Struct AssetResolver 

pub struct AssetResolver { /* private fields */ }

Resolver that registers parsers by extension and auto-converts non-Lua resources.

Parsers are registered per extension via .parser(). For unregistered extensions, no I/O is performed and None is returned.

Filenames are treated literally (no dot-to-path conversion).

Built-in parsers

Factory function	Conversion
json_parser()	Parse with serde_json -> Lua Table
text_parser()	Return as-is as Lua String

Examples

use mlua_pkg::resolvers::{AssetResolver, json_parser, text_parser};

let resolver = AssetResolver::new("./assets")?
    .parser("json", json_parser())
    .parser("sql", text_parser())
    .parser("css", text_parser());

Custom parsers can also be registered as closures:

use mlua_pkg::resolvers::{AssetResolver, json_parser};

let resolver = AssetResolver::new("./assets")?
    .parser("json", json_parser())
    .parser("csv", |lua, content| {
        // Split by lines and convert to a Lua table
        let t = lua.create_table()?;
        for (i, line) in content.lines().enumerate() {
            t.set(i + 1, lua.create_string(line)?)?;
        }
        Ok(mlua::Value::Table(t))
    });

I/O goes through the SandboxedFs trait. Use with_sandbox to inject test mocks or alternative backends.

Design decision: why extension keys are String

Parser registration uses HashMap<String, BoxFn>. String keys are chosen over enums to prioritize extensibility (Open/Closed), allowing users to freely register custom parsers for any extension.

Impact of a typo: parsers.get(ext) returns None -> safely falls through to the next Resolver. No panic/UB occurs. Setup code is small, so typos surface immediately in tests.

Errors

new() returns InitError::RootNotFound if the root does not exist.

Implementations

impl AssetResolver

pub fn new(root: impl Into<PathBuf>) -> Result<Self, InitError>

Build an AssetResolver backed by the real filesystem.

pub fn with_sandbox(sandbox: impl SandboxedFs + 'static) -> Self

Inject an arbitrary SandboxedFs implementation.

pub fn parser( self, ext: impl Into<String>, f: impl Fn(&Lua, &str) -> Result<Value> + Send + Sync + 'static, ) -> Self

Register a parser for an extension. Duplicate extensions are overwritten.

Trait Implementations

impl Resolver for AssetResolver

fn resolve(&self, lua: &Lua, name: &str) -> Option<Result<Value>>