Add seemingly working python bindings

.pre-commit-config.yaml

@@ -8,3 +8,7 @@ repos:
     rev: e2c2116d86a80e72e7146a06e68b7c228afc6319 # frozen: v0.6.13
     hooks:
       - id: cmake-format
+  - repo: https://github.com/psf/black
+    rev: 552baf822992936134cbd31a38f69c8cfe7c0f05 # frozen: 24.3.0
+    hooks:
+      - id: black

weaseljson.py

@@ -0,0 +1,251 @@
+import ctypes
+import json
+import enum
+import os
+from typing import Optional
+
+event_callback = ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+data_callback = ctypes.CFUNCTYPE(None, ctypes.c_void_p, ctypes.c_void_p, ctypes.c_int)
+
+
+class WeaselJsonCallbacks(ctypes.Structure):
+    _fields_ = [
+        ("on_begin_object", event_callback),
+        ("on_end_object", event_callback),
+        ("on_begin_string", event_callback),
+        ("on_string_data", data_callback),
+        ("on_end_string", event_callback),
+        ("on_begin_array", event_callback),
+        ("on_end_array", event_callback),
+        ("on_begin_number", event_callback),
+        ("on_number_data", data_callback),
+        ("on_end_number", event_callback),
+        ("on_true_literal", event_callback),
+        ("on_false_literal", event_callback),
+        ("on_null_literal", event_callback),
+    ]
+
+
+class WeaselJsonStatus(enum.Enum):
+    OK = 0
+    AGAIN = 1
+    REJECT = 2
+    OVERFLOW = 3
+
+
+class WeaselJsonParserBase:
+    def __init__(
+        self,
+        build_dir: Optional[str] = None,
+        stackSize: int = 1024,
+    ) -> None:
+        self._lib = None
+        if build_dir is None:
+            build_dir = os.path.dirname(__file__) + "/build"
+        for f in (build_dir + "/" + "libweaseljson.so",):
+            try:
+                self._lib = ctypes.cdll.LoadLibrary(f)
+            except OSError:
+                print("Could not load " + f)
+                pass
+
+        if self._lib is None:
+            import sys
+
+            print(
+                "Could not find libweaseljson implementation",
+                file=sys.stderr,
+            )
+            sys.exit(1)
+
+        self._lib.WeaselJsonParser_create.argtypes = (
+            ctypes.c_int,
+            ctypes.POINTER(WeaselJsonCallbacks),
+            ctypes.c_void_p,
+        )
+        self._lib.WeaselJsonParser_create.restype = ctypes.c_void_p
+        self._lib.WeaselJsonParser_reset.argtypes = (ctypes.c_void_p,)
+        self._lib.WeaselJsonParser_destroy.argtypes = (ctypes.c_void_p,)
+        self._lib.WeaselJsonParser_parse.argtypes = (
+            ctypes.c_void_p,
+            ctypes.c_void_p,
+            ctypes.c_int,
+        )
+        self._lib.WeaselJsonParser_parse.restype = WeaselJsonStatus
+
+        self.p = self._lib.WeaselJsonParser_create(
+            stackSize,
+            callbacks,
+            ctypes.cast(ctypes.pointer(ctypes.py_object(self)), ctypes.c_void_p),
+        )
+
+    def on_begin_object(self):
+        pass
+
+    def on_end_object(self):
+        pass
+
+    def on_begin_string(self):
+        pass
+
+    def on_string_data(self, data):
+        pass
+
+    def on_end_string(self):
+        pass
+
+    def on_begin_array(self):
+        pass
+
+    def on_end_array(self):
+        pass
+
+    def on_begin_number(self):
+        pass
+
+    def on_number_data(self, data):
+        pass
+
+    def on_end_number(self):
+        pass
+
+    def on_true_literal(self):
+        pass
+
+    def on_false_literal(self):
+        pass
+
+    def on_null_literal(self):
+        pass
+
+    def parse(self, data: bytes) -> WeaselJsonStatus:
+        buf = (ctypes.c_ubyte * len(data)).from_buffer(bytearray(data))
+        return self._lib.WeaselJsonParser_parse(self.p, buf, len(data))
+
+    def reset(self):
+        self._lib.WeaselJsonParser_reset(self.p)
+
+    def __enter__(self):
+        return self
+
+    def close(self) -> None:
+        if self.p is not None:
+            self._lib.WeaselJsonParser_destroy(self.p)
+            self.p = None
+
+    def __exit__(self, exception_type, exception_value, exception_traceback):
+        self.close()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_begin_object(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_begin_object()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_end_object(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_end_object()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_begin_string(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_begin_string()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p, ctypes.c_void_p, ctypes.c_int)
+def on_string_data(p, buf, len):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_string_data(bytes(ctypes.string_at(buf, len)))
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_end_string(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_end_string()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_begin_array(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_begin_array()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_end_array(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_end_array()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_begin_number(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_begin_number()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p, ctypes.c_void_p, ctypes.c_int)
+def on_number_data(p, buf, len):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_number_data(bytes(ctypes.string_at(buf, len)))
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_end_number(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_end_number()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_true_literal(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_true_literal()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_false_literal(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_false_literal()
+
+
+@ctypes.CFUNCTYPE(None, ctypes.c_void_p)
+def on_null_literal(p):
+    self = ctypes.cast(p, ctypes.POINTER(ctypes.py_object)).contents.value
+    self.on_null_literal()
+
+
+callbacks = WeaselJsonCallbacks(
+    on_begin_object,
+    on_end_object,
+    on_begin_string,
+    on_string_data,
+    on_end_string,
+    on_begin_array,
+    on_end_array,
+    on_begin_number,
+    on_number_data,
+    on_end_number,
+    on_true_literal,
+    on_false_literal,
+    on_null_literal,
+)
+
+
+class JsonParser(WeaselJsonParserBase):
+    # override callbacks
+    def on_string_data(self, data):
+        print(data)
+
+
+with JsonParser() as parser:
+    raw = json.dumps({"hello": "world", "foo": 42}).encode()
+    i = 0
+    stride = 1
+    while True:
+        slice = raw[i : i + stride]
+        s = parser.parse(slice)
+        if s != WeaselJsonStatus.AGAIN:
+            break
+        i += stride
+    print(s)