Cabbie confusion (or, why can't people just treat me like a car?)

I was mostly okay with the two ladies who slowed down behind me as I climbed Bank today, only to suddenly decide, just as I turned around to smile at them for hanging back, to accelerate past me fairly close so they could cut me off turning right into the Farm Boy parking lot. I mean, it seemed a little dumb to hang back for fifty feet, then suddenly decide you couldn't do it for another twenty, but what the hey.

But what happened with the cabbie a couple of blocks later baffles me.

Just as I swerved to the left to get around a particularly nasty cluster of potholes, a cab (what's the one with the orange signs?) passed me uncomfortably close. "Jerk," I said to myself, and shook my head. But then he put on his right turn signal, slowed in front of me, then swerved a little bit left - and stopped. In the middle of the street.

I had been moving left so I could pass him as he made his right turn, but when he didn't turn right, and in fact moved out and into my way again, I had to slam on the brakes and skid to a stop behind him. "What are you doing?" I said, loudly, and the driver waved at me to pass him on the right. He rolled his window down. Meanwhile I was trying to decide whether to pull out around him on the left, as I'd been going to do anyway, but as I was not at all sure what he thought he was doing I didn't think it was safe. So when the window rolled down, I moved up beside him and said, "What are you doing?" again. He waved at me to continue. "What are you doing?" I asked again, really, honestly, because I wanted to know what his thought process had been. He didn't answer, just kept flapping his hand at me to move on. So I did, and then he turned in to the driveway.

So, again, he'd passed me in order to start cutting me off, only to decide against it and wave me through, and when I stopped behind him he didn't just finish making his right into the driveway, he decided to sit there and engage in some utterly confusing signals.

Because he thought I had the right of way to undertake him while he was turning right (I don't)? Because he'd suddenly thought better of overtaking me and then trying to cut me off (if so, kudos, but don't try to make it right after the fact, buddy, just don't do it again)? Because I was on a bike and he just wanted me out of the way because he didn't know what to do with me (most likely, to be honest)?

This. This is why I wish people knew the rules about bikes. The well-meaning, the ignorant, and the just plain careless are kind of hard to tell apart and they're really hard to figure out or predict. If he'd just treated me like a slower-moving car (i.e., hung back and turned right behind me, or passed me, turned right, and expected me to move left to give him clearance) no one would have been confused, or wound up stopping in the middle of a major street.