ProductHolderIndexHelper.h

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#ifndef DataFormats_Provenance_ProductHolderIndexHelper_h
#define DataFormats_Provenance_ProductHolderIndexHelper_h

#include "FWCore/Utilities/interface/ProductHolderIndex.h"
#include "FWCore/Utilities/interface/ProductKindOfType.h"
#include "FWCore/Utilities/interface/TypeID.h"
#include "FWCore/Utilities/interface/propagate_const.h"

#include <iosfwd>
#include <memory>
#include <set>
#include <string>
#include <vector>

namespace edm {

  namespace productholderindexhelper {
    // The next function supports views. For the given wrapped type,
    // which must be Wrapper<T>,
    // this function returns the type of the contained type of T.
    // If the type is not a recongnized container, it returns
    // a TypeID(typeid(void)).
    TypeID getContainedTypeFromWrapper(TypeID const& wrappedtypeID, std::string const& className);

    // The next function supports views. For the given type T,
    // this function returns the type of the contained type of T.
    // If the type is not a recongnized container, it returns
    // a TypeID(typeid(void)).
    // This calls getContainedTypefromWrapped internally
    // If the TypeID for the wrapped type is already available,
    // it is faster to call getContainedTypeFromWrapper directly.
    TypeID getContainedType(TypeID const& typeID);
  }

  class ProductHolderIndexHelper {
  public:

    ProductHolderIndexHelper();

    // The accessors below return a ProductHolderIndex that matches 
    // the arguments or a set of matching indexes using the Matches
    // class. A returned index can have a value that indicates that it
    // is invalid or ambiguous and the client should check for these
    // values before using the index (see ProductIndexHolder.h).

    // If no matches are found or the ProductHolderIndexHelper
    // has not been frozen yet, then an invalid index or a Matches
    // object with numberOfMatches equal to 0 will be returned.

    // The ambiguous values can occur when the kind of type is ELEMENT_TYPE
    // type. ELEMENT_TYPE is the type or base type of an object
    // stored in a container that is the product. These types are used
    // with data requests that use Views. For PRODUCT_TYPE types, ambiguity
    // is not possible.

    // The next function returns the index for the one group that
    // matches the type, module label, instance, and process.
    // The 3 pointer arguments must point to C style strings terminated
    // by a '\0' with the one following possible exception. If the
    // process pointer is null or the process string empty, then
    // this returns the index of the special ProductHolder that
    // knows how to search for the product matching the type, module
    // label, and instance and which is from the most recent process.
    ProductHolderIndex index(KindOfType kindOfType,
                             TypeID const& typeID,
                             char const* moduleLabel,
                             char const* instance,
                             char const* process = 0) const;

    class Matches {
    public:
      Matches(ProductHolderIndexHelper const* productHolderIndexHelper,
              unsigned int startInIndexAndNames,
              unsigned int numberOfMatches);

      ProductHolderIndex index(unsigned int i) const;
      unsigned int numberOfMatches() const { return numberOfMatches_; }
      bool isFullyResolved(unsigned int i) const;
      char const* moduleLabel(unsigned int i) const;
      char const* processName(unsigned int i) const;
    private:
      ProductHolderIndexHelper const* productHolderIndexHelper_;
      unsigned int startInIndexAndNames_;
      unsigned int numberOfMatches_;
    };

    // Return ProductHolderIndex's for all product holders that
    // match the type, module label, and product instance name.
    // The pointer arguments must be C style strings terminated
    // by a '\0'.
    Matches
    relatedIndexes(KindOfType kindOfType,
                   TypeID const& typeID,
                   char const* moduleLabel,
                   char const* instance) const;

    // Return indexes for all groups that match the type.
    Matches
    relatedIndexes(KindOfType kindOfType,
                   TypeID const& typeID) const;

    // This will throw if called after the object is frozen.
    // The typeID must be for a type with a dictionary
    // (the calling function is expected to check that)
    // The pointer arguments must point at C style strings
    // terminated by '\0'.
    // 1. This creates an entry and new ProductHolderIndex for
    // the product if it does not already exist. If it
    // does exist then it throws.
    // 2. If it does not already exist, this will create an
    // entry and new ProductHolderIndex for the ProductHolder
    // that will search for the matching type, label, and
    // instance for the most recent process (internally indicated
    // by an empty process string).
    // This will then loop over the contained class (if it exists)
    // and the base classes of the contained class.
    // 1. If the matching type, label, instance, and process
    // already exist then that entry is modified and marked
    // ambiguous. If not, it inserts an entry which uses the same
    // ProductHolderIndex as the containing product.
    // 2. If it does not already exist it inserts a new
    // entry with a new ProductHolderIndex for the case
    // which searches for the most recent process.
    ProductHolderIndex
    insert(TypeID const& typeID,
           char const* moduleLabel,
           char const* instance,
           char const* process,
           TypeID const& containedTypeID);

    ProductHolderIndex
    insert(TypeID const& typeID,
           char const* moduleLabel,
           char const* instance,
           char const* process) {
      return insert(typeID, moduleLabel, instance, process, productholderindexhelper::getContainedType(typeID));
    }

    // Before the object is frozen the accessors above will
    // fail to find a match. Once frozen, no more new entries
    // can be added with insert.
    void setFrozen();

    std::vector<std::string> const& lookupProcessNames() const;

    class Range {
    public:
      Range(unsigned int begin, unsigned int end) : begin_(begin), end_(end) { }
      unsigned int begin() const { return begin_; }
      unsigned int end() const { return end_; }
    private:
      unsigned int begin_;
      unsigned int end_;
    };

    class IndexAndNames {
    public:
      IndexAndNames(ProductHolderIndex index, unsigned int start, unsigned int startProcess) :
        index_(index), startInBigNamesContainer_(start), startInProcessNames_(startProcess) { }
      ProductHolderIndex index() const { return index_; }
      unsigned int startInBigNamesContainer() const { return startInBigNamesContainer_; }
      unsigned int startInProcessNames() const { return startInProcessNames_; }
    private:
      ProductHolderIndex index_;
      unsigned int startInBigNamesContainer_;
      unsigned int startInProcessNames_;
    };

    unsigned int beginElements() const { return beginElements_; }
    std::vector<TypeID> const& sortedTypeIDs() const { return sortedTypeIDs_; }
    std::vector<Range> const& ranges() const { return ranges_; }
    std::vector<IndexAndNames> const& indexAndNames() const { return indexAndNames_; }
    std::vector<char> const& processNames() const { return processNames_; }

    // The next few functions are intended for internal use
    // but are public so tests can use them also.

    unsigned int indexToIndexAndNames(KindOfType kindOfType,
                                      TypeID const& typeID,
                                      char const* moduleLabel,
                                      char const* instance,
                                      char const* process) const;

    // Returns the index into sortedTypeIDs_. Returns the maximum unsigned
    // int value if the type is not there.
    unsigned int indexToType(KindOfType kindOfType, TypeID const& typeID) const;

    // Returns the index of the process name in processNames_. Returns the
    // maximum unsigned int value if the process name is not found.
    unsigned int processIndex(char const* process) const;

    // This will throw if it detects problems, but unless there is a bug
    // there should never be any. Mostly it is checking for things which
    // might cause out of bounds errors when accessing the vectors.
    void sanityCheck() const;

    ProductHolderIndex nextIndexValue() const { return nextIndexValue_; }

    // For debugging only
    void print(std::ostream& os) const;

  private:

    // Next available value for a ProductHolderIndex. This just
    // increments by one each time a new value is assigned.
    ProductHolderIndex nextIndexValue_;

    // This is an index into sortedTypeIDs_ that tells where
    // the entries corresponding to types of elements in containers
    // start.
    unsigned int beginElements_;

    // Sorted by putting all the product entries first and
    // then the element entries.  Then sorted by TypeID value.
    // Most lookups start here by finding the TypeID and
    // then using its position to find the corresponding Range
    // in the ranges_ vector below.
    std::vector<TypeID> sortedTypeIDs_;

    // There is a one to one correspondence between this vector
    // and sortedTypeIDs_ and the corresponding elements appear
    // in the same order. Each Range object holds the beginning and
    // end of the corresponding elements in the indexAndNames_
    // vector below.
    std::vector<Range> ranges_;

    // Each element of this vector contains a ProductHolderIndex.
    // It also contains indexes into vectors of characters that
    // hold the corresponding moduleLabel, instance, and process
    // name. Note this is sorted with product entries first then
    // element entries, then by TypeID, then by moduleLabel,
    // then by instance, and finally by process. Note that in
    // a subset of entries that have matching type/label/instance
    // the entry with an empty process name will always be the
    // first process and startInProcessNames_ will always be 0
    // for the empty process name.
    std::vector<IndexAndNames> indexAndNames_;

    // These contain C style strings terminated
    // by '\0' all concatenated together. In the
    // first vector the strings come in pairs,
    // always module label then instance.  The pairs
    // are ordered the same as the IndexAndNames
    // vector. Within a TypeID, the moduleLabel/instance
    // pair is not duplicated if it appears multiple times.
    // The second vector contains all the process names
    // in alphabetical order with no duplication. The
    // first element is always the empty string.
    std::vector<char> bigNamesContainer_; 
    std::vector<char> processNames_;

    // Duplicates the entries in processNames_ in
    // a convenient format.
    std::vector<std::string> lookupProcessNames_;

    // The rest of the data members are for temporary use
    // while the data structure is being filled.

    class Item {
    public:
      Item(KindOfType kindOfType,
           TypeID const& typeID,
           std::string const& moduleLabel,
           std::string const& instance,
           std::string const& process,
           ProductHolderIndex index);
      KindOfType kindOfType() const { return kindOfType_; }
      TypeID const& typeID() const { return typeID_; }
      std::string const& moduleLabel() const { return moduleLabel_; }
      std::string const& instance() const { return instance_; }
      std::string const& process() const { return process_; }
      ProductHolderIndex index() const { return index_; }

      void clearProcess() { process_.clear(); }
      void setIndex(ProductHolderIndex v) { index_ = v; }

      bool operator<(Item const& right) const;

    private:
      KindOfType kindOfType_;
      TypeID typeID_;
      std::string moduleLabel_;
      std::string instance_;
      std::string process_;
      ProductHolderIndex index_;
    };

    edm::propagate_const<std::unique_ptr<std::set<Item>>> items_;

    edm::propagate_const<std::unique_ptr<std::set<std::string>>> processItems_;
  };
}
#endif