Alec Thomas
91 lines
2.2 KiB
Go
91 lines
2.2 KiB
Go
package kong
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import (
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"encoding/json"
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"fmt"
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"io"
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"strings"
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)
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// A Resolver resolves a Flag value from an external source.
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type Resolver interface {
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// Validate configuration against Application.
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//
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// This can be used to validate that all provided configuration is valid within this application.
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Validate(app *Application) error
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// Resolve the value for a Flag.
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Resolve(context *Context, parent *Path, flag *Flag) (string, error)
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}
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// ResolverFunc is a convenience type for non-validating Resolvers.
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type ResolverFunc func(context *Context, parent *Path, flag *Flag) (string, error)
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var _ Resolver = ResolverFunc(nil)
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func (r ResolverFunc) Resolve(context *Context, parent *Path, flag *Flag) (string, error) { // nolint: golint
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return r(context, parent, flag)
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}
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func (r ResolverFunc) Validate(app *Application) error { return nil } // nolint: golint
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// JSON returns a Resolver that retrieves values from a JSON source.
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//
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// Hyphens in flag names are replaced with underscores.
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func JSON(r io.Reader) (Resolver, error) {
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values := map[string]interface{}{}
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err := json.NewDecoder(r).Decode(&values)
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if err != nil {
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return nil, err
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}
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var f ResolverFunc = func(context *Context, parent *Path, flag *Flag) (string, error) {
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name := strings.Replace(flag.Name, "-", "_", -1)
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raw, ok := values[name]
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if !ok {
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return "", nil
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}
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sep := flag.Tag.Sep
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value, err := jsonDecodeValue(sep, raw)
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if err != nil {
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return "", err
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}
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return value, nil
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}
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return f, nil
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}
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func jsonDecodeValue(sep rune, value interface{}) (string, error) {
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switch v := value.(type) {
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case string:
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return v, nil
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case float64:
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return fmt.Sprintf("%v", v), nil
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case []interface{}:
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out := []string{}
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for _, el := range v {
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sel, err := jsonDecodeValue(sep, el)
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if err != nil {
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return "", err
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}
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out = append(out, sel)
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}
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return JoinEscaped(out, sep), nil
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case map[string]interface{}:
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out := []string{}
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for key, el := range v {
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sel, err := jsonDecodeValue(sep, el)
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if err != nil {
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return "", err
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}
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out = append(out, fmt.Sprintf("%s=%s", key, sel))
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}
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return JoinEscaped(out, ';'), nil
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case bool:
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if v {
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return "true", nil
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}
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return "false", nil
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}
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return "", fmt.Errorf("unsupported JSON value %v (of type %T)", value, value)
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}
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