Enable syntax highlighting in f-strings

Author: cdonovick

Diff for: syntax/python.vim

@@ -103,7 +103,7 @@ else
     syn match   pythonStatement   '\<async\s\+def\>' nextgroup=pythonFunction skipwhite
     syn match   pythonStatement   '\<async\s\+with\>'
     syn match   pythonStatement   '\<async\s\+for\>'
-    syn cluster pythonExpression contains=pythonStatement,pythonRepeat,pythonConditional,pythonOperator,pythonNumber,pythonHexNumber,pythonOctNumber,pythonBinNumber,pythonFloat,pythonString,pythonBytes,pythonBoolean,pythonNone,pythonSingleton,pythonBuiltinObj,pythonBuiltinFunc,pythonBuiltinType
+    syn cluster pythonExpression contains=pythonStatement,pythonRepeat,pythonConditional,pythonOperator,pythonNumber,pythonHexNumber,pythonOctNumber,pythonBinNumber,pythonFloat,pythonString,pythonFString,pythonRawString,pythonRawFString,pythonBytes,pythonBoolean,pythonNone,pythonSingleton,pythonBuiltinObj,pythonBuiltinFunc,pythonBuiltinType
 endif
 
 
@@ -264,8 +264,8 @@ if s:Enabled('g:python_highlight_string_format')
         syn match pythonStrFormat '{\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)\=\%(\.\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\[\%(\d\+\|[^!:\}]\+\)\]\)*\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=}' contained containedin=pythonString,pythonUniString,pythonUniRawString,pythonRawString
     else
         syn match pythonStrFormat "{\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)\=\%(\.\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\[\%(\d\+\|[^!:\}]\+\)\]\)*\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=}" contained containedin=pythonString,pythonRawString
-        syn region pythonStrInterpRegion start="{"he=e+1,rs=e+1 end="\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=}"hs=s-1,re=s-1 extend contained containedin=pythonFString,pythonRawFString contains=pythonStrInterpRegion,@pythonExpression
-        syn match pythonStrFormat "{{\|}}" contained containedin=pythonString,pythonRawString,pythonFString,pythonRawFString
+        syn region pythonStrInterpRegion matchgroup=pythonStrFormat start="\({\)\@<!{\({\)\@!"he=e,rs=e end="\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=\(}\)\@<!}\(}\)\@!"hs=s,re=s extend contained containedin=pythonFString,pythonRawFString contains=pythonStrInterpRegion,@pythonExpression
+        syn match pythonStrFormat "{{\|}}" contained containedin=pythonFString,pythonRawFString
     endif
 endif
 
@@ -471,7 +471,6 @@ if v:version >= 508 || !exists('did_python_syn_inits')
         HiLink pythonBytesEscapeError   Error
         HiLink pythonFString            String
         HiLink pythonRawFString         String
-        HiLink pythonStrInterpRegion    Special
     endif
 
     HiLink pythonStrFormatting    Special