Enum Guard 

pub enum Guard {
    Attr {
        ns: Ns,
        key: Option<String>,
        val: Option<String>,
    },
}

One namespaced guard predicate. Every guard in the language is a namespace plus an optional subject plus an optional value; the single disjointness rule compares the whole triple, so no domain ever needs its own table.

Construction (fixed by the parser, never hand-built): os/bool carry the value ([os:linux]), env carries the variable as subject ([env:MODE], [env:MODE=dev]). family:unix and family:windows are accepted aliases lowered at parse to any(os:macos, os:linux) and os:windows respectively, so every platform check executes uniformly under the os: namespace.

Variants

Attr

Fields

ns: Ns

key: Option<String>

val: Option<String>

Implementations

impl Guard

pub fn is_disjoint_from(&self, other: &Self) -> bool

The one disjointness rule for the entire guard language: same namespace, same subject, both valued, different values. Everything else overlaps — different namespaces are independent axes, different subjects are independent variables, and a missing value is a presence claim compatible with any value. No per-domain tables: os:macos vs os:linux, env:MODE=dev vs env:MODE=prod, and bool:true vs bool:false all decide here.

Trait Implementations

impl Clone for Guard

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Guard

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

Formats the value using the given formatter.

impl Display for Guard

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

Bare form without brackets (the step renderer adds them): [os:linux] prints os:linux, [env:MODE=dev] prints eq(env:MODE, dev), [env:MODE] prints env:MODE. The eq() spelling roundtrips through the parser; the rest print verbatim. Roundtrips by construction.

impl Eq for Guard

impl From<Guard> for GuardExpr

fn from(guard: Guard) -> Self

Converts to this type from the input type.

impl PartialEq for Guard

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Guard