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

Parsing techniques are broadly categorized into Top-Down and Bottom-Up parsing:

• Bottom-Up Parsers: Construct a parse tree for an input string beginning at the leaves (bottom) and working up towards the root. Examples include:

  • Shift-reduce Parser (Option A)

  • LR Parsers (e.g., SLR, CLR, LALR) (Option D)

  • Operator precedence parser

• Top-Down Parsers: Construct a parse tree from the root down to the leaves. Examples include:

  • Recursive descent parser

  • Predictive Parser (Option B)

  • LL(1) Parser (Option C)

Therefore, the bottom-up parsers are A and D.