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                 std::cout << "Performing operator resolution on " << input.size() << " node(s)" << std::endl;
  17                 if(input.size() == 1)
  18                 {
  19                         output = input[0];
  20                         return;
  21                 }
  22
  23                 bool got_an_operator = false;
  24                 word extremum;
  25                 std::size_t extremum_offset;
  26
  27                 for(std::size_t i = 0, end = input.size(); i < end; i++)
  28                 {
  29                         parse_tree_node & current_node = input[i];
  30                         word precedence;
  31
  32                         bool is_initialised_unary_node =
  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
  37                         bool is_initialised_call_node =
  38                                 current_node.type == parse_tree_node_type::call &&
  39                                 current_node.call_pointer->initialised;
  40
  41                         if
  42                         (
  43                                 is_initialised_unary_node ||
  44                                 is_initialised_call_node
  45                         )
  46                                 continue;
  47
  48                         try
  49                         {
  50                                 if(get_parse_tree_node_precedence(current_node, precedence))
  51                                 {
  52                                         if
  53                                         (
  54                                                 !got_an_operator ||
  55                                                 precedence > extremum ||
  56                                                 (is_right_to_left_operator(current_node) && precedence == extremum)
  57                                         )
  58                                         {
  59                                                 got_an_operator = true;
  60                                                 extremum = precedence;
  61                                                 extremum_offset = i;
  62                                         }
  63                                 }
  64                         }
  65                         catch(ail::exception & exception)
  66                         {
  67                                 error(exception.get_message());
  68                         }
  69                 }
  70
  71                 if(!got_an_operator)
  72                         error("Failed to perform operator resolution");
  73
  74                 parse_tree_node & operator_node = input[extremum_offset];
  75                 std::size_t next_offset = extremum_offset + 1;
  76                 switch(operator_node.type)
  77                 {
  78                         case parse_tree_node_type::unary_operator_node:
  79                         {
  80                                 std::size_t argument_offset;
  81                                 if(operator_node.is_post_fix())
  82                                         argument_offset = extremum_offset - 1;
  83                                 else
  84                                         argument_offset = next_offset;
  85
  86                                 if(argument_offset >= input.size())
  87                                         error("Missing operator for unary argument");
  88
  89                                 parse_tree_unary_operator_node & unary_operator_node = *operator_node.unary_operator_pointer;
  90                                 unary_operator_node.argument = input[argument_offset];
  91                                 input.erase(input.begin() + argument_offset);
  92                                 break;
  93                         }
  94
  95                         case parse_tree_node_type::binary_operator_node:
  96                         {
  97                                 parse_tree_binary_operator_node & binary_operator_node = *operator_node.binary_operator_pointer;
  98
  99                                 if(extremum_offset == 0)
 100                                         error("Encountered a binary operator which lacks a left hand argument");
 101                                 else if(next_offset >= input.size())
 102                                         error("Encountered a binary operator which lacks a right hand argument");
 103
 104                                 parse_tree_nodes
 105                                         left_side(input.begin(), input.begin() + extremum_offset),
 106                                         right_side(input.begin() + next_offset, input.end());
 107
 108                                 operator_resolution(left_side, binary_operator_node.left_argument);
 109                                 operator_resolution(right_side, binary_operator_node.right_argument);
 110
 111                                 output = operator_node;
 112
 113                                 return;
 114                         }
 115
 116                         case parse_tree_node_type::call:
 117                                 call_check(extremum_offset);
 118                                 operator_node.call_pointer->function = input[0];
 119                                 input.erase(input.begin());
 120                                 break;
 121
 122                         case parse_tree_node_type::call_operator:
 123                         case parse_tree_node_type::spaced_call_operator:
 124                                 call_check(extremum_offset);
 125                                 operator_node.is_call();
 126                                 operator_node.call_pointer->function = input[0];
 127                                 input.erase(input.begin());
 128                                 if(operator_node.type != parse_tree_node_type::spaced_call_operator && next_offset != input.size())
 129                                 {
 130                                         //it's a unary call
 131                                         operator_node.call_pointer->arguments.push_back(input[next_offset]);
 132                                         input.erase(input.end() - 1);
 133                                 }
 134                                 break;
 135
 136                         default:
 137                                 error("Invalid operator node type encountered during operator resolution");
 138                 }
 139
 140                 operator_resolution(input, output);
 141         }
 142 }