codac2_sympy_bridge.h

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#pragma once
 
#include <functional>
#include <pybind11/embed.h>
 
#include "codac2_sympy.h"
#include "codac2_analytic_flat_input_layout.h"
 
namespace codac2::symbolic::detail
{
  class FlatSymbolTable
  {
    public:

      explicit FlatSymbolTable(const FunctionArgsList& args);

      pybind11::object by_flat_index(Index k) const;

      ScalarExpr codac_expr_by_name(const std::string& name) const;

      Index size() const;

      pybind11::object for_scalar_var(const ScalarVar& x) const;

      pybind11::object for_vector_component(const VectorVar& x, Index i) const;

      pybind11::object for_matrix_component(const MatrixVar& x, Index i, Index j) const;
 
    private:

      static std::string make_symbol_name(Index flat_index);

      const FlatInputBinding& binding_of(const ExprID& id) const;
 
      FlatInputLayout _layout; 
      std::vector<std::string> _names; 
      std::unordered_map<std::string,ScalarExpr> _codac_scalars; 
  };

  class SympyExporter
  {
    public:

      explicit SympyExporter(const FlatSymbolTable& symbols);

      pybind11::object export_scalar(const ScalarExpr& e) const;
 
    private:
 
      pybind11::object export_node(const std::shared_ptr<ExprBase>& e) const;
      pybind11::object export_vector_component(const std::shared_ptr<ExprBase>& e, Index i) const;
      pybind11::object export_matrix_component(const std::shared_ptr<ExprBase>& e, Index i, Index j) const;
      static double scalar_const_value(const ConstValueExpr<ScalarType>& c);
      static std::shared_ptr<ExprBase> child_at(const std::vector<std::shared_ptr<ExprBase>>& children, Index i);
 
      const FlatSymbolTable& _symbols; 
  };

  class SympyImporter
  {
    public:

      explicit SympyImporter(const FlatSymbolTable& symbols);

      ScalarExpr import_scalar(const pybind11::handle& obj) const;
 
    private:
 
      ScalarExpr import_add(const pybind11::handle& obj) const;
      ScalarExpr import_mul(const pybind11::handle& obj) const;
      ScalarExpr import_pow(const pybind11::handle& obj) const;
      ScalarExpr import_function(const pybind11::handle& obj) const;
 
      const FlatSymbolTable& _symbols; 
  };

  using SympyTransform = std::function<pybind11::object(
    const pybind11::object&, const pybind11::object&, const FlatSymbolTable&)>;

  class ScalarBridgeContext
  {
    public:

      explicit ScalarBridgeContext(const FunctionArgsList& args);

      const pybind11::object& sympy() const;

      const FlatSymbolTable& symbols() const;

      pybind11::object export_scalar(const ScalarExpr& y) const;

      ScalarExpr import_scalar(const pybind11::handle& obj) const;

      ScalarExpr transform_scalar_expr(const ScalarExpr& y, const SympyTransform& transform, bool do_expand = true) const;
 
    private:
      
      FlatSymbolTable _symbols; 
      SympyExporter _exporter;  
      SympyImporter _importer;  
  };

  void ensure_python_runtime();

  const pybind11::object& import_module(const char* module_name);

  const pybind11::object& import_sympy();

  const pybind11::object& import_polyfuncs();

  const pybind11::object& import_builtins();

  pybind11::object normalize_sympy_expr(const pybind11::object& sympy, pybind11::object expr, bool do_expand = true);

  ScalarExpr transform_scalar_expr(
    const FunctionArgsList& args,
    const ScalarExpr& y,
    const SympyTransform& transform,
    bool do_expand = true);
}