Simple program examples of interpreter mode in Python Design Mode Programming, python Design Mode

Simple program examples of interpreter mode in Python Design Mode Programming, python Design Mode

Pattern features: Given a language, define a representation of its syntax and define an interpreter which uses this representation to interpret sentences in the language.

Let's take a look at the following program structure:

class Context:  def __init__(self):    self.input=""    self.output=""class AbstractExpression:  def Interpret(self,context):    passclass Expression(AbstractExpression):  def Interpret(self,context):    print "terminal interpret"class NonterminalExpression(AbstractExpression):  def Interpret(self,context):    print "Nonterminal interpret"if __name__ == "__main__":  context= ""  c = []  c = c + [Expression()]  c = c + [NonterminalExpression()]  c = c + [Expression()]  c = c + [Expression()]  for a in c:    a.Interpret(context)

The class diagram it shows is as follows:

Let's look at an example:

# Encoding = UTF-8 ## by panda # interpreter mode def printInfo (info): print unicode (info, 'utf-8 '). encode ('gbk'), # context class: Playing content class PlayContext (): text = None PlayText = None # Abstract Expression class Expression (): def Interpret (self, context): if len (context. playText) = 0: return else: playKey = context. playText [0: 1] context. playText = context. playText [2:] tmp = context. playText. index ('') # locate the position where the first space appears playValue = context. playText [0: tmp] context. playText = context. playText [tmp + 1:] self. excute (playKey, playValue) def Excute (self, playKey, playValue): pass # Pitch class pitch (Expression): Pitch = None def Excute (self, key, value ): value = int (value) if value = 1: self. pitch = 'bass 'elif value = 2: self. pitch = 'sound' elif value = 3: self. pitch = 'tweeter 'printinfo (self. pitch) # Note class Note (Expression): Notes = {'C': 1, 'D': 2, 'E': 3, 'F': 4, 'G': 5, 'A': 6, 'B': 7,} note = None def Excute (self, key, value): self. note = self. notes [key] printInfo ('% d' % self. note) def clientUI (): context = PlayContext () context. playText = "O 2 E 0.5G 0.5 A 3 E 0.5G 0.5 D 3 E 0.5G 0.5 A 0.5 O 3 C 1 O 2 A 0.5G 1 C 0.5 E 0.5 D 3" expression = None; while (len (context. playText)> 0): str = context. playText [0: 1]; if (str = 'O'): expression = Pitch () elif (str = 'C' or str = 'D' or str = 'E' or str = 'F' or str = 'g' or str = 'A' or str = 'B' or str = 'P '): expression = Note () expression. interpret (context) return if _ name _ = '_ main _': clientUI ();

Class diagram:

Articles you may be interested in:

• Measure the test taker's knowledge about the observer mode and Strategy Mode in Python Design Mode Programming.
• An example of how to use the design pattern in Python
• Analysis of the key points of the Decorator pattern in Python
• Instance parsing Python Design Mode Programming-Application of Bridge Mode
• Examples of Adapter mode in Python Design Mode Programming
• Application Example of prototype in design mode in Python Program
• In-depth analysis of the use of builder mode in Python Design Mode Programming
• An example of how to use the abstract factory mode in Python Design Mode Programming
• The example explains how to use the factory method mode of programming in Python design mode.
• Detailed description of the use of the factory method mode in the design mode in the Python Program
• Use the simple factory mode for Python Design Mode Programming
• Example of using the responsibility chain mode and iterator mode in the design mode in Python