MultiFunction.cpp

#include <vector.h>


#include "MultiFunction.h"
#include "Sym.h"
#include "FunDef.h"

using namespace std;


typedef vector<double>::const_iterator data_ptr;
typedef vector<data_ptr> data_ptrs;
typedef data_ptrs::const_iterator arg_ptr;

#include "MultiFuncs.cpp"

typedef double (*fptr)( arg_ptr );

string print_function( fptr f) {
    if (f == multi_function::plus) return "+";
    if (f == multi_function::mult) return "*";
    if (f == multi_function::min) return "-";
    if (f == multi_function::inv) return "/";
    if (f == multi_function::exp) return "e";
    return "unknown";
}


struct Function {
    
    fptr function;
    arg_ptr args;

    double operator()() const { return function(args); }
};

static vector<Function> token_2_function;

Sym make_binary(Sym sym) {
    if (sym.args().size() == 2) return sym;
    SymVec args = sym.args();
    Sym an = args.back();
    args.pop_back();
    Sym nw = make_binary( Sym( sym.token(), args) );
    args.resize(2);
    args[0] = nw;
    args[1] = an;
    return Sym(sym.token(), args); 
}

class Compiler {
    
    public:

    enum func_type {constant, variable, function};
    
    typedef pair<func_type, unsigned> entry;

#if USE_TR1
            typedef std::tr1::unordered_map<Sym, entry, HashSym> HashMap;
#else
            typedef hash_map<Sym, entry, HashSym> HashMap;
#endif      
   
    HashMap map;
   
    vector<double> constants;
    vector<unsigned> variables;
    vector< fptr > functions;
    vector< vector<entry> > function_args;
    
    unsigned total_args;
    
    vector<entry> outputs;
   
    Compiler() : total_args(0) {}
    
    entry do_add(Sym sym) {

        HashMap::iterator it = map.find(sym);

        if (it == map.end()) { // new entry
            
            token_t token = sym.token();

            if (is_constant(token)) {
                constants.push_back( get_constant_value(token) ); // set value
                entry e = make_pair(constant, constants.size()-1);
                map.insert( make_pair(sym, e) );
                return e;
                
            } else if (is_variable(token)) {
                unsigned idx = get_variable_index(token);
                variables.push_back(idx);
                entry e = make_pair(variable, variables.size()-1);
                map.insert( make_pair(sym, e) );
                return e;
            } // else 
                
            fptr f;
            vector<entry> vec;
            const SymVec& args = sym.args();
            
            switch (token) {
                case sum_token:
                    {
                        if (args.size() == 0) {
                            return do_add( SymConst(0.0));
                        }
                        if (args.size() == 1) {
                            return do_add(args[0]);
                        }
                        if (args.size() == 2) {
                            vec.push_back(do_add(args[0]));
                            vec.push_back(do_add(args[1]));
                            f = multi_function::plus;
                            //cout << "Adding + " << vec[0].second << ' ' << vec[1].second << endl;
                            break;

                        } else {
                            return do_add( make_binary(sym) );
                        }
                        
                    }
                case prod_token:
                    {
                        if (args.size() == 0) {
                            return do_add( SymConst(1.0));
                        }
                        if (args.size() == 1) {
                            return do_add(args[0]);
                        }
                        if (args.size() == 2) {
                            vec.push_back(do_add(args[0]));
                            vec.push_back(do_add(args[1]));
                            f = multi_function::mult;
                            //cout << "Adding * " << vec[0].second << ' ' << vec[1].second << endl;
                            break;
                            

                        } else {
                            return do_add( make_binary(sym) );
                        }
                    }
                case sqr_token: 
                    {
                        SymVec newargs(2);
                        newargs[0] = args[0];
                        newargs[1] = args[0];
                       return do_add( Sym(prod_token, newargs)); 
                    }
                default :
                    {
                        if (args.size() != 1) {
                            cerr << "Unknown function " << sym << " encountered" << endl;
                            exit(1);
                        }
                        
                        vec.push_back(do_add(args[0]));

                        switch (token) {
                            case min_token: f = multi_function::min; break;
                            case inv_token: f = multi_function::inv; break;
                            case exp_token :f = multi_function::exp; break;
                            default :
                                {
                                    cerr << "Unimplemented token encountered " << sym << endl;
                                    exit(1);
                                }
                        }
                        
                        //cout << "Adding " << print_function(f) << ' ' << vec[0].second << endl;
                        
                        
                    }

            }
            
            total_args += vec.size();
            function_args.push_back(vec);
            functions.push_back(f);
            
            entry e = make_pair(function, functions.size()-1);
            map.insert( make_pair(sym, e) );
            return e;
            
        }
        
        return it->second; // entry
    }
   
    void add(Sym sym) {
        entry e = do_add(sym);
        outputs.push_back(e);
    }
    
};

class MultiFunctionImpl {
    public:
        
    // input mapping
    vector<unsigned> input_idx;
    
    unsigned constant_offset;
    unsigned var_offset;

    // evaluation
    vector<double> data;
    vector<Function> funcs;
    data_ptrs args;     
    
    vector<unsigned> output_idx;
    
    MultiFunctionImpl() {}

    void clear() {
        input_idx.clear();
        data.clear();
        funcs.clear();
        args.clear();
        output_idx.clear();
        constant_offset = 0;
    }
    
    void eval(const double* x, double* y) {
        unsigned i;
        // evaluate variables
        for (i = constant_offset; i < constant_offset + input_idx.size(); ++i) {
            data[i] = x[input_idx[i-constant_offset]];
        }

        for(; i < data.size(); ++i) {
            data[i] = funcs[i-var_offset]();
            //cout << i << " " << data[i] << endl;
        }

        for (i = 0; i < output_idx.size(); ++i) {
            y[i] = data[output_idx[i]];
        }
    }

    void eval(const vector<double>& x, vector<double>& y) {
        eval(&x[0], &y[0]);
    }
    
    void setup(const vector<Sym>& pop) {
        
        clear(); 
        Compiler compiler;
        
        for (unsigned i = 0; i < pop.size(); ++i) {
            Sym sym = (expand_all(pop[i]));
            compiler.add(sym);
        }
        
        // compiler is setup so get the data
        constant_offset = compiler.constants.size();
        var_offset = constant_offset + compiler.variables.size();
        int n = var_offset + compiler.functions.size();

        data.resize(n);
        funcs.resize(compiler.functions.size());
        args.resize(compiler.total_args);
        
        // constants
        for (unsigned i = 0; i < constant_offset; ++i) {
            data[i] = compiler.constants[i];
            //cout << i << ' ' << data[i] << endl;
        }
        
        // variables
        input_idx = compiler.variables;

        //for (unsigned i = constant_offset; i < var_offset; ++i) {
            //cout << i << " x" << input_idx[i-constant_offset] << endl;
        //}
        
        // functions
        unsigned which_arg = 0;
        for (unsigned i = 0; i < funcs.size(); ++i) {
            
            Function f;
            f.function = compiler.functions[i];
            
            //cout << i+var_offset << ' ' << print_function(f.function);
                
            // interpret args
            for (unsigned j = 0; j < compiler.function_args[i].size(); ++j) {
                
                Compiler::entry e = compiler.function_args[i][j];
                
                unsigned idx = e.second;
                
                switch (e.first) {
                    case Compiler::function: idx += compiler.variables.size();
                    case Compiler::variable: idx += compiler.constants.size();
                    case Compiler::constant: {}
                }

                args[which_arg + j] = data.begin() + idx;
                //cout << ' ' << idx << "(" << e.second << ")";
            }
            
            //cout << endl;

            f.args = args.begin() + which_arg;
            which_arg += compiler.function_args[i].size();
            funcs[i] = f;    
        }

        // output indices
        output_idx.resize(compiler.outputs.size());
        for (unsigned i = 0; i < output_idx.size(); ++i) {
            output_idx[i] = compiler.outputs[i].second;
            switch(compiler.outputs[i].first) {
                    case Compiler::function: output_idx[i] += compiler.variables.size();
                    case Compiler::variable: output_idx[i] += compiler.constants.size();
                    case Compiler::constant: {}
            }
            //cout << "out " << output_idx[i] << endl;
        }
    }
    
};  



MultiFunction::MultiFunction(const std::vector<Sym>& pop) : pimpl(new MultiFunctionImpl) {
    pimpl->setup(pop);
}

MultiFunction::~MultiFunction() { delete pimpl; }

void MultiFunction::operator()(const std::vector<double>& x, std::vector<double>& y) {
    pimpl->eval(x,y);
}

void MultiFunction::operator()(const double* x, double* y) {
    pimpl->eval(x,y);
}

---