"Dual Object Notation" -> "Twofold Object Notation"

[ton] / ton / tags.py

diff --git a/ton/tags.py b/ton/tags.py
new file mode 100644 (file)
index 0000000..db54dfe
--- /dev/null
+++ b/ton/tags.py
@@ -0,0 +1,138 @@
+import collections
+
+VOID = 0x00
+TRUE = 0x01
+FALSE = 0x02
+BOOL = (TRUE, FALSE)
+INT8 = 0x10
+INT16 = 0x11
+INT32 = 0x12
+INT64 = 0x13
+# These are to be supported in the future
+# FLOAT = 0x20
+# DOUBLE = 0x21
+BINARY = 0x30
+UTF8 = 0x31
+UTF16 = 0x32
+UTF32 = 0x33
+LIST = 0x40
+DICTIONARY = 0x41
+
+STRING_TAGS = set([UTF8, UTF16, UTF32])
+
+DEFAULT_INTEGER_ENCODING = INT32
+DEFAULT_STRING_ENCODING = UTF8
+
+TaggedObject = collections.namedtuple('TaggedObject', ['tag', 'value'])
+
+_TYPES_TO_TAGS = {
+    int: DEFAULT_INTEGER_ENCODING,
+    bytes: BINARY,
+    str: DEFAULT_STRING_ENCODING,
+    list: LIST,
+    dict: DICTIONARY,
+    collections.OrderedDict: DICTIONARY,
+}
+
+def _tag(o):
+    if isinstance(o, TaggedObject):
+        return o
+
+    if o is None:
+        return TaggedObject(tag = VOID, value = o)
+
+    if o is True:
+        return TaggedObject(tag = TRUE, value = o)
+
+    if o is False:
+        return TaggedObject(tag = FALSE, value = o)
+
+    return TaggedObject(tag = _TYPES_TO_TAGS[type(o)], value = o)
+
+_NONE = TaggedObject(tag = VOID, value = None)
+_TRUE = TaggedObject(tag = TRUE, value = True)
+_FALSE = TaggedObject(tag = FALSE, value = False)
+
+_TAGS_TO_IN_RANGE_PREDICATES = collections.OrderedDict([
+    (INT8,  lambda i: -128 <= i and i <= 127),
+    (INT16, lambda i: -32768 <= i and i <= 32767),
+    (INT32, lambda i: -2147483648 <= i and i <= 2147483647),
+    (INT64, lambda i: -9223372036854775808 <= i and i <= 9223372036854775807),
+])
+
+class TooWideError(Exception):
+    pass
+
+SMALLEST = object()
+
+def autotag(o, **kwargs):
+    preferred_integer_tag = kwargs.pop('preferred_integer_tag', DEFAULT_INTEGER_ENCODING)
+    preferred_string_tag = kwargs.pop('preferred_string_tag', DEFAULT_STRING_ENCODING)
+
+    if kwargs:
+        raise TypeError("autotag() got an unexpected keyword argument '{}'".format(
+            list(kwargs.keys())[0],
+        ))
+
+    if isinstance(o, TaggedObject):
+        return o
+
+    if o is None:
+        return _NONE
+
+    if o is True:
+        return _TRUE
+
+    if o is False:
+        return _FALSE
+
+    if isinstance(o, int):
+        if preferred_integer_tag is not SMALLEST and _TAGS_TO_IN_RANGE_PREDICATES[preferred_integer_tag](o):
+            return TaggedObject(tag = preferred_integer_tag, value = o)
+
+        else:
+            for tag, in_range_predicate in _TAGS_TO_IN_RANGE_PREDICATES.items():
+                if in_range_predicate(o):
+                    return TaggedObject(tag = tag, value = o)
+
+            raise TooWideError("Integer {} is too wide to be serialized")
+
+    if isinstance(o, str):
+        # TODO Support SMALLEST for preferred string tag
+        return TaggedObject(tag = preferred_string_tag, value = o)
+
+    if isinstance(o, bytes):
+        return TaggedObject(tag = BINARY, value = o)
+
+    if isinstance(o, list):
+        return TaggedObject(
+            tag = LIST,
+            value = [
+                autotag(
+                    i,
+                    preferred_integer_tag = preferred_integer_tag,
+                    preferred_string_tag = preferred_string_tag,
+                ) for i in o
+            ],
+        )
+
+    if isinstance(o, dict):
+        return TaggedObject(
+            tag = DICTIONARY,
+            value = collections.OrderedDict([
+                (
+                    autotag(
+                        key,
+                        preferred_integer_tag = preferred_integer_tag,
+                        preferred_string_tag = preferred_string_tag,
+                    ),
+                    autotag(
+                        value,
+                        preferred_integer_tag = preferred_integer_tag,
+                        preferred_string_tag = preferred_string_tag,
+                    ),
+                ) for key, value in o.items()
+            ]),
+        )
+
+    raise Exception('Unsupported type {}'.format(type(o)))