英文:
Replace one occurrence with regexp
问题
我想用正则表达式替换一个实例，而不是全部替换。我该如何使用Go的regexp库来实现这个功能？
输入：foobar1xfoobar2x
正则表达式：bar(.)x
替换：baz$1
ReplaceAllString输出：foobaz1foobaz2
ReplaceOneString输出：foobaz1foobar2x
英文:
I want to replace a only one instance with a regex rather than all of them. How would I do this with Go's regexp library?
input: foobar1xfoobar2x
regex: bar(.)x
replacement: baz$1
ReplaceAllString output: foobaz1foobaz2
ReplaceOneString output: foobaz1foobar2x
答案1
得分: 9
一般来说，如果你使用懒惰匹配并使用锚点来表示开头和结尾，你可以实现替换第一个匹配的行为：
使用 $1baz$2 替换 ^(.*?)bar(.*)$。
示例：
package main
import (
"fmt"
"regexp"
)
func main() {
src := "foobar1xfoobar2x"
pat := regexp.MustCompile("^(.*?)bar(.*)$")
repl := "baz$2"
output := pat.ReplaceAllString(src, repl)
fmt.Println(output)
}
输出
foobaz1xfoobar2x
英文:
In general, if you use lazy match and use anchors for beginning and end, you can have the replace first behavior:
replace `^(.*?)bar(.*)$` with `$1baz$2`.
Example:
package main
import (
"fmt"
"regexp"
)
func main() {
src := "foobar1xfoobar2x"
pat := regexp.MustCompile("^(.*?)bar(.*)$")
repl := "baz$2"
output := pat.ReplaceAllString(src, repl)
fmt.Println(output)
}
Output
foobaz1xfoobar2x
答案2
得分: 6
我遇到了同样的问题。我想出了一个最简洁的解决方案：
package main
import (
"fmt"
"regexp"
"strings"
)
func main() {
re, _ := regexp.Compile("[a-z]{3}")
s := "aaa bbb ccc"
// 替换所有字符串
fmt.Println(re.ReplaceAllString(s, "000"))
// 替换一个字符串
found := re.FindString(s)
if found != "" {
fmt.Println(strings.Replace(s, found, "000", 1))
}
}
运行结果：
$ go run test.go
000 000 000
000 bbb ccc
英文:
I had the same problem. The most clean solution I've come up with:
package main
import (
"fmt"
"regexp"
"strings"
)
func main() {
re, _ := regexp.Compile("[a-z]{3}")
s := "aaa bbb ccc"
// Replace all strings
fmt.Println(re.ReplaceAllString(s, "000"))
// Replace one string
found := re.FindString(s)
if found != "" {
fmt.Println(strings.Replace(s, found, "000", 1))
}
}
Running:
$ go run test.go
000 000 000
000 bbb ccc
答案3
得分: 3
我无法使用已接受的解决方案，因为我的模式非常复杂。
最终我使用了ReplaceAllStringFunc：
https://play.golang.org/p/ihtuIU-WEYG
package main
import (
"fmt"
"regexp"
)
var pat = regexp.MustCompile("bar(.)(x)")
func main() {
src := "foobar1xfoobar2x"
flag := false
output := pat.ReplaceAllStringFunc(src, func(a string) string {
if flag {
return a
}
flag = true
return pat.ReplaceAllString(a, "baz$1$2")
})
fmt.Println(output)
}
英文:
I cound't use accepted solution because my pattern was very complicated.
I ended up with using ReplaceAllStringFunc :
https://play.golang.org/p/ihtuIU-WEYG
package main
import (
"fmt"
"regexp"
)
var pat = regexp.MustCompile("bar(.)(x)")
func main() {
src := "foobar1xfoobar2x"
flag := false
output := pat.ReplaceAllStringFunc(src, func(a string) string {
if flag {
return a
}
flag = true
return pat.ReplaceAllString(a, "baz$1$2")
})
fmt.Println(output)
}
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