source/glsl/evaluate.cpp

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