https://boxbase.org/entries/2019/oct/14/lr1-parsing-tables/

+search lr 1 parsing table online generator

S' -> S
S -> A b c
S -> a b d
A -> a

----
'•', 'ε'
----

alphabet: 'a', 'b', 'c', 'd', '$'

# 0
S' ->•S 
S ->•A b c 
S ->•a b d 
A ->•a 

# 1 ( from #0, in 'a' )
S' -> S 
S -> A•b c 
S -> a•b d 
A -> a•

# 2 ( from #1, in 'b' )
S' -> S 
S -> A b•c 
S -> a b•d 
A -> a 

# 3 ( from #2, in 'c' )
S' -> S•
S -> A b c•
S -> a b d 
A -> a 

# 4 ( from #2, in 'd' )
S' -> S•
S -> A b c 
S -> a b d•
A -> a 

----

if each point that a '•' can be is like one bit,
then states can be represented somewhat efficiently as long binary numbers (maybe)

review with:
```
S -> X
X -> '(' X ')'
X -> 'x'
```
.. proof that a stack is needed

----

alphabet: '(', 'x', ')', '$'

#0 ( begin )
S ->•X
X ->•'(' X ')'
X ->•'x'

#1 ( from #0, in '(' ), ( from #1, in '(' )
S -> X
X ->•'('•X ')'
X ->•'x'

#2 ( from #1, in 'x' )
S -> X
X -> '(' X•')'
X -> 'x'•

[ TODO from #0, in 'x' ]

#3 ( from #2, in ')' )
S -> X•
X ->•'(' X•')'•
X ->•'x' 

#4 ( from #3, in '$' )
accept .., only if stack is empty

#5 ( from #0, in 'x' )
S -> X•
X -> '(' X ')'
X -> 'x'•

[ consider a rule `X -> '('+ X ')' ]