ANTLR What is simpliest way to realize python like indent-depending grammar?

Question

I am trying realize python like indent-depending grammar.

Source example:

ABC QWE
  CDE EFG
  EFG CDE
    ABC 
  QWE ZXC

As i see,

Answer 1

Have you looked at the Python ANTLR grammar?

Edit: Added psuedo Python code for creating INDENT/DEDENT tokens

UNKNOWN_TOKEN = 0
INDENT_TOKEN = 1
DEDENT_TOKEN = 2

# filestream has already been processed so that each character is a newline and
# every tab outside of quotations is converted to 8 spaces.
def GetIndentationTokens(filestream):
    # Stores (indentation_token, line, character_index)
    indentation_record = list()
    line = 0
    character_index = 0
    column = 0
    counting_whitespace = true
    indentations = list()
    for c in filestream:
        if IsNewLine(c):
            character_index = 0
            column = 0
            line += 1
            counting_whitespace = true
        elif c != ' ' and counting_whitespace:
            counting_whitespace = false
            if(len(indentations) == 0):
                indentation_record.append((token, line, character_index))
            else:
                while(len(indentations) > 0 and indentations[-1] != column:
                    if(column < indentations[-1]):
                        indentations.pop()
                        indentation_record.append((
                            DEDENT, line, character_index))
                    elif(column > indentations[-1]):
                        indentations.append(column)
                        indentation_record.append((
                            INDENT, line, character_index))

        if not IsNewLine(c):
            column += 1

        character_index += 1
    while(len(indentations) > 0):
        indentations.pop()
        indentation_record.append((DEDENT_TOKEN, line, character_index))
    return indentation_record