make initial implementation

credit
- https://github.com/AlphaModder/include-lua

README.md

@@ -11,20 +11,24 @@ and `require` the module.
 ## Synopsis
 
 ```rust
-use rlua_searcher::AddSearcher;
+use rlua::Lua;
+use rlua_searcher::{AddSearcher, Result};
+use std::collections::HashMap;
 
 fn main() {
     let lume = read_lume_to_string();
-    let name = "lume";
-    let map = HashMap::new<String, String>();
+    let name = "lume".to_string();
+    let mut map = HashMap::new();
     map.insert(name, lume);
 
-    let lua = Lua::new;
+    let lua = Lua::new();
 
-    let hello = lua.context::<_, rlua::Result<_>>(|lua_ctx| {
-        lua_ctx.add_searcher(map)?;
-        Ok(lua_ctx.load(r#"require("lume")"#).eval()?)
-    }).unwrap();
+    let hello = lua
+        .context::<_, Result<String>>(|lua_ctx| {
+            lua_ctx.add_searcher(map)?;
+            Ok(lua_ctx.load(r#"return require("lume")"#).eval()?)
+        })
+        .unwrap();
 
     // prints "hello lume"
     println!("{}", hello);

src/error.rs

@@ -0,0 +1,21 @@
+#[derive(Debug)]
+pub enum Error {
+    RLua(rlua::Error),
+}
+
+impl From<rlua::Error> for Error {
+    fn from(error: rlua::Error) -> Self {
+        Error::RLua(error)
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let res = match self {
+            Error::RLua(e) => format!("rlua error:\n{:#?}", e),
+        };
+        write!(f, "{}", res)
+    }
+}
+
+impl std::error::Error for Error {}

src/lib.rs

@@ -1,7 +1,7 @@
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
-    }
-}
+mod searcher;
+mod error;
+mod types;
+
+pub use crate::error::Error;
+pub use crate::searcher::AddSearcher;
+pub use crate::types::Result;

src/searcher.rs

@@ -0,0 +1,61 @@
+use rlua::{Context, MetaMethod, RegistryKey, Table, UserData, UserDataMethods, Value};
+use std::collections::HashMap;
+
+use crate::types::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.
+    modules: HashMap<String, String>,
+
+    /// 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<String, String>, globals: RegistryKey) -> Self {
+        Self { modules, globals }
+    }
+}
+
+impl UserData for Searcher {
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_meta_method(MetaMethod::Call, |lua_ctx, this, name: String| {
+            match this.modules.get(&name) {
+                Some(content) => Ok(Value::Function(
+                    lua_ctx
+                        .load(content)
+                        .set_name(&name)?
+                        .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<'a> {
+    /// 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<String, String>) -> Result<()>;
+}
+
+impl<'a> AddSearcher<'a> for Context<'a> {
+    fn add_searcher(&self, modules: HashMap<String, String>) -> 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())
+    }
+}

src/types.rs

@@ -0,0 +1,3 @@
+use crate::error::Error;
+
+pub type Result<A> = std::result::Result<A, Error>;

tests/tests.rs

@@ -0,0 +1,26 @@
+use rlua::Lua;
+use rlua_searcher::{AddSearcher, Result};
+use std::collections::HashMap;
+
+#[test]
+fn it_works() {
+    let lume = read_lume_to_string();
+    let name = "lume".to_string();
+    let mut map = HashMap::new();
+    map.insert(name, lume);
+
+    let lua = Lua::new();
+
+    let hello = lua
+        .context::<_, Result<String>>(|lua_ctx| {
+            lua_ctx.add_searcher(map)?;
+            Ok(lua_ctx.load(r#"return require("lume")"#).eval()?)
+        })
+        .unwrap();
+
+    assert_eq!("hello lume", hello);
+}
+
+fn read_lume_to_string() -> String {
+    r#"return "hello lume""#.to_string()
+}