Crystal-to-C++ transpiler
HEAD Latest release released
29 1
Stepan Melnikov


Build status

Crystal-to-C++ transpiler [WIP]

Generated code can be compiled with c++14 compiler (tested with g++ 6.2.0)

List of supported AST nodes can be found here

You can try it here

CLI Usage

  1. Compile src/cppize/transpiler.cr (it may take some time as it requires Crystal parser)
  2. Launch compiled executable with -h flag to view all command line flags

Implemented -fFEATUREs

Flag | Description ------|--------------- -funsafe-cast | Tells transpiler to transpile casts to C-style casts instead of static_casts -fprimitive-types | Tells transpiler to use fundamental C++ types when possible -fauto-module-type| Allows transpiler to detect if module is included
:warning: This option can slow down transpilation -fimplicit-static | Enables static module methods' calls

Library Usage

# Initialize transpiler
transpiler = Cppize::Transpiler.new

# Set error and warning callbacks
transpiler.on_warning{|e| puts e.to_s}
transpiler.on_error{|e| puts e.to_s; exit 1}

# Transpile file
transpiled_code = transpiler.parse_and_transpile_file("./file.cpp.cr")
# Transpile code from IO
transpiled_code = transpiler.parse_and_transpile_file(File.open("./file.cpp.cr"),"./file.cpp.cr")
# Transpile code from string
transpiled_code = transpiler.parse_and_transpile_file("def foo; bar(true) end","<test>")

Things to improve in already supported AST nodes

  1. Improve automatic return
  2. Improve module type detection (namespace / includable)


Implementing nodes

See src/cppize/nodes/expressions.cr for example

Adding transpile-time macros

See src/cppize/macros/__cpp__.cr for example


  1. Fork it ( https://github.com/unn4m3d/cppize/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request


  • unn4m3d unn4m3d - creator, maintainer
  github: unn4m3d/cppize
License MIT
Crystal none


Dependencies 0

Development Dependencies 0

Dependents 0

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