c# barcode generator code 39 Interpreter Pattern | in C#.NET

Creator Code39 in C#.NET Interpreter Pattern |

Interpreter Pattern |
Code 39 Extended Generator In C#
Using Barcode generator for .NET Control to generate, create ANSI/AIM Code 39 image in .NET applications.
www.OnBarcode.com
ANSI/AIM Code 39 Recognizer In C#.NET
Using Barcode decoder for .NET framework Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
The main operational part of the Mirrors system is its constructor:
ECC200 Creation In C#.NET
Using Barcode generation for Visual Studio .NET Control to generate, create Data Matrix image in .NET framework applications.
www.OnBarcode.com
Code 128C Generation In Visual C#
Using Barcode creation for VS .NET Control to generate, create Code 128 image in Visual Studio .NET applications.
www.OnBarcode.com
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 public Mirror(string spec) { objectStack = new Stack( ); objectStack.Push(null); // Register the commands commands = new List<Command>( ); commands.Add(new ElementCommand( )); commands.Add(new EndElementCommand( )); commands.Add(new AttributeCommand( )); Reader = new XmlTextReader(spec); while (Reader.Read( )) { InterpretCommands( ); bool b = Reader.IsEmptyElement; if (Reader.HasAttributes) { for (int i = 0; i < Reader.AttributeCount; i++) { Reader.MoveToAttribute(i); InterpretCommands( ); } } if (b) Pop( ); } }
QR Maker In Visual C#
Using Barcode generator for VS .NET Control to generate, create Denso QR Bar Code image in .NET framework applications.
www.OnBarcode.com
2D Creation In C#
Using Barcode drawer for .NET framework Control to generate, create 2D Barcode image in .NET applications.
www.OnBarcode.com
XMLTextReader (line 11) accepts the entire XML specification and emits elements one
Print Barcode In C#
Using Barcode generation for VS .NET Control to generate, create Barcode image in Visual Studio .NET applications.
www.OnBarcode.com
Printing DUN - 14 In C#
Using Barcode generation for Visual Studio .NET Control to generate, create UCC - 14 image in VS .NET applications.
www.OnBarcode.com
at a time. On line 13, we move to the command interpreter, which operates exactly according to the pattern in Figure 10-5. There are three classes in the hierarchy: ElementCommand, EndCommand, and AttributeCommand. Each has its own Interpret method. The first one is:
Make Code 3 Of 9 In None
Using Barcode printer for Font Control to generate, create Code 39 Extended image in Font applications.
www.OnBarcode.com
Code-39 Scanner In Visual Basic .NET
Using Barcode reader for VS .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
public class ElementCommand : Command { public override void Interpret (Mirror context) { if (context.Reader.NodeType != XmlNodeType.Element) return; Type type = GetTypeOf(context.Reader.Name); if (type == null) return; object o = Activator.CreateInstance(type); if (context.Peek( ) != null) ((Control)context.Peek( )).Controls.Add((Control)o); context.Push(o); } // Omit GetType method here }
PDF417 Recognizer In Visual Studio .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Painting UPC - 13 In None
Using Barcode encoder for Excel Control to generate, create EAN13 image in Microsoft Excel applications.
www.OnBarcode.com
The Interpret method checks that the XML node type from the reader is correct. It then gets the actual type of the node (for example, TextBox), creates an instance of that type, adds the control to the stack, and pushes it down. Correspondingly, an EndCommand (which the Interpreter encounters when it hits a /> symbol in XML) pops the stack. The AttributeCommand class is the only other class:
DataMatrix Printer In None
Using Barcode maker for Font Control to generate, create Data Matrix ECC200 image in Font applications.
www.OnBarcode.com
Make Code 39 Extended In Objective-C
Using Barcode generation for iPhone Control to generate, create Code 39 image in iPhone applications.
www.OnBarcode.com
|
USS-128 Creator In None
Using Barcode maker for Office Excel Control to generate, create UCC - 12 image in Excel applications.
www.OnBarcode.com
Making USS Code 128 In None
Using Barcode encoder for Office Excel Control to generate, create Code 128C image in Excel applications.
www.OnBarcode.com
10: Behavioral Patterns: Visitor, Interpreter, and Memento
Code 128A Creation In Java
Using Barcode generator for Java Control to generate, create Code 128A image in Java applications.
www.OnBarcode.com
Paint UPC Symbol In Java
Using Barcode creator for Java Control to generate, create UPC-A Supplement 5 image in Java applications.
www.OnBarcode.com
public class AttributeCommand : Command { public override void Interpret (Mirror context) { if (context.Reader.NodeType != XmlNodeType.Attribute) return; SetProperty(context.Peek( ), context.Reader.Name, context.Reader.Value); } public void SetProperty(object o, string name, string val) { Type type = o.GetType( ); PropertyInfo property = type.GetProperty(name); // Find an appropriate property to match the attribute name if (property.PropertyType.IsAssignableFrom(typeof(string))) { property.SetValue(o, val, null); } else if (property.PropertyType.IsSubclassOf(typeof(Enum))) { object ev = Enum.Parse(property.PropertyType, val, true); property.SetValue(o, ev, null); } else { MethodInfo m = property.PropertyType.GetMethod ("Parse", new Type[] { typeof(string) }); object newval = m.Invoke(null /*static */, new object[] { val }); property.SetValue(o, newval, null); } } }
Create European Article Number 13 In Visual Studio .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create EAN / UCC - 13 image in Visual Studio .NET applications.
www.OnBarcode.com
Painting UPCA In Java
Using Barcode creation for Android Control to generate, create UCC - 12 image in Android applications.
www.OnBarcode.com
It too checks the node type, then goes through each of the attributes (e.g., Top or Left) to find their types, and sets the values that follow accordingly (on the last line). This Interpret method makes heavy use of reflection to find out the types of the object attributes. Assuming the XML specification is in a file called calc_winforms.xml, the whole interpreter will be activated by one line:
Mirror m = new Mirror("calc_winforms.xml");
The full program is shown in the Appendix.
Ef ciency
No discussion involving reflection would be complete without mention of efficiency. Any program that relies on reflection has efficiency overheads because for every operation it first has to determine the type of the objects on which it s working. Quantifying these costs for small programs is difficult; however, the overhead is analogous to that incurred in the implementation of the Visitor pattern presented earlier: Examining the type of the object using the is operator Moving through the classes using dynamic dispatch Both of these defer object binding to runtime in order to increase flexibility.
Interpreter Pattern |
Use
The Interpreter pattern is coded up from scratch wherever there is a simple grammar to parse and interpret. For more complex grammars, such as those that describe programming languages or .NET APIs, parsing tools can be employed to set up the object structure. The corresponding Interpret methods can still be successfully written from scratch. In the Mirrors example, the System.Xml API from .NET provides the parser. In compilers, there are special parser generator tools that construct a parse tree from a grammar. Many domain-specific languages define their rules in terms of XML and rely on interpreters to activate them. For example, the Windows Vista operating system, in conjunction with Visual Studio, interprets XML for GUIs.
Use the Interpreter pattern when You have a grammar to be interpreted and: The grammar is not too large. Efficiency is not critical. Parsing tools are available. XML is an option for the specification.
Copyright © OnBarcode.com . All rights reserved.