Demangle the mangled names in C++ flamegraphs (perf)

demanglify.py

import cxxfilt

def toxml(s):
    s = str.replace(str(s), '&', '&')
    s = str.replace(str(s), '<', '&lt;')
    return str.replace(str(s), '>', '&gt;')

def tostr(s):
    s = str.replace(str(s), '&gt;', '>')
    s = str.replace(str(s), '&lt;', '<')
    return str.replace(str(s), '&amp;', '&')

# import re

fname = '/home/smartfm/isura/flamegraphs/flamegraphs/2019-06-04-10:55:20perf-kernel.svg'

def main():
    # doc = minidom.parse(fname)
    # path_strings = doc.getElementsByTagName('title')
    # doc.unlink()
    # for ps in path_strings[:10]:
    #     if ps.firstChild:
    #         print(repr(ps.firstChild.nodeValue.strip()))

    fstr = open(fname).read()
    outs = ''
    invalids = 0
    dc = 0
    f = True
    i = 0
    demangled = ''
    while i < len(fstr):
        if dc % 100 == 0 and dc != 0 and f:
            f = False
            print(dc)
        if fstr[i:i+7] == '<title>':
            for j in range(i + 7, len(fstr)):
                if fstr[j:j + 2] == ' (':
                    mangled = fstr[i + 7:j]
                    try:
                        demangled = cxxfilt.demangle(mangled)
                    except cxxfilt.InvalidName:
                        demangled = mangled
                    dc += 1
                    f = True
                    demangled = toxml(demangled)
                    outs += '<title>' + demangled
                    i = j
                    break
        if fstr[i:i + 5] == '<text':
            i += 5
            outs += '<text '
            if fstr[i + 1] != ' ':
                i += 1
                continue
            while fstr[i] != '>':
                i += 1
                outs += fstr[i]
            for j in range(i + 1, len(fstr)):
                if fstr[j:j + 7] == '</text>':
                    lentext = j - i - 1
                    newtext = fstr[i + 1:j]
                    if fstr[i + 1:j] != demangled and lentext != 0:
                        newtext = toxml(tostr(demangled)[:lentext - 2] + '..')
                    outs += newtext + '</text>'
                    i = j + 7 - 1
                    break
        else:
            outs += fstr[i]
        i += 1
    print(str.replace(fname, '.svg', '-demangled.svg'))
    open(str.replace(fname, '.svg', '-demangled.svg'), 'w').write(outs)


if __name__ == '__main__':
    main()