#123 Python f-strings

[Charles J. Tabony]

This patch only works with patch [#122]. It augments the Python syntax highlighting to hightlight f-strings nicely. It handles nesting of f-strings and escapes and raw strings and all that. Try using it to hightlight the following:

x=2
print( f"""\\\{{{f'{{x}}=={ {x} }'}}}""")
print(rf"""\\\{{{f'{{x}}=={ {x} }'}}}""")
print( f"""\\\{{{f'{{f"{{x:02}}"}}=={ {f"{x:02}"} }'}}}""")
# Output:
# \\{{x}=={2}}
# \\\{{x}=={2}}
# \\{{f"{x:02}"}=={'02'}}

# Syntax errors:
f' { '
f' } '

[Charles J. Tabony]

Oops! I accidentally still had the call transitions call "pythonf()" instead of "python()".

Also, I added support for formatting options after the fstring expressions (following a ":") and highlight them as "Constant".

I'm uploading a new "fstrings.patch". I don't know if that overwrites the first one or creates a new entry, and if the latter, how you distinguish them. If it's unclear at all, I'll upload a patch with a different name.

Here's a new example, now with nested formatting options:

x=2
print( f"""\\\{{{f'{{x}}=={ {x} }'}}}""")
print(rf"""\\\{{{f'{{x}}=={ {x} }'}}}""")
print( f"""\\\{{{f'{{f"{{x:{{x:{{2}}}}}}"}}=={ {f"{x:{x:2}}"} }'}}}""")
# Output:
# \\{{x}=={2}}
# \\\{{x}=={2}}
# \\{{f"{x:{x}}"}=={' 2'}}

# Syntax errors:
f' { '
f' } '

# Too deep:
print(f'{x:{x:{x}}}')