I'm trying to extract whatever data inside ${}.
For example, the data extracted from this string should be abc.
git commit -m '${abc}'
Here is the actual code:
re := regexp.MustCompile("${*}")
match := re.FindStringSubmatch(command)
But that doesn't work, any idea?
In regex, $, { and } have special meaning
$ <-- End of string
{} <-- Contains the range. e.g. a{1,2}
So you need to escape them in the regex. Because of things like this, it is best to use raw string literals when working with regular expressions:
re := regexp.MustCompile(`\$\{([^}]*)\}`)
match := re.FindStringSubmatch("git commit -m '${abc}'")
fmt.Println(match[1])
With double quotes (interpreted string literals) you need to also escape the backslashes:
re := regexp.MustCompile("\\$\\{(.*?)\\}")
re := regexp.MustCompile(`\$\{(.*?)\}`)
+? and *? are different quantifiers. In regex, every symbol matters and can change the output greatly.Try re := regexp.MustCompile(\$\{(.*)\})
* is a quantifier, you need something to quantify. . would do as it matches everything.
.* is a greedy subpattern and can overfire. Use with caution. It might work only with the current example, but not in real life scenario.
You can try with this too,
re := regexp.MustCompile("\\$\\{(.*?)\\}")
str := "git commit -m '${abc}'"
res := re.FindAllStringSubmatch(str, 1)
for i := range res {
//like Java: match.group(1)
fmt.Println("Message :", res[i][1])
}
For another approach, you can use os.Expand:
package main
import "os"
func main() {
command := "git commit -m '${abc}'"
var match string
os.Expand(command, func(s string) string {
match = s
return ""
})
println(match == "abc")
}
You can use named group to extract the value of a string.
import (
"fmt"
"regexp"
)
func main() {
command := "git commit -m '${abc}'"
r := regexp.MustCompile(`\$\{(?P<text>\w+)\}`)
subMatch := r.FindStringSubmatch(command)
fmt.Printf("text : %s", subMatch[1])
}
Because $, { and } all have special meaning in a regex and need to be backslashed to match those literal characters, because * doesn't work that way, and because you didn't actually include a capturing group for the data you want to capture. Try:
re := regexp.MustCompile(`\$\{.+?)\}`)
* in the OP pattern makes me think that the string inside {} can be empty. Thus, rock's answer seems to be closer to what OP needs.