swc_ecma_loader/resolvers/tsc.rs
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use std::path::{Component, PathBuf};
use anyhow::{bail, Context, Error};
use swc_common::FileName;
use tracing::{debug, info, trace, Level};
use crate::resolve::Resolve;
#[derive(Debug)]
enum Pattern {
Wildcard {
prefix: String,
},
/// No wildcard.
Exact(String),
}
/// Support for `paths` of `tsconfig.json`.
///
/// See https://www.typescriptlang.org/docs/handbook/module-resolution.html#path-mapping
#[derive(Debug)]
pub struct TsConfigResolver<R>
where
R: Resolve,
{
inner: R,
base_url: PathBuf,
paths: Vec<(Pattern, Vec<String>)>,
}
impl<R> TsConfigResolver<R>
where
R: Resolve,
{
///
/// # Parameters
///
/// ## base_url
///
/// See https://www.typescriptlang.org/tsconfig#baseUrl
///
/// The typescript documentation says `This must be specified if "paths"
/// is.`.
///
/// ## `paths`
///
/// Pass `paths` map from `tsconfig.json`.
///
/// See https://www.typescriptlang.org/tsconfig#paths
///
/// Note that this is not a hashmap because value is not used as a hash map.
pub fn new(inner: R, base_url: PathBuf, paths: Vec<(String, Vec<String>)>) -> Self {
if cfg!(debug_assertions) {
info!(
base_url = tracing::field::display(base_url.display()),
"jsc.paths"
);
}
let paths = paths
.into_iter()
.map(|(from, to)| {
assert!(
!to.is_empty(),
"value of `paths.{}` should not be an empty array",
from,
);
let pos = from.as_bytes().iter().position(|&c| c == b'*');
let pat = if from.contains('*') {
if from.as_bytes().iter().rposition(|&c| c == b'*') != pos {
panic!("`paths.{}` should have only one wildcard", from)
}
Pattern::Wildcard {
prefix: from[..pos.unwrap()].to_string(),
}
} else {
assert_eq!(
to.len(),
1,
"value of `paths.{}` should be an array with one element because the src \
path does not contains * (wildcard)",
from,
);
Pattern::Exact(from)
};
(pat, to)
})
.collect();
Self {
inner,
base_url,
paths,
}
}
}
impl<R> Resolve for TsConfigResolver<R>
where
R: Resolve,
{
fn resolve(&self, base: &FileName, src: &str) -> Result<FileName, Error> {
let _tracing = if cfg!(debug_assertions) {
Some(
tracing::span!(
Level::ERROR,
"tsc.resolve",
base_url = tracing::field::display(self.base_url.display()),
base = tracing::field::display(base),
src = tracing::field::display(src),
)
.entered(),
)
} else {
None
};
if src.starts_with('.') && (src == ".." || src.starts_with("./") || src.starts_with("../"))
{
return self
.inner
.resolve(base, src)
.context("not processed by tsc resolver because it's relative import");
}
if cfg!(debug_assertions) {
debug!("non-relative import");
}
if let FileName::Real(v) = base {
if v.components().any(|c| match c {
Component::Normal(v) => v == "node_modules",
_ => false,
}) {
return self.inner.resolve(base, src).context(
"not processed by tsc resolver because base module is in node_modules",
);
}
}
// https://www.typescriptlang.org/docs/handbook/module-resolution.html#path-mapping
for (from, to) in &self.paths {
match from {
Pattern::Wildcard { prefix } => {
let extra = src.strip_prefix(prefix);
let extra = match extra {
Some(v) => v,
None => {
if cfg!(debug_assertions) {
trace!("skip because src doesn't start with prefix");
}
continue;
}
};
if cfg!(debug_assertions) {
trace!("extra = {}", extra);
}
let mut errors = vec![];
for target in to {
let mut replaced = target.replace('*', extra);
let rel = format!("./{}", replaced);
let res = self.inner.resolve(base, &rel).with_context(|| {
format!(
"failed to resolve `{}`, which is expanded from `{}`",
replaced, src
)
});
errors.push(match res {
Ok(v) => return Ok(v),
Err(err) => err,
});
if cfg!(target_os = "windows") {
if replaced.starts_with("./") {
replaced = replaced[2..].to_string();
}
replaced = replaced.replace('/', "\\");
}
if to.len() == 1 {
return Ok(FileName::Real(self.base_url.join(replaced)));
}
}
bail!(
"`{}` matched `{}` (from tsconfig.paths) but failed to resolve:\n{:?}",
src,
prefix,
errors
)
}
Pattern::Exact(from) => {
// Should be exactly matched
if src == from {
let replaced = self.base_url.join(&to[0]);
if replaced.exists() {
return Ok(FileName::Real(replaced));
}
return self
.inner
.resolve(base, &format!("./{}", &to[0]))
.with_context(|| {
format!(
"tried to resolve `{}` because `{}` was exactly matched",
to[0], from
)
});
}
}
}
}
self.inner.resolve(base, src)
}
}