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expression.d
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expression.d
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/**
* Compiler implementation of the
* $(LINK2 http://www.dlang.org, D programming language).
*
* Copyright: Copyright (C) 1999-2019 by The D Language Foundation, All Rights Reserved
* Authors: $(LINK2 http://www.digitalmars.com, Walter Bright)
* License: $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
* Source: $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/expression.d, _expression.d)
* Documentation: https://dlang.org/phobos/dmd_expression.html
* Coverage: https://codecov.io/gh/dlang/dmd/src/master/src/dmd/expression.d
*/
module dmd.expression;
import core.stdc.stdarg;
import core.stdc.stdio;
import core.stdc.string;
import dmd.aggregate;
import dmd.aliasthis;
import dmd.apply;
import dmd.arrayop;
import dmd.arraytypes;
import dmd.ast_node;
import dmd.gluelayer;
import dmd.canthrow;
import dmd.complex;
import dmd.constfold;
import dmd.ctfeexpr;
import dmd.ctorflow;
import dmd.dcast;
import dmd.dclass;
import dmd.declaration;
import dmd.delegatize;
import dmd.dimport;
import dmd.dinterpret;
import dmd.dmodule;
import dmd.dscope;
import dmd.dstruct;
import dmd.dsymbol;
import dmd.dsymbolsem;
import dmd.dtemplate;
import dmd.errors;
import dmd.escape;
import dmd.expressionsem;
import dmd.func;
import dmd.globals;
import dmd.hdrgen;
import dmd.id;
import dmd.identifier;
import dmd.inline;
import dmd.mtype;
import dmd.nspace;
import dmd.objc;
import dmd.opover;
import dmd.optimize;
import dmd.root.ctfloat;
import dmd.root.filename;
import dmd.root.outbuffer;
import dmd.root.rmem;
import dmd.root.rootobject;
import dmd.safe;
import dmd.sideeffect;
import dmd.target;
import dmd.tokens;
import dmd.typesem;
import dmd.utf;
import dmd.visitor;
enum LOGSEMANTIC = false;
void emplaceExp(T : Expression, Args...)(void* p, Args args)
{
scope tmp = new T(args);
memcpy(p, cast(void*)tmp, __traits(classInstanceSize, T));
}
void emplaceExp(T : UnionExp)(T* p, Expression e)
{
memcpy(p, cast(void*)e, e.size);
}
// Return value for `checkModifiable`
enum Modifiable
{
/// Not modifiable
no,
/// Modifiable (the type is mutable)
yes,
/// Modifiable because it is initialization
initialization,
}
/****************************************
* Find the first non-comma expression.
* Params:
* e = Expressions connected by commas
* Returns:
* left-most non-comma expression
*/
inout(Expression) firstComma(inout Expression e)
{
Expression ex = cast()e;
while (ex.op == TOK.comma)
ex = (cast(CommaExp)ex).e1;
return cast(inout)ex;
}
/****************************************
* Find the last non-comma expression.
* Params:
* e = Expressions connected by commas
* Returns:
* right-most non-comma expression
*/
inout(Expression) lastComma(inout Expression e)
{
Expression ex = cast()e;
while (ex.op == TOK.comma)
ex = (cast(CommaExp)ex).e2;
return cast(inout)ex;
}
/*****************************************
* Determine if `this` is available by walking up the enclosing
* scopes until a function is found.
*
* Params:
* sc = where to start looking for the enclosing function
* Returns:
* Found function if it satisfies `isThis()`, otherwise `null`
*/
FuncDeclaration hasThis(Scope* sc)
{
//printf("hasThis()\n");
Dsymbol p = sc.parent;
while (p && p.isTemplateMixin())
p = p.parent;
FuncDeclaration fdthis = p ? p.isFuncDeclaration() : null;
//printf("fdthis = %p, '%s'\n", fdthis, fdthis ? fdthis.toChars() : "");
// Go upwards until we find the enclosing member function
FuncDeclaration fd = fdthis;
while (1)
{
if (!fd)
{
return null;
}
if (!fd.isNested() || fd.isThis() || (fd.isThis2 && fd.isMember2()))
break;
Dsymbol parent = fd.parent;
while (1)
{
if (!parent)
return null;
TemplateInstance ti = parent.isTemplateInstance();
if (ti)
parent = ti.parent;
else
break;
}
fd = parent.isFuncDeclaration();
}
if (!fd.isThis() && !(fd.isThis2 && fd.isMember2()))
{
return null;
}
assert(fd.vthis);
return fd;
}
/***********************************
* Determine if a `this` is needed to access `d`.
* Params:
* sc = context
* d = declaration to check
* Returns:
* true means a `this` is needed
*/
bool isNeedThisScope(Scope* sc, Declaration d)
{
if (sc.intypeof == 1)
return false;
AggregateDeclaration ad = d.isThis();
if (!ad)
return false;
//printf("d = %s, ad = %s\n", d.toChars(), ad.toChars());
for (Dsymbol s = sc.parent; s; s = s.toParentLocal())
{
//printf("\ts = %s %s, toParent2() = %p\n", s.kind(), s.toChars(), s.toParent2());
if (AggregateDeclaration ad2 = s.isAggregateDeclaration())
{
if (ad2 == ad)
return false;
else if (ad2.isNested())
continue;
else
return true;
}
if (FuncDeclaration f = s.isFuncDeclaration())
{
if (f.isMemberLocal())
break;
}
}
return true;
}
/******************************
* check e is exp.opDispatch!(tiargs) or not
* It's used to switch to UFCS the semantic analysis path
*/
bool isDotOpDispatch(Expression e)
{
if (auto dtie = e.isDotTemplateInstanceExp())
return dtie.ti.name == Id.opDispatch;
return false;
}
/****************************************
* Expand tuples.
* Input:
* exps aray of Expressions
* Output:
* exps rewritten in place
*/
extern (C++) void expandTuples(Expressions* exps)
{
//printf("expandTuples()\n");
if (exps is null)
return;
for (size_t i = 0; i < exps.dim; i++)
{
Expression arg = (*exps)[i];
if (!arg)
continue;
// Look for tuple with 0 members
if (auto e = arg.isTypeExp())
{
if (auto tt = e.type.toBasetype().isTypeTuple())
{
if (!tt.arguments || tt.arguments.dim == 0)
{
exps.remove(i);
if (i == exps.dim)
return;
i--;
continue;
}
}
}
// Inline expand all the tuples
while (arg.op == TOK.tuple)
{
TupleExp te = cast(TupleExp)arg;
exps.remove(i); // remove arg
exps.insert(i, te.exps); // replace with tuple contents
if (i == exps.dim)
return; // empty tuple, no more arguments
(*exps)[i] = Expression.combine(te.e0, (*exps)[i]);
arg = (*exps)[i];
}
}
}
/****************************************
* Expand alias this tuples.
*/
extern (C++) TupleDeclaration isAliasThisTuple(Expression e)
{
if (!e.type)
return null;
Type t = e.type.toBasetype();
while (true)
{
if (Dsymbol s = t.toDsymbol(null))
{
if (auto ad = s.isAggregateDeclaration())
{
s = ad.aliasthis;
if (s && s.isVarDeclaration())
{
TupleDeclaration td = s.isVarDeclaration().toAlias().isTupleDeclaration();
if (td && td.isexp)
return td;
}
if (Type att = t.aliasthisOf())
{
t = att;
continue;
}
}
}
return null;
}
}
extern (C++) int expandAliasThisTuples(Expressions* exps, size_t starti = 0)
{
if (!exps || exps.dim == 0)
return -1;
for (size_t u = starti; u < exps.dim; u++)
{
Expression exp = (*exps)[u];
if (TupleDeclaration td = exp.isAliasThisTuple)
{
exps.remove(u);
foreach (i, o; *td.objects)
{
auto d = o.isExpression().isDsymbolExp().s.isDeclaration();
auto e = new DotVarExp(exp.loc, exp, d);
assert(d.type);
e.type = d.type;
exps.insert(u + i, e);
}
version (none)
{
printf("expansion ->\n");
foreach (e; exps)
{
printf("\texps[%d] e = %s %s\n", i, Token.tochars[e.op], e.toChars());
}
}
return cast(int)u;
}
}
return -1;
}
/****************************************
* If `s` is a function template, i.e. the only member of a template
* and that member is a function, return that template.
* Params:
* s = symbol that might be a function template
* Returns:
* template for that function, otherwise null
*/
extern (C++) TemplateDeclaration getFuncTemplateDecl(Dsymbol s)
{
FuncDeclaration f = s.isFuncDeclaration();
if (f && f.parent)
{
if (auto ti = f.parent.isTemplateInstance())
{
if (!ti.isTemplateMixin() && ti.tempdecl)
{
auto td = ti.tempdecl.isTemplateDeclaration();
if (td.onemember && td.ident == f.ident)
{
return td;
}
}
}
}
return null;
}
/************************************************
* If we want the value of this expression, but do not want to call
* the destructor on it.
*/
Expression valueNoDtor(Expression e)
{
auto ex = lastComma(e);
if (auto ce = ex.isCallExp())
{
/* The struct value returned from the function is transferred
* so do not call the destructor on it.
* Recognize:
* ((S _ctmp = S.init), _ctmp).this(...)
* and make sure the destructor is not called on _ctmp
* BUG: if ex is a CommaExp, we should go down the right side.
*/
if (auto dve = ce.e1.isDotVarExp())
{
if (dve.var.isCtorDeclaration())
{
// It's a constructor call
if (auto comma = dve.e1.isCommaExp())
{
if (auto ve = comma.e2.isVarExp())
{
VarDeclaration ctmp = ve.var.isVarDeclaration();
if (ctmp)
{
ctmp.storage_class |= STC.nodtor;
assert(!ce.isLvalue());
}
}
}
}
}
}
else if (auto ve = ex.isVarExp())
{
auto vtmp = ve.var.isVarDeclaration();
if (vtmp && (vtmp.storage_class & STC.rvalue))
{
vtmp.storage_class |= STC.nodtor;
}
}
return e;
}
/*********************************************
* If e is an instance of a struct, and that struct has a copy constructor,
* rewrite e as:
* (tmp = e),tmp
* Input:
* sc = just used to specify the scope of created temporary variable
* destinationType = the type of the object on which the copy constructor is called;
* may be null if the struct defines a postblit
*/
private Expression callCpCtor(Scope* sc, Expression e, Type destinationType)
{
if (auto ts = e.type.baseElemOf().isTypeStruct())
{
StructDeclaration sd = ts.sym;
if (sd.postblit || sd.hasCopyCtor)
{
/* Create a variable tmp, and replace the argument e with:
* (tmp = e),tmp
* and let AssignExp() handle the construction.
* This is not the most efficient, ideally tmp would be constructed
* directly onto the stack.
*/
auto tmp = copyToTemp(STC.rvalue, "__copytmp", e);
if (sd.hasCopyCtor && destinationType)
tmp.type = destinationType;
tmp.storage_class |= STC.nodtor;
tmp.dsymbolSemantic(sc);
Expression de = new DeclarationExp(e.loc, tmp);
Expression ve = new VarExp(e.loc, tmp);
de.type = Type.tvoid;
ve.type = e.type;
return Expression.combine(de, ve);
}
}
return e;
}
/************************************************
* Handle the postblit call on lvalue, or the move of rvalue.
*
* Params:
* sc = the scope where the expression is encountered
* e = the expression the needs to be moved or copied (source)
* t = if the struct defines a copy constructor, the type of the destination
*
* Returns:
* The expression that copy constructs or moves the value.
*/
extern (D) Expression doCopyOrMove(Scope *sc, Expression e, Type t = null)
{
if (auto ce = e.isCondExp())
{
ce.e1 = doCopyOrMove(sc, ce.e1);
ce.e2 = doCopyOrMove(sc, ce.e2);
}
else
{
e = e.isLvalue() ? callCpCtor(sc, e, t) : valueNoDtor(e);
}
return e;
}
/****************************************************************/
/* A type meant as a union of all the Expression types,
* to serve essentially as a Variant that will sit on the stack
* during CTFE to reduce memory consumption.
*/
struct UnionExp
{
// yes, default constructor does nothing
extern (D) this(Expression e)
{
memcpy(&this, cast(void*)e, e.size);
}
/* Extract pointer to Expression
*/
extern (C++) Expression exp() return
{
return cast(Expression)&u;
}
/* Convert to an allocated Expression
*/
extern (C++) Expression copy()
{
Expression e = exp();
//if (e.size > sizeof(u)) printf("%s\n", Token::toChars(e.op));
assert(e.size <= u.sizeof);
switch (e.op)
{
case TOK.cantExpression: return CTFEExp.cantexp;
case TOK.voidExpression: return CTFEExp.voidexp;
case TOK.break_: return CTFEExp.breakexp;
case TOK.continue_: return CTFEExp.continueexp;
case TOK.goto_: return CTFEExp.gotoexp;
default: return e.copy();
}
}
private:
// Ensure that the union is suitably aligned.
align(8) union __AnonStruct__u
{
char[__traits(classInstanceSize, Expression)] exp;
char[__traits(classInstanceSize, IntegerExp)] integerexp;
char[__traits(classInstanceSize, ErrorExp)] errorexp;
char[__traits(classInstanceSize, RealExp)] realexp;
char[__traits(classInstanceSize, ComplexExp)] complexexp;
char[__traits(classInstanceSize, SymOffExp)] symoffexp;
char[__traits(classInstanceSize, StringExp)] stringexp;
char[__traits(classInstanceSize, ArrayLiteralExp)] arrayliteralexp;
char[__traits(classInstanceSize, AssocArrayLiteralExp)] assocarrayliteralexp;
char[__traits(classInstanceSize, StructLiteralExp)] structliteralexp;
char[__traits(classInstanceSize, NullExp)] nullexp;
char[__traits(classInstanceSize, DotVarExp)] dotvarexp;
char[__traits(classInstanceSize, AddrExp)] addrexp;
char[__traits(classInstanceSize, IndexExp)] indexexp;
char[__traits(classInstanceSize, SliceExp)] sliceexp;
char[__traits(classInstanceSize, VectorExp)] vectorexp;
}
__AnonStruct__u u;
}
/********************************
* Test to see if two reals are the same.
* Regard NaN's as equivalent.
* Regard +0 and -0 as different.
* Params:
* x1 = first operand
* x2 = second operand
* Returns:
* 1 if x1 is x2
* else 0
*/
int RealIdentical(real_t x1, real_t x2)
{
return (CTFloat.isNaN(x1) && CTFloat.isNaN(x2)) || CTFloat.isIdentical(x1, x2);
}
/************************ TypeDotIdExp ************************************/
/* Things like:
* int.size
* foo.size
* (foo).size
* cast(foo).size
*/
DotIdExp typeDotIdExp(const ref Loc loc, Type type, Identifier ident)
{
return new DotIdExp(loc, new TypeExp(loc, type), ident);
}
/***************************************************
* Given an Expression, find the variable it really is.
*
* For example, `a[index]` is really `a`, and `s.f` is really `s`.
* Params:
* e = Expression to look at
* Returns:
* variable if there is one, null if not
*/
VarDeclaration expToVariable(Expression e)
{
while (1)
{
switch (e.op)
{
case TOK.variable:
return (cast(VarExp)e).var.isVarDeclaration();
case TOK.dotVariable:
e = (cast(DotVarExp)e).e1;
continue;
case TOK.index:
{
IndexExp ei = cast(IndexExp)e;
e = ei.e1;
Type ti = e.type.toBasetype();
if (ti.ty == Tsarray)
continue;
return null;
}
case TOK.slice:
{
SliceExp ei = cast(SliceExp)e;
e = ei.e1;
Type ti = e.type.toBasetype();
if (ti.ty == Tsarray)
continue;
return null;
}
case TOK.this_:
case TOK.super_:
return (cast(ThisExp)e).var.isVarDeclaration();
default:
return null;
}
}
}
enum OwnedBy : ubyte
{
code, // normal code expression in AST
ctfe, // value expression for CTFE
cache, // constant value cached for CTFE
}
enum WANTvalue = 0; // default
enum WANTexpand = 1; // expand const/immutable variables if possible
/***********************************************************
* http://dlang.org/spec/expression.html#expression
*/
extern (C++) abstract class Expression : ASTNode
{
const TOK op; // to minimize use of dynamic_cast
ubyte size; // # of bytes in Expression so we can copy() it
ubyte parens; // if this is a parenthesized expression
Type type; // !=null means that semantic() has been run
Loc loc; // file location
extern (D) this(const ref Loc loc, TOK op, int size)
{
//printf("Expression::Expression(op = %d) this = %p\n", op, this);
this.loc = loc;
this.op = op;
this.size = cast(ubyte)size;
}
static void _init()
{
CTFEExp.cantexp = new CTFEExp(TOK.cantExpression);
CTFEExp.voidexp = new CTFEExp(TOK.voidExpression);
CTFEExp.breakexp = new CTFEExp(TOK.break_);
CTFEExp.continueexp = new CTFEExp(TOK.continue_);
CTFEExp.gotoexp = new CTFEExp(TOK.goto_);
CTFEExp.showcontext = new CTFEExp(TOK.showCtfeContext);
}
/**
* Deinitializes the global state of the compiler.
*
* This can be used to restore the state set by `_init` to its original
* state.
*/
static void deinitialize()
{
CTFEExp.cantexp = CTFEExp.cantexp.init;
CTFEExp.voidexp = CTFEExp.voidexp.init;
CTFEExp.breakexp = CTFEExp.breakexp.init;
CTFEExp.continueexp = CTFEExp.continueexp.init;
CTFEExp.gotoexp = CTFEExp.gotoexp.init;
CTFEExp.showcontext = CTFEExp.showcontext.init;
}
/*********************************
* Does *not* do a deep copy.
*/
final Expression copy()
{
Expression e;
if (!size)
{
debug
{
fprintf(stderr, "No expression copy for: %s\n", toChars());
printf("op = %d\n", op);
}
assert(0);
}
e = cast(Expression)mem.xmalloc(size);
//printf("Expression::copy(op = %d) e = %p\n", op, e);
return cast(Expression)memcpy(cast(void*)e, cast(void*)this, size);
}
Expression syntaxCopy()
{
//printf("Expression::syntaxCopy()\n");
//print();
return copy();
}
// kludge for template.isExpression()
override final DYNCAST dyncast() const
{
return DYNCAST.expression;
}
override const(char)* toChars()
{
OutBuffer buf;
HdrGenState hgs;
toCBuffer(this, &buf, &hgs);
return buf.extractChars();
}
final void error(const(char)* format, ...) const
{
if (type != Type.terror)
{
va_list ap;
va_start(ap, format);
.verror(loc, format, ap);
va_end(ap);
}
}
final void errorSupplemental(const(char)* format, ...)
{
if (type == Type.terror)
return;
va_list ap;
va_start(ap, format);
.verrorSupplemental(loc, format, ap);
va_end(ap);
}
final void warning(const(char)* format, ...) const
{
if (type != Type.terror)
{
va_list ap;
va_start(ap, format);
.vwarning(loc, format, ap);
va_end(ap);
}
}
final void deprecation(const(char)* format, ...) const
{
if (type != Type.terror)
{
va_list ap;
va_start(ap, format);
.vdeprecation(loc, format, ap);
va_end(ap);
}
}
/**********************************
* Combine e1 and e2 by CommaExp if both are not NULL.
*/
extern (D) static Expression combine(Expression e1, Expression e2)
{
if (e1)
{
if (e2)
{
e1 = new CommaExp(e1.loc, e1, e2);
e1.type = e2.type;
}
}
else
e1 = e2;
return e1;
}
extern (D) static Expression combine(Expression e1, Expression e2, Expression e3)
{
return combine(combine(e1, e2), e3);
}
extern (D) static Expression combine(Expression e1, Expression e2, Expression e3, Expression e4)
{
return combine(combine(e1, e2), combine(e3, e4));
}
/**********************************
* If 'e' is a tree of commas, returns the rightmost expression
* by stripping off it from the tree. The remained part of the tree
* is returned via e0.
* Otherwise 'e' is directly returned and e0 is set to NULL.
*/
extern (D) static Expression extractLast(Expression e, out Expression e0)
{
if (e.op != TOK.comma)
{
return e;
}
CommaExp ce = cast(CommaExp)e;
if (ce.e2.op != TOK.comma)
{
e0 = ce.e1;
return ce.e2;
}
else
{
e0 = e;
Expression* pce = &ce.e2;
while ((cast(CommaExp)(*pce)).e2.op == TOK.comma)
{
pce = &(cast(CommaExp)(*pce)).e2;
}
assert((*pce).op == TOK.comma);
ce = cast(CommaExp)(*pce);
*pce = ce.e1;
return ce.e2;
}
}
extern (D) static Expressions* arraySyntaxCopy(Expressions* exps)
{
Expressions* a = null;
if (exps)
{
a = new Expressions(exps.dim);
foreach (i, e; *exps)
{
(*a)[i] = e ? e.syntaxCopy() : null;
}
}
return a;
}
dinteger_t toInteger()
{
//printf("Expression %s\n", Token::toChars(op));
error("integer constant expression expected instead of `%s`", toChars());
return 0;
}
uinteger_t toUInteger()
{
//printf("Expression %s\n", Token::toChars(op));
return cast(uinteger_t)toInteger();
}
real_t toReal()
{
error("floating point constant expression expected instead of `%s`", toChars());
return CTFloat.zero;
}
real_t toImaginary()
{
error("floating point constant expression expected instead of `%s`", toChars());
return CTFloat.zero;
}
complex_t toComplex()
{
error("floating point constant expression expected instead of `%s`", toChars());
return complex_t(CTFloat.zero);
}
StringExp toStringExp()
{
return null;
}
TupleExp toTupleExp()
{
return null;
}
/***************************************
* Return !=0 if expression is an lvalue.
*/
bool isLvalue()
{
return false;
}
/*******************************
* Give error if we're not an lvalue.
* If we can, convert expression to be an lvalue.
*/
Expression toLvalue(Scope* sc, Expression e)
{
if (!e)
e = this;
else if (!loc.isValid())
loc = e.loc;
if (e.op == TOK.type)
error("`%s` is a `%s` definition and cannot be modified", e.type.toChars(), e.type.kind());
else
error("`%s` is not an lvalue and cannot be modified", e.toChars());
return new ErrorExp();
}
Expression modifiableLvalue(Scope* sc, Expression e)
{
//printf("Expression::modifiableLvalue() %s, type = %s\n", toChars(), type.toChars());
// See if this expression is a modifiable lvalue (i.e. not const)
if (checkModifiable(sc) == Modifiable.yes)
{
assert(type);
if (!type.isMutable())
{
if (auto dve = this.isDotVarExp())
{
if (isNeedThisScope(sc, dve.var))
for (Dsymbol s = sc.func; s; s = s.toParentLocal())
{
FuncDeclaration ff = s.isFuncDeclaration();
if (!ff)
break;
if (!ff.type.isMutable)
{
error("cannot modify `%s` in `%s` function", toChars(), MODtoChars(type.mod));
return new ErrorExp();
}
}
}
error("cannot modify `%s` expression `%s`", MODtoChars(type.mod), toChars());
return new ErrorExp();
}
else if (!type.isAssignable())
{
error("cannot modify struct instance `%s` of type `%s` because it contains `const` or `immutable` members",
toChars(), type.toChars());
return new ErrorExp();
}
}
return toLvalue(sc, e);
}
final Expression implicitCastTo(Scope* sc, Type t)
{
return .implicitCastTo(this, sc, t);
}
final MATCH implicitConvTo(Type t)
{
return .implicitConvTo(this, t);
}
final Expression castTo(Scope* sc, Type t)
{
return .castTo(this, sc, t);
}
/****************************************
* Resolve __FILE__, __LINE__, __MODULE__, __FUNCTION__, __PRETTY_FUNCTION__, __FILE_FULL_PATH__ to loc.
*/
Expression resolveLoc(const ref Loc loc, Scope* sc)
{
this.loc = loc;
return this;
}
/****************************************
* Check that the expression has a valid type.
* If not, generates an error "... has no type".
* Returns:
* true if the expression is not valid.
* Note:
* When this function returns true, `checkValue()` should also return true.
*/
bool checkType()
{
return false;
}
/****************************************
* Check that the expression has a valid value.
* If not, generates an error "... has no value".
* Returns:
* true if the expression is not valid or has void type.
*/
bool checkValue()
{
if (type && type.toBasetype().ty == Tvoid)
{
error("expression `%s` is `void` and has no value", toChars());
//print(); assert(0);
if (!global.gag)
type = Type.terror;
return true;
}