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lang: funcs: simple: Don't block on simple, pure, static functions

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I forgot to handle the special case of a function using this API that
received no inputs. It was waiting for the first input to come in, and
as a result was never producing any output.

Remember that functions like this should *almost* be thought of as
constants of the system. You would expect their output to never change
during the lifetime of a particular program invocation.
This commit is contained in:
James Shubin
2018-02-22 19:10:15 -05:00
parent 81a0e9e8c7
commit b0911c6d70
4 changed files with 55 additions and 86 deletions
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27
lang/funcs/simple/simple.go
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@@ -15,7 +15,7 @@
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package simple // TODO: should this be in its own individual package?
package simple
import (
"fmt"
@@ -30,7 +30,7 @@ import (
// RegisteredFuncs maps a function name to the corresponding static, pure func.
var RegisteredFuncs = make(map[string]*types.FuncValue) // must initialize
// Register registers a simple, static, pure function. It is easier to use that
// Register registers a simple, static, pure function. It is easier to use than
// the raw function API, but also limits you to simple, static, pure functions.
func Register(name string, fn *types.FuncValue) {
if _, exists := RegisteredFuncs[name]; exists {
@@ -88,16 +88,21 @@ func (obj *simpleFunc) Stream() error {
select {
case input, ok := <-obj.init.Input:
if !ok {
return nil // can't output any more
if len(obj.Fn.Type().Ord) > 0 {
return nil // can't output any more
}
// no inputs were expected, pass through once
}
//if err := input.Type().Cmp(obj.Info().Sig.Input); err != nil {
// return errwrap.Wrapf(err, "wrong function input")
//}
if ok {
//if err := input.Type().Cmp(obj.Info().Sig.Input); err != nil {
// return errwrap.Wrapf(err, "wrong function input")
//}
if obj.last != nil && input.Cmp(obj.last) == nil {
continue // value didn't change, skip it
if obj.last != nil && input.Cmp(obj.last) == nil {
continue // value didn't change, skip it
}
obj.last = input // store for next
}
obj.last = input // store for next
values := []types.Value{}
for _, name := range obj.Fn.Type().Ord {
@@ -121,7 +126,9 @@ func (obj *simpleFunc) Stream() error {
select {
case obj.init.Output <- obj.result: // send
// pass
if len(obj.Fn.Type().Ord) == 0 {
return nil // no more values, we're a pure func
}
case <-obj.closeChan:
return nil
}