woodpecker/yaml/expander/func.go

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package expander
import (
"fmt"
"regexp"
"strconv"
"strings"
)
// these are helper functions that bring bash-substitution to the drone yaml file.
// see http://tldp.org/LDP/abs/html/parameter-substitution.html
type substituteFunc func(str, key, val string) string
var substitutors = []substituteFunc{
substituteQ,
substitute,
substitutePrefix,
substituteSuffix,
substituteDefault,
substituteReplace,
substituteLeft,
substituteSubstr,
}
// substitute is a helper function that substitutes a simple parameter using
// ${parameter} notation.
func substitute(str, key, val string) string {
key = fmt.Sprintf("${%s}", key)
return strings.Replace(str, key, val, -1)
}
// substituteQ is a helper function that substitutes a simple parameter using
// "${parameter}" notation with the escaped value, using %q.
func substituteQ(str, key, val string) string {
key = fmt.Sprintf(`"${%s}"`, key)
val = fmt.Sprintf("%q", val)
return strings.Replace(str, key, val, -1)
}
// substitutePrefix is a helper function that substitutes paramters using
// ${parameter##prefix} notation with the parameter value minus the trimmed prefix.
func substitutePrefix(str, key, val string) string {
key = fmt.Sprintf("\\${%s##(.+)}", key)
reg, err := regexp.Compile(key)
if err != nil {
return str
}
for _, match := range reg.FindAllStringSubmatch(str, -1) {
if len(match) != 2 {
continue
}
val_ := strings.TrimPrefix(val, match[1])
str = strings.Replace(str, match[0], val_, -1)
}
return str
}
// substituteSuffix is a helper function that substitutes paramters using
// ${parameter%%suffix} notation with the parameter value minus the trimmed suffix.
func substituteSuffix(str, key, val string) string {
key = fmt.Sprintf("\\${%s%%%%(.+)}", key)
reg, err := regexp.Compile(key)
if err != nil {
return str
}
for _, match := range reg.FindAllStringSubmatch(str, -1) {
if len(match) != 2 {
continue
}
val_ := strings.TrimSuffix(val, match[1])
str = strings.Replace(str, match[0], val_, -1)
}
return str
}
// substituteDefault is a helper function that substitutes paramters using
// ${parameter=default} notation with the parameter value. When empty the
// default value is used.
func substituteDefault(str, key, val string) string {
key = fmt.Sprintf("\\${%s=(.+)}", key)
reg, err := regexp.Compile(key)
if err != nil {
return str
}
for _, match := range reg.FindAllStringSubmatch(str, -1) {
if len(match) != 2 {
continue
}
if len(val) == 0 {
str = strings.Replace(str, match[0], match[1], -1)
} else {
str = strings.Replace(str, match[0], val, -1)
}
}
return str
}
// substituteReplace is a helper function that substitutes paramters using
// ${parameter/old/new} notation with the parameter value. A find and replace
// is performed before injecting the strings, replacing the old pattern with
// the new value.
func substituteReplace(str, key, val string) string {
key = fmt.Sprintf("\\${%s/(.+)/(.+)}", key)
reg, err := regexp.Compile(key)
if err != nil {
return str
}
for _, match := range reg.FindAllStringSubmatch(str, -1) {
if len(match) != 3 {
continue
}
with := strings.Replace(val, match[1], match[2], -1)
str = strings.Replace(str, match[0], with, -1)
}
return str
}
// substituteLeft is a helper function that substitutes paramters using
// ${parameter:pos} notation with the parameter value, sliced up to the
// specified position.
func substituteLeft(str, key, val string) string {
key = fmt.Sprintf("\\${%s:([0-9]*)}", key)
reg, err := regexp.Compile(key)
if err != nil {
return str
}
for _, match := range reg.FindAllStringSubmatch(str, -1) {
if len(match) != 2 {
continue
}
index, err := strconv.Atoi(match[1])
if err != nil {
continue // skip
}
if index > len(val)-1 {
continue // skip
}
str = strings.Replace(str, match[0], val[:index], -1)
}
return str
}
// substituteLeft is a helper function that substitutes paramters using
// ${parameter:pos:len} notation with the parameter value as a substring,
// starting at the specified position for the specified length.
func substituteSubstr(str, key, val string) string {
key = fmt.Sprintf("\\${%s:([0-9]*):([0-9]*)}", key)
reg, err := regexp.Compile(key)
if err != nil {
return str
}
for _, match := range reg.FindAllStringSubmatch(str, -1) {
if len(match) != 3 {
continue
}
pos, err := strconv.Atoi(match[1])
if err != nil {
continue // skip
}
length, err := strconv.Atoi(match[2])
if err != nil {
continue // skip
}
if pos+length > len(val)-1 {
continue // skip
}
str = strings.Replace(str, match[0], val[pos:pos+length], -1)
}
return str
}