(ruby-use-smie): New var.
(ruby-smie-grammar): New constant.
(ruby-smie--bosp, ruby-smie--implicit-semi-p)
(ruby-smie--forward-token, ruby-smie--backward-token)
(ruby-smie-rules): New functions.
(ruby-mode-variables): Setup SMIE if applicable.
* test/indent/ruby.rb: Fix indentation after =; add more cases.
(ruby-syntax-propertize-function): Use it to recognize regexps.
Don't look at the text after regexp, just use the whitelist.
* test/indent/ruby.rb: Rearrange examples, add new ones.
Fixes: debbugs:6286
(ruby-syntax-propertize-regexp): Remove.
(ruby-syntax-propertize-function): Split regexp into chunks.
Match following code directly.
* test/indent/ruby.rb: New file, to test new syntax-propertize code.
