Struct TranscrCtx

struct TranscrCtx<'psess, 'itp> {
    psess: &'psess ParseSess,
    interp: &'itp FxHashMap<MacroRulesNormalizedIdent, NamedMatch>,
    marker: Marker,
    stack: SmallVec<[Frame<'itp>; 1]>,
    repeats: Vec<(usize, usize)>,
    result: Vec<TokenTree>,
    result_stack: Vec<Vec<TokenTree>>,
}

Context needed to perform transcription of metavariable expressions.

Fields

psess: &'psess ParseSess

interp: &'itp FxHashMap<MacroRulesNormalizedIdent, NamedMatch>

Map from metavars to matched tokens

marker: Marker

Allow marking spans.

stack: SmallVec<[Frame<'itp>; 1]>

The stack of things yet to be completely expanded.

We descend into the RHS (src), expanding things as we go. This stack contains the things we have yet to expand/are still expanding. We start the stack off with the whole RHS. The choice of spacing values doesn’t matter.

repeats: Vec<(usize, usize)>

A stack of where we are in the repeat expansion.

As we descend in the RHS, we will need to be able to match nested sequences of matchers. repeats keeps track of where we are in matching at each level, with the last element being the most deeply nested sequence. This is used as a stack.

result: Vec<TokenTree>

The resulting token stream from the TokenTree we just finished processing.

At the end, this will contain the full result of transcription, but at arbitrary points during transcribe, result will contain subsets of the final result.

Specifically, as we descend into each TokenTree, we will push the existing results onto the result_stack and clear results. We will then produce the results of transcribing the TokenTree into results. Then, as we unwind back out of the TokenTree, we will pop the result_stack and append results too it to produce the new results up to that point.

Thus, if we try to pop the result_stack and it is empty, we have reached the top-level again, and we are done transcribing.

result_stack: Vec<Vec<TokenTree>>

The in-progress result lives at the top of this stack. Each entered TokenTree adds a new entry.

Implementations

impl<'psess> TranscrCtx<'psess, '_>

fn visited_dspan(&mut self, dspan: DelimSpan) -> Span

Span marked with the correct expansion and transparency.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 192 bytes