match_empty.cc

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#include <map>
#include <set>

#include "src/conf/warn.h"
#include "src/globals.h"
#include "src/ir/rule_rank.h"
#include "src/ir/skeleton/path.h"
#include "src/ir/skeleton/skeleton.h"
#include "src/parse/rules.h"

namespace re2c
{

void Skeleton::warn_match_empty ()
{
    Node & head = nodes[0];

    head.calc_reachable ();
    const std::set<rule_t> & reach = head.reachable;

    // warn about rules that match empty string
    if (!head.rule.rank.is_none ())
    {
        bool reachable = head.end ();
        for (std::set<rule_t>::const_iterator i = reach.begin ();
            !reachable && i != reach.end (); ++i)
        {
            reachable |= i->rank.is_none ();
        }
        if (reachable)
        {
            warn.match_empty_string (rules[head.rule.rank].line);
        }
    }

    // warn about rules that match empty string with nonempty trailing context
    if (head.ctx)
    {
        for (std::set<rule_t>::const_iterator i = reach.begin (); i != reach.end (); ++i)
        {
            if (i->restorectx)
            {
                warn.match_empty_string (rules[i->rank].line);
            }
        }
    }
}

} // namespace re2c