/
aliasthis.d
164 lines (150 loc) · 4.5 KB
/
aliasthis.d
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// Compiler implementation of the D programming language
// Copyright (c) 1999-2015 by Digital Mars
// All Rights Reserved
// written by Walter Bright
// http://www.digitalmars.com
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
module ddmd.aliasthis;
import core.stdc.stdio;
import ddmd.aggregate;
import ddmd.declaration;
import ddmd.dscope;
import ddmd.dsymbol;
import ddmd.errors;
import ddmd.expression;
import ddmd.func;
import ddmd.globals;
import ddmd.hdrgen;
import ddmd.identifier;
import ddmd.mtype;
import ddmd.opover;
import ddmd.root.outbuffer;
import ddmd.tokens;
import ddmd.visitor;
/***********************************************************
* alias ident this;
*/
extern (C++) final class AliasThis : Dsymbol
{
public:
Identifier ident;
extern (D) this(Loc loc, Identifier ident)
{
super(null); // it's anonymous (no identifier)
this.loc = loc;
this.ident = ident;
}
override Dsymbol syntaxCopy(Dsymbol s)
{
assert(!s);
/* Since there is no semantic information stored here,
* we don't need to copy it.
*/
return this;
}
override void semantic(Scope* sc)
{
Dsymbol p = sc.parent.pastMixin();
AggregateDeclaration ad = p.isAggregateDeclaration();
if (!ad)
{
.error(loc, "alias this can only be a member of aggregate, not %s %s", p.kind(), p.toChars());
return;
}
assert(ad.members);
Dsymbol s = ad.search(loc, ident);
if (!s)
{
s = sc.search(loc, ident, null);
if (s)
.error(loc, "%s is not a member of %s", s.toChars(), ad.toChars());
else
.error(loc, "undefined identifier %s", ident.toChars());
return;
}
if (ad.aliasthis && s != ad.aliasthis)
{
.error(loc, "there can be only one alias this");
return;
}
/* disable the alias this conversion so the implicit conversion check
* doesn't use it.
*/
ad.aliasthis = null;
Dsymbol sx = s;
if (sx.isAliasDeclaration())
sx = sx.toAlias();
Declaration d = sx.isDeclaration();
if (d && !d.isTupleDeclaration())
{
Type t = d.type;
assert(t);
if (ad.type.implicitConvTo(t) > MATCHnomatch)
{
.error(loc, "alias this is not reachable as %s already converts to %s", ad.toChars(), t.toChars());
}
}
ad.aliasthis = s;
}
override const(char)* kind()
{
return "alias this";
}
AliasThis isAliasThis()
{
return this;
}
override void accept(Visitor v)
{
v.visit(this);
}
}
extern (C++) Expression resolveAliasThis(Scope* sc, Expression e, bool gag = false)
{
AggregateDeclaration ad = isAggregate(e.type);
if (ad && ad.aliasthis)
{
uint olderrors = gag ? global.startGagging() : 0;
Loc loc = e.loc;
Type tthis = (e.op == TOKtype ? e.type : null);
e = new DotIdExp(loc, e, ad.aliasthis.ident);
e = e.semantic(sc);
if (tthis && ad.aliasthis.needThis())
{
if (e.op == TOKvar)
{
if (auto fd = (cast(VarExp)e).var.isFuncDeclaration())
{
// Bugzilla 13009: Support better match for the overloaded alias this.
bool hasOverloads;
if (auto f = fd.overloadModMatch(loc, tthis, hasOverloads))
{
if (!hasOverloads)
fd = f; // use exact match
e = new VarExp(loc, fd, hasOverloads);
e.type = f.type;
e = new CallExp(loc, e);
goto L1;
}
}
}
/* non-@property function is not called inside typeof(),
* so resolve it ahead.
*/
{
int save = sc.intypeof;
sc.intypeof = 1; // bypass "need this" error check
e = resolveProperties(sc, e);
sc.intypeof = save;
}
L1:
e = new TypeExp(loc, new TypeTypeof(loc, e));
e = e.semantic(sc);
}
e = resolveProperties(sc, e);
if (gag && global.endGagging(olderrors))
e = null;
}
return e;
}