/**
  * reads a list of ShaderNode{} blocks
  *
  * @param statements the list of statements to parse
  * @throws IOException
  */
 protected void readShaderNode(List<Statement> statements) throws IOException {
   for (Statement statement : statements) {
     String line = statement.getLine();
     String[] split = statement.getLine().split("[ \\{]");
     if (line.startsWith("Definition")) {
       ShaderNodeDefinition def = findDefinition(statement);
       shaderNode.setDefinition(def);
       if (def.isNoOutput()) {
         techniqueDef.getShaderGenerationInfo().getUnusedNodes().remove(shaderNode.getName());
       }
     } else if (line.startsWith("Condition")) {
       String condition = line.substring(line.lastIndexOf(":") + 1).trim();
       extractCondition(condition, statement);
       shaderNode.setCondition(conditionParser.getFormattedExpression());
     } else if (line.startsWith("InputMapping")) {
       for (Statement statement1 : statement.getContents()) {
         VariableMapping mapping = readInputMapping(statement1);
         techniqueDef
             .getShaderGenerationInfo()
             .getUnusedNodes()
             .remove(mapping.getRightVariable().getNameSpace());
         shaderNode.getInputMapping().add(mapping);
       }
     } else if (line.startsWith("OutputMapping")) {
       for (Statement statement1 : statement.getContents()) {
         VariableMapping mapping = readOutputMapping(statement1);
         techniqueDef.getShaderGenerationInfo().getUnusedNodes().remove(shaderNode.getName());
         shaderNode.getOutputMapping().add(mapping);
       }
     } else {
       throw new MatParseException("ShaderNodeDefinition", split[0], statement);
     }
   }
 }
 /**
  * searcha variable in the given list and updates its type and namespace
  *
  * @param var the variable to update
  * @param list the variables list
  * @return true if the variable has been found and updated
  */
 protected boolean updateVariableFromList(ShaderNodeVariable var, List<ShaderNodeVariable> list) {
   for (ShaderNodeVariable shaderNodeVariable : list) {
     if (shaderNodeVariable.getName().equals(var.getName())) {
       var.setType(shaderNodeVariable.getType());
       var.setMultiplicity(shaderNodeVariable.getMultiplicity());
       var.setNameSpace(shaderNode.getName());
       return true;
     }
   }
   return false;
 }
  /**
   * reads an input mapping
   *
   * @param statement1 the statement being read
   * @return the mapping
   * @throws IOException
   */
  public VariableMapping readInputMapping(Statement statement1) throws IOException {
    VariableMapping mapping = null;
    try {
      mapping = parseMapping(statement1, new boolean[] {false, true});
    } catch (Exception e) {
      throw new MatParseException("Unexpected mapping format", statement1, e);
    }
    ShaderNodeVariable left = mapping.getLeftVariable();
    ShaderNodeVariable right = mapping.getRightVariable();
    if (!updateVariableFromList(left, shaderNode.getDefinition().getInputs())) {
      throw new MatParseException(
          left.getName() + " is not an input variable of " + shaderNode.getDefinition().getName(),
          statement1);
    }

    if (left.getType().startsWith("sampler") && !right.getNameSpace().equals("MatParam")) {
      throw new MatParseException("Samplers can only be assigned to MatParams", statement1);
    }

    if (right.getNameSpace().equals("Global")) {
      right.setType("vec4"); // Globals are all vec4 for now (maybe forever...)
      //        updateCondition(right, mapping);
      storeGlobal(right, statement1);

    } else if (right.getNameSpace().equals("Attr")) {
      if (shaderNode.getDefinition().getType() == Shader.ShaderType.Fragment) {
        throw new MatParseException(
            "Cannot have an attribute as input in a fragment shader" + right.getName(), statement1);
      }
      updateVarFromAttributes(mapping.getRightVariable(), mapping);
      //          updateCondition(mapping.getRightVariable(), mapping);
      storeAttribute(mapping.getRightVariable());
    } else if (right.getNameSpace().equals("MatParam")) {
      MatParam param = findMatParam(right.getName());
      if (param == null) {
        throw new MatParseException(
            "Could not find a Material Parameter named " + right.getName(), statement1);
      }
      if (shaderNode.getDefinition().getType() == Shader.ShaderType.Vertex) {
        if (updateRightFromUniforms(param, mapping, vertexDeclaredUniforms, statement1)) {
          storeVertexUniform(mapping.getRightVariable());
        }
      } else {
        if (updateRightFromUniforms(param, mapping, fragmentDeclaredUniforms, statement1)) {
          if (mapping.getRightVariable().getType().contains("|")) {
            String type = fixSamplerType(left.getType(), mapping.getRightVariable().getType());
            if (type != null) {
              mapping.getRightVariable().setType(type);
            } else {
              throw new MatParseException(
                  param.getVarType().toString()
                      + " can only be matched to one of "
                      + param.getVarType().getGlslType().replaceAll("\\|", ",")
                      + " found "
                      + left.getType(),
                  statement1);
            }
          }
          storeFragmentUniform(mapping.getRightVariable());
        }
      }

    } else if (right.getNameSpace().equals("WorldParam")) {
      UniformBinding worldParam = findWorldParam(right.getName());
      if (worldParam == null) {
        throw new MatParseException(
            "Could not find a World Parameter named " + right.getName(), statement1);
      }
      if (shaderNode.getDefinition().getType() == Shader.ShaderType.Vertex) {
        if (updateRightFromUniforms(worldParam, mapping, vertexDeclaredUniforms)) {
          storeVertexUniform(mapping.getRightVariable());
        }
      } else {
        if (updateRightFromUniforms(worldParam, mapping, fragmentDeclaredUniforms)) {
          storeFragmentUniform(mapping.getRightVariable());
        }
      }

    } else {
      ShaderNode node = nodes.get(right.getNameSpace());
      if (node == null) {
        throw new MatParseException(
            "Undeclared node"
                + right.getNameSpace()
                + ". Make sure this node is declared before the current node",
            statement1);
      }
      ShaderNodeVariable var = findNodeOutput(node.getDefinition().getOutputs(), right.getName());
      if (var == null) {
        throw new MatParseException(
            "Cannot find output variable" + right.getName() + " form ShaderNode " + node.getName(),
            statement1);
      }
      right.setNameSpace(node.getName());
      right.setType(var.getType());
      right.setMultiplicity(var.getMultiplicity());
      mapping.setRightVariable(right);
      storeVaryings(node, mapping.getRightVariable());
    }

    checkTypes(mapping, statement1);

    return mapping;
  }