I wanna know what type of parser is used in the gcc and turbo c++ compilers. whether a top-down or bottom-up parser is used..... ?
stevanity 4 Posting Whiz in Training
Ancient Dragon 5,243 Achieved Level 70 Team Colleague Featured Poster
parsers start at the top of the program (line 1) and work themselves down. The bottom up approach would be a little like you trying to read a book backwards.
stevanity 4 Posting Whiz in Training
Sorry...Top-down and bottom up parsing is not about the line where parsing starts..
Narue 5,707 Bad Cop Team Colleague
I wanna know what type of parser is used in the gcc and turbo c++ compilers. whether a top-down or bottom-up parser is used..... ?
GCC uses a hand written recursive descent parser (ie. it's top-down). I wouldn't be surprised if Turbo C++ worked the same way, though it might use one of the parser generators rather than a hand written approach.
mike_2000_17 2,669 21st Century Viking Team Colleague Featured Poster
With compilers in general, we often talk about the front-end and the back-end. The front-end is the program that parses the source code, verifies all the grammar and syntax rules, and basically produces a translation of it in some intermediate language (not human-readable but readable for the back-end). The back-end takes the intermediate source code and performs most of the optimizations and then compiles to native machine code. So, the back-end is usually common to an entire compiler suite (like GCC, ICC, Clang, etc.), and then there is one specific front-end for each programming language supported by the compiler suite.
Examples:
- Borland's Delphi and C++Builder compilers share the same back-end (meaning you can also link C++ object files ".obj" with Delphi compiled units ".dcu" together).
- All GCC compilers (C, C++, Objective-C, Ada, Fortran, Java, etc.) share the same back-end, but with different front-ends.
A prominent back-end is LLVM which is used by the Clang front-ends and other compilers.
Prominent front-ends are those of EDG, which are used by Intel and Comeau.
Whatever front-end, parsing the C++ language is not an easy task, because its grammar is complex and context-dependent. Recursive descent parsers are used with plenty of modifications to really get reliable and accurate parsing. There are also tools for generating parsers, including YACC and Boost.Spirit.
stevanity 4 Posting Whiz in Training
GCC uses a hand written recursive descent parser (ie. it's top-down). I wouldn't be surprised if Turbo C++ worked the same way, though it might use one of the parser generators rather than a hand written approach.
Thanks a lot!! That was very helpful... :)
And thanks to everyone who replied :)
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