crashkeys.dev
Markdown parser fork with extended syntax for personal use.
1//! Lots of helpers for dealing with SWC, particularly from unist, and for
2//! building its ES AST.
3
4use swc_core::common::{BytePos, Span, DUMMY_SP};
5use swc_core::ecma::visit::{noop_visit_mut_type, VisitMut};
6
7/// Visitor to fix SWC byte positions by removing a prefix.
8///
9/// > 👉 **Note**: SWC byte positions are offset by one: they are `0` when they
10/// > are missing or incremented by `1` when valid.
11#[derive(Debug, Default, Clone)]
12pub struct RewritePrefixContext {
13 /// Size of prefix considered outside this tree.
14 pub prefix_len: u32,
15}
16
17impl VisitMut for RewritePrefixContext {
18 noop_visit_mut_type!();
19
20 /// Rewrite spans.
21 fn visit_mut_span(&mut self, span: &mut Span) {
22 let mut result = DUMMY_SP;
23 if span.lo.0 > self.prefix_len && span.hi.0 > self.prefix_len {
24 result = create_span(span.lo.0 - self.prefix_len, span.hi.0 - self.prefix_len);
25 }
26
27 *span = result;
28 }
29}
30
31/// Generate a span.
32pub fn create_span(lo: u32, hi: u32) -> Span {
33 Span {
34 lo: BytePos(lo),
35 hi: BytePos(hi),
36 }
37}