实验目的

通过上机实习,加深对语法制导翻译原理的理解,掌握将语法分析所识别的语法成分变换为中间代码的语义翻译方法.

实验要求

采用递归下降语法制导翻译法,对算术表达式、赋值语句进行语义分析并生成四元式序列。



实验的输入和输出

输入是语法分析提供的正确的单词串，输出为三地址指令形式的四元式序列。

例如：对于语句串

begin a:=2+3*4 x:=(a+b)/c end#

输出的三地址指令如下：

（1）　　t1=3*4

（2）　　t2=2+t1

（3）　　a=t2

（4）　　t3=a+b

（5）　　t4=t3/c

（6）　　x=t4

-The experiment was on the plane, through internships, deepen their understanding of grammar-guided understanding of the principles of translation, grammatical analysis will have identified components of the grammar is transformed into intermediate code semantic translation. Experimental decline to adopt the recursive grammar-guided translation of arithmetic expressions, assignment and semantic analysis to generate quaternion sequence. Experimental input and output analysis input is the correct syntax of the word string, the output for the three forms of instruction address sequence quaternion. For example: string for the statement begin a: = 2+3* 4　x: = (a+ b)/c end# output of the three address instructions are as follows: (1) t1 = 3* 4 (2) t2 = 2+ t1 (3) a = t2 (4) t3 = a+ b (5) t4 = t3/c (6) x = t4