ComparisonConstraint.h

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// -*- Mode: c++; c-basic-offset: 4; tab-width: 4; -*-
 
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 *  file:  ComparisonConstraint.h
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#ifndef TCLAP_COMPARISON_CONSTRAINT_H
#define TCLAP_COMPARISON_CONSTRAINT_H
 
#include <tclap/PredicateConstraint.h>
 
#include <functional>
#include <sstream>
#include <string>
 
namespace TCLAP {
namespace internal {
 
// A single owned threshold supplies validation and both forms of help text.
template <class T, class Compare>
class ComparisonRule {
public:
    ComparisonRule(const T &bound, const std::string &relation,
                   const std::string &symbol)
        : _bound(bound), _relation(relation), _shortId() {
        std::ostringstream out;
        out << '[' << symbol << _bound << ']';
        _shortId = out.str();
    }
 
    bool operator()(const T &value) const { return Compare()(value, _bound); }
    std::string description() const {
        std::ostringstream out;
        out << "value must be " << _relation << ' ' << _bound;
        return out.str();
    }
    std::string shortID() const { return _shortId; }
 
private:
    T _bound;
    std::string _relation;
    std::string _shortId;
};
 
template <class T, class Compare>
class ComparisonConstraintBase
    : public PredicateConstraint<T, ComparisonRule<T, Compare>,
                                 RuleConstraintText> {
protected:
    ComparisonConstraintBase(const T &bound, const std::string &relation,
                             const std::string &symbol)
        : PredicateConstraint<T, ComparisonRule<T, Compare>,
                              RuleConstraintText>(
              ComparisonRule<T, Compare>(bound, relation, symbol),
              RuleConstraintText()) {}
};
 
}  // namespace internal
 
template <class T>
class LessThanConstraint
    : public internal::ComparisonConstraintBase<T, std::less<T> > {
public:
    explicit LessThanConstraint(const T &bound)
        : internal::ComparisonConstraintBase<T, std::less<T> >(
              bound, "less than", "<") {}
};
 
template <class T>
class LessThanOrEqualConstraint
    : public internal::ComparisonConstraintBase<T, std::less_equal<T> > {
public:
    explicit LessThanOrEqualConstraint(const T &bound)
        : internal::ComparisonConstraintBase<T, std::less_equal<T> >(
              bound, "less than or equal to", "<=") {}
};
 
template <class T>
class GreaterThanConstraint
    : public internal::ComparisonConstraintBase<T, std::greater<T> > {
public:
    explicit GreaterThanConstraint(const T &bound)
        : internal::ComparisonConstraintBase<T, std::greater<T> >(
              bound, "greater than", ">") {}
};
 
template <class T>
class GreaterThanOrEqualConstraint
    : public internal::ComparisonConstraintBase<T, std::greater_equal<T> > {
public:
    explicit GreaterThanOrEqualConstraint(const T &bound)
        : internal::ComparisonConstraintBase<T, std::greater_equal<T> >(
              bound, "greater than or equal to", ">=") {}
};
 
}  // namespace TCLAP
 
#endif  // TCLAP_COMPARISON_CONSTRAINT_H