scylardor / cminify

A basic minifier for C / C++

C Minifier

A basic, portable C/C++ minifier I initially wrote to minify shaders.

This basically trims whitespace and removes comments. It doesn't do any lexical analyzing, so complex or twisted cases may make it fail.

I hope it will be as useful to you as it is to me.

Requirements

• Python 2.7.6 and higher

Use

• python minifier.py source.c

Example

Given the following input file, test.c:

void	do_math(int * x) {
  *x += 5;
}

int	main(void) {
  int	result = -1, val = 4;

  do_math(&val);
  return result;
}

,

python minifier.py test.c will output the following result:

void do_math(int*x){*x+=5;}int main(void){int result=-1,val=4;do_math(&val);return result;}

License

GPL v3

cminify's Issues

Deprecated open file mode is being used causing ugly warning message

To replacate run script with latest Python.

Invalid output with two nested types of comments

Use case:
When the following comment is encountered, all code following the comment is ignored, and so the output is invalid and does no more compile:

/*
...some comments...
//*/
code

Two-word typenames are wrongly compressed

I usually typedef long double ldbl_t anyways, and I don't have a quick patch for this, but const long double t = ... becomes const long doublet=... and long long int a = ... is turned to long long inta=....

Replace variable names with single character names wherever possible.

It can probably be done using https://github.com/foonathan/cppast
Don't close this feature . If no one takes it up I'll probably send a pull request once I have bandwidth.

overly aggressive whitespace removal

from blog article published here,

minifying the following source code:

void printbin(long long val)
{
        int count = 63; 
        char binstr[65] = {0};

        if (!val) {
                printf("0b0");
                return;
        }   

        /* If negative, get the 2's complement */
        if (val < 0) {
                printf("-0b");
                val = ~val + 1;
         } else
                printf("0b");

         while (val && count >= 0) {
                binstr[count--] = "01"[val & 1]; 
                val >>= 1;
        }   

        count++;

        if (val)
                printf("OVERFLOW %s", binstr + count);
        else
                printf("%s", binstr + count);
}

produced:

void printbin(long long val){int count=63;char binstr[65]={0};if(!val){printf("0b0");return;}if(val<0){printf("-0b");val=~val+1;}elseprintf("0b");while(val && count>=0){binstr[count--]="01"[val & 1];val>>=1;}count++;if(val)printf("OVERFLOW %s",binstr+count);elseprintf("%s",binstr+count);}

it's missing a <SPACE> between the else and printf.

negative number macro not working

this was the input

define MAXIMUM_SCALE 16383

define ESCAPE 256

define DONE -1

define FLUSH -2

this was the output:

define MAXIMUM_SCALE 16383

define ESCAPE 256

define DONE-1

define FLUSH-2

define BUFFER_SIZE 256

Don't compress macro names with their definitions

I'm currently writing a patch for this and I'll create a pull request tomorrow, but basically this:

#define A ((uint8_t) 3)

is turned into

#define A((uint8_t)3)

which is probably not what you wanted

And this:

#define a(c, x) bv(c, x)

becomes

#define a(c,x)bv(c,x)

which is almost certainly not what you want

the patch is almost complete, i just need to clean up the fix a little and write tests.

Doesn't care about whitespace inside string literals

"a: %d %d %d\n"

becomes

"a:%d%d%d\n"

oops.

Ignored blank line at the beginning

If the first line is blank, cminify will not remove it.
Anyway, it works flawlessly in my code.

Runs together identifiers across linebreaks

Input:
`#include <stdio.h>

int
main(int argc, char **argv) {
printf("hello world\n");
}
`

Output:
#include<stdio.h> intmain(int argc,char**argv){printf("hello world\n");}
Note "intmain". Placing the return type of a function on the line before is often useful, since it lets you search for the definition of the function by searching for it at the beginning of a line.

Cannot Run on macOS 10.12.4, python 2.7.10

When I run the command python minifier.py A.cpp
It returns:

Traceback (most recent call last):
  File "minifier.py", line 220, in <module>
    main()
  File "minifier.py", line 217, in main
    minify_source_file(args, filename)
  File "minifier.py", line 185, in minify_source_file
    print(final_string)
UnboundLocalError: local variable 'final_string' referenced before assignment

How to fix it?

issue when there are multiple #define inside a function

Hi, I have seen some odd behavior, and it seems to me, that when there are two #defines inside a function, the minifier process puts them in one line. Outside a function there is no problem.

main() {
  #define ONE 1  
  #define TWO 2
}

Then:
./minifier.py test.c

main(){#define ONE 1#define TWO 2}

Which won't compile, with stray '#' in program error.