#Intended as an auxiliary program for citations.tex to alphabetize an output file based on the first group.

#Inputs file sort.tex, to sort as read, takes all data, and then reopens as write
f = open('sort.tex','r')
dat = f.readline().split('\\par ')
f.close()
f = open('sort.tex','w')

def firstgroup(line): #handles nested brackets to return (first group data, other data) tuple.
  nesting = 0
  for charind in range(len(line)):
    char = line[charind]
    if char == '{':
      nesting += 1
    if char == '}':
      nesting -= 1
    if nesting == 0:
      breakchar = charind+1
      break
  return (line[1:breakchar], line[breakchar:])

for lineind in range(len(dat)):
  line = dat[lineind]
  dat[lineind] = firstgroup(line)

dat.sort(key=lambda text : [ord(char) for char in text[0]])
f.write('\\par'.join([line[1] for line in dat]))