How should I fix my regular expression to parse this txt file?

This is part of my code that reads the text file I attached and searches the file name between 'subsystems.tbl\' and '.sub' according to the given 'sub_sys (Major Role)' and 'location (Minor Role)' using regular expressions.

if ismember(sub_sys, {'spr', 'dpr', 'bum', 'reb'})
    block_pattern = ['\/([^\/]+)\.', sub_sys];
elseif ismember(sub_sys, 'susp')
    block_pattern = ['\$[-]+\s*SUBSYSTEM[\s\S]*?Major Role : suspension','[\s\S]*?Minor Role : ', location, '[\s\S]*?USAGE\s*=\s*''<[^>]+>/subsystems.tbl/([^'']+)\.sub'''];
elseif ismember(sub_sys, {'steering', 'wheel'})
    block_pattern = ['\$[-]+\s*SUBSYSTEM[\s\S]*?Major Role : ', sub_sys, '[\s\S]*?Minor Role : ', location, '[\s\S]*?USAGE\s*=\s*''<[^>]+>/subsystems.tbl/([^'']+)\.sub'''];
elseif ismember(sub_sys, 'tir')
    block_pattern = ['PROPERTY_FILE\s*=\s*''[^'']+\/([^\/]+)\.tir'''];
end

name_tokens = regexp(file_content, block_pattern, 'tokens', 'once', 'dotexceptnewline');

it reads well for the front suspension system (susp, spr, dpr, bum, reb, steering, wheel, tir) and returns the correct paths, but for rear suspension system, my code reads rr_susp_path = 'AA_TCAR_WHEEL_RR_22inch' instead of giving me rr_susp_path = 'AA_TCAR_SUSP_RR_RWS_230607'

It seems that my regular expression is way too broad and causing this problem. How should I fix my regular expression?

Answer 1

[Stephen23]

"It seems that my regular expression is way too broad and causing this problem."

There are several locations where your regular expression matches unlimited amounts of (almost) anything:

• [^'']+
• [^>]+
• [\s\S]*

I doubt that you really want unlimited matches like that.

"How should I fix my regular expression?"

Perhaps something like this:

pf1 = 'suspension';
pf2 = 'rear';
tmp = strcat('\$\s+',{'Major';'Minor'},'\s+Role\s+:\s+',{pf1;pf2},'\s+');
rgx = ['(?<=',tmp{:},'(\$.+\s+)*USAGE\s+=.+?)\w+\.sub']

rgx = '(?<=\$\s+Major\s+Role\s+:\s+suspension\s+\$\s+Minor\s+Role\s+:\s+rear\s+(\$.+\s+)*USAGE\s+=.+?)\w+\.sub'

str = fileread('test_example.txt');
out = regexp(str,rgx,'match','once','dotexceptnewline')

out = 'AA_TCAR_SUSP_RR_RWS_230607.sub'

[Munho Noh]

Hello Steven, your answer is always helpful, thank you always.

I modified your answer a little bit like the following to capture only the file name except for the .sub extension.

block_pattern = ['(?<=\$\s+Major\s+Role\s+:\s+', sub_sys, '\s+\$\s+Minor\s+Role\s+:\s+', location, '\s+(\$.+\s+)*USAGE\s+=.+\/)(\w+)(?=\.sub)'];

Thank you for your good advice.