writing-a-rust-gem-from-scratch/

000.sh

$ bundle gem ruffle
# ...omitted
Gem 'ruffle' was successfully created. For more information on making a RubyGem visit https://bundler.io/guides/creating_gem.html

$ cd ruffle

001.sh

$ bundle install
You have one or more invalid gemspecs that need to be fixed.
The gemspec at /Users/brian/Code/github/briankung/ruffle/ruffle.gemspec is not valid. Please fix this
gemspec.
The validation error was 'metadata['homepage_uri'] has invalid link: "TODO: Put your gem's website or
public repo URL here."'

002.rb

# in ruffle.gemspec

Gem::Specification.new do |spec|
  # ...omitted

  spec.summary = "Write a short summary, because RubyGems requires one."
  spec.description = "Write a longer description or delete this line."
  spec.homepage = "https://example.com"

  # ...omitted

  spec.metadata["allowed_push_host"] = spec.homepage

  spec.metadata["homepage_uri"] = spec.homepage
  spec.metadata["source_code_uri"] = spec.homepage
  spec.metadata["changelog_uri"] = spec.homepage

  # ...omitted
end

003.sh

$ bundle
Fetching gem metadata from https://rubygems.org/...
Resolving dependencies...
# ...omitted
Fetching rspec 3.10.0
Installing rspec 3.10.0
Bundle complete! 3 Gemfile dependencies, 9 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.

004.sh

$ rake # defaults to rake spec

Ruffle
  has a version number
  does something useful (FAILED - 1)

Failures:

  1) Ruffle does something useful
     Failure/Error: expect(false).to eq(true)

       expected: true
            got: false

       (compared using ==)

       Diff:
       @@ -1 +1 @@
       -true
       +false

     # ./spec/ruffle_spec.rb:9:in `block (2 levels) in <top (required)>'
     # /Users/brian/Code/github/ianks/rubygems/bundler/spec/support/bundle.rb:8:in `load'
     # /Users/brian/Code/github/ianks/rubygems/bundler/spec/support/bundle.rb:8:in `<main>'

Finished in 0.00947 seconds (files took 0.07426 seconds to load)
2 examples, 1 failure

Failed examples:

rspec ./spec/ruffle_spec.rb:8 # Ruffle does something useful

005.rb

# in spec/ruffle_spec.rb

RSpec.describe Ruffle do
  it "has a #shuffle method" do
    expect(Ruffle).to respond_to(:shuffle)
  end
end

006.sh

Failures:

  1) Ruffle has a #shuffle method
     Failure/Error: expect(Ruffle).to respond_to(:shuffle)
       expected Ruffle to respond to :shuffle

007.sh

$ cargo init --lib
     Created library package

008.rb

# in Rakefile

require "bundler/gem_tasks"
require "rspec/core/rake_task"

RSpec::Core::RakeTask.new(:spec)

task default: :spec

009-2.rb

# in Rakefile, under `task default: :spec`

desc "Compile the ruffle crate"
task :compile do
  gemspec = File.expand_path('ruffle.gemspec')
  output = File.expand_path('ruffle.gem')

  `gem list -i "^ruffle$"`
  gem_installed = Process.last_status.success?

  system 'gem', 'uninstall', 'ruffle' if gem_installed
  system 'gem', 'build', gemspec, '--output', output
  system 'gem', 'install', output
end

# You can optionally have rake compile before every
# spec run by adding the :compile task as a
# prerequisite. This ended up being irritating while I
# got the Ruby parts working, so I've commented it out
# Rake::Task[:spec].prerequisites << :compile

010.sh

$ rake compile
ERROR:  While executing gem ... (NameError)
    uninitialized constant Gem::Ext::Builder::FileUtils
Did you mean?  FileTest
ERROR:  Error installing /Users/brian/Code/github/briankung/ruffle/ruffle.gem:
    ERROR: Failed to build gem native extension.

    No builder for extension 'Cargo.toml

// ...omitted

011-2.rb

# in Rakefile

desc "Compile the ruffle crate"
task :compile do
  system 'gem', '--version'
end

012.sh

$ rake compile
3.3.6
// ...omitted

013.sh

$ export RUBYGEMS_PATH=path/to/your/cargo-builder/rubygems

014-3.rb

# in Rakefile

desc "Compile the ruffle crate"
task :compile do
  cargo_builder_gem = [
    "ruby",
    "-I#{ENV["RUBYGEMS_PATH"]}/lib",
    "#{ENV["RUBYGEMS_PATH"]}/bin/gem"
  ]
  gemspec = File.expand_path('ruffle.gemspec')
  output = File.expand_path('ruffle.gem')

  `gem list -i "^ruffle$"`
  gem_installed = Process.last_status.success?

  system *cargo_builder_gem, 'uninstall', 'ruffle' if gem_installed
  system *cargo_builder_gem, 'build', gemspec, '--output', output
  system *cargo_builder_gem, 'install', output
end

015.sh

$ rake compile
true
Successfully uninstalled ruffle-0.1.0
  Successfully built RubyGem
  Name: ruffle
  Version: 0.1.0
  File: ruffle.gem
Successfully installed ruffle-0.1.0
1 gem installed

016.rb

# in ruffle.gemspec

Gem::Specification.new do |spec|
  # ...omitted
  spec.required_ruby_version = ">= 2.6.0"
  # 👇 Add this
  spec.extensions = ["Cargo.toml"]
  # ...
end

017.sh

error: the lock file /Users/brian/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/ruffle-0.1.0/Cargo.lock needs to be updated but --locked was passed to prevent this
If you want to try to generate the lock file without accessing the network, remove the --locked flag and use --offline instead.

018.rb

# in ruffle.gemspec

spec.files = Dir.chdir(File.expand_path(__dir__)) do
  `git ls-files -z`.split("\x0").reject do |f|
    (f == __FILE__) || f.match(%r{\A(?:(?:bin|test|spec|features)/|\.(?:git|travis|circleci)|appveyor)})
  end
end

019.rb

# in ruffle.gemspec

spec.files = ["Cargo.toml", "Cargo.lock", "src/lib.rs"]

020.sh

$ rake compile
    # ...omitted

   Compiling ruffle v0.1.0 (/Users/brian/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/ruffle-0.1.0)
    Finished release [optimized] target(s) in 0.47s

Dynamic library not found for Rust extension (in /Users/brian/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/extensions/x86_64-darwin-21/3.0.0/ruffle-0.1.0)

Make sure you set "crate-type" in Cargo.toml to "cdylib"

021.toml

# in Cargo.toml

[lib]
crate-type = ["cdylib"]

022.sh

$ rake compile
  Successfully built RubyGem
  Name: ruffle
  Version: 0.1.0
  File: ruffle.gem
Building native extensions. This could take a while...
Successfully installed ruffle-0.1.0
1 gem installed

023.toml

# in Cargo.toml

[dependencies]
rb-sys = { git = "https://github.com/ianks/rb-sys", tag = "v0.3.0" }

024.rs

// replace the contents of ruffle/src/lib.rs with the code below

use rb_sys::{
    rb_define_module, rb_define_module_function, rb_string_value_cstr, rb_utf8_str_new, VALUE,
};
use std::ffi::{CStr, CString};
use std::os::raw::{c_char, c_long};

#[inline]
unsafe fn cstr_to_string(str: *const c_char) -> String {
    CStr::from_ptr(str).to_string_lossy().into_owned()
}

#[no_mangle]
unsafe extern "C" fn pub_shuffle(_klass: VALUE, mut input: VALUE) -> VALUE {
    let ruby_string = cstr_to_string(rb_string_value_cstr(&mut input));
    let shuffled = ruby_string.chars().rev().collect::<String>();
    let shuffled_cstring = CString::new(shuffled).unwrap();
    let size = ruby_string.len() as c_long;

    rb_utf8_str_new(shuffled_cstring.as_ptr(), size)
}

#[allow(non_snake_case)]
#[no_mangle]
pub extern "C" fn Init_ruffle() {
    let name = CString::new("Ruffle").unwrap();
    let shuffle = CString::new("shuffle").unwrap();
    let callback = unsafe {
        std::mem::transmute::<
            unsafe extern "C" fn(VALUE, VALUE) -> VALUE,
            unsafe extern "C" fn() -> VALUE,
        >(pub_shuffle)
    };
    let klass = unsafe { rb_define_module(name.as_ptr()) };

    unsafe { rb_define_module_function(klass, shuffle.as_ptr(), Some(callback), 1) }
}

025.sh

$ rake compile spec

# ...omitted

Ruffle
  has a #shuffle method (FAILED - 1)

Failures:

  1) Ruffle has a #shuffle method
     Failure/Error: expect(Ruffle).to respond_to(:shuffle)
       expected Ruffle to respond to :shuffle
     # ./spec/ruffle_spec.rb:5:in `block (2 levels) in <top (required)>'

026.sh

$ rm lib/ruffle.rb

027.sh

$ rake spec

Ruffle
  has a #shuffle method

Finished in 0.00205 seconds (files took 0.09782 seconds to load)
1 example, 0 failures

028.rb

# in spec/ruffle_spec.rb

RSpec.describe Ruffle do
  # ...

  it "shuffles the characters in a string" do
    string = "Ruffle"
    expect(Ruffle.shuffle(string)).to_not eq(string)
    expect(Ruffle.shuffle(string)).to_not eq(string.reverse)
  end
end

029.sh

$ rake

Ruffle
  has a #shuffle method
  shuffles the characters in a string (FAILED - 1)

Failures:

  1) Ruffle shuffles the characters in a string
     Failure/Error: expect(Ruffle.shuffle(string)).to_not eq(string.reverse)

       expected: value != "elffuR"
            got: "elffuR"

030.rs

// in lib.rs

#[no_mangle]
unsafe extern "C" fn pub_shuffle(_klass: VALUE, mut input: VALUE) -> VALUE {
    let ruby_string = cstr_to_string(rb_string_value_cstr(&mut input));
    let shuffled = ruby_string.chars().rev().collect::<String>();
    let shuffled_cstring = CString::new(shuffled).unwrap();
    let size = ruby_string.len() as c_long;

    rb_utf8_str_new(shuffled_cstring.as_ptr(), size)
}

031.rs

// from https://stackoverflow.com/a/26035435/1042144

use rand::thread_rng;
use rand::seq::SliceRandom;

fn main() {
    let mut vec: Vec<u32> = (0..10).collect();
    vec.shuffle(&mut thread_rng());
    println!("{:?}", vec);
}

032.toml

# in Cargo.toml

[dependencies]
# ...
rand = "0.8.4"

033.rs

// in rust_ruby_example/src/lib.rs

let reversed = ruby_string.chars().rev().collect::<String>();
let reversed_cstring = CString::new(reversed).unwrap();

034.rs

mut input: VALUE

035.rs

rb_string_value_cstr(&mut input)

036.rs

cstr_to_string(rb_string_value_cstr(&mut input))

037.rs

let mut chars: Vec<char> = cstr_to_string(rb_string_value_cstr(&mut input))
    .chars()
    .collect();

038.rs

// at the top of lib.rs

use rand::seq::SliceRandom;
use rand::thread_rng;

039.rs

chars.shuffle(&mut thread_rng());

040.rs

// in lib.rs

#[no_mangle]
unsafe extern "C" fn pub_shuffle(_klass: VALUE, mut input: VALUE) -> VALUE {
    let mut chars: Vec<char> = cstr_to_string(rb_string_value_cstr(&mut input))
        .chars()
        .collect();
    chars.shuffle(&mut thread_rng());

    // ...we'll add more code here
}

041.rs

let shuffled: String = chars.iter().collect();
let size = shuffled.len() as c_long;

042.rs

let shuffled_cstring = CString::new(shuffled).unwrap();

043.rs

rb_utf8_str_new(shuffled_cstring.as_ptr(), size)

044.rs

// in lib.rs

#[no_mangle]
unsafe extern "C" fn pub_shuffle(_klass: VALUE, mut input: VALUE) -> VALUE {
    let mut chars: Vec<char> = cstr_to_string(rb_string_value_cstr(&mut input))
        .chars()
        .collect();
    chars.shuffle(&mut thread_rng());

    let shuffled: String = chars.iter().collect();
    let size = shuffled.len() as c_long;

    let shuffled_cstring = CString::new(shuffled).unwrap();

    rb_utf8_str_new(shuffled_cstring.as_ptr(), size)
}

045.rs

// in lib.rs (at the end)

#[allow(non_snake_case)]
#[no_mangle]
pub extern "C" fn Init_ruffle() {
    let name = CString::new("Ruffle").unwrap();
    let shuffle = CString::new("shuffle").unwrap();
    let callback = unsafe {
        std::mem::transmute::<
            unsafe extern "C" fn(VALUE, VALUE) -> VALUE,
            unsafe extern "C" fn() -> VALUE,
        >(pub_shuffle)
    };
    let klass = unsafe { rb_define_module(name.as_ptr()) };

    unsafe { rb_define_module_function(klass, shuffle.as_ptr(), Some(callback), 1) }
}

046.sh

$ rake compile spec
true
Successfully uninstalled ruffle-0.1.0
  Successfully built RubyGem
  Name: ruffle
  Version: 0.1.0
  File: ruffle.gem
Building native extensions. This could take a while...
Successfully installed ruffle-0.1.0
1 gem installed

Ruffle
  has a #shuffle method
  shuffles the characters in a string

Finished in 0.00249 seconds (files took 0.15933 seconds to load)
2 examples, 0 failures

copy-github-gist-link-on-click.js

document.querySelectorAll('a.wb-break-all').forEach(el => {
  el.addEventListener("click", async () => {
    await new Promise(r => setTimeout(r, 500));
		navigator.clipboard.writeText(window.location)
	});
})

output-all-wp-code-blocks.js

[...document.querySelectorAll('.wp-block-code')].map(el => {
	console.log(el.innerText);
	console.log("~~~~~~~~~~");
})

splitter.rb

files = ARGF.read.split("~~~~~~~~~~").map(&:strip)

files.each_with_index do |file, index|
  ext = case file[0]
  when '/' then 'rs'
  when '$' then 'sh'
  when '#' then 'rb'
  else 'txt'
  end

  File.write("%03d.#{ext}" % index, file.strip)
end

workflow.md

Right now the workflow for converting a wordpress blog post that has already had simple code embed blocks is:

1. Create a new github gist with a temporary file in it
2. Clone the gist using ssh: https://docs.github.com/en/get-started/writing-on-github/editing-and-sharing-content-with-gists/forking-and-cloning-gists
3. Load the blog post in question
4. Run the contents of output-all-wp-code-blocks.js in the browser console
5. Copy the console output (right click and select "Export visible messages to > clipboard")
6. cd into your github gist repository
7. Run this in terminal session pbpaste | ruby splitter.rb to generate files from the clipboard
8. delete the temporary file
9. Manually edit the files to make sure the file extensions are correct / review in general
10. commit and push to the gist
11. View the gist in the browser
12. Run the contents of copy-github-gist-link-on-click.js
13. Click the anchor links of each code snippet to copy the url
14. Paste the URL into the blog post above each code snippet to create a github gist embed
15. Review and confirm each gist corresponds to the wp code block
16. Delete the wp code blocks

...whew! Wtf that's what I did? Sigh