Design a compiler like C

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Hi :)
I'm developing a C like compiler and I whant to know, how it's work the include system... I mean, how the compiler works with the system include

The compiler read the entire code, and stores all includes found in one list and parser the includes, after finish the reading the current code?

C

// file main.c
#include <stdio.h> // store in one list

// continue the parse ...
int main()
{
    return 0;
}
// now, read the includes
// after finish the includes parse, gen code of sources

// just a sample
// file stdio.h
#include <types.h> // store in list
#include <bios.h>  // store in list

void printf(...)
{
}

void scanf(...)
{
}

Btw, I have developd an system ( only test ) to read the includes and, stop the parse, to read the include... ( it's a disgusting code, but, work... )
( link of sample )
https://gist.github.com/4399601[^]
Btw, What is the best way to read the includes... and work with includes files ??

Posted 28-Dec-12 5:51am

Alexandre Bencz

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Richard MacCutchan · Accepted Answer · 2012-12-28T06:31:00

Most compilers use a preprocessor to read the included headers and then convert all references, macros etc. into their final form. The converted output of the preprocessor is then fed into the compiler for conversion to object code. There are quite a few free tools available on the internet to help with building compilers, and Google should help you find them.

Andreas Gieriet · Accepted Answer · 2012-12-28T09:32:00

If you want to parse and process any language, you probably need to read some text books first.
E.g. C-Programming Language[^], or C11 Language Draft[^], etc.

E.g. the latter specifies the #include semantics as follows:
[...]
6.10.2 Source file inclusion

Constraints
A #include directive shall identify a header or source file that can be processed by the
implementation.
Semantics
A preprocessing directive of the form
# include <h-char-sequence> new-line
searches a sequence of implementation-defined places for a header identified uniquely by
the specified sequence between the < and > delimiters, and causes the replacement of that
directive by the entire contents of the header. How the places are specified or the header
identified is implementation-defined.
A preprocessing directive of the form
# include "q-char-sequence" new-line
causes the replacement of that directive by the entire contents of the source file identified
by the specified sequence between the " delimiters. The named source file is searched for in an implementation-defined manner. If this search is not supported, or if the search
fails, the directive is reprocessed as if it read
# include <h-char-sequence> new-line
with the identical contained sequence (including > characters, if any) from the original
directive.
[...]

Furthermore, some fallback is defined to avoid infinte inclusion loop (e.g. an implementaiton is not required to support more than 15 nested including levels, etc.).

Usually, including <...> searches first for system headers, "..." searches in the provided -I... paths first. But as stated above, it is implementation dependent. Check your target compiler for the implemented semantics of these includes.

Please note that the #include does not add the files in some "magic" list - it simply replaces the #include line literally by the content of the referenced file (as if you had written the content of the included file at the location of the #include line).

Cheers
Andi

PS: if you use with gcc the -E -C options, you see the effect of the inclusion and other preprocessing.

Design a compiler like C

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