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use std::collections::HashMap;
use std::path::{Path, PathBuf};
use crate::error::{Error, ImportError};
use crate::syntax;
use crate::syntax::{FilePath, ImportLocation, URL};
use crate::{Normalized, NormalizedExpr, Parsed, Resolved};
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>;
struct ResolveEnv {
cache: ImportCache,
stack: ImportStack,
}
impl ResolveEnv {
pub fn new() -> Self {
ResolveEnv {
cache: HashMap::new(),
stack: Vec::new(),
}
}
pub fn to_import_stack(&self) -> ImportStack {
self.stack.clone()
}
pub fn check_cyclic_import(&self, import: &Import) -> bool {
self.stack.contains(import)
}
pub fn get_from_cache(&self, import: &Import) -> Option<&Normalized> {
self.cache.get(import)
}
pub fn push_on_stack(&mut self, import: Import) {
self.stack.push(import)
}
pub fn pop_from_stack(&mut self) {
self.stack.pop();
}
pub fn insert_cache(&mut self, import: Import, expr: Normalized) {
self.cache.insert(import, expr);
}
}
fn resolve_import(
env: &mut ResolveEnv,
import: &Import,
root: &ImportRoot,
) -> 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(env, &path_buf).map_err(|e| {
ImportError::Recursive(import.clone(), Box::new(e))
})?)
}
_ => unimplemented!("{:?}", import),
}
}
fn load_import(env: &mut ResolveEnv, f: &Path) -> Result<Normalized, Error> {
Ok(do_resolve_expr(env, Parsed::parse_file(f)?)?
.typecheck()?
.normalize())
}
fn do_resolve_expr(
env: &mut ResolveEnv,
parsed: Parsed,
) -> Result<Resolved, ImportError> {
let Parsed(mut expr, root) = parsed;
let mut resolve = |import: Import| -> Result<Normalized, ImportError> {
if env.check_cyclic_import(&import) {
return Err(ImportError::ImportCycle(
env.to_import_stack(),
import,
));
}
match env.get_from_cache(&import) {
Some(expr) => Ok(expr.clone()),
None => {
// Push the current import on the stack
env.push_on_stack(import.clone());
// Resolve the import recursively
let expr = resolve_import(env, &import, &root)?;
// Remove import from the stack.
env.pop_from_stack();
// Add the import to the cache
env.insert_cache(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(&mut ResolveEnv::new(), e)
}
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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