#!/usr/bin/env python
# __author__ = "Ronie Martinez"
# __copyright__ = "Copyright 2018-2019, Ronie Martinez"
# __credits__ = ["Ronie Martinez"]
# __maintainer__ = "Ronie Martinez"
# __email__ = "ronmarti18@gmail.com"


def tokenize(data):
    iterable = iter(data)
    buffer = ''
    while True:
        try:
            char = next(iterable)
            if char == '\\':
                if buffer == '\\':
                    yield buffer + char
                    buffer = ''
                    continue
                elif len(buffer):
                    yield buffer
                buffer = char
                try:
                    buffer += next(iterable)
                except StopIteration:
                    break
            elif char.isalpha():
                if len(buffer):
                    if buffer.endswith('}'):
                        yield buffer
                        yield char
                        buffer = ''
                    elif buffer.startswith('\\'):
                        buffer += char
                else:
                    yield char
            elif char.isdigit():
                if len(buffer):
                    yield buffer
                buffer = char
                while True:
                    try:
                        char = next(iterable)
                    except StopIteration:
                        break
                    if char.isspace():
                        yield buffer
                        buffer = ''
                        break
                    elif char.isdigit() or char == '.':
                        buffer += char
                    else:
                        if buffer.endswith('.'):
                            yield buffer[:-1]
                            yield buffer[-1]
                        else:
                            yield buffer
                        buffer = ''
                        if char == '\\':
                            buffer = char
                        else:
                            yield char
                        break
            elif char.isspace():
                if len(buffer):
                    yield buffer
                    buffer = ''
            elif char in '{}*':
                if buffer.startswith(r'\begin') or buffer.startswith(r'\end'):
                    if buffer.endswith('}'):
                        yield buffer
                        yield char
                        buffer = ''
                    else:
                        buffer += char
                else:
                    if len(buffer):
                        yield buffer
                        buffer = ''
                    yield char
            else:
                if len(buffer):
                    yield buffer
                    buffer = ''
                if len(char):
                    yield char
        except StopIteration:
            break
    if len(buffer):
        yield buffer