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// Copyright 2015 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 buildutil
// This duplicated logic must be kept in sync with that from go build:
// $GOROOT/src/cmd/go/internal/work/build.go (tagsFlag.Set)
// $GOROOT/src/cmd/go/internal/base/flag.go (StringsFlag.Set)
// $GOROOT/src/cmd/internal/quoted/quoted.go (isSpaceByte, Split)
import (
"fmt"
"strings"
)
const TagsFlagDoc = "a list of `build tags` to consider satisfied during the build. " +
"For more information about build tags, see the description of " +
"build constraints in the documentation for the go/build package"
// TagsFlag is an implementation of the flag.Value and flag.Getter interfaces that parses
// a flag value the same as go build's -tags flag and populates a []string slice.
//
// See $GOROOT/src/go/build/doc.go for description of build tags.
// See $GOROOT/src/cmd/go/doc.go for description of 'go build -tags' flag.
//
// Example:
//
// flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
type TagsFlag []string
func (v *TagsFlag) Set(s string) error {
// See $GOROOT/src/cmd/go/internal/work/build.go (tagsFlag.Set)
// For compatibility with Go 1.12 and earlier, allow "-tags='a b c'" or even just "-tags='a'".
if strings.Contains(s, " ") || strings.Contains(s, "'") {
var err error
*v, err = splitQuotedFields(s)
if *v == nil {
*v = []string{}
}
return err
}
// Starting in Go 1.13, the -tags flag is a comma-separated list of build tags.
*v = []string{}
for _, s := range strings.Split(s, ",") {
if s != "" {
*v = append(*v, s)
}
}
return nil
}
func (v *TagsFlag) Get() interface{} { return *v }
func splitQuotedFields(s string) ([]string, error) {
// See $GOROOT/src/cmd/internal/quoted/quoted.go (Split)
// This must remain in sync with that logic.
var f []string
for len(s) > 0 {
for len(s) > 0 && isSpaceByte(s[0]) {
s = s[1:]
}
if len(s) == 0 {
break
}
// Accepted quoted string. No unescaping inside.
if s[0] == '"' || s[0] == '\'' {
quote := s[0]
s = s[1:]
i := 0
for i < len(s) && s[i] != quote {
i++
}
if i >= len(s) {
return nil, fmt.Errorf("unterminated %c string", quote)
}
f = append(f, s[:i])
s = s[i+1:]
continue
}
i := 0
for i < len(s) && !isSpaceByte(s[i]) {
i++
}
f = append(f, s[:i])
s = s[i:]
}
return f, nil
}
func (v *TagsFlag) String() string {
return "<tagsFlag>"
}
func isSpaceByte(c byte) bool {
// See $GOROOT/src/cmd/internal/quoted/quoted.go (isSpaceByte, Split)
// This list must remain in sync with that.
return c == ' ' || c == '\t' || c == '\n' || c == '\r'
}
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