I want to do string templating with py parsing. I have failed multiple times to define a grammar that can parse a string with inserted text inbetween "#{" and "}" (seems pretty basic) :
Example of grammar which doesn't work :
from pyparsing import CharsNotIn, FollowedBy, Group, Literal, OneOrMore, Suppress
# Define the unwanted sequence
hash_tag = Suppress(Literal('#{')) + CharsNotIn('}') + Suppress(Literal('}'))
text_part = CharsNotIn('#{')
# Combine the parts to match the entire string
parser = OneOrMore(Group(hash_tag) | text_part)
test_string = "Some text \n with a stranded # and a stranded { then a correct #{ insertion of \n some # other text } and then some text"
result = parser.searchString(test_string)
expected_result = ["Some text \n with a stranded # and a stranded { then a correct ",[" insertion of \n some # other text "]," and then some text"]
print(result)
The result is not the expected result (I get ["Some text \n with a stranded "])
I would use pyparsing's QuotedString class to define your template field, like this:
import pyparsing as pp
template_field = pp.QuotedString("#{", endQuoteChar="}",
escChar="\\",
multiline=True,
unquoteResults=True)
test_string = "Some text \n with a stranded # and a stranded { then a correct #{ insertion of \n some # other text } and then some text"
# just search for the template field
result = template_field.search_string(test_string)
expected_result = [[" insertion of \n some # other text "]]
print(result)
print(expected_result)
Since this is a templating kind of program, transform_string might do much of the search-and-replace work for you, if you can implement the transformation as a parse action:
# Using transform_string to transform the template_field
# (add some kind of transformation to the template_field using a parse action)
template_field.add_parse_action(lambda s, l, t: t[0].upper())
print(template_field.transform_string(test_string))