Parse trees and derivations in Compiler Design - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a parse tree in compiler design?

A parse tree is a tree that shows the syntactic structure of a string according to a grammar. It represents how the start symbol of the grammar derives the string step-by-step.

beginner

What is a derivation in the context of grammars?

A derivation is a sequence of production rule applications that shows how a string can be generated from the start symbol of a grammar.

intermediate

How does a leftmost derivation differ from a rightmost derivation?

In a leftmost derivation, the leftmost non-terminal is replaced first at each step. In a rightmost derivation, the rightmost non-terminal is replaced first.

beginner

Why are parse trees important in compilers?

Parse trees help compilers understand the structure of source code, which is essential for syntax checking and for generating intermediate code or machine code.

beginner

What does each node in a parse tree represent?

Each internal node represents a grammar symbol (non-terminal), and each leaf node represents a terminal symbol (token) from the input string.

What does a parse tree represent?

A The memory layout of variables

B The semantic meaning of a program

C The execution order of a program

D The syntactic structure of a string according to a grammar

A parse tree shows how a string is derived from the grammar's start symbol, representing its syntactic structure.

In a leftmost derivation, which non-terminal is replaced first?

A The rightmost non-terminal

B The leftmost non-terminal

C The middle non-terminal

D All non-terminals simultaneously

Leftmost derivation always replaces the leftmost non-terminal first at each step.

What is the root of a parse tree?

A The start symbol of the grammar

B A terminal symbol

C A leaf node

D A semantic action

The root of a parse tree is the start symbol from which the string is derived.

Which of the following is NOT represented in a parse tree?

A Semantic meanings

B Non-terminal symbols

C Production rules

D Terminal symbols

Parse trees represent syntax, not semantic meanings.

What does a derivation show?

A The runtime behavior of a program

B The memory usage of a program

C The sequence of grammar rule applications to generate a string

D The optimization steps in compilation

A derivation is the step-by-step application of grammar rules to produce a string.

Explain what a parse tree is and how it relates to derivations.

Think about how a grammar generates a string and how that process can be shown as a tree.

Describe the difference between leftmost and rightmost derivations with an example.

Focus on the order of replacing non-terminals during derivation.