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use std::collections::HashMap;
use std::path::{Path, PathBuf};
use crate::semantics::error::{Error, ImportError};
use crate::semantics::phase::{Normalized, NormalizedExpr, Parsed, Resolved};
use crate::syntax;
use crate::syntax::{FilePath, ImportLocation, URL};
type Import = syntax::Import<NormalizedExpr>;
/// A root from which to resolve relative imports.
#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) enum ImportRoot {
LocalDir(PathBuf),
}
type ImportCache = HashMap<Import, Normalized>;
pub(crate) type ImportStack = Vec<Import>;
fn resolve_import(
import: &Import,
root: &ImportRoot,
import_cache: &mut ImportCache,
import_stack: &ImportStack,
) -> Result<Normalized, ImportError> {
use self::ImportRoot::*;
use syntax::FilePrefix::*;
use syntax::ImportLocation::*;
let cwd = match root {
LocalDir(cwd) => cwd,
};
match &import.location {
Local(prefix, path) => {
let path_buf: PathBuf = path.file_path.iter().collect();
let path_buf = match prefix {
// TODO: fail gracefully
Parent => cwd.parent().unwrap().join(path_buf),
Here => cwd.join(path_buf),
_ => unimplemented!("{:?}", import),
};
Ok(load_import(&path_buf, import_cache, import_stack).map_err(
|e| ImportError::Recursive(import.clone(), Box::new(e)),
)?)
}
_ => unimplemented!("{:?}", import),
}
}
fn load_import(
f: &Path,
import_cache: &mut ImportCache,
import_stack: &ImportStack,
) -> Result<Normalized, Error> {
Ok(
do_resolve_expr(Parsed::parse_file(f)?, import_cache, import_stack)?
.typecheck()?
.normalize(),
)
}
fn do_resolve_expr(
parsed: Parsed,
import_cache: &mut ImportCache,
import_stack: &ImportStack,
) -> Result<Resolved, ImportError> {
let Parsed(mut expr, root) = parsed;
let mut resolve = |import: Import| -> Result<Normalized, ImportError> {
if import_stack.contains(&import) {
return Err(ImportError::ImportCycle(import_stack.clone(), import));
}
match import_cache.get(&import) {
Some(expr) => Ok(expr.clone()),
None => {
// Copy the import stack and push the current import
let mut import_stack = import_stack.clone();
import_stack.push(import.clone());
// Resolve the import recursively
let expr = resolve_import(
&import,
&root,
import_cache,
&import_stack,
)?;
// Add the import to the cache
import_cache.insert(import, expr.clone());
Ok(expr)
}
}
};
expr.traverse_resolve_mut(&mut resolve)?;
Ok(Resolved(expr))
}
pub(crate) fn resolve(e: Parsed) -> Result<Resolved, ImportError> {
do_resolve_expr(e, &mut HashMap::new(), &Vec::new())
}
pub(crate) fn skip_resolve_expr(
parsed: Parsed,
) -> Result<Resolved, ImportError> {
let mut expr = parsed.0;
let mut resolve = |import: Import| -> Result<Normalized, ImportError> {
Err(ImportError::UnexpectedImport(import))
};
expr.traverse_resolve_mut(&mut resolve)?;
Ok(Resolved(expr))
}
pub trait Canonicalize {
fn canonicalize(&self) -> Self;
}
impl Canonicalize for FilePath {
fn canonicalize(&self) -> FilePath {
let mut file_path = Vec::new();
let mut file_path_components = self.file_path.clone().into_iter();
loop {
let component = file_path_components.next();
match component.as_ref() {
// ───────────────────
// canonicalize(ε) = ε
None => break,
// canonicalize(directory₀) = directory₁
// ───────────────────────────────────────
// canonicalize(directory₀/.) = directory₁
Some(c) if c == "." => continue,
Some(c) if c == ".." => match file_path_components.next() {
// canonicalize(directory₀) = ε
// ────────────────────────────
// canonicalize(directory₀/..) = /..
None => file_path.push("..".to_string()),
// canonicalize(directory₀) = directory₁/..
// ──────────────────────────────────────────────
// canonicalize(directory₀/..) = directory₁/../..
Some(ref c) if c == ".." => {
file_path.push("..".to_string());
file_path.push("..".to_string());
}
// canonicalize(directory₀) = directory₁/component
// ─────────────────────────────────────────────── ; If "component" is not
// canonicalize(directory₀/..) = directory₁ ; ".."
Some(_) => continue,
},
// canonicalize(directory₀) = directory₁
// ───────────────────────────────────────────────────────── ; If no other
// canonicalize(directory₀/component) = directory₁/component ; rule matches
Some(c) => file_path.push(c.clone()),
}
}
FilePath { file_path }
}
}
impl<SE: Copy> Canonicalize for ImportLocation<SE> {
fn canonicalize(&self) -> ImportLocation<SE> {
match self {
ImportLocation::Local(prefix, file) => {
ImportLocation::Local(*prefix, file.canonicalize())
}
ImportLocation::Remote(url) => ImportLocation::Remote(URL {
scheme: url.scheme,
authority: url.authority.clone(),
path: url.path.canonicalize(),
query: url.query.clone(),
headers: url.headers.clone(),
}),
ImportLocation::Env(name) => ImportLocation::Env(name.to_string()),
ImportLocation::Missing => ImportLocation::Missing,
}
}
}
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