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Purpose: To allow nested For Loops with a minimum of syntax change from the standard For Loop.

Reason: I want to nest For Loops in Robot Framework. The code is working perfectly as a custom library/keyword in Robot Framework, but I'm asking for input to improve the code. I have no formal training in Python. This script was how I learned the language, so please don't expect it to be "Pythonic", I think the term is.

Sample Robot Framework code to run this keyword:

*** Settings ***
Library     ExtendedSelenium2Library
Library     Collections
Library     Loops.py

*** Variables ***
${gold_squadron} =  Gold
${red_squadron} =   Red

*** Test Cases ***
Test For Loop
    For Loop    IN RANGE    0   1   INDEX0
    ...     \\  For Loop    IN RANGE    1   6   INDEX1
    ...     \\  \\  Assign Internal Variable    {{standing_by}}     Standing By Red Leader
    ...     \\  \\  Run Keyword If      INDEX1 == 1     Log to Console  ${red_squadron} Leader Standing By
    ...     \\  \\  Run Keyword Unless  INDEX1 == 1     Log to Console  ${red_squadron} INDEX1 {{standing_by}}
    ...     \\  For Loop    IN RANGE    1   6   INDEX2
    ...     \\  \\  Assign Internal Variable    {{standing_by_2}}   Standing By Gold Leader
    ...     \\  \\  Run Keyword If      INDEX2 == 1     Log to Console  ${gold_squadron} Leader Standing By
    ...     \\  \\  Run Keyword Unless  INDEX2 == 1     Log to Console  ${gold_squadron} INDEX2 {{standing_by_2}}

And here is the code I'm working on.

from robot.libraries.BuiltIn import BuiltIn

# TODO: Create new types of For Loops and While Loops


class Loops(object):

    def __init__(self):
        self.selenium_lib = BuiltIn().get_library_instance('ExtendedSelenium2Library')
        self.internal_variables = {}

    def for_loop(self, loop_type, start, end, index_var, *keywords):
        #   Format the keywords
        keywords = self._format_loop(*keywords)

        #   Clean out the internal variables from previous iterations
        self.internal_variables = {}

        #   This is the actual looping part
        for loop_iteration in range(int(start), int(end)):
            keyword_set = self._index_var_swap(loop_iteration, index_var, *keywords)
            #   If it's a one-keyword list with no arguments, then I can use the fastest possible keyword to run it
            if len(keyword_set) == 1:
                BuiltIn().run_keyword(keyword_set)
            #   If it's a one-keyword list with arguments, then I can use a faster keyword to run it
            elif 'AND' not in keyword_set:
                BuiltIn().run_keyword(*keyword_set)
            #   If it's a multiple-keyword list, then I have to use Run Keywords
            else:
                BuiltIn().run_keywords(*keyword_set)

    def _format_loop(self, *keywords):
        keywords = list(keywords)   # I need to format the keywords as a list.
        changed = False             # Whether or not I changed anything in the previous iteration.
        index = 0                   # The item index I'm at in the list of keywords
        del_list = []               # The list of items I need to delete
        swap_list = []              # The list of items i need to swap to AND for the use of Run Keywords
        #   For each argument
        for x in keywords:
            #   Format it to a string
            x = str(x)
            #   If the keyword in question happens to be one of the 'Assign Internal Variable' keywords, then I need
            #       to run it now, not later.
            #   By splitting it up, I add a little complexity to the code but speed up execution when you're just
            #       assigning a scalar variable as opposed to having to search through the next few items just to find
            #       what I know is just going to be the next one.
            #   So, if it's the simple assignment...
            if x.lower() == 'assign internal variable':
                #   ...run the Assign Internal Variable keyword with the two inputs
                BuiltIn().run_keyword(x, *keywords[int(index)+1:int(index)+3])
            #   If it's the more complicated variable...
            elif x.lower() == 'assign internal variable to keyword':
                #   ...initialize variables...
                deliminator_search = 0
                k_check = x
                #   ...search the next few keywords for a deliminator...
                while k_check != '\\' and k_check != '\\\\':
                    deliminator_search = deliminator_search + 1
                    k_check = keywords[int(index)+deliminator_search]
                #   ...and run the Assign Internal Variable to Keyword keyword with the found keyword
                BuiltIn().run_keyword(x, *keywords[int(index)+1:int(index)+2+deliminator_search])

            #   If the previous element was not changed...
            if not changed:
                #   If the current item is not the last one on the list...
                if x != len(keywords) - 1:
                    #   If the current item is a deliminator...
                    if x == '\\':
                        #   If the next item is a deliminator, delete this item and set changed to True
                        if keywords[int(index) + 1] == '\\':
                            del_list.append(index)
                            changed = True
                        #   If the next item is not a deliminator...
                        else:
                            #   If this isn't the first deliminator on the list, swap it to an 'AND'
                            if index != 0:
                                swap_list.append(index)
                                changed = True
                            #   If this deliminator is in position index=0, just delete it
                            else:
                                del_list.append(index)
                                changed = True
                    #   If the current element is not a deliminator, then I don't need to touch anything.
                #   If the current element is the last one, then I don't need to touch anything
            #   If the previous element was changed, then I don't need to "change" this one...
            elif changed:
                changed = False
                #   ...but if it's a deliminator then I do need to set it up for the inner for loop it means.
                if keywords[index] == '\\':
                    keywords[index] = '\\\\'
            index = index + 1   # Advance the index

        # These actually do the swapping and deleting
        for thing in swap_list:
            keywords[thing] = 'AND'
        del_list.reverse()
        for item in del_list:
            del keywords[item]

        # I also need to activate my variables for this set of keywords to run.
        keywords = self._activate_variables(*keywords)

        return keywords

    @staticmethod
    def _index_var_swap(loop_iteration, index_var, *keywords):
        #   Format the keywords as a list for iteration
        keywords = list(keywords)
        index = 0
        #   For every line in keywords
        for line in keywords:
            #   Replace all instances of the index_var in the string with the loop iteration as a string
            keywords[index] = str(line).replace(str(index_var), str(loop_iteration))
            index = index + 1
        return keywords

    def assign_internal_variable(self, variable_name, assignment):
        # This keyword works like any other keyword so that it can be activated by BuiltIn.run_keywords
        # The syntax for an internal variable is '{{varName}}' where varName can be anything
        self.internal_variables[variable_name] = assignment

    def assign_internal_variable_to_keyword(self, variable_name, keyword, *assignment):
        # This keyword works like any other keyword so that it can be activated by BuiltIn.run_keywords
        # The syntax for an internal variable is '{{varName}}' where varName can be anything
        self.internal_variables[variable_name] = BuiltIn.run_keyword(keyword, *assignment)

    def _activate_variables(self, *keywords):
        #   Initialize variables
        keywords = list(keywords)   # Cast keywords as a List
        index = 0                   # The index of the keyword I'm looking at

        #   For each keyword
        for keyword in keywords:
            keyword = str(keyword)  # Cast keyword as a String
            assignment = False      # Whether or not the found variable name is in a variable assignment
            for key in self.internal_variables.keys():
                key = str(key)      # Cast key as a String
                #   If I can find the key in the keyword and it's not an assignment...
                if keyword.find(key) > -1 and not assignment:
                    #   ...replace the text of the key in the keyword.
                    keywords[index] = keyword.replace(str(key), str(self.internal_variables[key]))
                #   If the keyword I'm looking at is an assignment...
                if keyword.lower() == 'assign internal variable'\
                        and keyword.lower() != 'assign internal variable to keyword':
                    #   ...then my next keyword is going to definitely be a known variable, so I don't want to touch it.
                    assignment = True
                #   If the keyword I'm looking at is not an assignment...
                else:
                    #   ...set assignment to False just in case the previous one happened to be an assignment.
                    assignment = False
            index = index + 1   # Advance the index
        return keywords     # Return the list of keywords to be used in the format loop
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I found my shortcuts and performance enhancements via list comprehension.

Test Code:

*** Settings ***
Library     Loops.py

*** Variables ***
${blue_squadron} =      Blue
${gold_squadron} =      Gold
${green_squadron} =     Green
${red_squadron} =       Red

*** Test Cases ***
Test For Loop IN RANGE
    For Loop    IN RANGE    0   1   INDEX0
    ...     \\  For Loop    IN RANGE    1   6   INDEX1
    ...     \\  \\  {standing_by}=      standing by
    ...     \\  \\  Run Keyword If      INDEX1 == 1     Log to Console  This is ${red_squadron} Leader standing by
    ...     \\  \\  Run Keyword Unless  INDEX1 == 1     Log to Console  ${red_squadron} INDEX1 {standing_by}
    ...     \\  For Loop    IN RANGE    1   6   INDEX2
    ...     \\  \\  standing_by_2 =     standing by
    ...     \\  \\  Run Keyword If      INDEX2 == 1     Log to Console  This is ${gold_squadron} Leader standing by
    ...     \\  \\  Run Keyword Unless  INDEX2 == 1     Log to Console  ${gold_squadron} INDEX2 standing_by_2
    ...     \\  For Loop    IN RANGE    1   6   INDEX3
    ...     \\  \\  standing_by_3=      Get Blue Squadron
    ...     \\  \\  Run Keyword If      INDEX3 == 1     Log to Console  This is ${blue_squadron} Leader standing by
    ...     \\  \\  Run Keyword Unless  INDEX3 == 1     Log to Console  ${blue_squadron} INDEX3 standing_by_3
    ...     \\  For Loop    IN RANGE    1   6   INDEX4
    ...     \\  \\  standing_by_4 =     Get Green Squadron   null input
    ...     \\  \\  Run Keyword If      INDEX4 == 1     Log to Console  This is ${green_squadron} Leader standing by
    ...     \\  \\  Run Keyword Unless  INDEX4 == 1     Log to Console  ${green_squadron} INDEX4 standing_by_4

Test IN RANGE Edge Case 1 - Single Keyword with Single Argument
    For Loop    IN RANGE    0   1   INDEX0
    ...     \\  Log to Console  testlog

*** Keywords ***
Get Blue Squadron
    [Return]    standing by

Get Green Squadron
    [Arguments]     ${text}
    [Return]        standing by

Source Code:

from robot.libraries.BuiltIn import BuiltIn


class Loops(object):

    def __init__(self):
        self.internal_variables = {}

    def for_loop(self, loop_type, start, end, index_var, *keywords):
        keywords = self._format_loop(*keywords)     # Format the keywords
        self.internal_variables = {}    # Clean out internal variables
        for loop_iteration in range(int(start), int(end)):  # The actual looping part
            keyword_set = [k.replace(index_var, str(loop_iteration)) for k in keywords]     # Replace the index_var
            temp = self._run_keywords(*keyword_set)     # Run the keywords with this iteration.
            if not temp:
                break

    @staticmethod
    def _format_loop(*keywords):
        keywords = list(keywords)   # I need to format the keywords as a list.
        del_list = [i for i, x, in enumerate(keywords) if x == '\\'
                    and keywords[i - 1] == '\\' or i == 0]  # Delete indices on this list
        swap_list = [i for i, x, in enumerate(keywords) if x == '\\'
                     and (keywords[i - 1] != '\\' and keywords[i + 1] == '\\' and i != 0)]  # Swap indices on this list
        keywords = [k for i, k, in enumerate(['\\\\' if i in swap_list else x for i, x in enumerate(keywords)]
                                             ) if i not in del_list]     # Actually does the swapping/deleting.
        return keywords     # Return the formatted list of keywords

    def _run_keywords(self, *key_list):
        keys = [-1] + [i for i, k in enumerate(key_list) if k == '\\'] + [len(key_list)]    # Find the deliminators
        for i, d in list(enumerate(keys[:-1])):     # For each deliminator...
            key_name = key_list[d + 1]              # Get the name of the keyword
            key_args = key_list[d + 2:keys[i + 1]]  # Get the arguments for the keyword
            if str(key_name)[-2:] == ' =':          # If it's an internal variable, assign it.
                self._assign_internal_variable(key_name[:-2], *key_args)
            elif str(key_name)[-1:] == '=':         # If it's the other version, assign it.
                self._assign_internal_variable(key_name[:-1], *key_args)
            else:                                   # Otherwise, run the keyword
                for k in self.internal_variables.keys():
                    key_args = [x.replace(k, self.internal_variables[k]) for x in key_args]
                BuiltIn().run_keyword(key_name, *key_args)    # Run the keyword
        return True     # Required for "exit if" keyword when loop breaking is installed

    def _assign_internal_variable(self, variable_name, assignment, *arguments):
        if BuiltIn().run_keyword_and_return_status("Keyword Should Exist", assignment):
            self._assign_internal_variable(variable_name, BuiltIn().run_keyword(assignment, *arguments))
        else:
            self.internal_variables[variable_name] = assignment
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