Lumiera  0.pre.03
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access-casted-test.cpp
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1 /*
2  AccessCasted(Test) - verify helper to cast or convert as appropriate
3 
4  Copyright (C)
5  2008, Hermann Vosseler <Ichthyostega@web.de>
6 
7   **Lumiera** is free software; you can redistribute it and/or modify it
8   under the terms of the GNU General Public License as published by the
9   Free Software Foundation; either version 2 of the License, or (at your
10   option) any later version. See the file COPYING for further details.
11 
12 * *****************************************************************/
13 
20 #include "lib/test/run.hpp"
21 #include "lib/test/test-helper.hpp"
22 #include "lib/access-casted.hpp"
23 #include "lib/format-cout.hpp"
24 #include "lib/util.hpp"
25 
26 #include <utility>
27 #include <string>
28 
29 using std::move;
30 using std::string;
31 using std::ostream;
32 
33 using util::isSameObject;
34 
35 using LERR_(BOTTOM_VALUE);
36 using LERR_(WRONG_TYPE);
37 
38 
39 namespace util {
40 namespace test {
41 
42 
43 
44  namespace { // Test fixture...
45 
46  struct B {};
47  struct D : B {};
48 
49  struct E : D
50  {
51  virtual ~E() {};
52  };
53 
54  struct X
55  {
56  char x = 'x';
57  };
58 
59  struct F
60  : X
61  , E
62  { };
63 
64 
65  ostream& operator<< (ostream& s, const B& b) { return s << "B{} adr="<<&b; }
66  ostream& operator<< (ostream& s, const D& d) { return s << "D{} adr="<<&d; }
67  ostream& operator<< (ostream& s, const E& e) { return s << "E{} adr="<<&e; }
68  ostream& operator<< (ostream& s, const F& f) { return s << "F{} adr="<<&f; }
69 
70  }//(End)Test fixture
71 
72 
73 
74 
75 
76 
77  /*************************************************************************************************/
86  class AccessCasted_test : public Test
87  {
88  virtual void
89  run (Arg)
90  {
91 
92  D d;
93  D* pD =&d;
94  B* pB =pD;
95  D& rD = *pD;
96  B& rB = *pB;
97 
98  D*& rpD = pD;
99  B*& rpB = pB;
100 
101  E e;
102  E& rE = e;
103  F f;
104  E& rEF = f;
105  E* pEF = &f;
106  X* pXF = &f;
107  F* pF = &f;
108 
109  cout << "can_downcast<B,D> = " << can_downcast<B,D>::value <<endl;
110  cout << "can_downcast<B*,D*> = " << can_downcast<B*,D*>::value <<endl;
111  cout << "can_downcast<B&,D&> = " << can_downcast<B&,D&>::value <<endl;
112  cout << "can_downcast<B&,D*> = " << can_downcast<B&,D*>::value <<endl;
113  cout << "can_downcast<B*,D&> = " << can_downcast<B*,D&>::value <<endl;
114  cout << "can_downcast<B*&,D*&> = " << can_downcast<B*&,D*&>::value <<endl;
115  cout << "can_downcast<D*&,D*&> = " << can_downcast<D*&,D*&>::value <<endl;
116 
117  cout << "can_downcast<D*,E*> = " << can_downcast<D*,E*>::value <<endl;
118  cout << "can_downcast<E*,F*> = " << can_downcast<E*,F*>::value <<endl;
119 
120  cout << "has_RTTI<D*> = " << has_RTTI<D*>::value <<endl;
121  cout << "has_RTTI<E*> = " << has_RTTI<E*>::value <<endl;
122  cout << "has_RTTI<F*> = " << has_RTTI<F*>::value <<endl;
123 
124  cout << "is_convertible<D,D&> = " << std::is_convertible<D,D&>::value <<endl;
125  cout << "is_convertible<D&,D> = " << std::is_convertible<D&,D>::value <<endl;
126 
127 
128  cout << "can_use_dynamic_downcast<D,D&> = " << can_use_dynamic_downcast<D,D&>::value <<endl;
129  cout << "can_use_conversion<D,D&> = " << can_use_conversion<D,D&>::value <<endl;
130  cout << "can_use_dynamic_downcast<B*,D*> = " << can_use_dynamic_downcast<B*,D*>::value <<endl;
131  cout << "can_use_conversion<D*,B*> = " << can_use_conversion<D*,B*>::value <<endl;
132 
133  cout << "can_use_dynamic_downcast<D*&,D*&> = " << can_use_dynamic_downcast<D*&,D*&>::value <<endl;
134  cout << "can_use_conversion<D*&,D*&> = " << can_use_conversion<D*&,D*&>::value <<endl;
135  cout << "can_use_conversion<D*,E*> = " << can_use_conversion<D*,E*>::value <<endl;
136  cout << "can_use_dynamic_downcast<D*&,E*> = " << can_use_dynamic_downcast<D*&,E*>::value <<endl;
137  cout << "can_use_conversion<E*,F*> = " << can_use_conversion<E*,F*>::value <<endl;
138  cout << "can_use_dynamic_downcast<E*,F*> = " << can_use_dynamic_downcast<E*,F*>::value <<endl;
139 
140 
141 
142  cout << "=== standard case: References ==="<<endl;
143  cout << "Access(D as D&) --->" << AccessCasted<D&>::access(d) <<endl;
144  cout << "Access(D& as D&) --->" << AccessCasted<D&>::access(rD) <<endl;
145  D dd1(d);
146  // AccessCasted<D&>::access(move(dd1)); // does not compile since it would be dangerous; we can't take a l-value ref
147  // AccessCasted<D&&>::access(rD); // from a r-value (move) reference and we can't move a l-value ref
148  // AccessCasted<D&&>::access(d); //
149 
150  cout << "=== build a value object ==="<<endl;
151  cout << "Access(D as D) --->" << AccessCasted<D>::access(d) <<endl;
152  cout << "Access(D& as D) --->" << AccessCasted<D>::access(rD) <<endl;
153  cout << "Access(D&& as D) --->" << AccessCasted<D>::access(move(dd1)) <<endl;
154 
155  cout << "=== take a pointer ==="<<endl;
156  cout << "Access(D as D*) --->" << AccessCasted<D*>::access(d) <<endl;
157  cout << "Access(D& as D*) --->" << AccessCasted<D*>::access(rD) <<endl;
158  // AccessCasted<D*>::access(move(dd1)); // should not take value moved by r-value-ref as pointer, otherwise the moved object would be lost
159 
160  cout << "=== dereference a pointer ==="<<endl;
161  cout << "Access(D* as D&) --->" << AccessCasted<D&>::access(pD) <<endl;
162  cout << "Access(D* as D) --->" << AccessCasted<D>::access(pD) <<endl;
163  D* pdd1(pD);
164  cout << "Access(D*&& as D) --->" << AccessCasted<D>::access(move(pdd1)) <<endl;
165  D* pNull(0);
166  VERIFY_ERROR (BOTTOM_VALUE, AccessCasted<D>::access(pNull)); // run-time NULL check
167  // AccessCasted<D&&>::access(pD); // should not move away a value accessed through a pointer, there might be other users
168 
169  cout << "=== const correctness ==="<<endl;
170  cout << "Access(D as D const&) --->" << AccessCasted<D const&>::access(d) <<endl;
171  cout << "Access(D& as D const&) --->" << AccessCasted<D const&>::access(rD) <<endl;
172  cout << "Access(D as const D) --->" << AccessCasted<const D>::access(d) <<endl;
173  cout << "Access(D& as const D) --->" << AccessCasted<const D>::access(rD) <<endl;
174  cout << "Access(D as const D*) --->" << AccessCasted<const D*>::access(d) <<endl;
175  cout << "Access(D& as const D*) --->" << AccessCasted<const D*>::access(rD) <<endl;
176  cout << "Access(D* as D const&) --->" << AccessCasted<D const&>::access(pD) <<endl;
177  cout << "Access(D* as const D) --->" << AccessCasted<const D>::access(pD) <<endl;
178  const D cD(d);
179  D const& rcD(d);
180  const D* pcD(&cD);
181  cout << "Access(const D as D const&) --->" << AccessCasted<D const&>::access(cD) <<endl;
182  cout << "Access(D const& as D const&) --->" << AccessCasted<D const&>::access(rcD) <<endl;
183  cout << "Access(const D as const D) --->" << AccessCasted<const D>::access(cD) <<endl;
184  cout << "Access(D const& as const D) --->" << AccessCasted<const D>::access(rcD) <<endl;
185  cout << "Access(const D as const D*) --->" << AccessCasted<const D*>::access(cD) <<endl;
186  cout << "Access(D const& as const D*) --->" << AccessCasted<const D*>::access(rcD) <<endl;
187  cout << "Access(const D* as D const&) --->" << AccessCasted<D const&>::access(pcD) <<endl;
188  cout << "Access(const D* as const D) --->" << AccessCasted<const D>::access(pcD) <<endl;
189  cout << "Access(D const& as D) --->" << AccessCasted<D>::access(rcD) <<endl; // it's OK to construct a new (non-const) object from const ref
190  const D cD1(cD); // likewise it's OK to construct from move-ref. Actually, we're not
191  cout << "Access(D const&& as D) --->" << AccessCasted<D>::access(move(cD1)) <<endl; // moving anything, but it's up to the receiving ctor to prevent that
192  // AccessCasted<D&>::access(rcD); // normal ref from const ref is not const correct
193  // AccessCasted<D*>::access(rcD); // likewise, regular pointer from const ref prohibited
194  // AccessCasted<D&>::access(pcD); // likewise, regular ref from pointer-to-const
195  // AccessCasted<D*>::access(pcD); // and regular pointer from pointer-to-const
196  // AccessCasted<D&&>::access(rcD); // ruled out already because moving a reference is invalid
197  // AccessCasted<D&&>::access(pcD); // ruled out already because moving a dereferenced pointer is invalid
198  // AccessCasted<D&>::access(move(cD)); // ruled out already because taking reference from moved value is invalid
199  // AccessCasted<D*>::access(move(cD)); // and same for taking pointer from a moved value.
200 
201  cout << "=== work cases: actual conversions ==="<<endl;
202  cout << "Access(B& as B&) --->" << AccessCasted<B&>::access(rB) <<endl;
203  cout << "Access(D& as B&) --->" << AccessCasted<B&>::access(rD) <<endl;
204  cout << "Access(B* as B*) --->" << AccessCasted<B*>::access(pB) <<endl;
205  cout << "Access(D* as B*) --->" << AccessCasted<B*>::access(pD) <<endl;
206  cout << "Access(D& as B*) --->" << AccessCasted<B*>::access(rD) <<endl;
207  cout << "Access(D* as B&) --->" << AccessCasted<B&>::access(pD) <<endl;
208  cout << "Access(B*& as B*&) --->" << AccessCasted<B*&>::access(rpB) <<endl;
209  cout << "Access(D*& as D*&) --->" << AccessCasted<D*&>::access(rpD) <<endl;
210  cout << "Access(D& as const B*) --->" << AccessCasted<const B*>::access(rD) <<endl;
211  cout << "Access(D* as B const&) --->" << AccessCasted<B const&>::access(pD) <<endl;
212  cout << "Access(D const& as const B*) --->" << AccessCasted<const B*>::access(rcD) <<endl;
213  cout << "Access(const D* as B const&) --->" << AccessCasted<B const&>::access(pcD) <<endl;
214  // AccessCasted<B*&>::access(rpD); // ruled out, since it would allow to sneak-in a non-D object into the D*
215  // AccessCasted<D&>::access(rB); // any down-casts are ruled out,
216  // AccessCasted<D*>::access(pB); // since neither B nor D has RTTI
217  // AccessCasted<D&>::access(pB); //
218  // AccessCasted<D*>::access(rB); //
219  // AccessCasted<E&>::access(rD); // we need RTTI on both ends to perform a safe dynamic downcast.
220  // AccessCasted<D*>::access((B*)pD); // dangerous, since we have no way to know for sure it's indeed a D object
221  // AccessCasted<E*>::access(pDE); // same here, since E has RTTI but D hasn't, we have no way to find out the real type
222 
223  VERIFY_ERROR (WRONG_TYPE, AccessCasted<F&>::access(rE)); // allowed by typing, but fails at runtime since it isn't an F-object
224  cout << "Access(E(F)& as F&) --->" << AccessCasted<F&>::access(rEF) <<endl;
225  cout << "Access(E(F)* as F*) --->" << AccessCasted<F*>::access(pEF) <<endl;
226  cout << "Access(E(F)* as F&) --->" << AccessCasted<F&>::access(pEF) <<endl;
227  cout << "Access(E(F)& as F*) --->" << AccessCasted<F*>::access(pEF) <<endl;
228  cout << "Access(F* as X*) --->" << AccessCasted<X*>::access(pF) <<endl; // upcast to the other mixin is OK
229  cout << "Access(X(F)* as X*) --->" << AccessCasted<X*>::access(pXF) <<endl; // (and note: address adjustment due to mixin layout)
230  cout << "Access(F* as B&) --->" << AccessCasted<B&>::access(pF) <<endl; // upcast to base
231  cout << "Access(F* as E&) --->" << AccessCasted<E&>::access(pF) <<endl; // upcast to parent (retaining the RTTI)
232  // AccessCasted<X*>::access(pEF); // cross-cast not supported (to complicated to implement)
233  // AccessCasted<F*>::access(pXF); // downcast not possible, since X does not provide RTTI
234 
235  int i = 2;
236  float fp = 3.1415;
237  cout << "Access(int as double) --->" << AccessCasted<double>::access(i) <<endl;
238  cout << "Access(float as long) --->" << AccessCasted<long>::access(fp) <<endl;
239  // AccessCasted<double&>::access(i); // would undermine the type system, thus ruled out
240  // AccessCasted<double const&>::access(i); // allowed, but warning: returning reference to temporary (and the warning is justified)
241 
242  CHECK (isSameObject (d, AccessCasted<B&>::access(d)));
243  CHECK (isSameObject (rD, AccessCasted<B&>::access(pD)));
244  CHECK (isSameObject (d, AccessCasted<B const&>::access(pD)));
245  CHECK (!isSameObject (d, AccessCasted<B>::access(rD)));
246 
247  CHECK (isSameObject (f, AccessCasted<F&>::access(rEF)));
248  CHECK (!isSameObject (f, AccessCasted<X&>::access(pF))); // note: address adjustment due to layout of mixin object X
249  }
250  };
251 
252 
254  LAUNCHER (AccessCasted_test, "unit common");
255 
256 
257 
258 }} // namespace lib::meta::test
util::AccessCasted
Helper template to access a given value, possibly converted or casted in a safe way.
Definition: access-casted.hpp:143
format-cout.hpp
Automatically use custom string conversion in C++ stream output.
util::test::anonymous_namespace{access-casted-test.cpp}::D
Definition: access-casted-test.cpp:47
util::test::anonymous_namespace{access-casted-test.cpp}::B
Definition: access-casted-test.cpp:46
test
Definition: run.hpp:40
VERIFY_ERROR
#define VERIFY_ERROR(ERROR_ID, ERRONEOUS_STATEMENT)
Macro to verify that a statement indeed raises an exception.
Definition: test-helper.hpp:387
util::test::anonymous_namespace{access-casted-test.cpp}::E
Definition: access-casted-test.cpp:49
util::test::anonymous_namespace{access-casted-test.cpp}::X
Definition: access-casted-test.cpp:54
util::test::anonymous_namespace{access-casted-test.cpp}::F
Definition: access-casted-test.cpp:59
run.hpp
Simplistic test class runner.
util.hpp
Tiny helper functions and shortcuts to be used everywhere Consider this header to be effectively incl...
util::test::AccessCasted_test
Definition: access-casted-test.cpp:86
test-helper.hpp
A collection of frequently used helper functions to support unit testing.
access-casted.hpp
Helper for accessing a value, employing either a conversion or downcast, depending on the relation of...
util::isSameObject
bool isSameObject(A const &a, B const &b)
compare plain object identity, based directly on the referee&#39;s memory identities. ...
Definition: util.hpp:421