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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
commit43a123c1ae6613b3efeed291fa552ecd909d3acf (patch)
treefd92518b7024bc74031f78a1cf9e454b65e73665 /src/bufio/example_test.go
parentInitial commit. (diff)
downloadgolang-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.go139
1 files changed, 139 insertions, 0 deletions
diff --git a/src/bufio/example_test.go b/src/bufio/example_test.go
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+// 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" ""
+}