Function tplFun

pkg/engine/engine.go:153–195

As does 'tpl', so that nested calls to 'tpl' see the templates defined by their enclosing contexts.

(parent *template.Template, includedNames map[string]int, strict bool)

// As does 'tpl', so that nested calls to 'tpl' see the templates
// defined by their enclosing contexts.
func tplFun(parent *template.Template, includedNames map[string]int, strict bool) func(string, any) (string, error) {
	return func(tpl string, vals any) (string, error) {
		t, err := parent.Clone()
		if err != nil {
			return "", fmt.Errorf("cannot clone template: %w", err)
		}

		// Re-inject the missingkey option, see text/template issue https://github.com/golang/go/issues/43022
		// We have to go by strict from our engine configuration, as the option fields are private in Template.
		// TODO: Remove workaround (and the strict parameter) once we build only with golang versions with a fix.
		if strict {
			t.Option("missingkey=error")
		} else {
			t.Option("missingkey=zero")
		}

		// Re-inject 'include' so that it can close over our clone of t;
		// this lets any 'define's inside tpl be 'include'd.
		t.Funcs(template.FuncMap{
			"include": includeFun(t, includedNames),
			"tpl":     tplFun(t, includedNames, strict),
		})

		// We need a .New template, as template text which is just blanks
		// or comments after parsing out defines just adds new named
		// template definitions without changing the main template.
		// https://pkg.go.dev/text/template#Template.Parse
		// Use the parent's name for lack of a better way to identify the tpl
		// text string. (Maybe we could use a hash appended to the name?)
		t, err = t.New(parent.Name()).Parse(tpl)
		if err != nil {
			return "", fmt.Errorf("cannot parse template %q: %w", tpl, err)
		}

		var buf strings.Builder
		if err := t.Execute(&buf, vals); err != nil {
			return "", fmt.Errorf("error during tpl function execution for %q: %w", tpl, err)
		}

		// See comment in renderWithReferences explaining the <no value> hack.
		return strings.ReplaceAll(buf.String(), "<no value>", ""), nil
	}
}

// initFunMap creates the Engine's FuncMap and adds context-specific functions.
func (e Engine) initFunMap(t *template.Template) {