(* wmap Language Specification *)

(* Top-level structure *)
program = { line } ;
line = ( entity newline ) | ( ignored_line newline ) | newline ;

entity = vertex | edge | note | stage | group | inertia | evolution ;
ignored_line = ? any sequence of tokens that doesn't match entity grammar ? ;

(* Entities *)
vertex = vertex_label position [ shape ] ;
edge = vertex_label edge_type vertex_label ;
note = case_insensitive("[Note]") position text ;
stage = "[" stage_number "]" real_number ;
group = case_insensitive("[Group]") vertex_label { "," vertex_label } ;
inertia = case_insensitive("[Inertia]") vertex_label ;
evolution = case_insensitive("[Evolution]") vertex_label sign real_number ;

(* Component definitions *)
position = "(" real_number "," real_number ")" ;
shape = "[" shape_label "]" ;
edge_type = "--" | "->" ;
sign = "+" | "-" ;

(* Terminal symbols *)
vertex_label = preserved_case( { character - ( "-" | "+" | "," | "[" | "]" | "(" | ")" | newline ) } ) ;
text = preserved_case( { character - newline } ) ;
real_number = [ digit ] { digit } [ "." { digit } ] | "." digit { digit } ;
stage_number = case_insensitive( "i" | "ii" | "iii" | "iv" ) ;
shape_label = case_insensitive( "x" | "square" | "triangle" | "circle" ) ;

(* Lexical elements *)
character = ? any Unicode character ? ;
digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
newline = ? newline character ? ;

(* Lexical rules *)
case_insensitive(x) = ? case-insensitive match of x ? ;
preserved_case(x) = ? case-insensitive match of x, preserving original case for display ? ;

(* Notes *)
(* - Keywords and shape labels are case-insensitive *)
(* - Vertex labels are case-insensitive for matching but preserve original case *)
(* - Text content preserves original case *)
(* - Whitespace (except newlines) may appear between any tokens *)
(* - Each line contains exactly one entity *)
(* - Invalid lines should be ignored. *)