Error location in Camlp4

["Sham K" <shaawm@gmail.com>]

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Hello Everyone,

I have written a tokenizer (using parser constructs in camlp4) which
tokenizes a character stream of a string. I use this to define a lexer
(using Token.lexer_func_of_parser) as shown in turorials and manuals on
camlp4. Then I make use of EXTEND statements to interpret token stream to
according to  some syntax to build some Abstract syntax tree.

All this works fine. However, whenever there is error I just get
"Stdpp.Exc_located" with no indications of the location of error. (It is
just (_,_) )

The camlp4 manual says that in the action part of rules, a variable loc is
always defined which can be used to raise errors.
But the complier complains that loc is not defined when I try to use loc in
try ... with statements.

Can someone explain how I can print error locations. It works with standard
lexer plexer, but not with my lexer. I do not quite
see what else I should include in my lexer to enable error location
reporting.

Thanks for your time.
Sham

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