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comparison dmd/NullExp.d @ 0:10317f0c89a5

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Initial commit
author korDen
date Sat, 24 Oct 2009 08:42:06 +0400
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children cab4c37afb89
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-1:000000000000 0:10317f0c89a5
1 module dmd.NullExp;
2
3 import dmd.Expression;
4 import dmd.backend.elem;
5 import dmd.InterState;
6 import dmd.MATCH;
7 import dmd.Type;
8 import dmd.TY;
9 import dmd.TypeTypedef;
10 import dmd.OutBuffer;
11 import dmd.Loc;
12 import dmd.Scope;
13 import dmd.IRState;
14 import dmd.HdrGenState;
15 import dmd.TOK;
16 import dmd.backend.dt_t;
17 import dmd.backend.Util;
18
19 class NullExp : Expression
20 {
21 ubyte committed;
22
23 this(Loc loc)
24 {
25 super(loc, TOK.TOKnull, NullExp.sizeof);
26 }
27
28 Expression semantic(Scope sc)
29 {
30 version (LOGSEMANTIC) {
31 printf("NullExp.semantic('%s')\n", toChars());
32 }
33 // null is the same as (void*)0
34 if (!type)
35 type = Type.tvoid.pointerTo();
36
37 return this;
38 }
39
40 bool isBool(bool result)
41 {
42 assert(false);
43 }
44
45 int isConst()
46 {
47 assert(false);
48 }
49
50 void toCBuffer(OutBuffer buf, HdrGenState* hgs)
51 {
52 buf.writestring("null");
53 }
54
55 void toMangleBuffer(OutBuffer buf)
56 {
57 assert(false);
58 }
59
60 MATCH implicitConvTo(Type t)
61 {
62 static if (false) {
63 printf("NullExp.implicitConvTo(this=%s, type=%s, t=%s, committed = %d)\n",
64 toChars(), type.toChars(), t.toChars(), committed);
65 }
66 if (this.type.equals(t))
67 return MATCH.MATCHexact;
68
69 /* Allow implicit conversions from invariant to mutable|const,
70 * and mutable to invariant. It works because, after all, a null
71 * doesn't actually point to anything.
72 */
73 if (t.invariantOf().equals(type.invariantOf()))
74 return MATCH.MATCHconst;
75
76 // null implicitly converts to any pointer type or dynamic array
77 if (type.ty == TY.Tpointer && type.nextOf().ty == TY.Tvoid)
78 {
79 if (t.ty == TY.Ttypedef)
80 t = (cast(TypeTypedef)t).sym.basetype;
81 if (t.ty == TY.Tpointer || t.ty == TY.Tarray ||
82 t.ty == TY.Taarray || t.ty == TY.Tclass ||
83 t.ty == TY.Tdelegate)
84 {
85 return committed ? MATCH.MATCHconvert : MATCH.MATCHexact;
86 }
87 }
88
89 return Expression.implicitConvTo(t);
90 }
91
92 Expression castTo(Scope sc, Type t)
93 {
94 NullExp e;
95 Type tb;
96
97 //printf("NullExp::castTo(t = %p)\n", t);
98 if (type is t)
99 {
100 committed = 1;
101 return this;
102 }
103
104 e = cast(NullExp)copy();
105 e.committed = 1;
106 tb = t.toBasetype();
107 e.type = type.toBasetype();
108
109 if (tb !is e.type)
110 {
111 // null implicitly converts to any pointer type or dynamic array
112 if (e.type.ty == TY.Tpointer && e.type.nextOf().ty == TY.Tvoid &&
113 (tb.ty == TY.Tpointer || tb.ty == TY.Tarray || tb.ty == TY.Taarray ||
114 tb.ty == TY.Tdelegate))
115 {
116 static if (false) {
117 if (tb.ty == TY.Tdelegate)
118 {
119 TypeDelegate td = cast(TypeDelegate)tb;
120 TypeFunction tf = cast(TypeFunction)td.nextOf();
121
122 if (!tf.varargs && !(tf.arguments && tf.arguments.dim))
123 {
124 return Expression.castTo(sc, t);
125 }
126 }
127 }
128 }
129 else
130 {
131 return e.Expression.castTo(sc, t);
132 }
133 }
134 e.type = t;
135 return e;
136 }
137
138 Expression interpret(InterState* istate)
139 {
140 assert(false);
141 }
142
143 elem* toElem(IRState* irs)
144 {
145 return el_long(type.totym(), 0);
146 }
147
148 dt_t** toDt(dt_t** pdt)
149 {
150 assert(type);
151 return dtnzeros(pdt, cast(uint)type.size());
152 }
153 }
154