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