Enum Predicate 

pub enum Predicate {
    TargetOs(CmpOp, String),
    TargetArch(CmpOp, String),
    Feature(String),
    Env(String),
    Not(Box<Predicate>),
    And(Box<Predicate>, Box<Predicate>),
    Or(Box<Predicate>, Box<Predicate>),
}

A parsed required_when predicate — eagerly validated at load time.

Closed predicate set — no user-defined extensions:

• target_os == "value" / target_os != "value"
• target_arch == "value" / target_arch != "value"
• feature("name") — feature flag enabled in HostContext
• env("VAR") — environment variable VAR is set and non-empty
• !pred, pred && pred, pred || pred, (pred)

Variants

TargetOs(CmpOp, String)

TargetArch(CmpOp, String)

Feature(String)

Env(String)

Not(Box<Predicate>)

And(Box<Predicate>, Box<Predicate>)

Or(Box<Predicate>, Box<Predicate>)

Implementations

impl Predicate

pub fn evaluate(&self, ctx: &HostContext) -> bool

Evaluate this predicate against a host context.

Trait Implementations

impl Clone for Predicate

fn clone(&self) -> Predicate

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Predicate

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

Formats the value using the given formatter.

impl Eq for Predicate

impl PartialEq for Predicate

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Predicate