Problem Detail: I had written a compiler compiler a few years ago and I’m now cleaning it up, improving it, and turning it into C. I came across a terminology problem however that I remember in the past I couldn’t solve it either. Imagine an LL(k) stack. In this stack, you may have terminals, that are expected to be matched with the next token, or non-terminals that would expand based on the next token. In either case, there is a string in the stack. The word I am looking for, is a term that means either a terminal or non-terminal. Wikipedia was of no help. To clarify a bit more, imagine a grammar with $t = {a mid a text{ terminal}}$ and $T = {A mid A text{ non-terminal}}$. If you have a set $X = {x | x in t vee x in T}$, how would you refer to an element of $X$? “Grammar symbol”? “Grammar element”? “Terminal or non-terminal symbol”? I am in particular looking for a name as short and to the point as possible, since this will end up becoming a variable name!
Asked By : Shahbaz
Answered By : Raphael
The long forms “terminal symbol” and “nonterminal symbol” suggest that you are dealing first and foremost with “symbols”; “terminal” and “non-terminal” are qualifiying attributes that specify a symbol’s role in the grammar. A symbol that can be either one of terminal and non-terminal is, almost by virtue of logics, just an arbitrary symbol. Therefore, “symbol” seems to be the natural choice. I am pretty sure it is the term usually used, too, but such statements are hard to validate. If you want to stress that a given symbol can be either kind (in text), you can always use “arbitrary symbol (of grammar $G$)”, or define $X subseteq t cup T$ explicitly. In source code, I’d just use “symbol”.
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Question Source : http://cs.stackexchange.com/questions/2868
