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#include "indexer/drules_selector_parser.hpp"
#include "base/assert.hpp"
#include "std/algorithm.hpp"
namespace drule
{
namespace
{
bool IsTag(string const & str)
{
// tag consists of a-z or A-Z letters or _ and not empty
for (auto const c : str)
{
if (!(c >= 'a' && c <= 'z') && !(c >= 'A' && c <= 'Z') && c != '_')
return false;
}
return !str.empty();
}
} // namespace
bool ParseSelector(string const & str, SelectorExpression & e)
{
// See https://wiki.openstreetmap.org/wiki/MapCSS/0.2
// Now we support following expressions
// [tag!=value]
// [tag>=value]
// [tag<=value]
// [tag=value]
// [tag>value]
// [tag<value]
// [!tag]
// [tag]
if (str.empty())
return false; // invalid format
// [!tag]
if (str[0] == '!')
{
string tag(str.begin() + 1, str.end());
if (!IsTag(tag))
return false; // invalid format
e.m_operator = SelectorOperatorIsNotSet;
e.m_tag = move(tag);
e.m_value.clear();
return true;
}
// [tag]
if (IsTag(str))
{
e.m_operator = SelectorOperatorIsSet;
e.m_tag = str;
e.m_value.clear();
return true;
}
// Find first entrance of >, < or =
size_t pos = string::npos;
size_t len = 0;
char const c[] = { '>', '<', '=', 0 };
for (size_t i = 0; c[i] != 0; ++i)
{
size_t p = str.find(c[i]);
if (p != string::npos)
{
pos = (pos == string::npos) ? p : min(p, pos);
len = 1;
}
}
// If there is no entrance or no space for tag or value then it is invalid format
if (pos == 0 || len == 0 || pos == str.size()-1)
return false; // invalid format
// Dedicate the operator type, real operator position and length
SelectorOperatorType op = SelectorOperatorUnknown;
if (str[pos] == '>')
{
op = SelectorOperatorGreater;
if (str[pos+1] == '=')
{
++len;
op = SelectorOperatorGreaterOrEqual;
}
}
else if (str[pos] == '<')
{
op = SelectorOperatorLess;
if (str[pos+1] == '=')
{
++len;
op = SelectorOperatorLessOrEqual;
}
}
else
{
ASSERT(str[pos] == '=', ());
op = SelectorOperatorEqual;
if (str[pos-1] == '!')
{
--pos;
++len;
op = SelectorOperatorNotEqual;
}
}
string tag(str.begin(), str.begin() + pos);
if (!IsTag(tag))
return false; // invalid format
e.m_operator = op;
e.m_tag = move(tag);
e.m_value = string(str.begin() + pos + len, str.end());
return true;
}
} // namespace drule
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