[−][src]Crate uneval

Serde serializer generating Rust code.

This crate can be used to "embed" something into code, having only some serialized data, like JSON or YAML. This way, you'll mostly escape runtime cost of deserialization, nearly as if you've written the same data directly in code by hand. Of course, in most cases this cost is already negligible, but for crates which use large blobs of data this crate can come in handy, improving startup times.

Usage

In general, to embed some code into crate, you have to use the build script and include! macro. Inside the build script, you'll generate some code with one of the functions provided by uneval, and then include the generated file, like this:

ⓘThis example is not tested
let value = include!(concat!(env!(OUT_DIR), "/file_name.rs"));

Limitations

There are some cases when uneval will be unable to generate valid code. Namely:

  1. Since Serde doesn't provide us the full path to the type in question (and in most cases it's simply unable to), all the structs and enums used during value construction must be in scope. As a consequence, all of them must have distinct names - otherwise, there will be name clashes.
  2. This serializer is intended for use with derived implementation. It may return bogus results when used with customized Serialize.
  3. It is impossible to consume code for the type with private fields outside from the module it is defined in. In fact, to be able to use this type with uneval, you'll have to distribute two copies of your crate, one of which would only export the definition with derived Serialize to be used by serializer during the build-time of the second copy. (Isn't this a bit too complex?)
  4. It is impossible to use empty tuple structs (i.e. Empty()). From the Serde's point of view, they are indistinguishable from unit structs (i.e. Unit), but the same Rust syntax can't be used for both, and, since ordinary unit structs are much more common, it was decided to correctly handle them.

Re-exports

pub use funcs::to_file;
pub use funcs::to_out_dir;
pub use funcs::to_string;
pub use funcs::write;

Modules

error

Error returned by Uneval serializer.

funcs

Convenience functions to be used with Uneval.

ser

Implementation of the Uneval serializer.