Adding __repr__ for unions (#41)

Adds `__repr__` and `__str__` to union to print out all members, also
adjusts the formatting of structs to make it easier to follow:

```
Instruction: 0x12345678 (union):
 |- raw     -> Unsigned Scalar[32]: 0x12345678 (32 bits)
 |- add     -> Add: 0x12345678
                |- [ 1: 0] op    = 0x0
                |- [ 6: 2] tgt   = 0x1E
                |- [11: 7] src_a = 0xC
                |- [16:12] src_b = 0x5
 |- add_imm -> Add: 0x12345678
                |- [ 1: 0] op    = 0x0
                |- [ 6: 2] tgt   = 0x1E
                |- [11: 7] src_a = 0xC
                |- [16:12] src_b = 0x5
```

Author: Intuity

packtype/types/assembly.py

@@ -47,7 +47,7 @@ def _pt_lookup(self, field: type[Base] | Base) -> str:
 
     @property
     @functools.lru_cache  # noqa: B019
-    def _pt_fields(self) -> dict:
+    def _pt_fields(self) -> dict[Base, str]:
         return {getattr(self, x): x for x in self._PT_DEF.keys()}
 
 
@@ -136,8 +136,10 @@ def __str__(self) -> str:
         for fname in self._PT_DEF.keys():
             finst = getattr(self, fname)
             lsb, msb = self._PT_RANGES[fname]
+            width = msb - lsb + 1
             lines.append(
-                f" - [{msb:{max_bits}}:{lsb:{max_bits}}] {fname:{max_name}} = 0x{int(finst):X}"
+                f" |- [{msb:{max_bits}}:{lsb:{max_bits}}] {fname:{max_name}} "
+                f"= 0x{int(finst):0{(width + 3) // 4}X}"
             )
         return "\n".join(lines)
 

packtype/types/scalar.py

@@ -15,7 +15,13 @@ def _pt_name(cls) -> str:
         if cls._PT_ATTACHED_TO is not None:
             return cls._PT_ATTACHED_TO._pt_lookup(cls)
         else:
-            return NumericPrimitive._pt_name(cls)
+            return f"{['Unsigned', 'Signed'][cls._PT_SIGNED]} Scalar[{cls._PT_WIDTH}]"
+
+    def __str__(self) -> str:
+        return f"{type(self)._pt_name()}: 0x{int(self):0{(self._PT_WIDTH + 3) // 4}X}"
+
+    def __repr__(self):
+        return str(self)
 
 
 class Scalar(NumericPrimitive):

packtype/types/union.py

@@ -3,6 +3,7 @@
 #
 
 import functools
+import textwrap
 
 from .array import ArraySpec
 from .assembly import Assembly
@@ -30,6 +31,19 @@ def __init__(
         # NOTE: Fields are not constructed at this point, instead they are filled
         #       in lazily as they are requested by the consumer
 
+    def __str__(self) -> str:
+        parts = {}
+        for finst, fname in self._pt_fields.items():
+            parts[fname] = str(finst)
+        max_prefix = max(map(len, parts.keys()))
+        return f"{type(self).__name__}: 0x{int(self):X} (union):\n" + "\n".join(
+            (f" |- {p:{max_prefix}s} -> " + textwrap.indent(v, " " * (max_prefix + 8)).lstrip())
+            for p, v in parts.items()
+        )
+
+    def __repr__(self) -> str:
+        return self.__str__()
+
     def __getattribute__(self, fname: str):
         # Attempt to resolve the attribute from existing properties
         try:

tests/pysyntax/test_struct.py

@@ -94,10 +94,18 @@ class TestStruct:
         cd: Scalar[3]
         ef: Scalar[9]
 
-    inst = TestStruct._pt_unpack((39 << 15) | (5 << 12) | 123)
-    assert inst.ab.value == 123
-    assert inst.cd.value == 5
-    assert inst.ef.value == 39
+    value = (39 << 15) | (5 << 12) | 123
+    inst = TestStruct._pt_unpack(value)
+    assert inst.ab.value == (ab_value := 123)
+    assert inst.cd.value == (cd_value := 5)
+    assert inst.ef.value == (ef_value := 39)
+
+    assert str(inst) == (
+        f"TestStruct: 0x{value:06X}\n"
+        f" |- [11: 0] ab = 0x{ab_value:03X}\n"
+        f" |- [14:12] cd = 0x{cd_value:01X}\n"
+        f" |- [23:15] ef = 0x{ef_value:03X}"
+    )
 
 
 def test_struct_unpacking_from_msb():

tests/pysyntax/test_union.py

@@ -140,12 +140,27 @@ class Packet:
         raw: Scalar[32]
         header: Header
 
-    inst = Packet._pt_unpack((0x7 << 28) | (0x5 << 24) | (0x75 << 16) | 0x1234)
-    assert int(inst.raw) == (0x7 << 28) | (0x5 << 24) | (0x75 << 16) | 0x1234
-    assert int(inst.header.address) == 0x1234
-    assert int(inst.header.length) == 0x75
-    assert int(inst.header.mode) == 0x5
-    assert int(inst.header.flags) == 0x7
+    hdr_addr_val = 0x1234
+    hdr_len_val = 0x75
+    hdr_mode_val = 0x5
+    hdr_flags_val = 0x7
+    value = (hdr_flags_val << 28) | (hdr_mode_val << 24) | (hdr_len_val << 16) | hdr_addr_val
+    inst = Packet._pt_unpack(value)
+    assert int(inst.raw) == value
+    assert int(inst.header.address) == hdr_addr_val
+    assert int(inst.header.length) == hdr_len_val
+    assert int(inst.header.mode) == hdr_mode_val
+    assert int(inst.header.flags) == hdr_flags_val
+
+    assert str(inst) == (
+        f"Packet: 0x{value:08X} (union):\n"
+        f" |- raw    -> Unsigned Scalar[32]: 0x{value:08X}\n"
+        f" |- header -> Header: 0x{value:08X}\n"
+        f"               |- [15: 0] address = 0x{hdr_addr_val:04X}\n"
+        f"               |- [23:16] length  = 0x{hdr_len_val:02X}\n"
+        f"               |- [27:24] mode    = 0x{hdr_mode_val:01X}\n"
+        f"               |- [31:28] flags   = 0x{hdr_flags_val:01X}"
+    )
 
 
 def test_union_bad_widths():