divert(-1)changequote([,])

__HEADER([Josef Kubin], [2020/02/18], [gfiles])
___DESCR([minimal root script for simple projects])
___POINT([root script as small as possible])
___USAGE([m4 mroot.m4 stem.m4 branch.m4 sub_branch.m4 leaf.m4 data.mc > output.file])

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

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

# expands n-th argument if the macro has parentheses
# A([$1], [$2], …, [$n]) → $1 | $2 | $3 | $4 → β
define([FST], [ifelse([$#], [0], [[$0]], [$1])])
define([SND], [ifelse([$#], [0], [[$0]], [$2])])
define([TRD], [ifelse([$#], [0], [[$0]], [$3])])

# similar to previous (use Vim shortcuts Ctrl-a or Ctrl-x to change ARGn)
define([ARG1],	[$1])
define([ARG2],	[$2])
define([ARG3],	[$3])

# selects n-th argument
define([SARG1],	[[$1]])
define([SARG2],	[[$2]])
define([SARG3],	[[$3]])

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

# adds another layer of paired symbols
# (`brac', `npri', `quot' and `utfp' are not words from the dictionary)
define([BRAC], [[$@]])
define([NPRI], [$@])
define([QUOT], [`$@'])
define([UTFP], [⟦$@⟧])

# adds a left/right unpaired symbol bypassing the non-terminal control
define([LB], [ifelse([$#], [0], [[$0]], [changequote[dnl]
changequote([,])])])
define([RB], [ifelse([$#], [0], [[$0]], [changequote`'dnl[
]changequote([,])])])
define([LQ], [`])
define([RQ], ['])
define([LN], [])
define([RN], [])
define([LU], [⟦])
define([RU], [⟧])

# 'prints warning to stderr if something will be problematic
define([ROOT_WARNING], [errprint(__file__:__line__[: warning: $1
])])

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