Insert characters into string based on re ?

Frederic Rentsch anthra.norell at vtxmail.ch
Sat Oct 14 23:21:34 CEST 2006


Matt wrote:
> I am attempting to reformat a string, inserting newlines before certain
> phrases. For example, in formatting SQL, I want to start a new line at
> each JOIN condition. Noting that strings are immutable, I thought it
> best to spllit the string at the key points, then join with '\n'.
>
> Regexps can seem the best way to identify the points in the string
> ('LEFT.*JOIN' to cover 'LEFT OUTER JOIN' and 'LEFT JOIN'), since I need
> to identify multiple locationg in the string. However, the re.split
> method returns the list without the split phrases, and re.findall does
> not seem useful for this operation.
>
> Suggestions?
>
>   

Matt,

   You may want to try this solution:

 >>> import SE

 >>> Formatter = SE.SE (' "~(?i)(left|inner|right|outer).*join~=\n=" ')  
# Details explained below the dotted line
 >>> print Formatter ('select id, people.* from ids left outer join 
people where ...\nSELECT name, job from people INNER JOIN jobs WHERE 
...;\n')
select id, people.* from ids
left outer join people where ...
SELECT name, job from people
INNER JOIN jobs where ...;

You may add other substitutions as required one by one, interactively 
tweaking each one until it does what it is supposed to do:

 >>> Formatter = SE.SE ('''
    "~(?i)(left|inner|right|outer).*join~=\n  ="  # Add an indentation
    "where=\n  where"  "WHERE=\n  WHERE"          # Add a newline also 
before 'where'
    ";\n=;\n\n"                                   # Add an extra line feed
    "\n=;\n\n"                                    # And add any missing 
semicolon
    # etc.
''')

 >>> print Formatter ('select id, people.* from ids left outer join 
people where ...\nSELECT name, job from people INNER JOIN jobs WHERE 
...;\n')
select id, people.* from ids
  left outer join people
  where ...;

SELECT name, job from people
  INNER JOIN jobs
  WHERE ...;


http://cheeseshop.python.org/pypi?:action=display&name=SE&version=2.3


Frederic


----------------------------------------------------------------------------------------------------------------------

The anatomy of a replacement definition

 >>> Formatter = SE.SE (' "~(?i)(left|inner|right|outer).*join~=\n=" ')
                                                        
target=substitute   (first '=')

 >>> Formatter = SE.SE (' "~(?i)(left|inner|right|outer).*join~=\n=" ')
                                                                 = (each 
following '=' stands for matched target) 

 >>> Formatter = SE.SE (' "~(?i)(left|inner|right|outer).*join~=\n=" ')
                          ~                                  ~ (contain 
regular expression)

 >>> Formatter = SE.SE (' "~(?i)(left|inner|right|outer).*join~=\n=" ')
                         "                                        " 
(contain definition containing white space)




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