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最新推荐文章于 2021-03-26 05:16:45 发布

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最新推荐文章于 2021-03-26 05:16:45 发布

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分类专栏： C/C++/Python

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这篇博客介绍了如何使用Python将文本文件切分成段落。通过遇到空行来收集行，形成一个文本块。内容涉及一个名为util.py的文本块生成器，以及handler.py中可能包含的语法分析器、规则、过滤器和处理程序。示例展示了World Wide Spam, Inc.的公司历史、产品和联系方式。" 87604594,8346758,Android开发：网络状态与类型获取工具类,"['Android开发', '网络编程']

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一个纯文本test.txt

Welcome to World Wide Spam, Inc.


These are the corporate web pages of *World Wide Spam*, Inc. We hope
you find your stay enjoyable, and that you will sample many of our
products.

A short history of the company

World Wide Spam was started in the summer of 2000. The business
concept was to ride the dot-com wave and to make money both through
bulk email and by selling canned meat online.

After receiving several complaints from customers who weren't
satisfied by their bulk email, World Wide Spam altered their profile,
and focused 100% on canned goods. Today, they rank as the world's
13,892nd online supplier of SPAM.

Destinations

From this page you may visit several of our interesting web pages:

  - What is SPAM? (http://wwspam.fu/whatisspam)

  - How do they make it? (http://wwspam.fu/howtomakeit)

  - Why should I eat it? (http://wwspam.fu/whyeatit)

How to get in touch with us

You can get in touch with us in *many* ways: By phone (555-1234), by
email (wwspam@wwspam.fu) or by visiting our customer feedback page
(http://wwspam.fu/feedback).

初次实现

首先需要把文本切分成段落

找出块的一个简单方法就是收集遇到的所有行，直到遇到一个空行，然后返回已经收集的行。那些返回的行就是一个块

文本块生成器util.py

def lines(file):
    for line in file: yield line
    yield '\n'

def blocks(file):
    block = []
    for line in lines(file):
        if line.strip():
            block.append(line)
        elif block:
            yield ''.join(block).strip()
            block = []

添加一些html标识simple.py

import sys, re
from util import *

print '<html><head><title>...</title><body>'

title = True
for block in blocks(sys.stdin):
    block = re.sub(r'\*(.+?)\*', r'<em>\1</em>', block)
    if title:
        print '<h1>'
        print block
        print '</h1>'
        title = False
    else:
        print '<p>'
        print block
        print '</p>'

print '</body></html>'

在cmd里执行的时候输入simple.py <test.txt> test.html

<html><head><title>...</title><body>
<h1>
Welcome to World Wide Spam, Inc.
</h1>
<p>
These are the corporate web pages of <em>World Wide Spam</em>, Inc. We hope
you find your stay enjoyable, and that you will sample many of our
products.
</p>
<p>
A short history of the company
</p>
<p>
World Wide Spam was started in the summer of 2000. The business
concept was to ride the dot-com wave and to make money both through
bulk email and by selling canned meat online.
</p>
<p>
After receiving several complaints from customers who weren't
satisfied by their bulk email, World Wide Spam altered their profile,
and focused 100% on canned goods. Today, they rank as the world's
13,892nd online supplier of SPAM.
</p>
<p>
Destinations
</p>
<p>
From this page you may visit several of our interesting web pages:
</p>
<p>
- What is SPAM? (http://wwspam.fu/whatisspam)
</p>
<p>
- How do they make it? (http://wwspam.fu/howtomakeit)
</p>
<p>
- Why should I eat it? (http://wwspam.fu/whyeatit)
</p>
<p>
How to get in touch with us
</p>
<p>
You can get in touch with us in <em>many</em> ways: By phone (555-1234), by
email (wwspam@wwspam.fu) or by visiting our customer feedback page
(http://wwspam.fu/feedback).
</p>
</body></html>

下面我们进一步实现

语法分析器规则过滤器处理程序

handler.py

class Handler:
    """
    An object that handles method calls from the Parser.

    The Parser will call the start() and end() methods at the
    beginning of each block, with the proper block name as a
    parameter. The sub() method will be used in regular expression
    substitution. When called with a name such as 'emphasis', it will
    return a proper substitution function.
    """
    def callback(self, prefix, name, *args):
        method = getattr(self, prefix+name, None)
        if callable(method): return method(*args)
    def start(self, name):
        self.callback('start_', name)
    def end(self, name):
        self.callback('end_', name)
    def sub(self, name):
        def substitution(match):
            result = self.callback('sub_', name, match)
            if result is None: match.group(0)
            return result
        return substitution

class HTMLRenderer(Handler):
    """
    A specific handler used for rendering HTML.

    The methods in HTMLRenderer are accessed from the superclass
    Handler's start(), end(), and sub() methods. They implement basic
    markup as used in HTML documents.
    """
    def start_document(self):
        print '<html><head><title>...</title></head><body>'
    def end_document(self):
        print '</body></html>'
    def start_paragraph(self):
        print '<p>'
    def end_paragraph(self):
        print '</p>'
    def start_heading(self):
        print '<h2>'
    def end_heading(self):
        print '</h2>'
    def start_list(self):
        print '<ul>'
    def end_list(self):
        print '</ul>'
    def start_listitem(self):
        print '<li>'
    def end_listitem(self):
        print '</li>'
    def start_title(self):
        print '<h1>'
    def end_title(self):
        print '</h1>'
    def sub_emphasis(self, match):
        return '<em>%s</em>' % match.group(1)
    def sub_url(self, match):
        return '<a href="%s">%s</a>' % (match.group(1), match.group(1))
    def sub_mail(self, match):
        return '<a href="mailto:%s">%s</a>' % (match.group(1), match.group(1))
    def feed(self, data):
        print data

规则rules.py

class Rule:
    """
    Base class for all rules.
    """
    def action(self, block, handler):
        handler.start(self.type)
        handler.feed(block)
        handler.end(self.type)
        return True

class HeadingRule(Rule):
    """
    A heading is a single line that is at most 70 characters and
    that doesn't end with a colon.
    """
    type = 'heading'
    def condition(self, block):
        return not '\n' in block and len(block) <= 70 and not block[-1] == ':'

class TitleRule(HeadingRule):
    """
    The title is the first block in the document, provided that it is
    a heading.
    """
    type = 'title'
    first = True

    def condition(self, block):
        if not self.first: return False
        self.first = False
        return HeadingRule.condition(self, block)

class ListItemRule(Rule):
    """
    A list item is a paragraph that begins with a hyphen. As part of
    the formatting, the hyphen is removed.
    """
    type = 'listitem'
    def condition(self, block):
        return block[0] == '-'
    def action(self, block, handler):
        handler.start(self.type)
        handler.feed(block[1:].strip())
        handler.end(self.type)
        return True

class ListRule(ListItemRule):
    """
    A list begins between a block that is not a list item and a
    subsequent list item. It ends after the last consecutive list
    item.
    """
    type = 'list'
    inside = False
    def condition(self, block):
        return True
    def action(self, block, handler):
        if not self.inside and ListItemRule.condition(self, block):
            handler.start(self.type)
            self.inside = True
        elif self.inside and not ListItemRule.condition(self, block):
            handler.end(self.type)
            self.inside = False
        return False

class ParagraphRule(Rule):
    """
    A paragraph is simply a block that isn't covered by any of the
    other rules.
    """
    type = 'paragraph'
    def condition(self, block):
        return True

主程序markup.py

import sys, re
from handlers import *
from util import *
from rules import *

class Parser:
    """
    A Parser reads a text file, applying rules and controlling a
    handler.
    """
    def __init__(self, handler):
        self.handler = handler
        self.rules = []
        self.filters = []
    def addRule(self, rule):
        self.rules.append(rule)
    def addFilter(self, pattern, name):
        def filter(block, handler):
            return re.sub(pattern, handler.sub(name), block)
        self.filters.append(filter)
    def parse(self, file):
        self.handler.start('document')
        for block in blocks(file):
            for filter in self.filters:
                block = filter(block, self.handler)
            for rule in self.rules:
                if rule.condition(block):
                    last = rule.action(block, self.handler)
                    if last: break
        self.handler.end('document')

class BasicTextParser(Parser):
    """
    A specific Parser that adds rules and filters in its
    constructor.
    """
    def __init__(self, handler):
        Parser.__init__(self, handler)
        self.addRule(ListRule())
        self.addRule(ListItemRule())
        self.addRule(TitleRule())
        self.addRule(HeadingRule())
        self.addRule(ParagraphRule())

        self.addFilter(r'\*(.+?)\*', 'emphasis')
        self.addFilter(r'(http://[\.a-zA-Z/]+)', 'url')
        self.addFilter(r'([\.a-zA-Z]+@[\.a-zA-Z]+[a-zA-Z]+)', 'mail')

handler = HTMLRenderer()
parser = BasicTextParser(handler)

parser.parse(sys.stdin)

cmd执行命令markup.py <test.txt> test.html

<html><head><title>...</title></head><body>
<h1>
Welcome to World Wide Spam, Inc.
</h1>
<p>
These are the corporate web pages of <em>World Wide Spam</em>, Inc. We hope
you find your stay enjoyable, and that you will sample many of our
products.
</p>
<h2>
A short history of the company
</h2>
<p>
World Wide Spam was started in the summer of 2000. The business
concept was to ride the dot-com wave and to make money both through
bulk email and by selling canned meat online.
</p>
<p>
After receiving several complaints from customers who weren't
satisfied by their bulk email, World Wide Spam altered their profile,
and focused 100% on canned goods. Today, they rank as the world's
13,892nd online supplier of SPAM.
</p>
<h2>
Destinations
</h2>
<p>
From this page you may visit several of our interesting web pages:
</p>
<ul>
<li>
What is SPAM? (<a href="http://wwspam.fu/whatisspam">http://wwspam.fu/whatisspam</a>)
</li>
<li>
How do they make it? (<a href="http://wwspam.fu/howtomakeit">http://wwspam.fu/howtomakeit</a>)
</li>
<li>
Why should I eat it? (<a href="http://wwspam.fu/whyeatit">http://wwspam.fu/whyeatit</a>)
</li>
</ul>
<h2>
How to get in touch with us
</h2>
<p>
You can get in touch with us in <em>many</em> ways: By phone (555-1234), by
email (<a href="mailto:wwspam@wwspam.fu">wwspam@wwspam.fu</a>) or by visiting our customer feedback page
(<a href="http://wwspam.fu/feedback">http://wwspam.fu/feedback</a>).
</p>
</body></html>

效果图

Welcome to World Wide Spam, Inc.

These are the corporate web pages of World Wide Spam, Inc. We hope you find your stay enjoyable, and that you will sample many of our products.

A short history of the company

World Wide Spam was started in the summer of 2000. The business concept was to ride the dot-com wave and to make money both through bulk email and by selling canned meat online.

After receiving several complaints from customers who weren't satisfied by their bulk email, World Wide Spam altered their profile, and focused 100% on canned goods. Today, they rank as the world's 13,892nd online supplier of SPAM.

Destinations

From this page you may visit several of our interesting web pages:

What is SPAM? (http://wwspam.fu/whatisspam)
How do they make it? (http://wwspam.fu/howtomakeit)
Why should I eat it? (http://wwspam.fu/whyeatit)

How to get in touch with us

You can get in touch with us in many ways: By phone (555-1234), by email (wwspam@wwspam.fu) or by visiting our customer feedback page (http://wwspam.fu/feedback).