Here's Pew research, check page 12: http://assets.pewresearch.org/wp-content/uploads/sites/5/201...
Though I wouldn't call it "very far". Solidarity peak is the same as it was around 2008 (the Great Financial Crises I guess), regulation and waste views are interestingly conflicting, the anti-corporatism shift is happening across all cohorts, so again it doesn't seem like the Dems are going that much more left.
The views of immigration are very polarized. That's interesting, and probably the result of the excessive media coverage plus the very real recent underlying events.
The emptying out of the center is the effect of Trump.
Though it'll be interesting what will happen in the upcoming 2020 primaries. And we'll get a lot of data about what people value. (With the usual caveat about polling and statistics.)
The SF politicians who continue to higher office tend to be mainstream Democrats: Kamala Harris, Dianne Feinstein, Gavin Newsom, Scott Wiener, David Chiu, etc.
Does that make the Republican party nazi? Absolutely not and you should not project your feelings on an entire political branch.