gopl.io/ch7/xmlselect/main.go

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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
// See page 214.
//!+
// Xmlselect prints the text of selected elements of an XML document.
package main
import (
"encoding/xml"
"fmt"
"io"
"os"
"strings"
)
func main() {
dec := xml.NewDecoder(os.Stdin)
var stack []string // stack of element names
for {
tok, err := dec.Token()
if err == io.EOF {
break
} else if err != nil {
fmt.Fprintf(os.Stderr, "xmlselect: %v\n", err)
os.Exit(1)
}
switch tok := tok.(type) {
case xml.StartElement:
stack = append(stack, tok.Name.Local) // push
case xml.EndElement:
stack = stack[:len(stack)-1] // pop
case xml.CharData:
if containsAll(stack, os.Args[1:]) {
fmt.Printf("%s: %s\n", strings.Join(stack, " "), tok)
}
}
}
}
// containsAll reports whether x contains the elements of y, in order.
func containsAll(x, y []string) bool {
for len(y) <= len(x) {
if len(y) == 0 {
return true
}
if x[0] == y[0] {
y = y[1:]
}
x = x[1:]
}
return false
}
//!-