cli/command/image: use lazyregexp to compile regexes on first use

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

cli/command/image/build.go

@@ -10,7 +10,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"regexp"
 	"runtime"
 	"strings"
 
@@ -23,6 +22,7 @@ import (
 	"github.com/docker/cli/cli/internal/jsonstream"
 	"github.com/docker/cli/cli/streams"
 	"github.com/docker/cli/cli/trust"
+	"github.com/docker/cli/internal/lazyregexp"
 	"github.com/docker/cli/opts"
 	"github.com/docker/docker/api"
 	"github.com/docker/docker/api/types"
@@ -432,7 +432,7 @@ func validateTag(rawRepo string) (string, error) {
 	return rawRepo, nil
 }
 
-var dockerfileFromLinePattern = regexp.MustCompile(`(?i)^[\s]*FROM[ \f\r\t\v]+(?P<image>[^ \f\r\t\v\n#]+)`)
+var dockerfileFromLinePattern = lazyregexp.New(`(?i)^[\s]*FROM[ \f\r\t\v]+(?P<image>[^ \f\r\t\v\n#]+)`)
 
 // resolvedTag records the repository, tag, and resolved digest reference
 // from a Dockerfile rewrite.

internal/lazyregexp/lazyregexp.go

@@ -71,6 +71,10 @@ func (r *Regexp) ReplaceAllStringFunc(src string, repl func(string) string) stri
 	return r.re().ReplaceAllStringFunc(src, repl)
 }
 
+func (r *Regexp) ReplaceAllLiteralString(src, repl string) string {
+	return r.re().ReplaceAllLiteralString(src, repl)
+}
+
 func (r *Regexp) SubexpNames() []string {
 	return r.re().SubexpNames()
 }