source/glsl/evaluate.cpp

   1 #include "evaluate.h"
   2
   3 namespace Msp {
   4 namespace GL {
   5 namespace SL {
   6
   7 ExpressionEvaluator::ExpressionEvaluator():
   8         variable_values(0),
   9         result(0.0f),
  10         result_valid(false)
  11 { }
  12
  13 ExpressionEvaluator::ExpressionEvaluator(const ValueMap &v):
  14         variable_values(&v),
  15         result(0.0f),
  16         result_valid(false)
  17 { }
  18
  19 void ExpressionEvaluator::visit(Literal &literal)
  20 {
  21         if(literal.token=="true")
  22                 result = 1.0f;
  23         else if(literal.token=="false")
  24                 result = 0.0f;
  25         else
  26                 result = lexical_cast<float>(literal.token);
  27         result_valid = true;
  28 }
  29
  30 void ExpressionEvaluator::visit(ParenthesizedExpression &parexp)
  31 {
  32         parexp.expression->visit(*this);
  33 }
  34
  35 void ExpressionEvaluator::visit(VariableReference &var)
  36 {
  37         if(!var.declaration)
  38                 return;
  39
  40         if(variable_values)
  41         {
  42                 ValueMap::const_iterator i = variable_values->find(var.declaration);
  43                 if(i!=variable_values->end())
  44                         i->second->visit(*this);
  45         }
  46         else if(var.declaration->init_expression)
  47                 var.declaration->init_expression->visit(*this);
  48 }
  49
  50 void ExpressionEvaluator::visit(UnaryExpression &unary)
  51 {
  52         result_valid = false;
  53         unary.expression->visit(*this);
  54         if(!result_valid)
  55                 return;
  56
  57         if(unary.oper=="!")
  58                 result = !result;
  59         else
  60                 result_valid = false;
  61 }
  62
  63 void ExpressionEvaluator::visit(BinaryExpression &binary)
  64 {
  65         result_valid = false;
  66         binary.left->visit(*this);
  67         if(!result_valid)
  68                 return;
  69
  70         float left_result = result;
  71         result_valid = false;
  72         binary.right->visit(*this);
  73         if(!result_valid)
  74                 return;
  75
  76         if(binary.oper=="<")
  77                 result = (left_result<result);
  78         else if(binary.oper=="<=")
  79                 result = (left_result<=result);
  80         else if(binary.oper==">")
  81                 result = (left_result>result);
  82         else if(binary.oper==">=")
  83                 result = (left_result>=result);
  84         else if(binary.oper=="==")
  85                 result = (left_result==result);
  86         else if(binary.oper=="!=")
  87                 result = (left_result!=result);
  88         else if(binary.oper=="&&")
  89                 result = (left_result && result);
  90         else if(binary.oper=="||")
  91                 result = (left_result || result);
  92         else
  93                 result_valid = false;
  94 }
  95
  96 } // namespace SL
  97 } // namespace GL
  98 } // namespace Msp