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📁 建立《编译原理网络课程》的目的不仅使学生掌握构造编译程序的原理和技术
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<p><b>例5.15 </b>如果把表5.3中建立语法树的语法制导定义转化成翻译模式，那么关于E的产生式和语义动作就变为：<br>
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;E→E<span class="down"><sub>1</sub></span>＋T  
{B.nptr:=mknode('+',E<span class="down"><sub>1</sub></span>.nptr,T.nptr)}<br>
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;E→E<span class="down"><sub>1</sub></span>-T&nbsp;  
{E.ntpr:=mknode('-',E<span class="down"><sub>1</sub></span>.nptr,T.nptr)}<br>
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;E→T &nbsp;&nbsp;&nbsp; {E.ntpr:=T.nptr} 
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<p>当从翻译模式中消除左递归时，非终结符号E对应于翻译模式（5.2）中的A，前面两个产生式中的＋T和－T对应为Y;第三个产生式中的T对应于X。由表5.3的全部内容经过转化的翻译模式由图5.17表示。有关T的产生式和语义动作与表5.3中原有定义相似。
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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; E→T&nbsp; {R.i:=T.nptr}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;R&nbsp;｛E.nptr:=R.s}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;R→＋<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;T&nbsp;｛R.i:=mknode('+',R.i,R.nptr)}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;R<span class="down"><sub>1</sub></span>&nbsp;｛R.s:=R<span class="down"><sub>1</sub></span>.s}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;R→-<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;T&nbsp;&nbsp;｛R<span class="down"><sub>1</sub></span>.i:=mknode('-',R.i,T.nptr)}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;R<span class="down"><sub>l</sub></span>  
&nbsp;{R.s:=R<sub>1</sub>.s}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;R→ε&nbsp;｛R.s:=R.i}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;T→(<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;E<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;)  
&nbsp;&nbsp;{T.nptr:=E.nptr}<br>
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;T→<b>id&nbsp;</b> {T.nptr:=mkleaf(<b>id</b>,<b>id</b>.entry)}<br> 
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;T→<b>num</b> ｛T.nptr:=mkleaf(<b>num</b>,<b>num</b>.val)}<br> 
&nbsp;&nbsp;&nbsp;<br>
&nbsp;&nbsp;&nbsp; <font face="楷体_GB2312">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  
&nbsp;图5.17&nbsp;&nbsp; 构造语法树的翻译模式</font><br>
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