Which of the following is/are Bottom-Up Parser(s)?

Answer: Shift-reduce Parser and LR Parser are bottom-up parsers.

Short explanation:

Bottom-up parsers construct the parse tree starting from the input symbols (the leaves) and work upward by reducing substrings to nonterminals until the start symbol is reached.

• Shift-reduce Parser: Uses a stack to shift input tokens and apply reductions; this process builds the parse tree from the bottom up.

• LR Parser: A family of bottom-up parsers (LR(0), SLR, LALR, LR(1)) that use states and parsing tables to decide shift/reduce actions and handle a wide class of grammars.

Why the other choices are not bottom-up:

• Predictive Parser: This is a top-down approach that predicts which production to use based on lookahead, expanding from the start symbol rather than reducing input substrings.

• LL(1) Parser: A specific top-down parser using one-token lookahead; it constructs the parse tree by choosing productions and expanding nodes from the top down.

Final selection:

Select the shift-reduce parser and the LR parser as bottom-up parsers.