1
2 /* Compiler implementation of the D programming language
3 * Copyright (C) 1999-2019 by The D Language Foundation, All Rights Reserved
4 * written by Walter Bright
5 * http://www.digitalmars.com
6 * Distributed under the Boost Software License, Version 1.0.
7 * http://www.boost.org/LICENSE_1_0.txt
8 * https://github.com/D-Programming-Language/dmd/blob/master/src/staticcond.c
9 */
10
11 #include "mars.h"
12 #include "expression.h"
13 #include "mtype.h"
14 #include "scope.h"
15
16 Expression *semantic(Expression *e, Scope *sc);
17
18 /********************************************
19 * Semantically analyze and then evaluate a static condition at compile time.
20 * This is special because short circuit operators &&, || and ?: at the top
21 * level are not semantically analyzed if the result of the expression is not
22 * necessary.
23 * Params:
24 * exp = original expression, for error messages
25 * Returns:
26 * true if evaluates to true
27 */
28
evalStaticCondition(Scope * sc,Expression * exp,Expression * e,bool & errors)29 bool evalStaticCondition(Scope *sc, Expression *exp, Expression *e, bool &errors)
30 {
31 if (e->op == TOKandand)
32 {
33 AndAndExp *aae = (AndAndExp *)e;
34 bool result = evalStaticCondition(sc, exp, aae->e1, errors);
35 if (errors || !result)
36 return false;
37 result = evalStaticCondition(sc, exp, aae->e2, errors);
38 return !errors && result;
39 }
40
41 if (e->op == TOKoror)
42 {
43 OrOrExp *ooe = (OrOrExp *)e;
44 bool result = evalStaticCondition(sc, exp, ooe->e1, errors);
45 if (errors)
46 return false;
47 if (result)
48 return true;
49 result = evalStaticCondition(sc, exp, ooe->e2, errors);
50 return !errors && result;
51 }
52
53 if (e->op == TOKquestion)
54 {
55 CondExp *ce = (CondExp *)e;
56 bool result = evalStaticCondition(sc, exp, ce->econd, errors);
57 if (errors)
58 return false;
59 Expression *leg = result ? ce->e1 : ce->e2;
60 result = evalStaticCondition(sc, exp, leg, errors);
61 return !errors && result;
62 }
63
64 unsigned nerrors = global.errors;
65
66 sc = sc->startCTFE();
67 sc->flags |= SCOPEcondition;
68
69 e = semantic(e, sc);
70 e = resolveProperties(sc, e);
71
72 sc = sc->endCTFE();
73 e = e->optimize(WANTvalue);
74
75 if (nerrors != global.errors ||
76 e->op == TOKerror ||
77 e->type->toBasetype() == Type::terror)
78 {
79 errors = true;
80 return false;
81 }
82
83 if (!e->type->isBoolean())
84 {
85 exp->error("expression %s of type %s does not have a boolean value", exp->toChars(), e->type->toChars());
86 errors = true;
87 return false;
88 }
89
90 e = e->ctfeInterpret();
91
92 if (e->isBool(true))
93 return true;
94 else if (e->isBool(false))
95 return false;
96
97 e->error("expression %s is not constant", e->toChars());
98 errors = true;
99 return false;
100 }
101