https://github.com/lefticus/cons_expr

https://github.com/lefticus/cons_expr

Last synced: 2 months ago
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• Host: GitHub
• URL: https://github.com/lefticus/cons_expr
• Owner: lefticus
• License: mit
• Created: 2023-04-29T22:14:47.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2024-08-26T03:32:19.000Z (5 months ago)
• Last Synced: 2024-08-26T04:34:36.655Z (5 months ago)
• Language: C++
• Size: 171 KB
• Stars: 54
• Watchers: 5
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# cons_expr

[![ci](https://github.com/lefticus/cons_expr/actions/workflows/ci.yml/badge.svg)](https://github.com/lefticus/cons_expr/actions/workflows/ci.yml)

[![codecov](https://codecov.io/gh/lefticus/cons_expr/branch/main/graph/badge.svg)](https://codecov.io/gh/lefticus/cons_expr)

[![CodeQL](https://github.com/lefticus/cons_expr/actions/workflows/codeql-analysis.yml/badge.svg)](https://github.com/lefticus/cons_expr/actions/workflows/codeql-analysis.yml)

## About cons_expr

**cons_expr** is:

* Scheme-inspired

   * scheme syntax and features

   * does *not* support pairs or macros

   * any value once captured is const

   * any redefinition of a value shadows the previous value

* Constexpr-capable

   * `cons_expr::cons_expr` is `constinit` meaning that it is *always* 0-cost to construct a cons_expr interpreter

   * Any script can be executed at compile time.

   * Why execute script at compile time?

     * I don't know your other use cases

     * But you can use this feature to set up your entire scripting environment at compile time, then execute scripts at runtime

* Simple and small

   * I'm attempting to keep the code as compact as possible. As of now it is "feature complete." Any additional features will go as add-ons in the "utility" header

   * I'm not happy with the `fix_identifiers` family of functions. They need to be simplified and made better.

   * Compilation of entire engine is just a few seconds, even with optimizations.

* Easy to use

   * Include one header and go! See [examples](examples).

* Embeddable scripting language 

   * Bi-directional support for functions between script and C++.

   * All supported types must be known at [compile time](https://github.com/lefticus/cons_expr/blob/main/test/tests.cpp#L57C1-L91).

* For C++23

   * Currently only known to work with GCC 13.1.

## Command Line Inspection Tool

`ccons_expr` can be used to execute scripts and inspect the state of the runtime system live

[![asciicast](https://asciinema.org/a/ZJWpwSjkFqt7Fl750HpeiT3Eg.svg)](https://asciinema.org/a/ZJWpwSjkFqt7Fl750HpeiT3Eg)

## Important Notes

* Objects are never destroyed, but because they are treated as immutable, they are reused as much as possible.

* All types contained in the script are required to be `trivial`

* If you expand beyond the statically allocated storage, dynamic storage is utilized. If you maintain dynamic storage from compile-time to run-time, you will get a compile time error.