Fix invalid top-level declaration errors causing a deadlock

2 files changed, 17 insertions, 8 deletions

diff --git a/cer.go b/cer.go
index 2bc4d61..310f2d0 100644
--- a/cer.go
+++ b/cer.go
@@ -14,7 +14,7 @@ import (
 )
 
 func main() {
-	errs := make(chan error, 1024)
+	errs := make(chan error, 1)
 
 	toks := make(chan token, 1024)
 	go lex(os.Stdin, toks, errs)
@@ -23,7 +23,7 @@ func main() {
 	// 	fmt.Println(token)
 	// }
 
-	root := make(chan *rootExpr, 1)
+	root := make(chan *rootExpr)
 	go parse(&tokens{
 		src:  toks,
 		toks: make([]token, 0, len(toks)),
@@ -31,7 +31,10 @@ func main() {
 
 	// fmt.Printf("%+v\n", <-expr)
 
-	go generate(<-root, os.Stdout, errs)
+	ast, ok := <-root
+	if ok {
+		go generate(ast, os.Stdout, errs)
+	}
 
 	err := <-errs
 	if err != nil {
diff --git a/parse.go b/parse.go
index b204468..8ac4c5d 100644
--- a/parse.go
+++ b/parse.go
@@ -65,16 +65,22 @@ func (t *tokens) mustMatch(kind tokenKind) error {
 }
 
 func parse(toks *tokens, root chan<- *rootExpr, errs chan<- error) {
-	root <- parseRoot(toks, errs)
+	defer close(root)
+
+	expr, err := parseRoot(toks, errs)
+	if err != nil {
+		errs <- err
+	} else {
+		root <- expr
+	}
 }
 
-func parseRoot(toks *tokens, errs chan<- error) *rootExpr {
+func parseRoot(toks *tokens, errs chan<- error) (*rootExpr, error) {
 	toplevels := make([]expression, 0)
 	for !toks.eof() {
 		toplevel, err := parseToplevel(toks)
 		if err != nil {
-			errs <- err
-			continue
+			return nil, err
 		}
 
 		if toplevel != nil {
@@ -84,7 +90,7 @@ func parseRoot(toks *tokens, errs chan<- error) *rootExpr {
 
 	return &rootExpr{
 		toplevels: toplevels,
-	}
+	}, nil
 }
 
 func parseToplevel(toks *tokens) (expression, error) {