82 lines
1.8 KiB
Go
82 lines
1.8 KiB
Go
package bufr
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import (
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"bufio"
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"io"
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"strings"
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"git.tordarus.net/Tordarus/dstruct"
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)
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type Reader struct {
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buf *dstruct.Stack[rune]
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src *bufio.Reader
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}
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func NewReader(r io.Reader) *Reader {
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return &Reader{
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buf: new(dstruct.Stack[rune]),
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src: bufio.NewReader(r),
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}
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}
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// Rune returns the next rune in r
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func (r *Reader) Rune() (rune, error) {
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rn, _, err := r.src.ReadRune()
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if err == nil {
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r.buf.Push(rn)
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}
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return rn, err
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}
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// UnreadRune unreads the last rune.
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// The next read will include the unread rune.
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// It returns ErrNothingToUnread if there wasn't any read yet
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func (r *Reader) UnreadRune() error {
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if r.buf.Empty() {
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return ErrNothingToUnread.New()
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}
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if err := r.src.UnreadRune(); err == nil {
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r.buf.Pop()
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} else {
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r.src = prependRune(r.buf.Pop(), r.src)
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}
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return nil
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}
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// UnreadString calls UnreadRune for each rune in str
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// The actual runes are irrelevant.
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// Only the rune count of str determines the amount of UnreadRune calls.
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// The first error occured will be returned immediately.
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func (r *Reader) UnreadString(str string) error {
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for range str {
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err := r.UnreadRune()
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if err != nil {
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return err
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}
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}
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return nil
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}
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// StringWhile reads runes and calls f for each one.
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// It returns all runes as a string for which f returned true.
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// It stops when f returns false or an error occured.
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// The rune for which f returned false will not be unread.
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func (r *Reader) StringWhile(f func(rn rune) bool) (string, error) {
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s := new(strings.Builder)
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var err error
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for rn, err := r.Rune(); err == nil && f(rn); rn, err = r.Rune() {
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s.WriteRune(rn)
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}
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return s.String(), err
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}
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// StringUntil is a shorthand for r.StringWhile(func(rn rune) bool { return !f(rn) })
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func (r *Reader) StringUntil(f func(rn rune) bool) (string, error) {
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return r.StringWhile(func(rn rune) bool { return !f(rn) })
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}
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