1use crate::create_error;2use crate::error::{Error, Result};3use fs::File;4use std::fs;5use std::io::Read;6use std::{cell::RefCell, collections::HashMap, path::PathBuf, rc::Rc};78pub trait ImportResolver {9 fn resolve_file(&self, from: &PathBuf, path: &PathBuf) -> Result<Rc<PathBuf>>;10 fn load_file_contents(&self, resolved: &PathBuf) -> Result<Rc<str>>;11}1213pub struct DummyImportResolver;14impl ImportResolver for DummyImportResolver {15 fn resolve_file(&self, from: &PathBuf, path: &PathBuf) -> Result<Rc<PathBuf>> {16 create_error(Error::ImportNotSupported(from.clone(), path.clone()))17 }18 fn load_file_contents(&self, _resolved: &PathBuf) -> Result<Rc<str>> {19 20 panic!("dummy resolver can't load any file")21 }22}23impl Default for Box<dyn ImportResolver> {24 fn default() -> Self {25 Box::new(DummyImportResolver)26 }27}2829pub struct FileImportResolver {30 pub library_paths: Vec<PathBuf>,31}32impl ImportResolver for FileImportResolver {33 fn resolve_file(&self, from: &PathBuf, path: &PathBuf) -> Result<Rc<PathBuf>> {34 let mut new_path = from.clone();35 new_path.push(path);36 if new_path.exists() {37 Ok(Rc::new(new_path))38 } else {39 for library_path in self.library_paths.iter() {40 let mut cloned = library_path.clone();41 cloned.push(path);42 if cloned.exists() {43 return Ok(Rc::new(cloned));44 }45 }46 create_error(Error::ImportFileNotFound(from.clone(), path.clone()))47 }48 }49 fn load_file_contents(&self, id: &PathBuf) -> Result<Rc<str>> {50 let mut file = File::open(id).map_err(|_e| {51 create_error::<()>(Error::ResolvedFileNotFound(id.clone()))52 .err()53 .unwrap()54 })?;55 let mut out = String::new();56 file.read_to_string(&mut out).map_err(|_e| {57 create_error::<()>(Error::ImportBadFileUtf8(id.clone()))58 .err()59 .unwrap()60 })?;61 Ok(out.into())62 }63}6465type ResolutionData = (PathBuf, PathBuf);66pub struct CachingImportResolver {67 resolution_cache: RefCell<HashMap<ResolutionData, Result<Rc<PathBuf>>>>,68 loading_cache: RefCell<HashMap<PathBuf, Result<Rc<str>>>>,69 inner: Box<dyn ImportResolver>,70}71impl ImportResolver for CachingImportResolver {72 fn resolve_file(&self, from: &PathBuf, path: &PathBuf) -> Result<Rc<PathBuf>> {73 self.resolution_cache74 .borrow_mut()75 .entry((from.clone(), path.clone()))76 .or_insert_with(|| self.inner.resolve_file(from, path))77 .clone()78 }79 fn load_file_contents(&self, resolved: &PathBuf) -> Result<Rc<str>> {80 self.loading_cache81 .borrow_mut()82 .entry(resolved.clone())83 .or_insert_with(|| self.inner.load_file_contents(resolved))84 .clone()85 }86}