Files
rlua-searcher/src/searcher.rs
2022-06-27 13:38:18 +10:00

415 lines
14 KiB
Rust

use rlua::{Context, Function, MetaMethod, RegistryKey, Table, UserData, UserDataMethods, Value};
use std::borrow::Cow;
use std::collections::HashMap;
use std::fs::File;
use std::io::Read;
use std::path::{Path, PathBuf};
use crate::types::{CatMap, Result};
/// Stores Lua modules indexed by module name, and provides an `rlua::MetaMethod` to
/// enable `require`ing the stored modules by name in an `rlua::Context`.
struct Searcher {
/// A `HashMap` of Lua modules in string representation, indexed by module name.
///
/// Uses `Cow<'static, str>` types to allow both `&'static str` and owned `String`.
modules: HashMap<Cow<'static, str>, Cow<'static, str>>,
/// An `rlua::RegistryKey` whose value is the Lua environment within which the user
/// made the request to instantiate a `Searcher` for `modules`.
globals: RegistryKey,
}
impl Searcher {
fn new(modules: HashMap<Cow<'static, str>, Cow<'static, str>>, globals: RegistryKey) -> Self {
Self { modules, globals }
}
}
impl UserData for Searcher {
fn add_methods<'lua, M>(methods: &mut M)
where
M: UserDataMethods<'lua, Self>,
{
methods.add_meta_method(MetaMethod::Call, |lua_ctx, this, name: String| {
let name = Cow::from(name);
match this.modules.get(&name) {
Some(content) => {
let content = match content {
Cow::Borrowed(content) => content,
Cow::Owned(content) => content.as_str(),
};
Ok(Value::Function(
lua_ctx
.load(content)
.set_name(name.as_ref())?
.set_environment(lua_ctx.registry_value::<Table>(&this.globals)?)?
.into_function()?,
))
}
None => Ok(Value::Nil),
}
});
}
}
/// Like `Searcher`, but with `modules` values given as paths to files the content of
/// which can be read as Lua source code.
///
/// Facilitates Lua module reloading, and module reloading of any other programming
/// language whose source code can be compiled to Lua.
struct PathSearcherPoly<P>
where
P: 'static + AsRef<Path> + Send,
{
modules: HashMap<Cow<'static, str>, P>,
globals: RegistryKey,
/// Function to read file content as Lua source code.
transform: Box<dyn Fn(PathBuf) -> rlua::Result<String> + Send>,
}
impl<P> PathSearcherPoly<P>
where
P: 'static + AsRef<Path> + Send,
{
fn new(
modules: HashMap<Cow<'static, str>, P>,
globals: RegistryKey,
transform: Box<dyn Fn(PathBuf) -> rlua::Result<String> + Send>,
) -> Self {
Self {
modules,
globals,
transform,
}
}
}
impl<P> UserData for PathSearcherPoly<P>
where
P: 'static + AsRef<Path> + Send,
{
fn add_methods<'lua, M>(methods: &mut M)
where
M: UserDataMethods<'lua, Self>,
{
methods.add_meta_method(MetaMethod::Call, |lua_ctx, this, name: String| {
let name = Cow::from(name);
match this.modules.get(&name) {
Some(ref path) => {
let path = path.as_ref().to_path_buf();
let content = (this.transform)(path)?;
Ok(Value::Function(
lua_ctx
.load(&content)
.set_name(name.as_ref())?
.set_environment(lua_ctx.registry_value::<Table>(&this.globals)?)?
.into_function()?,
))
}
None => Ok(Value::Nil),
}
});
}
}
/// Like `Searcher`, but with closures as `modules` values, to facilitate setting up an
/// `rlua::Context` with Rust code.
///
/// Enables exposing `UserData` types to an `rlua::Context`.
struct ClosureSearcher {
/// Closures must accept three parameters:
///
/// 1. An `rlua::Context`, which the closure can do what it wants with.
///
/// 2. An `rlua::Table` containing globals (i.e. Lua's `_G`), which can be passed to
/// `Chunk.set_environment()`.
///
/// 3. The name of the module to be loaded (`&str`).
///
/// Closures must return an `rlua::Result`-wrapped `Function`. This `Function` acts as
/// the module loader.
modules: HashMap<
Cow<'static, str>,
Box<
dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+ Send,
>,
>,
globals: RegistryKey,
}
impl ClosureSearcher {
fn new(
modules: HashMap<
Cow<'static, str>,
Box<
dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+ Send,
>,
>,
globals: RegistryKey,
) -> Self {
Self { modules, globals }
}
}
impl UserData for ClosureSearcher {
fn add_methods<'lua, M>(methods: &mut M)
where
M: UserDataMethods<'lua, Self>,
{
methods.add_meta_method(
MetaMethod::Call,
|lua_ctx: Context<'lua>, this, name: String| {
let name = Cow::from(name);
match this.modules.get(&name) {
Some(ref closure) => Ok(Value::Function(closure(
lua_ctx,
lua_ctx.registry_value::<Table>(&this.globals)?,
name.as_ref(),
)?)),
None => Ok(Value::Nil),
}
},
);
}
}
/// Like `Searcher`, but with function pointers as `modules` values, to facilitate setting
/// up an `rlua::Context` with Rust code.
///
/// Enables exposing `UserData` types to an `rlua::Context`.
struct FunctionSearcher {
/// Functions must accept three parameters:
///
/// 1. An `rlua::Context`, which the function body can do what it wants with.
///
/// 2. An `rlua::Table` containing globals (i.e. Lua's `_G`), which can be passed to
/// `Chunk.set_environment()`.
///
/// 3. The name of the module to be loaded (`&str`).
///
/// Functions must return an `rlua::Result`-wrapped `Function`. This `Function` acts
/// as the module loader.
modules: HashMap<
Cow<'static, str>,
for<'ctx> fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>,
>,
globals: RegistryKey,
}
impl FunctionSearcher {
fn new(
modules: HashMap<
Cow<'static, str>,
for<'ctx> fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>,
>,
globals: RegistryKey,
) -> Self {
Self { modules, globals }
}
}
impl UserData for FunctionSearcher {
fn add_methods<'lua, M>(methods: &mut M)
where
M: UserDataMethods<'lua, Self>,
{
methods.add_meta_method(
MetaMethod::Call,
|lua_ctx: Context<'lua>, this, name: String| {
let name = Cow::from(name);
match this.modules.get(&name) {
Some(ref function) => Ok(Value::Function(function(
lua_ctx,
lua_ctx.registry_value::<Table>(&this.globals)?,
name.as_ref(),
)?)),
None => Ok(Value::Nil),
}
},
);
}
}
/// Like `Searcher`, but with `CatMap` to facilitate indexing heterogenous strings and paths -
/// all presumed to resolve to Lua module content - by module names in `modules`.
struct CatSearcher {
modules: CatMap,
globals: RegistryKey,
}
impl CatSearcher {
fn new(modules: CatMap, globals: RegistryKey) -> Self {
Self { modules, globals }
}
}
impl UserData for CatSearcher {
fn add_methods<'lua, M>(methods: &mut M)
where
M: UserDataMethods<'lua, Self>,
{
methods.add_meta_method(MetaMethod::Call, |lua_ctx, this, name: String| {
let name = Cow::from(name);
match this.modules.get(&name) {
Some(content) => {
let content = content
.cat()
.map_err(|e| rlua::Error::RuntimeError(format!("io error: {}", e)))?;
Ok(Value::Function(
lua_ctx
.load(&content)
.set_name(name.as_ref())?
.set_environment(lua_ctx.registry_value::<Table>(&this.globals)?)?
.into_function()?,
))
}
None => Ok(Value::Nil),
}
});
}
}
/// Extend `rlua::Context` to support `require`ing Lua modules by name.
pub trait AddSearcher {
/// Add a `HashMap` of Lua modules indexed by module name to Lua's `package.searchers`
/// table in an `rlua::Context`, with lookup functionality provided by the
/// `rlua_searcher::Searcher` struct.
fn add_searcher(&self, modules: HashMap<Cow<'static, str>, Cow<'static, str>>) -> Result<()>;
/// Like `add_searcher`, but with `modules` values given as paths to files containing
/// Lua source code to facilitate module reloading.
fn add_path_searcher<P>(&self, modules: HashMap<Cow<'static, str>, P>) -> Result<()>
where
P: 'static + AsRef<Path> + Send;
/// Like `add_path_searcher`, but with user-provided closure for transforming source
/// code to Lua.
fn add_path_searcher_poly<P>(
&self,
modules: HashMap<Cow<'static, str>, P>,
transform: Box<dyn Fn(PathBuf) -> rlua::Result<String> + Send>,
) -> Result<()>
where
P: 'static + AsRef<Path> + Send;
/// Like `add_searcher`, but with user-provided closure for `rlua::Context` setup.
fn add_closure_searcher(
&self,
modules: HashMap<
Cow<'static, str>,
Box<
dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+ Send,
>,
>,
) -> Result<()>;
/// Like `add_searcher`, but with user-provided function for `rlua::Context` setup.
fn add_function_searcher(
&self,
modules: HashMap<
Cow<'static, str>,
for<'ctx> fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>,
>,
) -> Result<()>;
/// Like `add_searcher`, except `modules` can contain heterogenous strings and paths
/// indexed by module name.
fn add_cat_searcher(&self, modules: CatMap) -> Result<()>;
}
impl<'a> AddSearcher for Context<'a> {
fn add_searcher(&self, modules: HashMap<Cow<'static, str>, Cow<'static, str>>) -> Result<()> {
let globals = self.globals();
let searchers: Table = globals.get::<_, Table>("package")?.get("searchers")?;
let registry_key = self.create_registry_value(globals)?;
let searcher = Searcher::new(modules, registry_key);
searchers
.set(searchers.len()? + 1, searcher)
.map_err(|e| e.into())
}
fn add_path_searcher<P>(&self, modules: HashMap<Cow<'static, str>, P>) -> Result<()>
where
P: 'static + AsRef<Path> + Send,
{
let transform = Box::new(|path| {
let mut content = String::new();
let mut file = File::open(path)
.map_err(|e| rlua::Error::RuntimeError(format!("io error: {:#?}", e)))?;
file.read_to_string(&mut content)
.map_err(|e| rlua::Error::RuntimeError(format!("io error: {:#?}", e)))?;
Ok(content)
});
self.add_path_searcher_poly(modules, transform)
}
fn add_path_searcher_poly<P>(
&self,
modules: HashMap<Cow<'static, str>, P>,
transform: Box<dyn Fn(PathBuf) -> rlua::Result<String> + Send>,
) -> Result<()>
where
P: 'static + AsRef<Path> + Send,
{
let globals = self.globals();
let searchers: Table = globals.get::<_, Table>("package")?.get("searchers")?;
let registry_key = self.create_registry_value(globals)?;
let searcher = PathSearcherPoly::new(modules, registry_key, transform);
searchers
.set(searchers.len()? + 1, searcher)
.map_err(|e| e.into())
}
fn add_closure_searcher(
&self,
modules: HashMap<
Cow<'static, str>,
Box<
dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+ Send,
>,
>,
) -> Result<()> {
let globals = self.globals();
let searchers: Table = globals.get::<_, Table>("package")?.get("searchers")?;
let registry_key = self.create_registry_value(globals)?;
let searcher = ClosureSearcher::new(modules, registry_key);
searchers
.set(searchers.len()? + 1, searcher)
.map_err(|e| e.into())
}
fn add_function_searcher(
&self,
modules: HashMap<
Cow<'static, str>,
for<'ctx> fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>,
>,
) -> Result<()> {
let globals = self.globals();
let searchers: Table = globals.get::<_, Table>("package")?.get("searchers")?;
let registry_key = self.create_registry_value(globals)?;
let searcher = FunctionSearcher::new(modules, registry_key);
searchers
.set(searchers.len()? + 1, searcher)
.map_err(|e| e.into())
}
fn add_cat_searcher(&self, modules: CatMap) -> Result<()> {
let globals = self.globals();
let searchers: Table = globals.get::<_, Table>("package")?.get("searchers")?;
let registry_key = self.create_registry_value(globals)?;
let searcher = CatSearcher::new(modules, registry_key);
searchers
.set(searchers.len()? + 1, searcher)
.map_err(|e| e.into())
}
}