Alec Thomas
69 lines
1.9 KiB
Go
69 lines
1.9 KiB
Go
package kong
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import (
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"encoding/json"
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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) (interface{}, 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) (interface{}, error)
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var _ Resolver = ResolverFunc(nil)
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func (r ResolverFunc) Resolve(context *Context, parent *Path, flag *Flag) (interface{}, error) { // nolint: revive
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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: revive
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// JSON returns a Resolver that retrieves values from a JSON source.
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//
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// Flag names are used as JSON keys indirectly, by tring snake_case and camelCase variants.
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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) (interface{}, error) {
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name := strings.ReplaceAll(flag.Name, "-", "_")
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snakeCaseName := snakeCase(flag.Name)
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raw, ok := values[name]
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if ok {
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return raw, nil
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} else if raw, ok = values[snakeCaseName]; ok {
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return raw, nil
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}
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raw = values
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for _, part := range strings.Split(name, ".") {
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if values, ok := raw.(map[string]interface{}); ok {
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raw, ok = values[part]
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if !ok {
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return nil, nil
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}
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} else {
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return nil, nil
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}
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}
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return raw, nil
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}
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return f, nil
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}
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func snakeCase(name string) string {
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name = strings.Join(strings.Split(strings.Title(name), "-"), "") //nolint: staticcheck
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return strings.ToLower(name[:1]) + name[1:]
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}
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