Function helpWithFunction

pkg/sql/parser/help.go:94–137

helpWithFunction is to be used in parser actions to mark the parser "in error", with the error set to a contextual help message about the current built-in function.

(sqllex sqlLexer, f tree.ResolvableFunctionReference)

// "in error", with the error set to a contextual help message about
// the current built-in function.
func helpWithFunction(sqllex sqlLexer, f tree.ResolvableFunctionReference) int {
	// A resolver is not needed because we do not provide contextual help
	// messages for user-defined functions.
	d, err := f.Resolve(context.Background(), tree.EmptySearchPath, nil /* resolver */)
	if err != nil {
		return 1
	}

	props, _ := builtinsregistry.GetBuiltinProperties(d.Name)
	msg := HelpMessage{
		Function: f.String(),
		HelpMessageBody: HelpMessageBody{
			Category: props.Category,
			SeeAlso:  docs.URL("functions-and-operators.html"),
		},
	}

	var buf bytes.Buffer
	w := tabwriter.NewWriter(&buf, 0, 0, 1, ' ', 0)

	// Each function definition contains one or more overloads. We need
	// to extract them all; moreover each overload may have a different
	// documentation, so we need to also combine the descriptions
	// together.
	lastInfo := ""
	for i, b := range d.Overloads {
		if b.Info != "" && b.Info != lastInfo {
			if i > 0 {
				fmt.Fprintln(w, "---")
			}
			fmt.Fprintf(w, "\n%s\n\n", b.Info)
			fmt.Fprintln(w, "Signature")
		}
		lastInfo = b.Info

		simplifyRet := b.Class == tree.GeneratorClass
		fmt.Fprintf(w, "%s%s\n", d.Name, b.Signature(simplifyRet))
	}
	_ = w.Flush()
	msg.Text = buf.String()

	sqllex.(*lexer).SetHelp(msg)
	return 1
}

func helpWithFunctionByName(sqllex sqlLexer, s string) int {
	un := &tree.UnresolvedName{NumParts: 1, Parts: tree.NameParts{s}}