gparticle_options.cc

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// gparticle
#include "gparticle_options.h"
#include "gparticleConventions.h"
 
// namespace to define options
namespace gparticle {
using std::string;
using std::vector;
 
// Build a vector of configured Gparticle instances from the structured "gparticle" option node.
// The detailed API contract is documented in gparticle_options.h.
vector<GparticlePtr> getGParticles(const std::shared_ptr<GOptions>& gopts, std::shared_ptr<GLogger>& logger) {
    // Retrieve the structured option node that contains an array of particle definitions.
    auto gparticle_node = gopts->getOptionNode("gparticle");
 
    vector<GparticlePtr> gparticles;
    // Reserve storage up-front to avoid reallocations (and therefore avoid extra shared_ptr moves).
    gparticles.reserve(gparticle_node.size()); // no reallocations ⇒ no moves
 
    // Translate each structured node item into a configured Gparticle instance.
    for (auto gparticle_item : gparticle_node) {
        // Each get_variable_in_option<T>(...) call:
        // - extracts the key from this structured item
        // - applies the provided default if the key is missing
        // - keeps the typing explicit (string/int/double)
        gparticles.emplace_back(std::make_shared<Gparticle>(
            gopts->get_variable_in_option<string>(gparticle_item, "name", goptions::NODFLT),
            gopts->get_variable_in_option<int>(gparticle_item, "multiplicity", 1),
            gopts->get_variable_in_option<double>(gparticle_item, "p", GPARTICLENOTDEFINED),
            gopts->get_variable_in_option<double>(gparticle_item, "delta_p", 0),
            gopts->get_variable_in_option<string>(gparticle_item, "punit", "MeV"),
            gopts->get_variable_in_option<string>(gparticle_item, "randomMomentumModel", "uniform"),
 
            gopts->get_variable_in_option<double>(gparticle_item, "theta", 0),
            gopts->get_variable_in_option<double>(gparticle_item, "delta_theta", 0),
            gopts->get_variable_in_option<string>(gparticle_item, "randomThetaModel", "uniform"),
            gopts->get_variable_in_option<double>(gparticle_item, "phi", 0),
            gopts->get_variable_in_option<double>(gparticle_item, "delta_phi", 0),
            gopts->get_variable_in_option<string>(gparticle_item, "aunit", "deg"),
 
            gopts->get_variable_in_option<double>(gparticle_item, "vx", 0),
            gopts->get_variable_in_option<double>(gparticle_item, "vy", 0),
            gopts->get_variable_in_option<double>(gparticle_item, "vz", 0),
 
            gopts->get_variable_in_option<double>(gparticle_item, "delta_vx", 0),
            gopts->get_variable_in_option<double>(gparticle_item, "delta_vy", 0),
            gopts->get_variable_in_option<double>(gparticle_item, "delta_vz", 0),
            gopts->get_variable_in_option<string>(gparticle_item, "vunit", "cm"),
 
            gopts->get_variable_in_option<string>(gparticle_item, "randomVertexModel", "uniform"),
            logger
        ));
    }
 
    return gparticles;
}
 
 
// Define the gparticle option schema and its human-readable help text.
// The detailed API contract is documented in gparticle_options.h.
GOptions defineOptions() {
    GOptions goptions(GPARTICLE_LOGGER);
 
    string help = "Adds a particle to the event generator \n ";
    help        += "The particle is generated with a fixed or randomized momentum, angles, and vertex.  \n \n";
    help        += "Examples: \n";
    help        += "• 5 GeV electron along z: \n";
    help        += "-gparticle=\"[{pname: e-, p: 5000}]\" \n \n";
    help        += "• three particles, one electron and two protons, identical except spread in theta: \n \n";
    help        +=
        "-gparticle=\"[{name: e-, p: 2300, theta: 23.0}, {name: proton, multiplicity: 2, p: 1200, theta: 14.0, delta_theta: 10}]\"\n";
 
    // The variable definitions below determine:
    // - key name as it appears in the structured option item
    // - default value (or "no default" marker)
    // - user-facing description used by help/usage output
    vector<GVariable> gparticle_v = {
        {"name", goptions::NODFLT, "Particle name (mandatory),  for example \"proton\""},
        {"multiplicity", 1, "How many copies of this particle will be generated in each event"},
        {"p", goptions::NODFLT, "Particle momentum"},
        {"delta_p", 0, "Particle momentum range, centered on p."},
        {"punit", "MeV", "Geant4 Unit for the particle momentum. "},
        {"randomMomentumModel", "uniform", "Momentum randomization. 'gaussian' (use deltas as sigmas)"},
        {"theta", 0, "Particle polar angle. "},
        {"delta_theta", 0, "Particle polar angle range, centered on theta. "},
        {
            "randomThetaModel", "uniform",
            "Distribute cos(theta) or theta. 'cosine': cos(theta) is uniform. 'uniform': theta is uniform"
        },
        {"phi", 0, "Particle azimuthal angle. "},
        {"delta_phi", 0, "Particle azimuthal angle range, centered on phi. "},
        {"aunit", "deg", "Geant4 unit for the particle angles.  "},
        {"vx", 0, "Particle vertex x component. "},
        {"vy", 0, "Particle vertex y component. "},
        {"vz", 0, "Particle vertex z component. "},
        {"delta_vx", 0, "Particle vertex range of the x component. "},
        {"delta_vy", 0, "Particle vertex range of the y component. "},
        {"delta_vz", 0, "Particle vertex range of the z component. "},
        {"vunit", "cm", "Unit for the particle vertex. "},
        {
            "randomVertexModel", "uniform",
            "Vertex randomization. Default: 'uniform'. Alternative: 'gaussian' (use deltas as sigmas), 'sphere'"
        }
    };
 
    goptions.defineOption("gparticle", "define the generator particle(s)", gparticle_v, help);
 
    return goptions;
}
} // namespace gparticle