important

Question 1

What is an attribute grammar?

Answer 1

A grammar that adds attributes and equations to describe properties of AST nodes.

Question 2

What is an intrinsic attribute?

Answer 2

An attribute set during AST creation, like token values or children.

Question 3

What is a synthesized attribute?

Answer 3

An attribute computed from the node or its children, flows upward.

Add.val = left.val + right.val
→ If left = 3 and right = 5, then Add.val = 8
Flows up from children to parent.

Question 4

What is an inherited attribute?

Answer 4

An attribute passed from parent to child, flows downward.

Add.type = int → passed to both children.
Int.expectedType = int
Flows down from parent to children.

Question 5

What are the major compiler phases?

Answer 5

Lexical Analysis (Scanning) – breaks source code into tokens.

Syntactic Analysis (Parsing) – constructs a parse tree from tokens.

Semantic Analysis – checks for type errors, undeclared variables, etc.

Intermediate Code Generation – produces platform-independent code.

Optimization – improves code performance or size.

Target Code Generation – translates intermediate code into assembly/machine code.

Question 6

true/false

Answer 6

Every LL(1) grammar must be unambiguous.
✅ True

If a production is Nullable, its FOLLOW set must be considered in the LL(1) table.
✅ True

A grammar with a collision in the LL(1) table is not LL(1).
✅ True

The FIRST set of a terminal is the terminal itself.
✅ True

Nullable(X) is true if X can derive ε (the empty string).
✅ True

The FOLLOW set of the start symbol includes the end-of-file symbol $.
✅ True

Fixed-point iteration can be used to compute Nullable, FIRST, and FOLLOW sets.
✅ True

If a nonterminal can derive a terminal directly, that terminal is in its FIRST set.
✅ True

LL(1) parsers use a single lookahead token to choose a production.
✅ True

Nullable values can be computed by recursive or iterative methods.
✅ True

Question 7

true/false2

Answer 7

Nullable(e) is always true.
✅ True

If a nonterminal X has a production X → ε, then X is Nullable.
✅ True

FIRST(X) includes all terminals that X can derive at the beginning of some sentence.
✅ True

FOLLOW(X) includes terminals that can appear immediately after X in a derivation.
✅ True

The FOLLOW set helps handle Nullable productions in the LL(1) table.
✅ True

If a grammar has two productions with the same FIRST set, it is not LL(1).
✅ True

A grammar with left recursion cannot be parsed by an LL(1) parser.
✅ True

The LL(1) parsing table must have at most one entry per cell.
✅ True

Fixed-point iteration ensures that Nullable computation will terminate.
✅ True

The FIRST set is computed recursively and depends on Nullable.
✅ True

If a nonterminal’s production has a sequence of symbols, the FIRST of that sequence depends on the Nullable status of the symbols.
✅ True

FOLLOW(S) always includes $ if S is the start symbol.
✅ True

An LL(1) grammar allows predictive parsing without backtracking.
✅ True

The computation of FOLLOW uses both FIRST and Nullable.
✅ True

A Nullable production can cause multiple entries in the LL(1) table if FOLLOW is not handled.
✅ True

A terminal symbol cannot be Nullable.
✅ True

In fixed-point iteration, values only change from false to true for Nullable.
✅ True

The FIRST set of a sequence may include tokens from multiple nonterminals if they are Nullable.
✅ True

LL(1) parsing is a top-down parsing strategy.
✅ True

If a production is selected in multiple table cells, the grammar is not LL(1).
✅ True

Question 8

what does shift mean?

Answer 8

Push token onto task and read next token

Question 9

what does reduce mean?

Answer 9

Pop RHS , Push LHS , build part of tree

Question 10

what is common prefix ?

Answer 10

when two productions of the same nonterminal start with the same symbols

Question 11

what is left recursion?

Answer 11

When non-terminal calls itself at the beginning of production

Question 12

what does it mean a grammar to be ambiguous

Answer 12

if a sentence in language derived by two or more different parse trees

Question 13

what is nullable , first, follow

Answer 13

nullable: A nonterminal X is Nullable if it can derive the empty string

First: is the set of terminals that can appear first in any string derived from X.

Follow: is the set of terminals that can appear immediately after X in some derivation.

Question 14

how we decide if grammar is LL(1) or not

Answer 14

If any cell has more than one production, the grammar is not LL(1)

Question 15

What does collison mean in LL(1) table?

Answer 15

if both element are in the same cell