Repo created

libs/indexer/drules_selector_parser.cpp

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+#include "indexer/drules_selector_parser.hpp"
+
+#include "base/assert.hpp"
+
+#include <algorithm>
+
+namespace drule
+{
+using namespace std;
+
+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 = std::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 = std::move(tag);
+  e.m_value = string(str.begin() + pos + len, str.end());
+  return true;
+}
+
+}  // namespace drule