Define a find_symbols taking iterators

This will make it easier to accumulate the set of symbols from a range,
which is often how the find_symbols function is used.

Author: romainbrenguier

src/util/find_symbols.h

@@ -10,6 +10,7 @@ Author: Daniel Kroening, [email protected]
 #ifndef CPROVER_UTIL_FIND_SYMBOLS_H
 #define CPROVER_UTIL_FIND_SYMBOLS_H
 
+#include <algorithm>
 #include <set>
 #include <unordered_set>
 
@@ -26,6 +27,19 @@ void find_symbols(
   const exprt &src,
   find_symbols_sett &dest);
 
+/// \return set of sub-expressions of the expressions contained in the range
+///   defined by \p begin and \p end which have id ID_symbol or ID_next_symbol
+template <typename iteratort>
+find_symbols_sett find_symbols(iteratort begin, iteratort end)
+{
+  static_assert(
+    std::is_base_of<exprt, typename iteratort::value_type>::value,
+    "find_symbols takes exprt iterators as arguments");
+  find_symbols_sett result;
+  std::for_each(begin, end, [&](const exprt &e){ find_symbols(e, result); });
+  return result;
+}
+
 void find_symbols(
   const exprt &src,
   find_symbols_sett &dest,