Remove unused boolean_t token type

code/query/boolean.cxx

@@ -1,31 +0,0 @@
-#include <code/query/boolean.hxx>
-
-namespace code::query
-{
-
-  boolean_t::
-  boolean_t(source_location_t origin, bool value)
-    : origin_{move(origin)}, value_{value}
-  {}
-
-  source_location_t const&
-  boolean_t::
-  origin() const
-  {
-    return origin_;
-  }
-
-  bool
-  boolean_t::
-  value() const
-  {
-    return value_;
-  }
-
-  string
-  to_string(boolean_t const& boolean)
-  {
-    return boolean.value() ? "true" : "false";
-  }
-
-} // namespace code::query

code/query/boolean.hxx

@@ -1,32 +0,0 @@
-#ifndef code__query__boolean_hxx_
-#define code__query__boolean_hxx_
-
-#include <code/query/source-location.hxx>
-#include <code/query/types.hxx>
-
-namespace code::query
-{
-
-  class boolean_t
-  {
-  public:
-    boolean_t(source_location_t, bool);
-
-    source_location_t const&
-    origin() const;
-
-    bool
-    value() const;
-
-  private:
-    source_location_t origin_;
-    bool value_;
-
-  };
-
-  string
-  to_string(boolean_t const&);
-
-} // namespace code::query
-
-#endif

code/query/match.cxx

@@ -1,5 +1,4 @@
 #include <code/query/match.hxx>
-#include <code/query/boolean.hxx>
 #include <code/query/logical-and.hxx>
 #include <code/query/logical-not.hxx>
 #include <code/query/logical-or.hxx>
@@ -15,7 +14,6 @@ namespace code::query
     class matcher_t
       : public visitor_t,
         public basic_visitor_t<term_t>,
-        public basic_visitor_t<boolean_t>,
         public basic_visitor_t<tag_t>,
         public basic_visitor_t<logical_and_t>,
         public basic_visitor_t<logical_not_t>,
@@ -60,12 +58,6 @@ namespace code::query
         result = predicate_(e);
       }
 
-      void
-      visit(boolean_t const& e) override
-      {
-        result = e.value();
-      }
-
       void
       visit(logical_and_t const& e) override
       {

code/query/syntactical-analyzer.cxx

@@ -1,4 +1,3 @@
-#include <code/query/boolean.hxx>
 #include <code/query/logical-and.hxx>
 #include <code/query/logical-not.hxx>
 #include <code/query/logical-or.hxx>