add old hlang draft

Signed-off-by: Xe <me@christine.website>

1 files changed, 59 insertions, 0 deletions

diff --git a/cmd/hlang/h/simplify.go b/cmd/hlang/h/simplify.go
new file mode 100644
index 0000000..36013df
--- /dev/null
+++ b/cmd/hlang/h/simplify.go
@@ -0,0 +1,59 @@
+package h
+
+import (
+	"strings"
+
+	"github.com/eaburns/peggy/peg"
+)
+
+// RemoveSpace removes whitespace-only nodes.
+func RemoveSpace(n *peg.Node) { removeSpace(n) }
+
+func removeSpace(n *peg.Node) bool {
+	if whitespace(n.Text) {
+		return false
+	}
+	if len(n.Kids) == 0 {
+		return true
+	}
+	var kids []*peg.Node
+	for _, k := range n.Kids {
+		if removeSpace(k) {
+			kids = append(kids, k)
+		}
+	}
+	n.Kids = kids
+	return len(n.Kids) > 0
+}
+
+// SpaceChars is the string of all whitespace characters.
+const SpaceChars = "\x20"
+
+func whitespace(s string) bool {
+	for _, r := range s {
+		if !strings.ContainsRune(SpaceChars, r) {
+			return false
+		}
+	}
+	return true
+}
+
+// CollapseLists collapses chains of single-kid nodes.
+func CollapseLists(n *peg.Node) {
+	if collapseLists(n) == 1 {
+		n.Kids = n.Kids[0].Kids
+	}
+}
+
+func collapseLists(n *peg.Node) int {
+	var kids []*peg.Node
+	for _, k := range n.Kids {
+		if gk := collapseLists(k); gk == 1 {
+			kids = append(kids, k.Kids[0])
+		} else {
+			kids = append(kids, k)
+		}
+	}
+	n.Kids = kids
+	return len(n.Kids)
+}