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From: vaib on 19 Jun 2008 17:29
hi all . i am trying to build a parser in ANSI C . I made a lexical
analyser in the same language a while ago . It was a very simple lexer
that tokenised a simple C source code text file - basically a very
simple lexer . I had made use of hash tables for the data structure .
Now i want to know how to build a parser . I'll let you know what i
know about parser building - i'll need a grammar written in the form
of regular expressions , i would need to implement something called a
parse tree in a data structure of my choice and so on . The problem is
that i know stuff here and there but i haven't got a full picture as
to what approach is to be taken to attack the problem ,i.e, i do not
know the steps involved in the learning curve for parser building .
Can anyone out there kindly layout the steps to be taken in proper
order ? i want to have a working parser in the next 15 days since
thats the amount of time after which my college resumes . I have
compiler construction in my next semester so i want to have atleast
the front-end ready before the course starts . I do not want a very
efficient , high-end or hi-tech parser - just a simple one that
demonstrates the concept decently . Any language whose grammar (in the
form of REs) is available would do , its not that i want to stick with
C alone since i made my lexer for that . It would be very appreciative
if anyone who's made a parser before in C could lend me the source
code for studying purposes . Resorces that would not take much time
are welcome - you see , since i have time constraints i'd like to get
to the coding part as soon as possible (and please tell me where to
get that grammar from too) .
Thanking in anticipation . Vaib .
From: Jerry Coffin on 20 Jun 2008 01:17
In article <6349c591-c73b-4122-9b5d-76f2705754f3
@t12g2000prg.googlegroups.com>, vaibhavpanghal(a)gmail.com says...
> hi all . i am trying to build a parser in ANSI C . I made a lexical
> analyser in the same language a while ago . It was a very simple lexer
> that tokenised a simple C source code text file - basically a very
> simple lexer . I had made use of hash tables for the data structure .
> Now i want to know how to build a parser . I'll let you know what i
> know about parser building - i'll need a grammar written in the form
> of regular expressions , i would need to implement something called a
> parse tree in a data structure of my choice and so on .

Not so. Lexers are typically written in terms of regular expression, but
parsers usually are not. To write a parser you normally start by writing
the grammar in something like Backus-Naur Form. From there, you can
write the parser by hand, typically using recursive descent, or you can
generate it with a compiler-compiler such as yacc, Bison, Byacc, Antlr,
or any number of others.

--
Later,
Jerry.

The universe is a figment of its own imagination.
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