54 lines
2.2 KiB
BNF
54 lines
2.2 KiB
BNF
# Root: Handles empty arrays, loose lists, or coordinate blocks
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root ::= (block_sequence | empty_scene)? ws?
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empty_scene ::= "[]"
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block_sequence ::= block (ws_or_nl* block)*
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# A block is a raw tag name or a fully positioned layout primitive
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block ::= primitive (anchor? vector)?
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primitive ::= "[" [a-zA-Z0-9_-]+ "]"
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anchor ::= "[abs]" | "[@" [0-9]+ ("," ws? "@" [0-9]+)* "]"
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# Vector strings support flat numbers, expressions, nested matrices, or config parameters
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# Enforces a valid item before and after every comma to break on double commas ,,
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vector ::= "[" value ("," ws? value)* "]"
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value ::= nested_array | parameter_assignment | expression | attribute | signed_num | boolean_flag | variable
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# Captures matrices like [1,1,1.5] or [-0.6,0.6,-0.4] cleanly
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nested_array ::= "[" value ("," ws? value)* "]"
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# Captures both taper=(z,0.5) and functional variations like taper(z,0.7) or noise(0.4)
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parameter_assignment ::= [a-zA-Z_-]+ "=(" ws? [xyz] ws? "," ws? signed_num ws? ")" | [a-zA-Z_-]+ "(" ws? [xyz] ws? "," ws? num ws? ")" | [a-zA-Z_-]+ "(" num ")"
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# Expressions handle explicit signs directly adjacent to implicit multi-variables
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expression ::= term (op term)*
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# Fully parses 'fw * 4', implicit coefficients like '-4fw', '-4fd', or solo variables
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# FIX: Added sign? variable to cleanly handle prefixed variables like -fd or -hh
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term ::= variable ("*" (variable | signed_num))? | signed_num variable? | sign? variable | "sym(" ws? expression ws? ")"
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variable ::= "fw" | "hw" | "fd" | "hd" | "fh" | "hh" | "bd" | "bh" | "@idx" | "@" [0-9]+
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boolean_flag ::= "surf" | "-%"
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# Layout modifier keywords or attributes
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attribute ::= "noise=" signed_num | "mesh" | "surf" | "-%"
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# STRICT number definition - only one sign character allowed total
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positive_num ::= [0-9]+ ("." [0-9]+)?
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negative_num ::= "-" [0-9]+ ("." [0-9]+)?
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num ::= positive_num | negative_num
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# FIX: Changed to sign? positive_num to allow things like +5 or -5 without doubling up a negative_num's minus sign
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signed_num ::= sign? positive_num | negative_num
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# SINGLE sign only - completely kills any '--' variants instantly
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sign ::= "+" | "-"
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op ::= "+" | "-" | "*" | "/"
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ws ::= [ \t]+
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ws_or_nl ::= [ \t\r\n]+ |