*** Need help translating this to perl6. I will pay for working hours. Please contact leszek at dubiel dot pl first. ***

lists-and-trees

This program is used to store structural data based on numbers, names (identifiers) and freeform text. It is used in business computations so numbers format is restricted. Structure is expressed with parenthesis (, ).

Numbers

Zero must be expressed as 0.0 (zero, dot, zero). Nonzero numbers must always start with sign - or +, then set of digits, dot ., another set of digits.

These are valid numbers: +1.0, -0.5123, +12312312.0.

Extra zeros at the start or end of number are not allowed. These are invalid numbers: +1.000 (extra zeros at the end), -010.5 (extra zero at the beginning), 234.4 (missing sign) 123 (no sign, no decimals), .123, +.23, +0.0 (signed zero).

Perl uses 8 bytes to store floating point number, so there are 15 significant digits. Thus the smallest and the biggest possible positive numbers are +0.00000000000001 and +99999999999999.9.

Names

Identifier, also called name, is unquoted text consisting of alphanumerics and underscore. First character must be a letter. Last character must not be an underscore. Underscores are not allowed to be on consecutive positions. Name matches regular expression ^[[:alpha:]](_?[[:alnum:]])*$.

These are valid names: Alfa_123, betaX123z.

These are invalid names: _alfa (underscore first), alfa__beta (two underscores in a row), alfa-a (non alphanumeric char), 1alfa (digit not allowed as first char).

Texts

Texts are sequences of unicode charactes enclosed in double quotes ". Only printable chars are allowed. Only four backslash escape sequences are allowed: \\ (backslash itself), \" (for double quote in text), \t (tab), \n (new line).

Valid texts: "Print \"Hello World\"!", "Hate using backslashes \\ \\ \\ ...".

Invalid texts: "Alfa \' Beta" (wrong escape sequence), texts that contain control chars, "alfa"beta" (unquted ").

Parameters

Parameters are associative arrays, sets of name-values, can be nested. Paramters definition consists of left paren (, list of name-value pairs, right parenthesis ). Name is as described above, and value is number, name, text or another list of parameters.

Empty list of parameters: ().

Simple set of name-values: ( First_Name John Address "Wall Street 123, USA" Balance -123.99 ).

Nested parameters: ( Login alfa Valid_Until (Year "2019" Month "02" Day "20") Permissions (Read Yes Write No Touch ( Always No Remarks "only when file nonexistent") ) ).

More complicated, not pretty printed:

	(
		Order_Number "PN/123/90"
		Order_Date (
			Year "2009"
			Month "12"
			Day "24"
		)
		Client "Metron Tech"
		Client_Data (                # comment on this line 
			Name "Metron_Tech"
			Address (
				Country "Poland"
				City "Krakow"
				Street "Podhalanska 242s"
				Post (
					Code "34-700"
					Name "Poczta Rabka"
				)
			)
			TaxId "7223-1123-132"          # pleas check that info 
			Remarks "Other name could be \"Metron Technology\"..."
		)
	)

Lists

List is an ordered set of names with parameters assigned to these names. Lists is made of left paren (, sequence of pairs, right paren ). Every pair is name and parameters.

Example of list:

(
	Oranges  (Qty +5.0) 
	Bananas  (Qty +1.0) 
	Eggs     (Qty +10.0)
	Flour    (Qty +2.5 Unit kg Remarks "type 500") 
	Oranges  (Qty -2.0   Info "actually three will do" )
	Omni	(Qty -45.0 Who "Kowlaski Sp. z o.o" Anum +123.988732)
	Atos	(Qty -4.0)
	Pluton	(Znum 0.0 Qty -9.0 When "2009-12-31")
	Helios	(Qty -1.0)
)

Trees

Finally trees are similar to lists, but have one more element -- subtree, or child nodes that come as a third element of every node. Tree definition starts with (, then goes sequence of tripples name plus parameters plus subtree, finally ends with ). Subtree is identical to tree: left paren, sequence of tripples, right paren. Here is an example:

(
	Section_1   (Pages "2-12"  Author "Kowalski")  (
		Chapter_1_1  (Pages "2-8") (
		)
		Chapter_1_2  (Pages "9-12") ( 
		)
	)
	Section_2   (Pages "13-20"   Inof "Many authors-- see below"  Page_Count +6.0) (
		Chapter_2_1   (Pages "13-18" Author "Nowak" Title "Perl5 solution") (
		)
		Chapter_2_2   (Pages "19-20"  Author "Alfa"   Title "Discussion on Perl5") (
		)
	)
)

Another tree, empty subtrees collapsed to (), more compact representation:

	(
 		A (Info "this is node A") (
 			B (Info "This is node B, parent is A") ()
 			C (Info "This is node C, has 3 children") (
 				D (X +4.5 Y -5.0) ()
 				E (X +4.9 Y -9.0) ()
 				F (X +2.1 Y -12.0) ()
 			)
 			G (Info "This is child G of node A") ()
 		)
 		B (Info "This is node B") ()
 		A (Info "this is another with name A") (
 			X () ()
 			Y () ()
 		)	
 	)

License

leszekdubiel/lists-and-trees

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