【Codewars python 4kyu】: Breadcrumb Generator

问题描述:

As breadcrumb menùs are quite popular today, I won't digress much on explaining them, leaving the wiki link to do all the dirty work in my place.

What might not be so trivial is instead to get a decent breadcrumb from your current url. For this kata, your purpose is to create a function that takes a url, strips the first part (labelling it always 

HOME

) and then builds it making each element but the last a 

<a>

 element linking to the relevant path; last has to be a 

<span>

 element getting the 

active

class

.

All elements need to be turned to uppercase and separated by a separator, given as the second parameter of the function; the last element can terminate in some common extension like 

.html

, 

.htm

, 

.php

 or 

.asp

; if the name of the last element is 

index

.something, you treat it as if it wasn't there, sending users automatically to the upper level folder.

A few examples can be more helpful than thousands of words of explanation, so here you have them:

generate_bc("mysite.com/pictures/holidays.html", " : ") == '<a href="/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >HOME</a> : <a href="/pictures/" target="_blank" rel="external nofollow" >PICTURES</a> : <span class="active">HOLIDAYS</span>'
generate_bc("www.codewars.com/users/GiacomoSorbi", " / ") == '<a href="/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >HOME</a> / <a href="/users/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >USERS</a> / <span class="active">GIACOMOSORBI</span>'
generate_bc("www.microsoft.com/docs/index.htm", " * ") == '<a href="/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >HOME</a> * <span class="active">DOCS</span>'
           

Seems easy enough?

Well, probably not so much, but we have one last extra rule: if one element (other than the root/home) is longer than 30 characters, you have to shorten it, acronymizing it (i.e.: taking just the initials of every word); url will be always given in the format 

this-is-an-element-of-the-url

 and you should ignore words in this array while acronymizing: 

["the","of","in","from","by","with","and", "or", "for", "to", "at", "a"]

; a url composed of more words separated by 

-

 and equal or less than 30 characters long needs to be just uppercased with hyphens replaced by spaces.

Ignore anchors (

www.url.com#lameAnchorExample

) and parameters (

www.url.com?codewars=rocks&pippi=rocksToo

) when present.

Examples:

generate_bc("mysite.com/very-long-url-to-make-a-silly-yet-meaningful-example/example.htm", " > ") == '<a href="/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >HOME</a> > <a href="/very-long-url-to-make-a-silly-yet-meaningful-example/" target="_blank" rel="external nofollow" >VLUMSYME</a> > <span class="active">EXAMPLE</span>'
generate_bc("www.very-long-site_name-to-make-a-silly-yet-meaningful-example.com/users/giacomo-sorbi", " + ") == '<a href="/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >HOME</a> + <a href="/users/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >USERS</a> + <span class="active">GIACOMO SORBI</span>'
           

You will always be provided valid url to webpages in common formats, so you probably shouldn't bother validating them.

If you like to test yourself with actual work/interview related kata, please also consider this one about building a string filter for Angular.js.

Special thanks to the colleague that, seeing my code and commenting that I worked on that as if it was I was on CodeWars, made me realize that it could be indeed a good idea for a kata :)

代码实现：

#codewars第二十一题（繁琐）
def generate_bc(url, separator):
    if '//' in url:
        url = url[url.index('//') + 2:]

    url = url.rstrip('/')

    try:
        for i, c in enumerate(url):
            if c in ['?', '#']:
                url = url[0:i]
                break

        menus = url.split('/')[1:]
        if menus and 'index.' == menus[-1][0:6]:
            menus = menus[:-1]
        if not menus:
            return '<span class="active">HOME</span>'

        breadcrumb = '<a href="/" target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow"  target="_blank" rel="external nofollow" >HOME</a>'

        for i, e in enumerate(menus[:-1]):
            breadcrumb += separator + '<a href="/{}/" target="_blank" rel="external nofollow" >{}</a>'.format('/'.join(menus[:i + 1]), get_element_name(e))

        breadcrumb += separator + '<span class="active">{}</span>'.format(get_element_name(menus[-1]))
        return breadcrumb
    except:
        return url


ignore_words = ["the", "of", "in", "from", "by", "with", "and", "or", "for", "to", "at", "a"]


def get_element_name(element):
    acronyms = element.split('-')
    for i, c in enumerate(acronyms[-1]):
        if c == '.':
            acronyms[-1] = acronyms[-1][:i]
            break

    if len(element) > 30:
        for i, c in reversed(list(enumerate(acronyms))):
            if c in ignore_words:
                acronyms.pop(i)
        return ''.join([s[0].upper() for s in acronyms])

    return ' '.join([s.upper() for s in acronyms])


#另解
from re import sub

ignoreList = ["THE", "OF", "IN", "FROM", "BY", "WITH", "AND",  "OR",  "FOR",  "TO",  "AT",  "A"]

def generate_bc(url, separator):
    # remove leading http(s):// and trailing /
    url = sub("https?://", "", url.strip("/"))
    
    # skip index files
    url = sub("/index\..+$", "", url)
    
    # split url for processing
    url = url.split("/")
    
    # remove file extensions, anchors and parameters
    url[-1] = sub("[\.#\?].*", "", url[-1])
    
    # first element is always "home"
    menu = ["HOME"]
    # generate breadcrumb items
    for item in url[1:]:
        # replace dashes and set to uppercase
        item = sub("-", " ", item.upper())
        # create acronym if too long
        if len(item) > 30:
            item = "".join([w[0] for w in item.split() if w not in ignoreList])
        menu.append(item)
    
    # generate paths
    path = ["/"]
    for i in range(len(url) - 1):
        path.append(path[i] + url[i+1] + "/")
    
    # generate html code
    html = []
    for i in range(len(url) - 1):
        html.append("<a href=\"" + path[i] + "\">" + menu[i] +"</a>")
    html.append("<span class=\"active\">" + menu[-1] +"</span>")
    
    return separator.join(html)