From c772eefd2dcedca88b4d735397e1633ffae78883 Mon Sep 17 00:00:00 2001
From: Charles Oliver Nutter <headius@headius.com>
Date: Wed, 8 Feb 2023 21:01:46 +0100
Subject: [PATCH] Stub out extension build on JRuby

JRuby currently ships its own internal bigdecimal extension as
part of the core libraries. In order for users to be able to add
bigdecimal to their Gemfile or gem dependencies, we need to stub
out the C extension and just load the extension shipped with
JRuby.

In the future we will try to move our BigDecimal implementation
into the gem, but for now this is the simplest way to make it
installable on JRuby.

See #169
---
 Gemfile            |  2 +-
 Rakefile           |  7 ++++++-
 bigdecimal.gemspec | 24 +++++++++++++++---------
 lib/bigdecimal.rb  |  6 +++++-
 4 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/Gemfile b/Gemfile
index 06413ee9..288db6ec 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gemspec
 
 gem "benchmark_driver"
-gem "fiddle"
+gem "fiddle", platform: :ruby
 gem "rake", ">= 12.3.3"
 gem "rake-compiler", ">= 0.9"
 gem "minitest", "< 5.0.0"
diff --git a/Rakefile b/Rakefile
index 8fd7c14b..706b7fa9 100644
--- a/Rakefile
+++ b/Rakefile
@@ -6,7 +6,12 @@ require "rake/extensiontask"
 require "rake/testtask"
 
 spec = eval(File.read('bigdecimal.gemspec'))
-Rake::ExtensionTask.new('bigdecimal', spec)
+if RUBY_ENGINE == 'jruby'
+  # JRuby's extension is included with JRuby currently
+  task :compile do; end
+else
+  Rake::ExtensionTask.new('bigdecimal', spec)
+end
 
 Rake::TestTask.new do |t|
   t.libs << 'test/lib'
diff --git a/bigdecimal.gemspec b/bigdecimal.gemspec
index d2157571..e4ab290b 100644
--- a/bigdecimal.gemspec
+++ b/bigdecimal.gemspec
@@ -12,17 +12,8 @@ Gem::Specification.new do |s|
   s.licenses       = ["Ruby", "bsd-2-clause"]
 
   s.require_paths = %w[lib]
-  s.extensions    = %w[ext/bigdecimal/extconf.rb]
   s.files         = %w[
     bigdecimal.gemspec
-    ext/bigdecimal/bigdecimal.c
-    ext/bigdecimal/bigdecimal.h
-    ext/bigdecimal/bits.h
-    ext/bigdecimal/feature.h
-    ext/bigdecimal/missing.c
-    ext/bigdecimal/missing.h
-    ext/bigdecimal/missing/dtoa.c
-    ext/bigdecimal/static_assert.h
     lib/bigdecimal.rb
     lib/bigdecimal/jacobian.rb
     lib/bigdecimal/ludcmp.rb
@@ -33,6 +24,21 @@ Gem::Specification.new do |s|
     sample/nlsolve.rb
     sample/pi.rb
   ]
+  if Gem::Platform === s.platform and s.platform =~ 'java' or RUBY_ENGINE == 'jruby'
+    s.platform      = 'java'
+  else
+    s.extensions    = %w[ext/bigdecimal/extconf.rb]
+    s.files.append %w[
+      ext/bigdecimal/bigdecimal.c
+      ext/bigdecimal/bigdecimal.h
+      ext/bigdecimal/bits.h
+      ext/bigdecimal/feature.h
+      ext/bigdecimal/missing.c
+      ext/bigdecimal/missing.h
+      ext/bigdecimal/missing/dtoa.c
+      ext/bigdecimal/static_assert.h
+    ]
+  end
 
   s.required_ruby_version = Gem::Requirement.new(">= 2.5.0")
 end
diff --git a/lib/bigdecimal.rb b/lib/bigdecimal.rb
index 8fd2587c..82b3e1b7 100644
--- a/lib/bigdecimal.rb
+++ b/lib/bigdecimal.rb
@@ -1 +1,5 @@
-require 'bigdecimal.so'
+if RUBY_ENGINE == 'jruby'
+  JRuby::Util.load_ext("org.jruby.ext.bigdecimal.BigDecimalLibrary")
+else
+  require 'bigdecimal.so'
+end