mesongen.py

#!/usr/bin/env python3
# mesongen.py: update special meson.build files
import os
from fnmatch import fnmatch
from re import compile
# marker to process file
marker = 'meson.build.gen'
buildfile = 'meson.build'
newline = os.linesep.encode('utf-8')
matchexp = compile(r'#\s*%s\s*' % marker)


def isgenerated(hdr):
    ''' get end of header marker '''
    match = matchexp.match(hdr.decode('utf-8'))
    return match if match is None else match.end()


def write_entries(f, elem):
    ''' write file entries to output '''
    for e in elem:
        f.write(b'  \'')
        f.write(e.encode('utf-8'))
        f.write(b'\',' + newline)


def content(pattern, path='.', match=None):
    ''' collect matching filenames '''
    if type(pattern) == str:
        pattern = pattern.split()
    buf = []
    for f in os.listdir(path):
        fn = os.path.join(path, f)
        if os.path.isfile(fn):
            m = './' + f if match is None else match + '/' + f
            for p in pattern:
                if not p.count('/'):
                    if fnmatch(f, p):
                        buf.append(f if match is None else m)
                        break
                else:
                    if fnmatch(m, p):
                        buf.append(f if match is None else m)
                        break
        elif os.path.isdir(fn):
            m = f if match is None else match + '/' + f
            buf = buf + content(pattern, fn, m)
    return buf


def update(path=buildfile, clear=False):
    ''' rewrite build file '''
    header = open(path, 'rb').readline()
    pos = isgenerated(header)
    if pos is None:
        return False
    
    if clear is True:
        open(path, 'wb').write(header)
        return True
    
    pattern = header[pos:].decode('utf-8')
    buf = content(pattern.split(), os.path.dirname(path))
    buf.sort()
    
    with open(path, 'wb') as out:
        out.write(header)
        if not pattern.endswith(os.linesep):
            out.write(newline)
        out.write(b'src = files(' + newline)
        write_entries(out, buf)
        out.write(b')' + newline)
    
    return True


def update_recursive(path='.', clear=False):
    ''' rewrite all build files in path'''
    for root, dirs, files in os.walk(path):
        if files.count(buildfile):
            update(os.path.join(root, buildfile), clear)


if __name__ == "__main__":
    from sys import exit, stderr, argv
    if len(argv) < 2:
        update_recursive('.')
    elif argv[1] == 'clean':
        if len(argv) < 3:
            update_recursive('.', clear=True)
        else:
            for d in argv[2:]:
                if not update(d, clear=True):
                    exit(1)
    elif argv[1] == 'gen':
        if len(argv) < 3:
            update_recursive('.')
        else:
            for d in argv[2:]:
                if not update(d):
                    exit(1)
    else:
        stderr.write('bad operation: ' + argv[1] + os.linesep)
        exit(2)