Clarification on docs regarding EBNF

[IK]

Hi team,

I'm playing around with a toy parser for Lua. While reviewing The Complete Syntax of Lua in the manual: https://www.lua.org/manual/5.4/manual.html#9. I found a suspicious bit that looks as follows:

attnamelist ::= Name attrib {‘,’ Name attrib} 

attrib ::= [‘<’ Name ‘>’]

1. As I understand the attrib is optional, and should therefore be denoted using braces:

attrib ::= {‘<’ Name ‘>’}

2. The attrib symbol is currently referencing the overloaded Name symbol.

As of version v5.4 there exist only 2 possibilities for the attrib value

- const

- close

I believe it would make more sense to declare attrib as
attrib ::= {‘<’ closed | close ‘>’}

Best,

IK

[Philippe Verdy]

Rounded braces in EBNF syntax are for optional *unlimited repetitions* of its content (so 0 to n):

  attnamelist ::= Name attrib {‘,’ Name attrib} 

Square brackets in EBNF syntax are for an optional *single* occurences (so 0 to 1). So the following is correct (no braces):

   attrib ::= [‘<’ Name ‘>’]

And it is *currently* the same as the following as the attribute Name is only defined for closed and close (no braces):

   attrib ::= [‘<’ closed | close ‘>’]

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