[antlr-interest] understanding the intuition behind LL(k) parsers and LR(k) parsers

[Mark Felzer]

Hey guys,

Maybe you can help me visualize the basic idea behind the two approaches 
to AST tree generation.
As I understand it a top-down parser..will start with the first input 
symbol of the program file,check if its a terminal/nonterminal, then it 
expands it..looking for the next predicted symbol. A bottom up parser 
has to start with some kind of "last terminal" then build the tree in 
upward direction. Intuitively where would the bottom-up parser start if 
presented an input file. How does it find this starting point, of the 
parse.It ha to be the deepest part of the tree. But how do you detect 
this, without expending the tree first from top-bottom? Is my thinking 
faulted?


Thank You.
Mark F.