C# Variables.Add方法代码示例

        protected override object EvalExpression(ParseTree tree, params object[] paramlist)
        {
            // if only left hand side available, this is not an assignment, simple evaluate expression
            if (nodes.Count == 1)
                return this.GetValue(tree, TokenType.AssignmentExpression, 0); // return the result

            if (nodes.Count != 3)
            {
                tree.Errors.Add(new ParseError("Illegal EvalExpression format", 1092, this));
                return null;
            }

            // ok, this is an assignment so declare the function or variable
                // assignment only allowed to function or to a variable
                ParseNode v = GetFunctionOrVariable(nodes[0]);
                if (v == null)
                {
                    tree.Errors.Add(new ParseError("Can only assign to function or variable", 1020, this));
                    return null;
                }

                ParseTreeEvaluator root = tree as ParseTreeEvaluator;
                if (root == null)
                {
                    tree.Errors.Add(new ParseError("Invalid parser used", 1040, this));
                    return null;
                }

                if (root.Context == null)
                {
                    tree.Errors.Add(new ParseError("No context defined", 1041, this));
                    return null;
                }

                if (v.Token.Type == TokenType.VARIABLE)
                {

                    // simply overwrite any previous defnition
                    string key = v.Token.Text;
                    root.Context.Globals[key] = this.GetValue(tree, TokenType.AssignmentExpression, 1);
                    return null;
                }
                else if (v.Token.Type == TokenType.Function)
                {

                    string key = v.Nodes[0].Token.Text;

                    // function lookup is case insensitive
                    if (root.Context.Functions.ContainsKey(key.ToLower()))
                        if (!(root.Context.Functions[key.ToLower()] is DynamicFunction))
                        {
                            tree.Errors.Add(new ParseError("Built in functions cannot be overwritten", 1050, this));
                            return null;
                        }

                    // lets determine the input variables.
                    // functions must be of te form f(x;y;z) = x+y*z;
                    // check the function parameters to be of type Variable, error otherwise
                    Variables vars = new Variables();
                    ParseNode paramsNode = v.Nodes[2];
                    if (paramsNode.Token.Type == TokenType.Params)
                    {   // function has parameters, so check if they are all variable declarations
                        for (int i = 0; i < paramsNode.Nodes.Count; i += 2)
                        {
                            ParseNode varNode = GetFunctionOrVariable(paramsNode.Nodes[i]);
                            if (varNode == null || varNode.Token.Type != TokenType.VARIABLE)
                            {
                                tree.Errors.Add(new ParseError("Function declaration may only contain variables", 1051, this));
                                return null;
                            }
                            // simply declare the variable, no need to evaluate the value of it at this point.
                            // evaluation will be done when the function is executed
                            // note, variables are Case Sensitive (!)
                            vars.Add(varNode.Token.Text, null);
                        }
                    }
                    // we have all the info we need to know to declare the dynamicly defined function
                    // pass on nodes[2] which is the Right Hand Side (RHS) of the assignment
                    // nodes[2] will be evaluated at runtime when the function is executed.
                    DynamicFunction dynf = new DynamicFunction(key, nodes[2], vars, vars.Count, vars.Count);
                    root.Context.Functions[key.ToLower()] = dynf;
                    return null;
                }

            // in an assignment, dont return any result (basically void)
            return null;
        }

        public Variables GetVariableValues(Document document, ISchema schema, VariableDefinitions variableDefinitions, Inputs inputs)
        {
            var variables = new Variables();
            variableDefinitions.Apply(v =>
            {
                var variable = new Variable();
                variable.Name = v.Name;

                object variableValue = null;
                inputs?.TryGetValue(v.Name, out variableValue);
                variable.Value = GetVariableValue(document, schema, v, variableValue);

                variables.Add(variable);
            });
            return variables;
        }

        public Variables GetVariableValues(ISchema schema, VariableDefinitions variableDefinitions, Inputs inputs)
        {
            var variables = new Variables();
            variableDefinitions.Apply(v =>
            {
                var variable = new Variable();
                variable.Name = v.Name;

                object variableValue;
                if (inputs != null && inputs.TryGetValue(v.Name, out variableValue))
                {
                    var valueAst = variableValue.AstFromValue(schema, v.Type.GraphTypeFromType(schema));
                    variable.Value = GetVariableValue(schema, v, valueAst);
                }
                else
                {
                    variable.Value = GetVariableValue(schema, v, v.DefaultValue);
                }

                variables.Add(variable);
            });
            return variables;
        }