parser/operator.cpp

   1 #include <ail/file.hpp>
   2 #include <ail/string.hpp>
   3 #include <fridh/parser.hpp>
   4 #include <fridh/lexer.hpp>
   5
   6 namespace fridh
   7 {
   8         void call_check(std::size_t extremum_offset)
   9         {
  10                 if(extremum_offset != 1)
  11                         throw ail::exception("Invalid call offset encountered during operator resolution");
  12         }
  13
  14         void parser::operator_resolution(parse_tree_nodes & input, parse_tree_node & output)
  15         {
  16                 if(input.size() == 1)
  17                 {
  18                         output = input[0];
  19                         return;
  20                 }
  21
  22                 bool got_an_operator = false;
  23                 word extremum;
  24                 std::size_t extremum_offset;
  25
  26                 for(std::size_t i = 0, end = input.size(); i < end; i++)
  27                 {
  28                         parse_tree_node & current_node = input[i];
  29                         word precedence;
  30
  31                         if
  32                         (
  33                                 current_node.type == parse_tree_node_type::unary_operator_node &&
  34                                 current_node.unary_operator_pointer->argument.type != parse_tree_node_type::uninitialised
  35                         )
  36                                 continue;
  37
  38                         try
  39                         {
  40                                 if(get_parse_tree_node_precedence(current_node, precedence))
  41                                 {
  42                                         if
  43                                         (
  44                                                 !got_an_operator ||
  45                                                 precedence > extremum ||
  46                                                 (is_right_to_left_operator(current_node) && precedence == extremum)
  47                                         )
  48                                         {
  49                                                 got_an_operator = true;
  50                                                 extremum = precedence;
  51                                                 extremum_offset = i;
  52                                         }
  53                                 }
  54                         }
  55                         catch(ail::exception & exception)
  56                         {
  57                                 error(exception.get_message());
  58                         }
  59                 }
  60
  61                 if(!got_an_operator)
  62                         error("Failed to perform operator resolution");
  63
  64                 parse_tree_node & operator_node = input[extremum_offset];
  65                 std::size_t next_offset = extremum_offset + 1;
  66                 switch(operator_node.type)
  67                 {
  68                         case parse_tree_node_type::unary_operator_node:
  69                         {
  70                                 std::size_t argument_offset;
  71                                 if(operator_node.is_post_fix())
  72                                         argument_offset = extremum_offset - 1;
  73                                 else
  74                                         argument_offset = next_offset;
  75
  76                                 parse_tree_unary_operator_node & unary_operator_node = *operator_node.unary_operator_pointer;
  77                                 unary_operator_node.argument = input.at(argument_offset);
  78                                 input.erase(input.begin() + argument_offset);
  79                                 break;
  80                         }
  81
  82                         case parse_tree_node_type::binary_operator_node:
  83                         {
  84                                 parse_tree_binary_operator_node & binary_operator_node = *operator_node.binary_operator_pointer;
  85
  86                                 parse_tree_nodes
  87                                         left_side(input.begin(), input.begin() + extremum_offset),
  88                                         right_side(input.begin() + next_offset, input.end());
  89
  90                                 operator_resolution(left_side, binary_operator_node.left_argument);
  91                                 operator_resolution(right_side, binary_operator_node.right_argument);
  92
  93                                 output = operator_node;
  94
  95                                 return;
  96                         }
  97
  98                         case parse_tree_node_type::call:
  99                                 //this is questionable
 100                                 call_check(extremum_offset);
 101                                 operator_node.call_pointer->function = input[0];
 102                                 input.erase(input.begin());
 103                                 break;
 104
 105                         case parse_tree_node_type::call_operator:
 106                         case parse_tree_node_type::spaced_call_operator:
 107                                 call_check(extremum_offset);
 108                                 operator_node.is_call();
 109                                 operator_node.call_pointer->function = input[0];
 110                                 input.erase(input.begin());
 111                                 if(operator_node.type != parse_tree_node_type::spaced_call_operator && next_offset != input.size())
 112                                 {
 113                                         //it's an unary call
 114                                         operator_node.call_pointer->arguments.push_back(input[next_offset]);
 115                                         input.erase(input.end() - 1);
 116                                 }
 117                                 break;
 118
 119                         default:
 120                                 error("Invalid operator node type encountered during operator resolution");
 121                 }
 122
 123                 operator_resolution(input, output);
 124         }
 125 }