It shouldn't be too involved to produce whatever well-typed Ur
expressions you want to represent locations.
On 03/16/2015 07:40 PM, Sergey Mironov wrote:
2015-03-16 3:29 GMT+03:00 Adam Chlipala <[email protected]>:
Let's see if I understand right: you want some token you can write in source
code, to be replaced at compile time by the location of the token, along the
lines of C's __FILE__ and __LINE__.
Yes, exactly!
Yes, it sounds like an easy feature to add. I would actually do it entirely
in the parser. I'd extend src/urweb.lex with a production for a new
reserved identifier for this 'macro', and I'd extend one of the expression
nonterminals in src/urweb.grm with a rule that translates the source
location of said token into an Ur/Web string literal, using
[ErrorMsg.spanToString], getting ahold of the span in the same way that it
is already being produced to label each expression with its location for
purposes of later error messages.
The only note from me: I plan to build source urls using the location
information, so it's better to have an access to line/character
position as integers. String representation would probably require
writing a parser (which is still better than nothing, of cause!)
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