粗略地说它的实现思想是对输入符号串自左向右进行扫描，并将输入符逐个移入一个后进先出栈中，边移入边分析，一旦栈顶符号串形成某个句型的句柄时，（该句柄对应某产生式的右部），就用该产生式的左部非终结符代替相应右部的文法符号串。-Rough idea is that it s the realization of the input symbol string to be scanned from left to right, and enter the site one by one into a LIFO stack, the edges into the side of analysis, once the Top-symbol string a sentence to form a handle when (the handle of a production corresponds to the right of way), on the use of the production left the Department of non-terminator in place of the right of the corresponding string of grammar symbols.