84 lines
3.2 KiB
Python
84 lines
3.2 KiB
Python
import stdio
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import t, c
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import string
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from inherit_test import Animal, Dog
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# ============================================================
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# 虚分派测试：通过虚表指针验证虚分派机制
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#
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# 本测试验证：方法调用通过对象的 __vtable__ 字段进行虚分派，
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# 而非通过变量声明类型直接调用。
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#
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# 测试方法：
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# 1. 创建 Animal 对象 a（Animal 虚表，Speak 返回 0）
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# 2. 创建 Dog 对象 d
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# 3. 用内联汇编将 d 的虚表指针复制到 a
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# 4. 调用 a.Speak() — 应返回 1（Dog.Speak），证明虚分派生效
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#
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# 如果是直接调用（非虚分派），a.Speak() 会调用 Animal.Speak 返回 0
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#
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# 注意：Animal 和 Dog 类从 inherit_test.py 导入（命名空间隔离）
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# ============================================================
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def virtual_dispatch_test() -> int:
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stdio.printf("vdispatch: === Test Start ===\n")
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# 创建对象
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a: Animal = Animal(42)
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d: Dog = Dog(100, 7)
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# ============================================================
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# 测试 1: 直接分派（基线验证）
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# ============================================================
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stdio.printf("vdispatch: === Test 1: Direct Dispatch ===\n")
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a_speak: int = a.Speak()
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stdio.printf("vdispatch: a.Speak()=%d (expected 0)\n", a_speak)
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if a_speak != 0:
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stdio.printf("[FAIL] a.Speak()=%d expected 0\n", a_speak)
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return 1
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d_speak: int = d.Speak()
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stdio.printf("vdispatch: d.Speak()=%d (expected 1)\n", d_speak)
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if d_speak != 1:
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stdio.printf("[FAIL] d.Speak()=%d expected 1\n", d_speak)
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return 1
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# ============================================================
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# 测试 2: 虚分派验证（复制虚表指针）
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#
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# 将 Dog 的虚表指针复制到 Animal 对象 a
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# 虚表指针位于结构体偏移 0（__vtable__ 字段）
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# 复制后 a.Speak() 应通过虚表分发到 Dog.Speak（返回 1）
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# ============================================================
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stdio.printf("vdispatch: === Test 2: Virtual Dispatch ===\n")
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# 使用 string.memcpy 复制虚表指针（8字节，结构体偏移0）
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# 将 d 的虚表指针复制到 a，使 a.Speak() 分发到 Dog.Speak
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string.memcpy(c.Addr(a), c.Addr(d), 8)
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a_speak2: int = a.Speak()
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stdio.printf("vdispatch: a.Speak()=%d (expected 1 after vtable copy)\n", a_speak2)
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if a_speak2 != 1:
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stdio.printf("[FAIL] a.Speak()=%d expected 1 after vtable copy\n", a_speak2)
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return 1
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# ============================================================
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# 测试 3: GetName 验证（未被覆盖的虚方法）
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#
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# Dog 没有覆盖 GetName，Dog 虚表中 GetName 槽位指向 Animal.GetName
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# a.GetName() 应返回 a.name (42)，证明虚表槽位一致性
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# ============================================================
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stdio.printf("vdispatch: === Test 3: GetName After VTable Copy ===\n")
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a_name: int = a.GetName()
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stdio.printf("vdispatch: a.GetName()=%d (expected 42)\n", a_name)
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if a_name != 42:
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stdio.printf("[FAIL] a.GetName()=%d expected 42\n", a_name)
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return 1
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stdio.printf("vdispatch: === All Tests Passed ===\n")
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return 0
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