allocate only once in generated code

internal/self/self.gen.go

@@ -899,7 +899,7 @@ func parseInput(r io.Reader, p parser, b builder, kw []parser, maxTraceLength in
 
 // eo head
 
-func Parse(r io.Reader) (Node, error) {
+var selfParse = func() func(io.Reader) (Node, error) {
 
 	var p183 = sequenceParser{id: 183, commit: 768, name: "syntax", ranges: [][]int{{0, -1}, {1, 1}, {0, -1}}}
 	var p181 = choiceParser{id: 181, commit: 2}
@@ -1469,6 +1469,11 @@ func Parse(r io.Reader) (Node, error) {
 	b183.items = []builder{&b181, &b182, &b181}
 
 	var keywords = []parser{}
-
+	return func(r io.Reader) (Node, error) {
 		return parseInput(r, &p183, &b183, keywords, 0)
 	}
+}()
+
+func Parse(r io.Reader) (Node, error) {
+	return selfParse(r)
+}

syntax.go

@@ -539,12 +539,7 @@ func (s *Syntax) Generate(o GeneratorOptions, w io.Writer) error {
 	fprintln()
 	fprintln()
 
-	if o.Export {
+	fprintf(`var %sParse = func() func(io.Reader) (Node, error) {`, o.PackageName)
-		fprint(`func Parse(r io.Reader) (Node, error) {`)
-	} else {
-		fprint(`func parse(r io.Reader) (node, error) {`)
-	}
-
 	fprintln()
 
 	done := make(map[string]bool)
@@ -573,8 +568,22 @@ func (s *Syntax) Generate(o GeneratorOptions, w io.Writer) error {
 	fprint(`}`)
 
 	fprintln()
+	fprint(`return func(r io.Reader) (Node, error) {`)
 	fprintln()
 	fprintf(`return parseInput(r, &p%d, &b%d, keywords, 0)`, s.root.parser().nodeID(), s.root.builder().nodeID())
+	fprint(`}`)
+	fprintln()
+	fprint(`}()`)
+	fprintln()
+
+	if o.Export {
+		fprint(`func Parse(r io.Reader) (Node, error) {`)
+	} else {
+		fprint(`func parse(r io.Reader) (node, error) {`)
+	}
+
+	fprintln()
+	fprintf(`return %sParse(r)`, o.PackageName)
 	fprintln()
 	fprint(`}`)
 	fprintln()