Re: syntax checkers, was Formatting of Language LRMs

Ivan Godard <ivan@ootbcomp.com> wrote:


(snip)


> If the document were a compiler written in Java (i.e. a recognizer and
> checker) then formally there is no difference. Practically, an immense
> difference. VWG is an ASL for specifying languages. All of Algol68 in
> VWG was about four pages of appendix; a compiler for Algol68 written in
> Java would be much more than that, even after you strip out optimization
> and code generation.


There are programs written for OS/360 called "syntax checkers".
They are not compilers, but only enough of one to tell whether
the input is valid syntax in the specific language.


I never used the actual program, but the PLM (Program Logic Manual)
has the (I believe) BNF form for the language, unlike the normal
compiler manuals.


As far as I know, they were not normally used in batch systems, but
were for use by TSO.


Seems to me it should be possible to write a program that will
take BNF input, and a program that is supposed to be written in
that language, and will tell you whether or not it is.


-- glen


[That's basically what yacc and other parser generators do, they
compile BNF or something similar into a program that recognizes input
in the BNF. Of course, for syntax checking you also have to tokenize
the input which is another whole can of worms. -John]

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