149 lines
3.3 KiB
Go
149 lines
3.3 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.milar.in/milarin/ds"
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)
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type Reader struct {
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buf ds.Stack[posRune]
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src *bufio.Reader
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pos *Position
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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: ds.NewArrayStack[posRune](),
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src: bufio.NewReader(r),
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pos: &Position{},
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}
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}
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func (r *Reader) psrn(rn rune) posRune {
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return posRune{
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Rune: rn,
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Pos: *r.pos,
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}
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}
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func (r *Reader) Pos() (index, line, column int) {
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return r.pos.Index, r.pos.Line, r.pos.Column
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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(r.psrn(rn))
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r.pos.Advance(rn)
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}
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return rn, err
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}
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// PeekRune returns the next rune in r without advancing reader position.
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// The next read will return the same rune again.
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func (r *Reader) PeekRune() (rune, error) {
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rn, err := r.Rune()
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if err != nil {
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return 0, err
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}
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if err := r.UnreadRune(); err != nil {
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return 0, err
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}
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return rn, nil
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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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rn := r.buf.Pop()
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*r.pos = rn.Pos
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} else {
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rn := r.buf.Pop()
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*r.pos = rn.Pos
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r.src = prependRune(rn.Rune, 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 + one addtional rune for the separator rune
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// The actual runes in str 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 r.UnreadRune()
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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 rn rune
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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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// PeekStringWhile acts as StringWhile but does not advance reader position
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func (r *Reader) PeekStringWhile(f func(rn rune) bool) (string, error) {
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str, err := r.StringWhile(f)
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if err != nil {
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return "", err
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}
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if err := r.UnreadString(str); err != nil {
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return "", err
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}
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return str, nil
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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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// PeekStringUntil acts as StringUntil but does not advance reader position
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func (r *Reader) PeekStringUntil(f func(rn rune) bool) (string, error) {
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str, err := r.StringUntil(f)
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if err != nil {
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return "", err
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}
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if err := r.UnreadString(str); err != nil {
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return "", err
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}
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return str, nil
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}
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// Commit clears the internal buffer and therefore removes all data which were already read.
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// After calling Commit any unreads will return ErrNothingToUnread until another read occured.
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func (r *Reader) Commit() {
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r.buf.Clear()
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}
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