本项目取材自《Python基础教程（第三版）》人民邮电出版社
目标：
本项目给纯文本文件添加格式，使文档转换成其他类型的文档（以HTML为例）
思路：
- 从原文件提取有用信息：
- 文档结构---成为目标文档添加HTML标签的依据
- 文档内容---成为目标文档的内容
- 制定原结构与HTML对应的规则
- 一种是直接添加标签
- 一种是用新标签替换旧标记
- 编写实际执行添加、置换操作的处理程序
- 编写主逻辑程序，创建实际的规则对象，并应用到原文档上，控制输入输出
具体实现：
#util.py
#这个模块的功能是为了将原文档分成块，以作为规则匹配程序的输入
def lines(file):
"""在文件末尾添加空行（结束标志）"""
for line in file: yield line #这里的一个line代表文档中的一段话
yield '\n'
def blocks(file):
"""一段话生成一个文本块"""
block = []
for line in lines(file):
if line.strip():
block.append(line)
elif block:
yield ''.join(block).strip()
block = []
#handlers.py
#这个模块的作用是将已经匹配好规则的文本块进行标签加工，添加开始结束标签，或者将某类标记替换成HTML标签（注释、列表项等）
class Handler:
"""
start()、end()根据传入的参数调用具体的标签方法，并具有一定的异常处理能力，忽略未定义的标签方法调用
sub()根据传入的MatchObject对象调用对应的置换方法
"""
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):
"""
用于渲染HTML的具体处理程序，其中定义了各类标签方法的具体实现，这些方法由超类的方法来访问
feed方法用在start、end之间，给结果字符串添加文本内容
"""
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>')
#下面这几个方法的实际调用者是re.sub()，如re.sub(pattern, sub_emphasis(), block)，
#re.sub方法会将对block进行模式匹配后的结果（一个MatchObject对象）传入sub_emphasis，最终返回置换完成的字符串
def sub_emphasis(self, match):
return '<em>{}</em>'.format(match.group(1)) #等价于renturn '<em>/1</em>'
def sub_url(self, match):
return '<a href="{}">{}</a>'.format(match.group(1), match.group(1))
def sub_mail(self, match):
return '<a href="mailto:{}">{}</a>'.format(match.group(1), match.group(1))
def feed(self, data):
print(data)
#rules.py
#这个模块制定了一系列规则，这些规则会匹配各类文档块，并调用相应的标签处理程序
class Rule:
"""
所有规则的基类，定义了大多数情况通用的action方法
"""
def action(self, block, handler):
handler.start(self.type)
handler.feed(block)
handler.end(self.type)
return True
class HeadingRule(Rule):
"""
标题只包含一行，不超过70个字符且不以冒号结尾
"""
type = 'heading'
def condition(self, block):
return not '\n' in block and len(block) <= 70 and not block[-1] == ':'
class TitleRule(HeadingRule):
"""
题目是文档中的第一个文本块，前提条件是它属于标题
"""
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):
"""
列表项是以字符打头的段落。在设置格式的过程中，将把连字符删除
"""
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):
"""
列表以紧跟在非列表项文本块后面的列表项打头，以相连的最后一个列表项结束
"""
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):
"""
段落是不符合其他规则的文本块
"""
type = 'paragraph'
def condition(self, block):
return True
#markup.py
#负责整合调用各模块
import sys, re
from handlers import *
from util import *
from rules import *
class Parser:
"""
Paeser读取文本文件，应用规则并控制处理程序
"""
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):
"""
在构造函数中添加规则和过滤器的Parser子类
注意：规则列表的添加顺序是有要求的，condition判断失败才会匹配下一条规则
"""
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)
这样就完成了，可以用下面这段文本做个实验，看看结果如何。
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).