Struct ArgSpec 

pub struct ArgSpec {
    pub name: Cow<'static, str>,
    pub kind: ArgKind,
    pub doc: Cow<'static, str>,
    pub prompt: Cow<'static, str>,
    pub default: ArgDefault,
    pub completion: Option<Cow<'static, str>>,
    pub picker: Option<Cow<'static, str>>,
}

One argument’s metadata. A command’s args_schema is the ordered list of these. Drives:

1. The : parser front-end’s structured-args extraction (when the syntax permits; delimiter-syntax commands still own their own parse_args).
2. Keymap binding pre-supply: a binding may set some args ahead of time and prompt for the rest.
3. Command palette / interactive form: each missing arg becomes a prompt with the schema-supplied prompt text + completion.
4. :describe-command enumeration.

Fields

name: Cow<'static, str>

Identifier shown in :describe-command output and used as the minibuffer prompt label.

PL8.F: Cow<'static, str> — a builtin passes a zero-cost Cow::Borrowed literal; a plugin-contributed schema (crossing WIT) passes Cow::Owned that frees on unregister_plugin, replacing the old Box::leak intern.

kind: ArgKind

The value type this slot expects; drives the parser, the prompt’s capture mode (ArgKind::Chord) and :describe-command.

doc: Cow<'static, str>

One-line documentation. Surfaced in palette tooltips and :describe-command.

prompt: Cow<'static, str>

Prompt shown when the runtime needs to ask for this arg interactively. Empty string means “use name as the prompt”.

default: ArgDefault

Fallback when the caller does not supply this arg; see ArgDefault for which variants the host currently acts on.

completion: Option<Cow<'static, str>>

Name of the registered completion source (gen:commands, gen:files, etc. – see lattice-completion) that fires when the user is typing this arg. None = no completion (free-form text). Wire-form is the source name (not its runtime id) so the schema is constructable as a literal.

picker: Option<Cow<'static, str>>

YR.6: name of a registered picker source offered for this argument (magit-revision, magit-branch, …). None = no picker.

Deliberately a second field rather than a variant of Self::completion, because the two name entries in two registries and that split is a decision, not an accident: completion names a CandidateGenerator (engine shape — prefix, buffer, command registry), picker names a PickerSourceGenerator (surface shape — needs PickerContext). completion-pipeline-unification.md slice 7d.1 chose to keep both rather than bloat one context or type-erase it, so an argument can legitimately have both: <Tab> completes inline, the picker opens the richer surface for the same question.

Implementations

impl ArgSpec

pub fn required( name: impl Into<Cow<'static, str>>, kind: ArgKind, doc: impl Into<Cow<'static, str>>, ) -> Self

Sugar for declaring a required arg with no fancy default: empty prompt (falls back to name), no completion, no picker.

Examples

use lattice_grammar::{ArgDefault, ArgKind, ArgSpec};

let spec = ArgSpec::required("path", ArgKind::String, "File to open.")
    .with_completion("gen:files");
assert_eq!(spec.default, ArgDefault::Required);
assert_eq!(spec.completion.as_deref(), Some("gen:files"));
assert!(spec.picker.is_none());

let opt = ArgSpec::optional("count", ArgKind::Int, "Repeat count.");
assert_eq!(opt.default, ArgDefault::None);

pub fn optional( name: impl Into<Cow<'static, str>>, kind: ArgKind, doc: impl Into<Cow<'static, str>>, ) -> Self

Sugar for declaring an optional arg (ArgDefault::None); otherwise as Self::required.

pub fn with_completion(self, source_name: impl Into<Cow<'static, str>>) -> Self

Builder helper: attach a completion source by registered name.

pub fn with_picker(self, source_name: impl Into<Cow<'static, str>>) -> Self

Builder helper: attach a picker source by registered name.

Composable with Self::with_completion — an argument may offer inline completion on <Tab> and a picker on <C-x><C-o>, and several magit arguments do exactly that.

Trait Implementations

impl Clone for ArgSpec

fn clone(&self) -> ArgSpec

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ArgSpec

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ArgSpec

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for ArgSpec

fn eq(&self, other: &ArgSpec) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for ArgSpec

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ArgSpec