pub struct SyntaxContext(_);
Expand description

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

Implementations

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

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).

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).

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));
}

Trait Implementations

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

This method tests for !=.

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Auto Trait Implementations

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🔬 This is a nightly-only experimental API. (toowned_clone_into)

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