diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /src/bufio/example_test.go | |
parent | Initial commit. (diff) | |
download | golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/bufio/example_test.go')
-rw-r--r-- | src/bufio/example_test.go | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/src/bufio/example_test.go b/src/bufio/example_test.go new file mode 100644 index 0000000..a864d11 --- /dev/null +++ b/src/bufio/example_test.go @@ -0,0 +1,139 @@ +// Copyright 2013 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package bufio_test + +import ( + "bufio" + "fmt" + "os" + "strconv" + "strings" +) + +func ExampleWriter() { + w := bufio.NewWriter(os.Stdout) + fmt.Fprint(w, "Hello, ") + fmt.Fprint(w, "world!") + w.Flush() // Don't forget to flush! + // Output: Hello, world! +} + +func ExampleWriter_AvailableBuffer() { + w := bufio.NewWriter(os.Stdout) + for _, i := range []int64{1, 2, 3, 4} { + b := w.AvailableBuffer() + b = strconv.AppendInt(b, i, 10) + b = append(b, ' ') + w.Write(b) + } + w.Flush() + // Output: 1 2 3 4 +} + +// The simplest use of a Scanner, to read standard input as a set of lines. +func ExampleScanner_lines() { + scanner := bufio.NewScanner(os.Stdin) + for scanner.Scan() { + fmt.Println(scanner.Text()) // Println will add back the final '\n' + } + if err := scanner.Err(); err != nil { + fmt.Fprintln(os.Stderr, "reading standard input:", err) + } +} + +// Return the most recent call to Scan as a []byte. +func ExampleScanner_Bytes() { + scanner := bufio.NewScanner(strings.NewReader("gopher")) + for scanner.Scan() { + fmt.Println(len(scanner.Bytes()) == 6) + } + if err := scanner.Err(); err != nil { + fmt.Fprintln(os.Stderr, "shouldn't see an error scanning a string") + } + // Output: + // true +} + +// Use a Scanner to implement a simple word-count utility by scanning the +// input as a sequence of space-delimited tokens. +func ExampleScanner_words() { + // An artificial input source. + const input = "Now is the winter of our discontent,\nMade glorious summer by this sun of York.\n" + scanner := bufio.NewScanner(strings.NewReader(input)) + // Set the split function for the scanning operation. + scanner.Split(bufio.ScanWords) + // Count the words. + count := 0 + for scanner.Scan() { + count++ + } + if err := scanner.Err(); err != nil { + fmt.Fprintln(os.Stderr, "reading input:", err) + } + fmt.Printf("%d\n", count) + // Output: 15 +} + +// Use a Scanner with a custom split function (built by wrapping ScanWords) to validate +// 32-bit decimal input. +func ExampleScanner_custom() { + // An artificial input source. + const input = "1234 5678 1234567901234567890" + scanner := bufio.NewScanner(strings.NewReader(input)) + // Create a custom split function by wrapping the existing ScanWords function. + split := func(data []byte, atEOF bool) (advance int, token []byte, err error) { + advance, token, err = bufio.ScanWords(data, atEOF) + if err == nil && token != nil { + _, err = strconv.ParseInt(string(token), 10, 32) + } + return + } + // Set the split function for the scanning operation. + scanner.Split(split) + // Validate the input + for scanner.Scan() { + fmt.Printf("%s\n", scanner.Text()) + } + + if err := scanner.Err(); err != nil { + fmt.Printf("Invalid input: %s", err) + } + // Output: + // 1234 + // 5678 + // Invalid input: strconv.ParseInt: parsing "1234567901234567890": value out of range +} + +// Use a Scanner with a custom split function to parse a comma-separated +// list with an empty final value. +func ExampleScanner_emptyFinalToken() { + // Comma-separated list; last entry is empty. + const input = "1,2,3,4," + scanner := bufio.NewScanner(strings.NewReader(input)) + // Define a split function that separates on commas. + onComma := func(data []byte, atEOF bool) (advance int, token []byte, err error) { + for i := 0; i < len(data); i++ { + if data[i] == ',' { + return i + 1, data[:i], nil + } + } + if !atEOF { + return 0, nil, nil + } + // There is one final token to be delivered, which may be the empty string. + // Returning bufio.ErrFinalToken here tells Scan there are no more tokens after this + // but does not trigger an error to be returned from Scan itself. + return 0, data, bufio.ErrFinalToken + } + scanner.Split(onComma) + // Scan. + for scanner.Scan() { + fmt.Printf("%q ", scanner.Text()) + } + if err := scanner.Err(); err != nil { + fmt.Fprintln(os.Stderr, "reading input:", err) + } + // Output: "1" "2" "3" "4" "" +} |