terraform/vendor/github.com/beevik/etree/helpers.go

189 lines
3.9 KiB
Go
Raw Normal View History

// Copyright 2015 Brett Vickers.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package etree
import (
"io"
"strings"
)
// A simple stack
type stack struct {
data []interface{}
}
func (s *stack) empty() bool {
return len(s.data) == 0
}
func (s *stack) push(value interface{}) {
s.data = append(s.data, value)
}
func (s *stack) pop() interface{} {
value := s.data[len(s.data)-1]
s.data[len(s.data)-1] = nil
s.data = s.data[:len(s.data)-1]
return value
}
func (s *stack) peek() interface{} {
return s.data[len(s.data)-1]
}
// A fifo is a simple first-in-first-out queue.
type fifo struct {
data []interface{}
head, tail int
}
func (f *fifo) add(value interface{}) {
if f.len()+1 >= len(f.data) {
f.grow()
}
f.data[f.tail] = value
if f.tail++; f.tail == len(f.data) {
f.tail = 0
}
}
func (f *fifo) remove() interface{} {
value := f.data[f.head]
f.data[f.head] = nil
if f.head++; f.head == len(f.data) {
f.head = 0
}
return value
}
func (f *fifo) len() int {
if f.tail >= f.head {
return f.tail - f.head
}
return len(f.data) - f.head + f.tail
}
func (f *fifo) grow() {
c := len(f.data) * 2
if c == 0 {
c = 4
}
buf, count := make([]interface{}, c), f.len()
if f.tail >= f.head {
copy(buf[0:count], f.data[f.head:f.tail])
} else {
hindex := len(f.data) - f.head
copy(buf[0:hindex], f.data[f.head:])
copy(buf[hindex:count], f.data[:f.tail])
}
f.data, f.head, f.tail = buf, 0, count
}
// countReader implements a proxy reader that counts the number of
// bytes read from its encapsulated reader.
type countReader struct {
r io.Reader
bytes int64
}
func newCountReader(r io.Reader) *countReader {
return &countReader{r: r}
}
func (cr *countReader) Read(p []byte) (n int, err error) {
b, err := cr.r.Read(p)
cr.bytes += int64(b)
return b, err
}
// countWriter implements a proxy writer that counts the number of
// bytes written by its encapsulated writer.
type countWriter struct {
w io.Writer
bytes int64
}
func newCountWriter(w io.Writer) *countWriter {
return &countWriter{w: w}
}
func (cw *countWriter) Write(p []byte) (n int, err error) {
b, err := cw.w.Write(p)
cw.bytes += int64(b)
return b, err
}
// isWhitespace returns true if the byte slice contains only
// whitespace characters.
func isWhitespace(s string) bool {
for i := 0; i < len(s); i++ {
if c := s[i]; c != ' ' && c != '\t' && c != '\n' && c != '\r' {
return false
}
}
return true
}
// spaceMatch returns true if namespace a is the empty string
// or if namespace a equals namespace b.
func spaceMatch(a, b string) bool {
switch {
case a == "":
return true
default:
return a == b
}
}
// spaceDecompose breaks a namespace:tag identifier at the ':'
// and returns the two parts.
func spaceDecompose(str string) (space, key string) {
colon := strings.IndexByte(str, ':')
if colon == -1 {
return "", str
}
return str[:colon], str[colon+1:]
}
// Strings used by crIndent
const (
crsp = "\n "
crtab = "\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"
)
// crIndent returns a carriage return followed by n copies of the
// first non-CR character in the source string.
func crIndent(n int, source string) string {
switch {
case n < 0:
return source[:1]
case n < len(source):
return source[:n+1]
default:
return source + strings.Repeat(source[1:2], n-len(source)+1)
}
}
// nextIndex returns the index of the next occurrence of sep in s,
// starting from offset. It returns -1 if the sep string is not found.
func nextIndex(s, sep string, offset int) int {
switch i := strings.Index(s[offset:], sep); i {
case -1:
return -1
default:
return offset + i
}
}
// isInteger returns true if the string s contains an integer.
func isInteger(s string) bool {
for i := 0; i < len(s); i++ {
if (s[i] < '0' || s[i] > '9') && !(i == 0 && s[i] == '-') {
return false
}
}
return true
}