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package participle
import (
"bytes"
"fmt"
"strings"
"github.com/alecthomas/participle/lexer"
)
type stringerVisitor struct {
bytes.Buffer
seen map[node]bool
}
func stringern(n node, depth int) string {
v := &stringerVisitor{seen: map[node]bool{}}
v.visit(n, depth, false)
return v.String()
}
func stringer(n node) string {
return stringern(n, 1)
}
func (s *stringerVisitor) visit(n node, depth int, disjunctions bool) {
if s.seen[n] || depth <= 0 {
fmt.Fprintf(s, "...")
return
}
s.seen[n] = true
switch n := n.(type) {
case *disjunction:
for i, c := range n.nodes {
if i > 0 {
fmt.Fprint(s, " | ")
}
s.visit(c, depth, disjunctions || len(n.nodes) > 1)
}
case *strct:
s.visit(n.expr, depth, disjunctions)
case *sequence:
c := n
for i := 0; c != nil && depth-i > 0; c, i = c.next, i+1 {
if c != n {
fmt.Fprint(s, " ")
}
s.visit(c.node, depth-i, disjunctions)
}
if c != nil {
fmt.Fprint(s, " ...")
}
case *parseable:
fmt.Fprintf(s, "<%s>", strings.ToLower(n.t.Name()))
case *capture:
if _, ok := n.node.(*parseable); ok {
fmt.Fprintf(s, "<%s>", strings.ToLower(n.field.Name))
} else {
if n.node == nil {
fmt.Fprintf(s, "<%s>", strings.ToLower(n.field.Name))
} else {
s.visit(n.node, depth, disjunctions)
}
}
case *reference:
fmt.Fprintf(s, "<%s>", strings.ToLower(n.identifier))
case *optional:
fmt.Fprint(s, "[ ")
s.visit(n.node, depth, disjunctions)
fmt.Fprint(s, " ]")
case *repetition:
fmt.Fprint(s, "{ ")
s.visit(n.node, depth, disjunctions)
fmt.Fprint(s, " }")
case *literal:
fmt.Fprintf(s, "%q", n.s)
if n.t != lexer.EOF && n.s == "" {
fmt.Fprintf(s, ":%s", n.tt)
}
case *group:
fmt.Fprint(s, "(")
if child, ok := n.expr.(*group); ok && child.mode == groupMatchOnce {
s.visit(child.expr, depth, disjunctions)
} else if child, ok := n.expr.(*capture); ok {
if grandchild, ok := child.node.(*group); ok && grandchild.mode == groupMatchOnce {
s.visit(grandchild.expr, depth, disjunctions)
} else {
s.visit(n.expr, depth, disjunctions)
}
} else {
s.visit(n.expr, depth, disjunctions)
}
fmt.Fprint(s, ")")
switch n.mode {
case groupMatchNonEmpty:
fmt.Fprintf(s, "!")
case groupMatchZeroOrOne:
fmt.Fprintf(s, "?")
case groupMatchZeroOrMore:
fmt.Fprintf(s, "*")
case groupMatchOneOrMore:
fmt.Fprintf(s, "+")
}
default:
panic("unsupported")
}
}