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✨ feat: varexpr - add new internal package varexpr for parse ENV var
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,145 @@ | ||
| // Package varexpr provides some commonly ENV var parse functions. | ||
| // | ||
| // parse env value, allow expressions: | ||
| // | ||
| // ${VAR_NAME} Only var name | ||
| // ${VAR_NAME | default} With default value, if value is empty. | ||
| // ${VAR_NAME | ?error} With error on value is empty. | ||
| // | ||
| // Examples: | ||
| // | ||
| // only key - "${SHELL}" | ||
| // with default - "${NotExist | defValue}" | ||
| // multi key - "${GOPATH}/${APP_ENV | prod}/dir" | ||
| package varexpr | ||
|
|
||
| import ( | ||
| "errors" | ||
| "os" | ||
| "regexp" | ||
| "strings" | ||
| ) | ||
|
|
||
| // SepChar separator char | ||
| const SepChar = "|" | ||
|
|
||
| // ParseOptFn option func | ||
| type ParseOptFn func(o *ParseOpts) | ||
|
|
||
| // ParseOpts parse options for ParseValue | ||
| type ParseOpts struct { | ||
| // Getter Env value provider func. | ||
| Getter func(string) string | ||
| // ParseFn custom parse expr func. expr like "${SHELL}" "${NotExist|defValue}" | ||
| ParseFn func(string) (string, error) | ||
| // Regexp custom expression regex. | ||
| Regexp *regexp.Regexp | ||
| // Keyword check chars for expression. default is "${" | ||
| Keyword string | ||
| } | ||
|
|
||
| // must add "?" - To ensure that there is no greedy match | ||
| var envRegex = regexp.MustCompile(`\${.+?}`) | ||
| var std = New() | ||
|
|
||
| // Parse parse ENV var value from input string, support default value. | ||
| // | ||
| // Format: | ||
| // | ||
| // ${var_name} Only var name | ||
| // ${var_name | default} With default value | ||
| // ${var_name | ?error} With error on value is empty. | ||
| func Parse(val string) (string, error) { | ||
| return std.Parse(val) | ||
| } | ||
|
|
||
| // SafeParse parse ENV var value from input string, support default value. | ||
| func SafeParse(val string) string { | ||
| s, _ := std.Parse(val) | ||
| return s | ||
| } | ||
|
|
||
| // ParseWith parse ENV var value from input string, support default value. | ||
| func ParseWith(val string, optFns ...ParseOptFn) (string, error) { | ||
| return New(optFns...).Parse(val) | ||
| } | ||
|
|
||
| // Parser parse ENV var value from input string, support default value. | ||
| type Parser struct { | ||
| ParseOpts | ||
| } | ||
|
|
||
| // New create a new Parser | ||
| func New(optFns ...ParseOptFn) *Parser { | ||
| opts := &ParseOpts{ | ||
| Getter: os.Getenv, | ||
| Regexp: envRegex, | ||
| Keyword: "${", | ||
| } | ||
| for _, fn := range optFns { | ||
| fn(opts) | ||
| } | ||
|
|
||
| return &Parser{ParseOpts: *opts} | ||
| } | ||
|
|
||
| // Parse parse ENV var value from input string, support default value. | ||
| // | ||
| // Format: | ||
| // | ||
| // ${var_name} Only var name | ||
| // ${var_name | default} With default value | ||
| // ${var_name | ?error} With error on value is empty. | ||
| func (p *Parser) Parse(val string) (newVal string, err error) { | ||
| if p.Regexp == nil { | ||
| p.Regexp = envRegex | ||
| } | ||
|
|
||
| if p.Keyword != "" && !strings.Contains(val, p.Keyword) { | ||
| return val, nil | ||
| } | ||
|
|
||
| // parse expression | ||
| newVal = p.Regexp.ReplaceAllStringFunc(val, func(s string) string { | ||
| if err != nil { | ||
| return s | ||
| } | ||
| s, err = p.parseOne(s) | ||
| return s | ||
| }) | ||
| return | ||
| } | ||
|
|
||
| // parse one node expression. | ||
| func (p *Parser) parseOne(eVar string) (val string, err error) { | ||
| if p.ParseFn != nil { | ||
| return p.ParseFn(eVar) | ||
| } | ||
|
|
||
| // eVar like "${NotExist|defValue}", first remove "${" and "}", then split it | ||
| ss := strings.SplitN(eVar[2:len(eVar)-1], SepChar, 2) | ||
| var name, def string | ||
|
|
||
| // with default value. ${NotExist|defValue} | ||
| if len(ss) == 2 { | ||
| name, def = strings.TrimSpace(ss[0]), strings.TrimSpace(ss[1]) | ||
| } else { | ||
| name = strings.TrimSpace(ss[0]) | ||
| } | ||
|
|
||
| // get ENV value by name | ||
| val = p.Getter(name) | ||
| if val == "" && def != "" { | ||
| // check def is "?error" | ||
| if def[0] == '?' { | ||
| msg := "value is required for var: " + name | ||
| if len(def) > 1 { | ||
| msg = def[1:] | ||
| } | ||
| err = errors.New(msg) | ||
| } else { | ||
| val = def | ||
| } | ||
| } | ||
| return | ||
| } |
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