<编译原理 - 函数绘图语言解释器（3）解释器 - python>
背景
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编译原理上机实现一个对函数绘图语言的解释器 - 用除C外的不同种语言实现
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设计思路：
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将语法分析器并入绘图功能
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继承语法分析器覆盖重写
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用Pycharm写了一个.py文件：
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semanticfunc.py
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输入流是语法分析器得到的语法树，输出流是绘制的图像
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测试文本序列：
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//----------------测试程序1：分别测试------------------------
ORIGIN IS (100,300); // Sets the offset of the origin
ROT IS 0; // Set rotation Angle.
SCALE IS (1,1); // Set the abscissa and ordinate scale.
FOR T FROM 0 TO 200 STEP 1 DRAW (T,0); // The trajectory of the x-coordinate.
FOR T FROM 0 TO 150 STEP 1 DRAW (0,-T); // The trajectory of the y-coordinate.
FOR T FROM 0 TO 120 STEP 1 DRAW (T,-T); // The trajectory of the function f[t]=t.
FOR T FROM 0 TO 2*PI STEP PI/50 DRAW(COS(T),SIN(T));
//---------测试程序2----------
ORIGIN IS (20, 200);
ROT IS 0;
SCALE IS (40, 40);
FOR T FROM 0 TO 2*PI STEP PI/50 DRAW (T, -SIN(T));
ORIGIN IS (20, 240);
FOR T FROM 0 TO 2*PI STEP PI/50 DRAW (T, -SIN(T));
ORIGIN IS (20, 280);
FOR T FROM 0 TO 2*PI STEP PI/50 DRAW (T, -SIN(T));
//-----------------测试程序3--------------
ORIGIN IS (380, 240);
SCALE IS (80, 80/3);
ROT IS PI/2+0*PI/3 ;
FOR T FROM -PI TO PI STEP PI/50 DRAW (COS(T), SIN(T));
ROT IS PI/2+2*PI/3;
FOR T FROM -PI TO PI STEP PI/50 DRAW (COS(T), SIN(T));
ROT IS PI/2-2*PI/3;
FOR T FROM -PI TO PI STEP PI/50 DRAW (COS(T), SIN(T));
//-------------------测试程序4-------------
ORIGIN IS(580, 240);
SCALE IS (80, 80);
ROT IS 0;
FOR T FROM 0 TO 2*PI STEP PI/50 DRAW(COS(T),SIN(T));
FOR T FROM 0 TO PI*20 STEP PI/50 DRAW((1-1/(10/7))*COS(T)+1/(10/7)*COS(-T*((10/7)-1)),(1-1/(10/7))*SIN(T)+1/(10/7)*SIN(-T*((10/7)-1)));
//-------------------测试程序5------------
//------------ 函数复杂度图形：-----------
ROT IS 0; -- 不旋转
ORIGIN IS (50, 400); -- 设置新原点（距系统默认原点的偏移量）
SCALE IS (2,1); -- 设置比例
FOR T FROM 0 TO 300 STEP 1 DRAW (T,0); -- 横坐标
FOR T FROM 0 TO 300 STEP 1 DRAW (0,-T); -- 纵坐标
SCALE IS (2,1); -- 设置比例
FOR T FROM 0 TO 300 STEP 1 DRAW (T,-T); -- 函数F(T)=T的轨迹
SCALE IS (2,0.1); -- 设置比例
FOR T FROM 0 TO 55 STEP 1 DRAW (T,-T*T); -- 函数F(T)=T*T的轨迹
SCALE IS (10,5); -- 设置比例
FOR T FROM 0 TO 60 STEP 1 DRAW (T,-SQRT(T)); -- 函数F(T)=SQRT(T)的轨迹
SCALE IS (20,0.1); -- 设置比例
FOR T FROM 0 TO 8 STEP 0.1 DRAW (T,-EXP(T)); -- 函数F(T)=EXP(T)的轨迹
SCALE IS (2,20); -- 设置比例
FOR T FROM 0 TO 300 STEP 1 DRAW (T,-LN(T)); -- 函数F(T)=LN(T)的轨迹
Step 1 ：semanticfunc.py - 继承语法分析器并入绘制功能
#!/usr/bin/env python
# encoding: utf-8
'''
@author: 黄龙士
@license: (C) Copyright 2019-2021,China.
@contact: iym070010@163.com
@software: xxxxxxx
@file: semanticfunc.py.py
@time: 2019/11/30 10:47
@desc:
'''
import parserfunc as pf
import scannerclass as sc
import numpy as np
import turtle
import sys
import matplotlib
import matplotlib.pyplot as plt
class semantic(pf.Parsef):
def initPaint(self): # 初始化画布
self.fig = plt.figure()
self.ax = self.fig.add_subplot(111)
def Errmsg(self): #出错处理
sys.exit(1)
def CalcCoord(self,x,y): # 计算点坐标 即比例旋转平移变换 x,y都是二元组
x = x * self.Scale_x
y = y * self.Scale_y ## 进行比例变换
tmp_x = x * np.cos(self.Rot_angle) + y * np.sin(self.Rot_angle)
y = y * np.cos(self.Rot_angle) - x * np.sin(self.Rot_angle)
x= tmp_x ## 旋转变换
x = x + self.Origin_x
y = y + self.Origin_y ## 进行平移变换
return x,y
def DrawLoop(self):
x,y = self.CalcCoord(self.x_ptr,self.y_ptr)
self.ax.scatter(x,y)
def Statement(self): ## 重写statement ，让每次ForStatement执行完毕后画图
self.enter("Statement")
if self.token.type == sc.Token_Type.ORIGIN:
self.OriginStatement()
elif self.token.type == sc.Token_Type.SCALE:
self.ScaleStatement()
elif self.token.type == sc.Token_Type.ROT:
self.RotStatement()
elif self.token.type == sc.Token_Type.FOR:
self.ForStatement()
self.DrawLoop()
# elif self.token.type == sc.Token_Type.CONST_ID or self.token.type == sc.Token_Type.L_BRACKET or
# self.Expression()
else: self.SyntaxError(2)
self.back("Statement")
# 绘图语言解释器入口（与主程序的外部接口）
def Parser(self): # 语法分析器的入口
self.enter("Parser")
if (self.scanner.fp == None): # 初始化词法分析器
print("Open Source File Error !
")
else:
self.FetchToken() # 获取第一个记号
self.Program() # 递归下降分析
plt.show()
self.scanner.CloseScanner() # 关闭词法分析器
self.back("Parser")
Step 2 ：semanticmain.py - 解释器主函数入口
#!/usr/bin/env python
# encoding: utf-8
'''
@author: 黄龙士
@license: (C) Copyright 2019-2021,China.
@contact: iym070010@163.com
@software: xxxxxxx
@file: parsermain.py
@time: 2019/11/26 22:31
@desc:
'''
import scannerfunc as sf
# import parserfunc as pf
import semanticfunc as paint
import os
file_name = 'test.txt'
scanner = sf.scanner(file_name)
semantic = paint.semantic(scanner)
semantic.initPaint()
semantic.Parser()
# parser = pf.Parsef(scanner)
# parser.Parser()
# os.system("pause")
实现结果
- 对于测试程序（1）：
- 对于测试程序（2）：
- 对于测试程序（3）：
- 对于测试程序（4）：
- 对于测试程序（5）：
