Top-down vs bottom-up parsing overview in Compiler Design - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the parsing method that starts from the root and expands downwards.

Compiler Design

The parsing method that starts from the root and expands downwards is called [1] parsing.

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Atop-down

Bbottom-up

Cshift-reduce

DLR

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing top-down with bottom-up parsing.

Thinking bottom-up parsing starts from the root.

Top-down parsing begins from the start symbol (root) and tries to rewrite it to the input string by expanding productions.

2fill in blank

medium

Complete the code to identify the parsing method that starts from the input symbols and builds up to the root.

Compiler Design

The parsing method that starts from the input symbols and builds up to the root is called [1] parsing.

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Atop-down

Bpredictive

Cbottom-up

Drecursive descent

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing bottom-up with top-down parsing.

Assuming bottom-up parsing starts from the root.

Bottom-up parsing starts from the leaves (input symbols) and tries to reconstruct the parse tree up to the start symbol (root).

3fill in blank

hard

Fix the error in the statement about parsing methods.

Compiler Design

Top-down parsing uses [1] to decide which production to apply next.

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Astack

Bbacktracking

Cshift-reduce

Dlookahead

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing shift-reduce with top-down parsing.

Thinking top-down parsing always backtracks.

Top-down parsers often use lookahead tokens to decide which production rule to apply next without backtracking.

4fill in blank

hard

Fill both blanks to complete the description of bottom-up parsing.

Compiler Design

Bottom-up parsing uses a [1] to hold symbols and applies [2] actions to reduce input to the start symbol.

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Astack

Bqueue

Cshift-reduce

Dpredictive

Attempts:

3 left

💡 Hint

Common Mistakes

Using queue instead of stack for bottom-up parsing.

Confusing predictive parsing with bottom-up parsing.

Bottom-up parsers use a stack to hold symbols and perform shift and reduce actions to build the parse tree from input to start symbol.

5fill in blank

hard

Fill all three blanks to complete the summary of parsing differences.

Compiler Design

In top-down parsing, the parser starts from the [1] and uses [2] to predict productions, while bottom-up parsing starts from the [3] and uses shift-reduce actions.

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Astart symbol

Blookahead

Cinput symbols

Dstack

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up start symbol and input symbols.

Confusing lookahead with stack.

Top-down parsing starts from the start symbol and uses lookahead tokens to predict productions. Bottom-up parsing starts from input symbols and uses shift-reduce actions to build the parse tree.