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tagm.go
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tagm.go
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package cli
import (
"fmt"
"strconv"
)
type multiTag struct {
value string
cache map[string][]string
}
func newMultiTag(v string) multiTag {
return multiTag{
value: v,
}
}
func (x *multiTag) scan() (map[string][]string, error) {
v := x.value
ret := make(map[string][]string)
// This is mostly copied from reflect.StructTag.Get
for v != "" {
i := 0
// Skip whitespace
for i < len(v) && (v[i] == ' ' || v[i] == '\t' || v[i] == '\n') {
i++
}
v = v[i:]
if v == "" {
break
}
// Scan to colon to find key
i = 0
for i < len(v) && v[i] != ' ' && v[i] != '\t' && v[i] != '\n' && v[i] != ':' && v[i] != '"' {
i++
}
if i >= len(v) {
return nil, fmt.Errorf("expected `:' after key name, but got end of tag (in `%v`)", x.value)
}
if v[i] != ':' {
return nil, fmt.Errorf("expected `:' after key name, but got `%v' (in `%v`)", v[i], x.value)
}
if i+1 >= len(v) {
return nil, fmt.Errorf("expected `\"' to start tag value at end of tag (in `%v`)", x.value)
}
if v[i+1] != '"' {
return nil, fmt.Errorf("expected `\"' to start tag value, but got `%v' (in `%v`)", v[i+1], x.value)
}
name := v[:i]
v = v[i+1:]
// Scan quoted string to find value
i = 1
for i < len(v) && v[i] != '"' {
if v[i] == '\n' {
return nil, fmt.Errorf("unexpected newline in tag value `%v' (in `%v`)", name, x.value)
}
if v[i] == '\\' {
i++
}
i++
}
if i >= len(v) {
return nil, fmt.Errorf("expected end of tag value `\"' at end of tag (in `%v`)", x.value)
}
val, err := strconv.Unquote(v[:i+1])
if err != nil {
return nil, fmt.Errorf("Malformed value of tag `%v:%v` => %v (in `%v`)", name, v[:i+1], err, x.value)
}
v = v[i+1:]
ret[name] = append(ret[name], val)
}
return ret, nil
}
func (x *multiTag) cached() map[string][]string {
if x.cache == nil {
cache, err := x.scan()
if err != nil {
cache = make(map[string][]string)
}
x.cache = cache
}
return x.cache
}
func (x *multiTag) Get(key string) string {
c := x.cached()
if v, ok := c[key]; ok {
return v[len(v)-1]
}
return ""
}