Add Julia/C++ bindings for MUSICA

[sjsprecious]

This PR is purely done by Claude, which follows the wrapper code under the python and javascript folders to add the Julia and C++ bindings for necessary MUSICA code.

I tested it with Julia/1.11 and all the tests passed.

[github-actions]

📄 Documentation for this branch is available at: https://ncar.github.io/musica/branch/add_julia_cxx_bindings/

[Copilot]

Pull request overview

This PR adds comprehensive Julia bindings for the MUSICA chemical kinetics library (MICM). It wraps the existing C++ API using CxxWrap, following the patterns established by the Python and JavaScript bindings.

Changes:

• Added C++/CxxWrap binding layer (musica_julia.cpp) exposing MICM solver creation, state management, conditions, solver parameters, and solve functionality to Julia
• Added Julia-side wrapper types and functions (Musica.jl + micm/*.jl) providing a high-level Julia API with proper types, enums, and idiomatic Julia conventions
• Fixed a CMake bug where POSITION_INDEPENDENT_CODE was set on the wrong target (musica → musica_julia), and restructured Musica_jll as an optional dependency

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
julia/CMakeLists.txt	Bugfix: set PIC on musica_julia instead of musica
julia/Project.toml	Move Musica_jll from deps to extras; remove compat entry
julia/bindings/musica_julia.cpp	C++ binding layer exposing MICM types and functions via CxxWrap
julia/src/Musica.jl	Main module: library loading, includes, and exports
julia/src/micm/constants.jl	Physical constants (Avogadro, Boltzmann, gas constant)
julia/src/micm/solver.jl	SolverType enum
julia/src/micm/solver_result.jl	SolverState enum, SolverStats, SolverResult types
julia/src/micm/conditions.jl	Conditions struct with ideal gas law computation
julia/src/micm/solver_parameters.jl	Rosenbrock and BackwardEuler parameter types with C++ conversion
julia/src/micm/utils.jl	flat_index helper for vector-ordered memory layout
julia/src/micm/state.jl	State type with concentration/condition/rate parameter management
julia/src/micm/micm.jl	MICM wrapper with create_state, solve!, parameter management
julia/test/runtests.jl	Comprehensive tests covering all new functionality

Comments suppressed due to low confidence (1)

julia/Project.toml:14

• Musica_jll was moved from [deps] to [extras], but it's not listed in the [targets] test list either. This means it won't be available as a dependency in any context — neither at runtime nor during tests. The @eval using Musica_jll in Musica.jl will always fail (caught by try/catch), so the package will only work when MUSICA_JULIA_LIB is set.

If this is intentional (e.g., the JLL hasn't been updated yet), consider adding a code comment explaining why. Otherwise, either keep Musica_jll in [deps] or add it to the test targets: test = ["Test", "Musica_jll"].

[extras]
Musica_jll = "f5e5459d-1a87-5129-97d9-bab22ca84fbb"
Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"

[targets]
test = ["Test"]

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[Copilot]

Pull request overview

This PR adds comprehensive Julia bindings for the MUSICA chemical kinetics library (MICM solver), following the patterns established in the existing Python and JavaScript wrappers. It provides a full Julia API including solver creation, state management, condition setting, and solving, all backed by CxxWrap-based C++ bindings.

Changes:

• Added C++ binding layer (musica_julia.cpp) exposing MICM solver, state, conditions, and solver parameters to Julia via CxxWrap
• Added Julia module files implementing high-level wrappers for MICM including MICM, State, Conditions, solver parameter types, enums, and utility functions
• Updated build infrastructure (CMakeLists, Dockerfile, CI workflow, Project.toml) to support the new bindings with proper library discovery and linking

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
julia/bindings/musica_julia.cpp	C++ binding layer exposing MICM types and functions to Julia via CxxWrap
julia/src/Musica.jl	Main module restructured to load CxxWrap bindings and export new types/functions
julia/src/micm/micm.jl	High-level MICM solver wrapper struct and methods
julia/src/micm/state.jl	State management including concentrations, conditions, and rate parameters
julia/src/micm/solver.jl	SolverType enum definition
julia/src/micm/solver_result.jl	SolverState enum, SolverStats, and SolverResult types
julia/src/micm/solver_parameters.jl	Rosenbrock and BackwardEuler solver parameter types with C++ conversion
julia/src/micm/conditions.jl	Conditions struct with ideal gas law auto-calculation
julia/src/micm/constants.jl	Physical constants (Avogadro, Boltzmann, gas constant)
julia/src/micm/utils.jl	Vector-ordering index calculation utility
julia/test/runtests.jl	Comprehensive tests covering all new functionality
julia/CMakeLists.txt	Fixed PIC target name and added STL library link
julia/Project.toml	Moved Musica_jll to extras, removed compat entry
docker/Dockerfile.julia	Updated build to discover CxxWrap prefix and set library path
.github/workflows/julia.yml	Added CxxWrap prefix discovery, library path setup, and PIC flag

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