Module spec 

Cold-path metadata, and writing it out as a spec.

The tables in the crate root are what a parse reads: names, shorts, whether a flag takes a value. Everything else a CLI knows about itself — help text, choices, defaults, what a command does to the world — lives here instead, in a parallel tree that points at those tables.

Two reasons for the split. A successful parse never touches any of this, so keeping it out of the hot tables keeps them dense; and a CLI that wants only a parser does not compile it at all, since this module is behind the spec feature.

What the metadata does not do is repeat the tables. FlagMeta borrows the Flag it describes, so long and short forms have exactly one definition and cannot drift from what the parser matches.

Emitting

Everything here lowers into the spec without loss, which is deliberate: a field the spec cannot express would make the emitted KDL a summary rather than a definition. When something is missing the spec gains it first — help_heading went in that way.

Structs

ArgMeta

What a positional argument knows about itself beyond how it parses.

ArgumentState

Presence information exposed across a flattened CommandArgs boundary.

Candidate

Something a shell could offer at the cursor.

ChoiceAliasMeta

ChoiceMeta

CommandMeta

What a command knows about itself beyond how it parses.

CommandOverlay

One sparse metadata override applied by SpecView.

CompleteCtx

What a completion callback is told about the cursor.

DefaultIf

A default that applies when another flag is given.

DefaultViewOmitter

The omission policy used by generated executable-view entry points.

Example

A worked example, for documentation.

FlagMeta

What a flag knows about itself beyond how it parses.

FlattenGroup

A run of one command’s flags that arrived from a flattened Args type.

GroupMeta

A set of one command’s arguments that relate to one another as a set.

RequiredIfEq

A selector/value comparison used by conditional requiredness.

RequiresIf

A flag required when the declaring flag is explicitly given value.

Spec

A whole CLI: the root command plus what describes the program itself.

SpecView

A borrowed, sparse view over a derive-generated Spec.

ViewMeta

A named executable surface emitted into the portable spec.

Enums

CommandSelector

A command selected for a cold-path metadata override.

Effect

What running a command does to the world.

SettingGiven

One value a flag was given, in a vocabulary this crate can hold.

Traits

ArgGroup

An enum whose variants are one command’s mutually exclusive switch flags.

CommandArgs

Omitted

Supplies a typed placeholder for fields outside an executable view.

Subcommands

An enum whose variants are a command’s subcommands.

ValueEnum

A struct that describes one command’s flags and arguments.

ViewCommandArgs

View-aware construction for a derived command or flattened argument group.

ViewSubcommands

View-aware construction for a derived subcommand enum.

Functions

choice_matches

concat_aliases

Join command alias lists at compile time.

concat_arg_metas

Join groups of argument metadata into one, at compile time.

concat_bindings

The bindings of several commands, joined into one array.

concat_flag_metas

Join groups of flag metadata into one, at compile time.

concat_group_metas

Join groups of group metadata into one, at compile time.

flag_selector_count

How many flags on command accept selector.

view_for_program

The declared executable view selected by argv0, if any.

Type Aliases

Completer

A function that answers for one argument or flag value.