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01185e436f
This adds a new generic result type (motivated by golang/go#70084) to try it out, and uses it in the new lineutil package (replacing the old lineread package), changing that package to return iterators: sometimes over []byte (when the input is all in memory), but sometimes iterators over results of []byte, if errors might happen at runtime. Updates #12912 Updates golang/go#70084 Change-Id: Iacdc1070e661b5fb163907b1e8b07ac7d51d3f83 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
73 lines
1.5 KiB
Go
73 lines
1.5 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package lineiter iterates over lines in things.
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package lineiter
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import (
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"bufio"
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"bytes"
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"io"
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"iter"
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"os"
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"tailscale.com/types/result"
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)
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// File returns an iterator that reads lines from the named file.
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//
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// The returned substrings don't include the trailing newline.
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// Lines may be empty.
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func File(name string) iter.Seq[result.Of[[]byte]] {
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f, err := os.Open(name)
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return reader(f, f, err)
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}
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// Bytes returns an iterator over the lines in bs.
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// The returned substrings don't include the trailing newline.
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// Lines may be empty.
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func Bytes(bs []byte) iter.Seq[[]byte] {
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return func(yield func([]byte) bool) {
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for len(bs) > 0 {
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i := bytes.IndexByte(bs, '\n')
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if i < 0 {
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yield(bs)
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return
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}
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if !yield(bs[:i]) {
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return
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}
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bs = bs[i+1:]
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}
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}
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}
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// Reader returns an iterator over the lines in r.
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//
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// The returned substrings don't include the trailing newline.
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// Lines may be empty.
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func Reader(r io.Reader) iter.Seq[result.Of[[]byte]] {
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return reader(r, nil, nil)
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}
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func reader(r io.Reader, c io.Closer, err error) iter.Seq[result.Of[[]byte]] {
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return func(yield func(result.Of[[]byte]) bool) {
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if err != nil {
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yield(result.Error[[]byte](err))
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return
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}
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if c != nil {
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defer c.Close()
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}
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bs := bufio.NewScanner(r)
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for bs.Scan() {
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if !yield(result.Value(bs.Bytes())) {
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return
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}
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}
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if err := bs.Err(); err != nil {
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yield(result.Error[[]byte](err))
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}
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}
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}
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