Edited overview and Scope
This problem boils down to the following problem; given a source file, automatically place open and closing braces for optional control blocks in C/C++. These blocks are if, else, do, while, and for afaik.
Overview
I am attempting to trace and analyze various loops, statements, and the like in a massive code repository that I have not written myself. My end goal is to perform timing statistics on all loops (will be expanded to other things in the future, but out of scope for this problem) in a given source of code. These trace functions do various things, but they all follow a similar issue; being placed before and after a block of interest is executed.
In essence, I want to transform the code:
for (i = 0; i < some_condition; i++) {
some_code = goes(here);
}
for (i = 0; i < some_condition; i++)
{
some_code = goes(here);
}
for (i = 0; i < some_condition; i++) { some_code = goes(here); }
for (i = 0; i < some_condition; i++)
some_code = goes(here);
for (i = 0; i < some_condition; i++)
for (i = 0; i < some_condition; i++)
some_code = goes(here);
to the following:
S_TRACE(); for (i = 0; i < some_condition; i++) {
some_code = goes(here);
} E_TRACE();
S_TRACE(); for (i = 0; i < some_condition; i++)
{
some_code = goes(here);
} E_TRACE();
S_TRACE(); for (i = 0; i < some_condition; i++) { some_code = goes(here); } E_TRACE();
S_TRACE(); for (i = 0; i < some_condition; i++) {
some_code = goes(here); } E_TRACE();
S_TRACE(); for (i = 0; i < some_condition; i++) {
S_TRACE(); for (i = 0; i < some_condition; i++) {
some_code = goes(here); } E_TRACE(); } E_TRACE();
Basically, without new lines of code added, I want to insert a function before the statement begins (easy) and after the statement (which can be hard). For example, the following code is actually in the repository of code:
for( int i = 0; names[i]; i++ )
if( !STRCMP( arg, names[i] ) )
{
*dst = names[i];
return 0;
}
return -1;
Terrible readability aside, I'd like to place braces on this type of loop, and insert my tracing functions. Arguments to the function (to account for nesting) I have omitted.
Current Implementation
My current implementation uses regex in Python, as I'm fairly comfortable and quick in this language. Relevant segments of implementation are as follows:
import re
source = []
loops = [r"^\s*(for\s*\(.*\))\s*($|{\s*$|\s*)", r"^\s*(while\s*\(.*\))\s*($|{\s*$|\s*)", r"^\s*(do)\s*({?)$"]
def analyize_line(out_file):
lnum, lstr = source.pop(0)
for index, loop_type in enumerate(loops):
match = re.findall(loop_type, lstr)
if match:
print(lnum + 1, ":", match[0][0])
if '{' in match[0][1]:
out_file.write(lstr.replace(match[0][0], "S_TRACE(); {}".format(match[0][0])))
look_ahead_place()
return
else:
last_chance = lstr + source[0][1]
last_match = re.findall(loop_type, last_chance)
if last_match and '{' in last_match[0][1]:
# same as above
out_file.write(lstr.replace(match[0][0], "S_TRACE(); {}".format(match[0][0])))
lcnum, lcstr = source.pop(0)
out_file.write(lcstr)
look_ahead_place()
else:
# No matching bracket, make one
out_file.write(lstr.replace(match[0][0], "S_TRACE(); {} {{".format(match[0][0])))
look_ahead_and_place_bracket()
return
# if we did not match, just a normal line
out_file.write(lstr)
def look_ahead_place():
depth = 1
for idx, nl in enumerate(source):
substr = ""
for c in nl[1]:
substr += c
if depth > 0:
if c == '{':
depth += 1
elif c == '}':
depth -= 1
if depth == 0:
substr += " E_TRACE(); "
if depth == 0:
source[idx][1] = substr
return
print("Error finding closing bracket here!")
exit()
def look_ahead_and_place_bracket():
for idx, nl in enumerate(source):
# Is the next line a scopable? how to handle multiline? ???
# TODO
return
def trace_loops():
global source
src_filename = "./example.c"
src_file = open(src_filename)
out_file = open(src_filename + ".tr", 'w')
source = [[number, line] for number, line in enumerate(src_file.readlines())]
while len(source) > 0:
analyize_line(out_file)
trace_loops()
The example.c is the example provided above for demonstration purposes. I am struggling to come up with an algorithm that will handle both inline loops, loops with no matching braces, and loops that contain no braces but have multiline inners.
Any help in the development of my algorithm would be much appreciated. Let me know in the comments if there is something that needs to be addressed more.
EDIT :: Further Examples and Expected Results
Characters that are added are surrounded by < and > tokens for visibility.
Nested Brace-less:
for( int i = 0; i < h->fdec->i_plane; i++ )
for( int y = 0; y < h->param.i_height >> !!i; y++ )
fwrite( &h->fdec->plane[i][y*h->fdec->i_stride[i]], 1, h->param.i_width >> !!i, f );
<S_TRACE(); >for( int i = 0; i < h->fdec->i_plane; i++ )< {>
<S_TRACE(); >for( int y = 0; y < h->param.i_height >> !!i; y++ )< {>
fwrite( &h->fdec->plane[i][y*h->fdec->i_stride[i]], 1, h->param.i_width >> !!i, f );< } E_TRACE();>< } E_TRACE();>
Nested Mixed:
for( int i = 0; i < h->fdec->i_plane; i++ ) {
for( int y = 0; y < h->param.i_height >> !!i; y++ )
fwrite( &h->fdec->plane[i][y*h->fdec->i_stride[i]], 1, h->param.i_width >> !!i, ff );
}
<S_TRACE(); >for( int i = 0; i < h->fdec->i_plane; i++ ) {
<S_TRACE(); >for( int y = 0; y < h->param.i_height >> !!i; y++ )< {>
fwrite( &h->fdec->plane[i][y*h->fdec->i_stride[i]], 1, h->param.i_width >> !!i, ff );< } E_TRACE();>
}< E_TRACE();>
Large Multiline Nested Brace-less:
for( int i = 0; i < h->sh.i_mmco_command_count; i++ )
for( int j = 0; h->frames.reference[j]; j++ )
if( h->frames.reference[j]->i_poc == h->sh.mmco[i].i_poc )
x264_frame_push_unused(
h,
x264_frame_shift( &h->frames.reference[j] )
);
<S_TRACE(); >for( int i = 0; i < h->sh.i_mmco_command_count; i++ )< {>
<S_TRACE(); >for( int j = 0; h->frames.reference[j]; j++ )< {>
if( h->frames.reference[j]->i_poc == h->sh.mmco[i].i_poc )
x264_frame_push_unused(
h,
x264_frame_shift( &h->frames.reference[j] )
);< } E_TRACE();>< } E_TRACE();>
This Gross Multiliner:
for( int j = 0;
j < ((int) offsetof(x264_t,stat.frame.i_ssd) - (int) offsetof(x264_t,stat.frame.i_mv_bits)) / (int) sizeof(int);
j++ )
((int*)&h->stat.frame)[j] += ((int*)&t->stat.frame)[j];
for( int j = 0; j < 3; j++ )
h->stat.frame.i_ssd[j] += t->stat.frame.i_ssd[j];
h->stat.frame.f_ssim += t->stat.frame.f_ssim;
<S_TRACE(); >for( int j = 0;
j < ((int) offsetof(x264_t,stat.frame.i_ssd) - (int) offsetof(x264_t,stat.frame.i_mv_bits)) / (int) sizeof(int);
j++ )< {>
((int*)&h->stat.frame)[j] += ((int*)&t->stat.frame)[j];< } E_TRACE();>
<S_TRACE(); >for( int j = 0; j < 3; j++ )< {>
h->stat.frame.i_ssd[j] += t->stat.frame.i_ssd[j];< } E_TRACE();>
h->stat.frame.f_ssim += t->stat.frame.f_ssim;
If Statement Edgecase:
Perhaps my implementation requires an inclusion of if statements to account for this?
if( h->sh.i_type != SLICE_TYPE_I )
for( int i_list = 0; i_list < 2; i_list++ )
for( int i = 0; i < 32; i++ )
h->stat.i_mb_count_ref[h->sh.i_type][i_list][i] += h->stat.frame.i_mb_count_ref[i_list][i];
