// specValues returns the list of initialization expressions
// for the given part (spec) of a constant declaration.
// TODO(gri) Make this more efficient by caching results
// (using a map in checker).
func (check *checker) specValues(spec *ast.ValueSpec) []ast.Expr {
if len(spec.Values) > 0 {
return spec.Values
}
// find the corresponding values
for _, file := range check.pkg.Files {
for _, d := range file.Decls {
if d, ok := d.(*ast.GenDecl); ok && d.Tok == token.CONST {
var values []ast.Expr
for _, s := range d.Specs {
if s, ok := s.(*ast.ValueSpec); ok {
if len(s.Values) > 0 {
values = s.Values
}
if s == spec {
return values
}
}
}
}
}
}
check.invalidAST(spec.Pos(), "no initialization values provided")
return nil
}
// arityMatch checks that the lhs and rhs of a const or var decl
// have the appropriate number of names and init exprs. For const
// decls, init is the value spec providing the init exprs; for
// var decls, init is nil (the init exprs are in s in this case).
func (check *checker) arityMatch(s, init *ast.ValueSpec) {
l := len(s.Names)
r := len(s.Values)
if init != nil {
r = len(init.Values)
}
switch {
case init == nil && r == 0:
// var decl w/o init expr
if s.Type == nil {
check.errorf(s.Pos(), "missing type or init expr")
}
case l < r:
if l < len(s.Values) {
// init exprs from s
n := s.Values[l]
check.errorf(n.Pos(), "extra init expr %s", n)
} else {
// init exprs "inherited"
check.errorf(s.Pos(), "extra init expr at %s", init.Pos())
}
case l > r && (init != nil || r != 1):
n := s.Names[r]
check.errorf(n.Pos(), "missing init expr for %s", n)
}
}