/* UGI Grammar v0 — W3C EBNF */
/* Generated from ugi_registry_v0.json */
/* Compatible with bottlecaps.de/rr/ui */

/* === Top-level === */

ugi_string ::= 'ugi:' version '@' handle ':' field_list

version ::= digit+ ( '/' digit+ )?

/* handle: alphanumeric, hyphens, underscores, dots */
handle ::= ( alpha | digit | '-' | '_' | '.' )+

field_list ::= field ( ',' field )*

/* === Field dispatch === */

field ::= field_a
       | field_b
       | field_c
       | field_d
       | field_e
       | field_f
       | field_g
       | field_h
       | field_i
       | field_j
       | field_k
       | field_l
       | field_m
       | field_o
       | field_p
       | field_q
       | field_r
       | field_s
       | field_t
       | field_v
       | field_w
       | field_x
       | field_y
       | field_z

/* === Common rules === */

odigit ::= [0-7]

paid ::= '$'

aspire ::= '+' odigit

paid_aspire ::= paid aspire?

modifier ::= paid_aspire | aspire

alternative ::= '/' odigit

/* custom sub-ID: ~ followed by 2+ alpha chars */
custom_sub ::= '~' alpha alpha alpha*

/* sub-ID: 1-4 alpha chars */
sub_id ::= alpha alpha? alpha? alpha?

/* === Per-field rules === */

/* a — Age (direct) */
field_a ::= 'a' odigit

/* b — Build (special) */
field_b ::= 'b' odigit aspire? '/' odigit aspire?

/* c — Clothing (direct) */
field_c ::= 'c' odigit ( alternative | aspire )?

/* d — Editor / IDE (multi) */
field_d_entry ::= ( sub_id | custom_sub ) odigit ( aspire )?
field_d ::= 'd' field_d_entry+

/* e — Education (direct) */
field_e ::= 'e' odigit ( aspire )?

/* f — Food / Cooking (direct) */
field_f ::= 'f' odigit ( modifier )?

/* g — Geek Specialization (special) */
g_domain ::= alpha alpha alpha? alpha? paid?
g_custom ::= '~' alpha alpha alpha*
field_g ::= 'g' ( g_domain | g_custom ) ( '/' ( g_domain | g_custom ) )*

/* h — Hair (multi) */
field_h_entry ::= ( sub_id | custom_sub ) odigit ( aspire )?
field_h ::= 'h' field_h_entry+

/* i — AI Stance (direct) */
field_i ::= 'i' odigit

/* j — Gaming (multi) */
field_j_entry ::= ( sub_id | custom_sub ) odigit ( modifier )?
field_j ::= 'j' field_j_entry+

/* k — Books (direct) */
field_k ::= 'k' odigit ( aspire )?

/* l — Spoken Languages (multi) */
field_l_entry ::= alpha alpha odigit ( modifier )?
field_l ::= 'l' field_l_entry+

/* m — Music (multi) */
field_m_entry ::= ( sub_id | custom_sub ) odigit
field_m ::= 'm' field_m_entry+

/* o — Operating System (multi) */
field_o_entry ::= ( sub_id | custom_sub ) odigit ( modifier )?
field_o ::= 'o' field_o_entry+

/* p — Programming Languages (multi) */
field_p_entry ::= ( sub_id | custom_sub ) odigit ( modifier )?
field_p ::= 'p' field_p_entry+

/* q — Security / Hacking (direct) */
field_q ::= 'q' odigit ( alternative | modifier )?

/* r — Religion (single) */
field_r ::= 'r' ( sub_id | custom_sub ) odigit

/* s — Sex / Relationships (direct) */
field_s ::= 's' odigit ( alternative | aspire )?

/* t — TV / Film (multi) */
field_t_entry ::= ( sub_id | custom_sub ) odigit
field_t ::= 't' field_t_entry+

/* v — Politics (special) */
field_v ::= 'v' odigit '/' odigit

/* w — Hardware (direct) */
field_w ::= 'w' odigit ( modifier )?

/* x — Comics / Manga (multi) */
field_x_entry ::= ( sub_id | custom_sub ) odigit
field_x ::= 'x' field_x_entry+

/* y — Fitness (direct) */
field_y ::= 'y' odigit ( modifier )?

/* z — Maker / DIY (direct) */
field_z ::= 'z' odigit ( modifier )?

/* === Block format === */

ugi_block ::= block_header newline block_first_line newline block_field_line+ block_footer

block_header ::= '------- BEGIN UGI BLOCK -------'
block_footer ::= '-------- END UGI BLOCK --------'

block_first_line ::= 'v:' version ' @' handle ( ' ' block_geek_field )?

block_geek_field ::= 'G' ( g_domain | g_custom ) ( '/' ( g_domain | g_custom ) )*

block_field_line ::= block_field ( ' ' block_field )* newline

block_field ::= alpha ( alpha | digit | '$' | '+' | '/' | '~' )+

/* === Terminals === */

alpha ::= [a-zA-Z]
digit ::= [0-9]
newline ::= #xD #xA | #xA