dnl vim:mps+=\:
dnl
dnl DO NOT EDIT! This file is generated automatically!
dnl
divert(-1)changequote(,)

__AUTHOR(⟦Josef Kubin⟧, ⟦2021,01,30⟧, ⟦https://github.com/jkubin/m4root⟧)
___DESCR(⟦the most general (root) rules for all scripts⟧)
__REASON(⟦script decomposition; NO repeated information anywhere else⟧)
___USAGE(⟦m4 root.m4 stem.m4 branch.m4 sub_branch.m4 leaf.m4 data.mc > output.file⟧)

# prerequisites for understanding M4
#
# https://en.wikipedia.org/wiki/Automata_theory
# https://en.wikipedia.org/wiki/Formal_grammar
#
# Formal Grammar (Chomsky type)
# G = (N, Σ, P, S)
# N: nonempty finite set of non-terminal symbols
# Σ: finite set of terminal symbols
#    N ∩ Σ = ø
# P: finite set of production rules
#    (N ∪ Σ)* N (N ∪ Σ)* → (N ∪ Σ)*
# S: is the start symbol
#    S ∈ N
#
# https://en.wikipedia.org/wiki/Context-free_grammar
#
# production rules in Context-free grammar (type 2)
# P: A → β
#    A ∈ N
#    β ∈ (N ∪ Σ)*
#
# production rules in M4
# A → β
# define(A, β)
#
# A → ε
# define(A, )
# define(A)

# adds LOUD alert for unsuspecting users
define(DONTE, ifelse($#, 0, $0,
DO NOT EDIT! This file is generated automatically!))

# adds an unpaired quote symbol Left/Right:
# LL() → 
# RR() → 
#
define(LL, ifelse($#, 0, $0, changequotednl
changequote(,)))
define(RR, ifelse($#, 0, $0, changequote`'dnl
changequote(,)))

# expands n-th argument (use Vim shortcuts Ctrl-a or Ctrl-x to change ARGn)
define(ARG1,	$1)
define(ARG2,	$2)
define(ARG3,	$3)
define(ARG4,	$4)
define(ARG5,	$5)
define(ARG6,	$6)
define(ARG7,	$7)
define(ARG8,	$8)
define(ARG9,	$9)

# selects n-th argument
define(SARG1,	$1)
define(SARG2,	$2)
define(SARG3,	$3)
define(SARG4,	$4)
define(SARG5,	$5)
define(SARG6,	$6)
define(SARG7,	$7)
define(SARG8,	$8)
define(SARG9,	$9)

# adds number of arguments (used for loops)
define(NAR, $#)

# adds another universal pair of symbols that protects unwanted expansion
# (`paYr' is not a word from the dictionary)
define(PAYR, $@)

# expands the last argument
# A($1, $2, …, $n) → $$# → $n → β
define(EXPAND_LAST_ARG, define(#, $$#)indir(#, $@))

# selects the last argument
# A($1, $2, …, $n) → $$# → $n
define(SELECT_LAST_ARG, define(#, $$#)indir(#, $@))

# expands the last but one (there must be at least two arguments)
# A($1, $2, …, $n) → $decr($#) → $(n-1) → β
define(EXPAND_LAST_BUT_ONE, define(#, $decr($#))indir(#, $@))

# selects the last but one (there must be at least two arguments)
# A($1, $2, …, $n) → $decr($#) → $(n-1)
define(SELECT_LAST_BUT_ONE, define(#, LL()$decr($#)RR())indir(#, $@))

# prints an informative message to stderr
define(ROOT_INFO, errprint(__file__:__line__: info: $1
))

# prints a warning message to stderr if something is strange
define(ROOT_WARNING, errprint(__file__:__line__: warning: $1
))

# aborts a script if something goes wrong and prints the reason to stderr
define(ROOT_ERROR, errprint(__file__:__line__: error: $1
)m4exit(1))