Nested Loop lines in a file n times (Example 3) below: Python

Question

I have a file with lines which need to be repeated as many times as the decimal/hex value mentioned in the first line.

Input Example:

Loop  3  {Line1}  ##the line is within curly braces so I used regex but not printing it out right. 
Label: Blank {Line2}
Jump Label {Line3}

Output Example:

Line1
Line2
Line3
Line2
Line3
Line2
Line3

My code so far:

line_1_ = re.compile(r'Loop\s*([0-9]+|0x[0-9a-fA-F]+)\s*\{(\w+)\}', re.DOTALL)
for match in line_1_.finditer(inputfileContents):
    looptimes =  int(match.group(1))
    line_1 = match.group(2)
    jump = re.search(r'Jump\s*(\w+)\s*\{(.*?)\}', inputfileContents, re.DOTALL)
    label = re.search(r'(\w+):\s*(\w+)\s*\{(\w+)\}', inputfileContents, re.DOTALL)
    for i in range(looptimes):
        if jump.group(1) == label.group(1):
            print '%s\n%s' % (label.group(3), jump.group(2))

Error: I cannot increment a line with line++. Which I understand as it is a string but not sure how to increment it otherwise.

Effectively it is just repeating Line2 and Line 3 3 times. But if there are multiple lines between the Jump and loop it has to print all the lines starting from Label statement to the jump statement including the jump statement.

This doesn't work if there are multiple lines between the jump and label statements...

Example 2:

Blank {Line0}
Loop  3  {Line1}  
Label: Blank {Line2}
       Blank {Line3}
       Blank {Line4}
Jump Label {Line5}
Blank {Line6}

Expected Output int he above case:

Line0
Line1
Line2
Line3
Line4
Line5
Line2
Line3
Line4
Line5
Line2
Line3
Line4
Line5
Line6

Example 3:

Blank  {Line0}
Loop 3 {Line1}
Label2 {Line2}
Blank  {Line3}
Loop 2 {Line4}  
Label1:{Line5}
Blank  {Line6}
Jump Label1 {Line7}
Blank  {Line8}
Jump Label2 {Line9}
Blank  {Line10}

Output I need:

Line0
Line1
Line2
Line3
Line4
Line5
Line6
Line7
Line5
Line6
Line7
Line8
Line9
Line2
Line3
Line4
Line5
Line6
Line7
Line5
Line6
Line7
Line8
Line9
Line2
Line3
Line4
Line5
Line6
Line7
Line5
Line6
Line7
Line8
Line9
Line10

I tried to implement @Samy Arous method from here: Using Python to Parse a File for Nested Loops but couldn't implement it so far.

Welcome to Stack Overflow! It looks like you want us to write some code for you. While many users are willing to produce code for a coder in distress, they usually only help when the poster has already tried to solve the problem on their own. A good way to demonstrate this effort is to include the code you've written so far, example input (if there is any), the expected output, and the output you actually get (console output, tracebacks, etc.). The more detail you provide, the more answers you are likely to receive. Check the FAQ and How to Ask. — Adam Smith
– Adam Smith, Commented Sep 29, 2014 at 23:40
I should probably not use regex, but with ragex I can check for each part of the line .. I dint post it earlier because my code is not going the right direction... — Doodle
– Doodle, Commented Sep 29, 2014 at 23:56
Is your output example what you want, or what you are getting? — Ethan Furman
– Ethan Furman, Commented Sep 30, 2014 at 0:31
I am getting that output right now. But I need to change this so that it is able to print out multiple lines between Jump and Label.. Right now if I add couple lines between the two statements my code will break. — Doodle
– Doodle, Commented Sep 30, 2014 at 0:35
I have edited including the possible input for which my code is not working.. — Doodle
– Doodle, Commented Sep 30, 2014 at 0:39

John Zwinck · Accepted Answer · 2014-09-30 06:59:29Z

0

I found it easier without regex:

import sys

infile = sys.stdin

def extract(line):
    return line[line.find('{') + 1: line.rfind('}')]

for first in infile:
    if first.startswith('Loop '):
        break
    else:
        print extract(first)

count = int(first.split()[1])
lines = [extract(first)] + map(extract, infile)

while count > 0:
    print '\n'.join(lines)
    count -= 1

edited Sep 30, 2014 at 6:59

answered Sep 30, 2014 at 0:41

John Zwinck

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8 Comments

Doodle Over a year ago

I used regex because these are not the only lines int he infile, it has many and I am matching those lines that are int his format..

John Zwinck Over a year ago

OK well you can do that part by splitting the line and checking the first token (if it's Loop or Label or Jump etc.). I don't think you need regexes still. Anyway, all the example inputs you've posted so far work with the code I wrote above; perhaps you can add a more full example with expected output.

Doodle Over a year ago

Thanks yes it works. Could you suggest a link for the return statement you have used? I am trying to understand that..

John Zwinck Over a year ago

I just return a "slice" of line by the expression line[start:end], where start is the first character to include, i.e. one past the { and end is the first character to exclude, i.e. the final }.

Doodle Over a year ago

I just added a line for which this breaks. My file is huge and I have many different kinds of lines.. So processing each line as I read and when I read the Loop line I need to Loop the jump statement that many times

|

Doodle · Accepted Answer · 2014-10-02 23:22:59Z

This works when there are multiple loop statements in a file

import sys

inputtfile = sys.stdin
inputfileContents = open(r'path to input file')


def extract(line):
    return line[line.find('{') + 1: line.rfind('}')]

loopCount = 0
loopLines = []
inLoop = False
for line in inputfileContents:
    if line.startswith('Loop '):
        loopCount = int(line.split()[1])
    inLoop = True
    loopLines.append(extract(line))
    elif line.startswith('Jump '):
        loopLines.append(extract(line))
        for i in range(loopCount):
            for loopLine in loopLines:
                print loopLine

    #reset state variables to track next possible loop
    loopCount = 0
    inLoop = False
    loopLines = []
    elif inLoop:
        loopLines.append(extract(line))
    else:
        print extract(line)

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