Struct syntax::ext::hygiene::SyntaxContext

pub struct SyntaxContext(_);

A SyntaxContext represents a chain of macro expansions (represented by marks).

Methods

impl SyntaxContext

pub const fn empty() -> SyntaxContext

pub fn allocate_directly(expansion_info: ExpnInfo) -> SyntaxContext

pub fn apply_mark(self, mark: Mark) -> SyntaxContext

Extend a syntax context with a given mark and default transparency for that mark.

pub fn apply_mark_with_transparency(     self,     mark: Mark,     transparency: Transparency ) -> SyntaxContext

Extend a syntax context with a given mark and transparency

pub fn remove_mark(&mut self) -> Mark

Pulls a single mark off of the syntax context. This effectively moves the context up one macro definition level. That is, if we have a nested macro definition as follows:

macro_rules! f {
   macro_rules! g {
       ...
   }
}

and we have a SyntaxContext that is referring to something declared by an invocation of g (call it g1), calling remove_mark will result in the SyntaxContext for the invocation of f that created g1. Returns the mark that was removed.

Important traits for Vec<u8>

impl Write for Vec<u8>

pub fn marks(self) -> Vec<(Mark, Transparency)>

pub fn adjust(&mut self, expansion: Mark) -> Option<Mark>

Adjust this context for resolution in a scope created by the given expansion. For example, consider the following three resolutions of f:

mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
m!(f);
macro m($f:ident) {
    mod bar {
        pub fn f() {} // `f`'s `SyntaxContext` has a single `Mark` from `m`.
        pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
    }
    foo::f(); // `f`'s `SyntaxContext` has a single `Mark` from `m`
    //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
    //| and it resolves to `::foo::f`.
    bar::f(); // `f`'s `SyntaxContext` has a single `Mark` from `m`
    //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
    //| and it resolves to `::bar::f`.
    bar::$f(); // `f`'s `SyntaxContext` is empty.
    //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
    //| and it resolves to `::bar::$f`.
}

This returns the expansion whose definition scope we use to privacy check the resolution, or None if we privacy check as usual (i.e. not w.r.t. a macro definition scope).

pub fn glob_adjust(     &mut self,     expansion: Mark,     glob_ctxt: SyntaxContext ) -> Option<Option<Mark>>

Adjust this context for resolution in a scope created by the given expansion via a glob import with the given SyntaxContext. For example:

m!(f);
macro m($i:ident) {
    mod foo {
        pub fn f() {} // `f`'s `SyntaxContext` has a single `Mark` from `m`.
        pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
    }
    n(f);
    macro n($j:ident) {
        use foo::*;
        f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
        //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
        $i(); // `$i`'s `SyntaxContext` has a mark from `n`
        //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
        $j(); // `$j`'s `SyntaxContext` has a mark from `m`
        //^ This cannot be glob-adjusted, so this is a resolution error.
    }
}

This returns None if the context cannot be glob-adjusted. Otherwise, it returns the scope to use when privacy checking (see adjust for details).

pub fn reverse_glob_adjust(     &mut self,     expansion: Mark,     glob_ctxt: SyntaxContext ) -> Option<Option<Mark>>

Undo glob_adjust if possible:

if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
    assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
}

pub fn modern(self) -> SyntaxContext

pub fn modern_and_legacy(self) -> SyntaxContext

pub fn outer(self) -> Mark

Trait Implementations

impl PartialOrd<SyntaxContext> for SyntaxContext

fn partial_cmp(&self, other: &SyntaxContext) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &SyntaxContext) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &SyntaxContext) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &SyntaxContext) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &SyntaxContext) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Hash for SyntaxContext

fn hash<__H>(&self, state: &mut __H) where     __H: Hasher,

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where     H: Hasher,

Feeds a slice of this type into the given [Hasher].

impl Clone for SyntaxContext

fn clone(&self) -> SyntaxContext

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Decodable for SyntaxContext

fn decode<D>(&mut D) -> Result<SyntaxContext, <D as Decoder>::Error> where     D: Decoder,

impl Default for SyntaxContext

fn default() -> SyntaxContext

Returns the "default value" for a type.

impl Debug for SyntaxContext

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

Formats the value using the given formatter.

impl Copy for SyntaxContext

impl Ord for SyntaxContext

fn cmp(&self, other: &SyntaxContext) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

impl Eq for SyntaxContext

impl PartialEq<SyntaxContext> for SyntaxContext

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=.

impl Encodable for SyntaxContext

fn encode<E>(&self, &mut E) -> Result<(), <E as Encoder>::Error> where     E: Encoder,