Computing - Syntax Diagrams

Created: January 22, 2021

See also:

[[Computing - Backus-Naur Form]]A

2021-01-22

What is a syntax diagram?

A graphical equivalent of BNF.

PHOTO SYNTAX DIAGRAM TERMINAL SYMBOL What does this represent in a syntax diagram?

A terminal symbol.

PHOTO SYNTAX DIAGRAM NON TERMINAL SYMBOL What does this represent in a syntax diagram?

A non-terminal symbol.

PHOTO SYNTAX DIAGRAM REPEATED NON TERMINAL SYMBOL What does this represent in a syntax diagram?

A non-terminal symbol that can be used more than once.

Can you picture what a non-zero digit would look like in a syntax diagram?

PHOTO SYNTAX DIAGRAM NON ZERO DIGIT

Can you picture what an integer would look like in a syntax diagram, made from a “non-zero-digit” and a “digit” category?

PHOTO SYNTAX DIAGRAM INTEGER

PHOTO SYNTAX DIAGRAM DIGIT What does the fork on the left hand side of this syntax diagram mean?

A digit can either be a non-zero digit or a zero.

PHOTO SYNTAX DIAGRAM DIGIT How would you write this in BNF using a “non-zero-digit” category?

 
<digit> ::= <non-zero-digit>|0

PHOTO SYNTAX DIAGRAM INTEGER How would you write this in BNF using a “non-zero-digit” and a “digit” category?

 
<integer> ::= <non-zero-digit>|<integer><digit>

When drawing a syntax diagram, should you write recursive rules or iterative ones?

Iterative rules.

Question

Are you allowed to use recursive definitions in syntax diagrams??



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