Fixes triple-quoted string parsing (PY-84, PY-87).

python/src/com/jetbrains/python/lexer/Python.flex

@@ -43,9 +43,23 @@ RAW_STRING=[Rr]{QUOTED_STRING}
 QUOTED_STRING=({TRIPLE_APOS_LITERAL})|({QUOTED_LITERAL})|({DOUBLE_QUOTED_LITERAL})|({TRIPLE_QUOTED_LITERAL})
 QUOTED_LITERAL="'"([^\\\'\r\n]|{ESCAPE_SEQUENCE}|(\\[\r\n]))*("'"|\\)?
 DOUBLE_QUOTED_LITERAL=\"([^\\\"\r\n]|{ESCAPE_SEQUENCE}|(\\[\r\n]))*?(\"|\\)?
+ESCAPE_SEQUENCE=\\[^\r\n]
+
+/*
 TRIPLE_QUOTED_LITERAL="\"\"\""~([^\\]"\"\"\"")
 TRIPLE_APOS_LITERAL="\'\'\'"~([^\\]"\'\'\'")
-ESCAPE_SEQUENCE=\\[^\r\n]
+*/
+THREE_QUO = (\"\"\")
+ESCAPED_CHAR = (\\[^] | [^\\])
+NONQUO_CHAR = (\\[^] | [^i\\\"])
+STRING_3CHAR_QUO = ({ESCAPED_CHAR}{1,2}? {NONQUO_CHAR})
+TRIPLE_QUOTED_LITERAL = {THREE_QUO} {STRING_3CHAR_QUO}* {THREE_QUO}
+
+THREE_APOS = (\'\'\')
+NONAPOS_CHAR = (\\[^] | [^i\\\'])
+STRING_3CHAR_APOS = ({ESCAPED_CHAR}{1,2}? {NONAPOS_CHAR})
+TRIPLE_APOS_LITERAL = {THREE_APOS} {STRING_3CHAR_APOS}* {THREE_APOS}
+
 
 %%