func buildCast(b *builder, expr *ast.CallExpr, t types.T) tast.Expr {
pos := expr.Lparen.Pos
args := buildExprList(b, expr.Args)
if args == nil {
return nil
}
ref := args.R()
if !ref.IsSingle() {
b.Errorf(pos, "cannot convert %s to %s", ref, t)
return nil
}
srcType := ref.T
if c, ok := srcType.(*types.Const); ok {
if v, ok := types.NumConst(srcType); ok && types.IsInteger(t) {
return constCast(b, pos, v, args, t)
}
srcType = c.Type // using the underlying type
}
if types.IsInteger(t) && types.IsInteger(srcType) {
return tast.NewCast(args, t)
}
if regSizeCastable(t, srcType) {
return tast.NewCast(args, t)
}
b.Errorf(pos, "cannot convert from %s to %s", srcType, t)
return nil
}
func constCast(
b *builder, pos *lex8.Pos, v int64, from tast.Expr, to types.T,
) tast.Expr {
if types.IsInteger(to) && types.InRange(v, to) {
return tast.NewCast(from, to)
}
b.Errorf(pos, "cannot cast %d to %s", v, to)
return nil
}
func binaryOpPtr(b *builder, opTok *lex8.Token, A, B tast.Expr) tast.Expr {
op := opTok.Lit
atyp := A.R().T
btyp := B.R().T
switch op {
case "==", "!=":
if types.IsNil(atyp) {
A = tast.NewCast(A, btyp)
} else if types.IsNil(btyp) {
B = tast.NewCast(B, atyp)
}
return &tast.OpExpr{A, opTok, B, tast.NewRef(types.Bool)}
}
b.Errorf(opTok.Pos, "%q on pointers", op)
return nil
}
func assign(b *builder, dest, src tast.Expr, op *lex8.Token) tast.Stmt {
destRef := dest.R()
srcRef := src.R()
ndest := destRef.Len()
nsrc := srcRef.Len()
if ndest != nsrc {
b.Errorf(op.Pos, "cannot assign %s to %s", nsrc, ndest)
return nil
}
for i := 0; i < ndest; i++ {
r := destRef.At(i)
if !r.Addressable {
b.Errorf(op.Pos, "assigning to non-addressable")
return nil
}
destType := r.Type()
srcType := srcRef.At(i).Type()
if !types.CanAssign(destType, srcType) {
b.Errorf(op.Pos, "cannot assign %s to %s", srcType, destType)
return nil
}
}
// insert casting if needed
if srcList, ok := tast.MakeExprList(src); ok {
newList := tast.NewExprList()
for i, e := range srcList.Exprs {
t := e.Type()
if types.IsNil(t) {
e = tast.NewCast(e, destRef.At(i).Type())
} else if v, ok := types.NumConst(t); ok {
e = constCast(b, nil, v, e, destRef.At(i).Type())
if e == nil {
panic("bug")
}
}
newList.Append(e)
}
src = newList
}
return &tast.AssignStmt{dest, op, src}
}
func varDeclPrepare(
b *builder, toks []*lex8.Token, lst *tast.ExprList, t types.T,
) *tast.ExprList {
ret := tast.NewExprList()
for i, tok := range toks {
e := lst.Exprs[i]
etype := e.Type()
if types.IsNil(etype) {
e = tast.NewCast(e, t)
} else if v, ok := types.NumConst(etype); ok {
e = constCast(b, tok.Pos, v, e, t)
if e == nil {
return nil
}
}
ret.Append(e)
}
return ret
}
func buildReturnStmt(b *builder, stmt *ast.ReturnStmt) tast.Stmt {
pos := stmt.Kw.Pos
if stmt.Exprs == nil {
if b.retType == nil || b.retNamed {
return &tast.ReturnStmt{}
}
b.Errorf(pos, "expects return %s", fmt8.Join(b.retType, ","))
return nil
}
if b.retType == nil {
b.Errorf(pos, "function expects no return value")
return nil
}
src := b.buildExpr(stmt.Exprs)
if src == nil {
return nil
}
srcRef := src.R()
nret := len(b.retType)
nsrc := srcRef.Len()
if nret != nsrc {
b.Errorf(pos, "expect (%s), returning (%s)",
fmt8.Join(b.retType, ","), srcRef,
)
return nil
}
for i := 0; i < nret; i++ {
t := b.retType[i]
srcType := srcRef.At(i).Type()
if !types.CanAssign(t, srcType) {
b.Errorf(pos, "expect (%s), returning (%s)",
fmt8.Join(b.retType, ","), srcRef,
)
return nil
}
}
// insert implicit type casts
if srcList, ok := tast.MakeExprList(src); ok {
newList := tast.NewExprList()
for i, e := range srcList.Exprs {
t := e.Type()
if types.IsNil(t) {
e = tast.NewCast(e, b.retType[i])
} else if v, ok := types.NumConst(t); ok {
e = constCast(b, nil, v, e, b.retType[i])
if e == nil {
panic("bug")
}
}
newList.Append(e)
}
src = newList
}
return &tast.ReturnStmt{src}
}
func buildCallExpr(b *builder, expr *ast.CallExpr) tast.Expr {
f := b.buildExpr(expr.Func)
if f == nil {
return nil
}
pos := ast.ExprPos(expr.Func)
fref := f.R()
if !fref.IsSingle() {
b.Errorf(pos, "%s is not callable", fref)
return nil
}
if t, ok := fref.T.(*types.Type); ok {
return buildCast(b, expr, t.T)
}
builtin, ok := fref.T.(*types.BuiltInFunc)
if ok {
switch builtin.Name {
case "len":
return buildCallLen(b, expr, f)
case "make":
return buildCallMake(b, expr, f)
}
b.Errorf(pos, "builtin %s() not implemented", builtin.Name)
return nil
}
funcType, ok := fref.T.(*types.Func)
if !ok {
b.Errorf(pos, "function call on non-callable: %s", fref)
return nil
}
args := buildExprList(b, expr.Args)
if args == nil {
return nil
}
argsRef := args.R()
nargs := argsRef.Len()
if nargs != len(funcType.Args) {
b.Errorf(ast.ExprPos(expr), "argument expects (%s), got (%s)",
fmt8.Join(funcType.Args, ","), args,
)
return nil
}
// type check on each argument
for i := 0; i < nargs; i++ {
argType := argsRef.At(i).Type()
expect := funcType.Args[i].T
if !types.CanAssign(expect, argType) {
pos := ast.ExprPos(expr.Args.Exprs[i])
b.Errorf(pos, "argument %d expects %s, got %s",
i+1, expect, argType,
)
return nil
}
}
// insert casting when it is a literal expression list.
callArgs, ok := tast.MakeExprList(args)
if ok {
castedArgs := tast.NewExprList()
for i := 0; i < nargs; i++ {
argExpr := callArgs.Exprs[i]
argType := argExpr.Type()
expect := funcType.Args[i].T
// insert auto casts for consts
if types.IsNil(argType) {
castedArgs.Append(tast.NewCast(argExpr, expect))
} else if _, ok := types.NumConst(argType); ok {
castedArgs.Append(tast.NewCast(argExpr, expect))
} else {
castedArgs.Append(argExpr)
}
}
args = castedArgs
}
retRef := tast.Void
for _, t := range funcType.RetTypes {
retRef = tast.AppendRef(retRef, tast.NewRef(t))
}
return &tast.CallExpr{f, args, retRef}
}