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extracting string.Template substitution placeholders

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  extracting string.Template substitution placeholders "Eric S. Johansson" <esj@harvee.org> - 2014-01-12 10:08 -0500
    Re: extracting string.Template substitution placeholders Steven D'Aprano <steve@pearwood.info> - 2014-01-13 07:24 +0000
      Re: extracting string.Template substitution placeholders "Eric S. Johansson" <esj@harvee.org> - 2014-01-14 22:07 -0500
    Re: extracting string.Template substitution placeholders gmflanagan <cyclebelfast@gmail.com> - 2014-01-16 22:07 -0800
      Re: extracting string.Template substitution placeholders Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-01-17 09:25 +0000

#63776 — extracting string.Template substitution placeholders

As part of speech recognition accessibility tools that I'm building, I'm 
using string.Template. In order to construct on-the-fly grammar, I need 
to know all of the identifiers before the template is filled in. what is 
the best way to do this?

can string.Template handle recursive expansion i.e. an identifier 
contains a template.

Thanks
--- eric

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#63813

On Sun, 12 Jan 2014 10:08:31 -0500, Eric S. Johansson wrote:

> As part of speech recognition accessibility tools that I'm building, I'm
> using string.Template. In order to construct on-the-fly grammar, I need
> to know all of the identifiers before the template is filled in. what is
> the best way to do this?


py> import string
py> t = string.Template("$sub some $text $here")
py> t.template
'$sub some $text $here'

Now just walk the template for $ signs. Watch out for $$ which escapes 
the dollar sign. Here's a baby parser:

def get_next(text, start=0):
    while True:
        i = text.find("$", start)
        if i == -1:
            return
        if text[i:i+2] == '$$':
            start += i
            continue
        j = text.find(' ', i)
        if j == -1:
            j = len(text)
        assert i < j
        return (text[i:j], j)

start = 0
while start < len(t.template):
    word, start = get_next(t.template, start)
    print(word)


> can string.Template handle recursive expansion i.e. an identifier
> contains a template.

If you mean, recursive expand the template until there's nothing left to 
substitute, then no, not directly. You would have to manually expand the 
template yourself.


-- 
Steven

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#63959

On 1/13/2014 2:24 AM, Steven D'Aprano wrote:
> On Sun, 12 Jan 2014 10:08:31 -0500, Eric S. Johansson wrote:
>
>
> Now just walk the template for $ signs. Watch out for $$ which escapes
> the dollar sign. Here's a baby parser:
found a different way

import string
cmplxstr="""a simple $string a longer $string a $last line"""
nst=string.Template(cmplxstr)

identifiers = {}

while True:
     try:
         result = nst.substitute(identifiers)
     except KeyError, error:
         print error
         identifiers[error[0]] = "x"
     else:
         break
print "loop done"

  ------
at the end I only care about the keys in identifier which I fill in 
after user interaction.

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#64142

On Sunday, January 12, 2014 3:08:31 PM UTC, Eric S. Johansson wrote:
> As part of speech recognition accessibility tools that I'm building, I'm 
> 
> using string.Template. In order to construct on-the-fly grammar, I need 
> 
> to know all of the identifiers before the template is filled in. what is 
> 
> the best way to do this?
> 

Try this:

import string
cmplxstr="""a simple $string a longer $string a $last line ${another} one"""

def finditer(s):
    for match in string.Template.pattern.finditer(s):
        arg = match.group('braced') or match.group('named')
        if arg:
            yield arg


if __name__ == '__main__':
    print set(finditer(cmplxstr))

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#64150

On 17/01/2014 06:07, gmflanagan wrote:
> On Sunday, January 12, 2014 3:08:31 PM UTC, Eric S. Johansson wrote:
>> As part of speech recognition accessibility tools that I'm building, I'm
>>
>> using string.Template. In order to construct on-the-fly grammar, I need
>>
>> to know all of the identifiers before the template is filled in. what is
>>
>> the best way to do this?
>>
>
> Try this:
>
> import string
> cmplxstr="""a simple $string a longer $string a $last line ${another} one"""
>
> def finditer(s):
>      for match in string.Template.pattern.finditer(s):
>          arg = match.group('braced') or match.group('named')
>          if arg:
>              yield arg
>
>
> if __name__ == '__main__':
>      print set(finditer(cmplxstr))
>

Would you please read and action this 
https://wiki.python.org/moin/GoogleGroupsPython to prevent us seeing the 
double line spacing above, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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