129 lines
3.0 KiB
Go
129 lines
3.0 KiB
Go
package component
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import (
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"context"
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"fmt"
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"log/slog"
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"slices"
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"strings"
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)
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type componentKey int
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const storageKey componentKey = iota
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// Component identifies a named unit within a module and its position in the call hierarchy.
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type Component interface {
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Module() string
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Path() []string
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PathString() string
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LogValue() slog.Value
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}
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type component struct {
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module string
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path []string
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}
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func (c component) Module() string { return c.module }
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func (c component) Path() []string { return slices.Clone(c.path) }
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func (c component) PathString() string { return strings.Join(c.path, ".") }
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func (c component) LogValue() slog.Value {
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return slog.GroupValue(
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slog.String("module", c.module),
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slog.String("path", c.PathString()),
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)
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}
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func insert(ctx context.Context, module string, name string, path []string) context.Context {
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return context.WithValue(ctx, storageKey, component{
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module: module,
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path: append(path, name),
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})
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}
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// FromContext retrieves the current component from the context; returns nil if none is present.
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func FromContext(ctx context.Context) Component {
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c, ok := ctx.Value(storageKey).(component)
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if !ok {
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return nil
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}
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return c
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}
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// FieldsFromContext returns the component as a string map with keys "module" and "path"; returns nil if none is present.
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func FieldsFromContext(ctx context.Context) map[string]string {
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c := FromContext(ctx)
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if c == nil {
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return nil
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}
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return map[string]string{
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"module": c.Module(),
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"path": c.PathString(),
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}
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}
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// New sets a new component on the context, resetting any existing component.
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func New(ctx context.Context, module string, name string) (context.Context, error) {
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if ctx == nil {
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return nil, fmt.Errorf("context is nil")
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}
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if module == "" {
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return nil, fmt.Errorf("module cannot be empty")
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}
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if name == "" {
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return nil, fmt.Errorf("name cannot be empty")
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}
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return insert(ctx, module, name, []string{}), nil
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}
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// Extend appends name to the current component path, inheriting its module.
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func Extend(ctx context.Context, name string) (context.Context, error) {
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if ctx == nil {
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return nil, fmt.Errorf("context is nil")
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}
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c := FromContext(ctx)
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if c == nil {
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return nil, fmt.Errorf("missing parent component")
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}
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if name == "" {
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return nil, fmt.Errorf("name cannot be empty")
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}
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return insert(ctx, c.Module(), name, c.Path()), nil
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}
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// MustNew is New but panics on error.
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func MustNew(ctx context.Context, module string, name string) context.Context {
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if ctx == nil {
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panic("context is nil")
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}
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if module == "" {
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panic("module cannot be empty")
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}
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if name == "" {
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panic("name cannot be empty")
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}
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return insert(ctx, module, name, []string{})
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}
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// MustExtend is Extend but panics on error.
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func MustExtend(ctx context.Context, name string) context.Context {
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if ctx == nil {
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panic("context is nil")
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}
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c := FromContext(ctx)
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if c == nil {
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panic("missing parent component")
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}
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if name == "" {
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panic("name cannot be empty")
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}
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return insert(ctx, c.Module(), name, c.Path())
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}
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