"Welcome back, Mr. Potter, welcome back."
Harry didn't know what to say. Everyone was looking at him. The old woman with the pipe was puffing on it without realizing it had gone out. Hagrid was beaming.
Then there was a great scraping of chairs and the next moment, Harry found himself shaking hands with everyone in the Leaky Cauldron.
"Doris Crockford, Mr. Potter, can't believe I'm meeting you at last."
"So proud, Mr. Potter, I'm just so proud."
"Always wanted to shake your hand –– I'm all of a flutter."
(Harry Potter and the Sorcerer's Stone)
There seem to be not a few ‘all of a Noun’ phrases –– all of a dither, all of a heap, all of a jump, all of a muddle. Is ‘all of a’ a kind of determiner?