hlang/h/simplify.go

60 lines
1.0 KiB
Go

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)
}