex engines."""
-    regex, error = parse_retree.parse(
-        [_undo_escaping_backslash_x_u_and_U_in_pattern(pattern)]
-    )
+    regex, error = parse_retree.parse([pattern])
     if error is not None:
         raise ValueError(
             f"The pattern could not be parsed: {pattern!r}; error was: {error}"

aas_core_codegen/parse/retree/_parse.py

@@ -1,5 +1,5 @@
 """Parse a regular expression defined over a possibly-formatted string."""
-
+import collections.abc
 import io
 import math
 import re
@@ -89,7 +89,16 @@ class Cursor:
             )
             for first, second in zip(values, values[1:])
         ),
-        "No consecutive strings"
+        "No consecutive strings expected in the parsed sequence of an AST expression "
+        "representing a string interpolation"
+    )
+    # NOTE (mristin, 2024-05-08):
+    # We add a runtime test here since it already happened that we supplied ``values``
+    # as a string during development, causing an unnecessary long debugging session.
+    @require(
+        lambda values:
+        isinstance(values, collections.abc.Sequence),
+        "values must be a sequence"
     )
     # fmt: on
     def __init__(self, values: Sequence[Union[str, FormattedValue]]) -> None:

test_data/java/test_main/aas_core_meta.v3/expected_output/xmlization/Xmlization.java

@@ -22378,7 +22378,7 @@ public static class Serialize
     public static void to(
       IClass that,
       XMLStreamWriter writer) throws SerializeException {
-      VisitorWithWriter visitor = new VisitorWithWriter(); 
+      VisitorWithWriter visitor = new VisitorWithWriter();
       visitor.visit(
         that, writer);
     }