A Collection of Code Snippets in as Many Programming Languages as Possible
This project is maintained by TheRenegadeCoder
Welcome to the Insertion Sort in M4 page! Here, you'll find the source code for this program as well as a description of how the program works.
divert(-1)
define(`show_usage',
`Usage: please provide a list of at least two integers to sort in the format "1, 2, 3, 4, 5"
m4exit(`1')')
dnl Reference: https://www.gnu.org/software/m4/manual/m4.html#index-array
dnl array_get(var_name, idx)
define(`array_get', `defn(format(``%s[%s]'', `$1', `$2'))')
dnl array_set(var_name, idx, value)
define(`array_set', `define(format(``%s[%s]'', `$1', `$2'), `$3')')
dnl is_valid(n)
define(`is_valid', `eval(regexp(`$1', `^\s*-?[0-9]+\s*$') >= 0)')
dnl parse_int_list(varname, args):
dnl varname[length] = 0
dnl foreach arg in args:
dnl if not is_valid(arg):
dnl Return 0
dnl varname[varname[length]] = arg
dnl varname[length] = varname[length] + 1
dnl Return 1
define(`parse_int_list',
`array_set(`$1', `length', 0)dnl
_parse_int_list(`$1', $2)'dnl
)
define(`_parse_int_list',
`ifelse(is_valid(`$2'), 0, `0',
`array_set(`$1', array_get(`$1', `length'), `$2')dnl
array_set(`$1', `length', incr(array_get(`$1', `length')))dnl
ifelse(eval($# > 2), 1, `_parse_int_list(`$1', shift(shift($@)))', `1')'dnl
)'dnl
)
dnl show_int_list(varname):
dnl for i = 0 to n-1:
dnl if i > 0:
dnl Output ", "
dnl Output varname[i]
define(`show_int_list', `_show_int_list(`$1', 0)')
define(`_show_int_list',
`ifelse(eval($2 < array_get(`$1', `length')), 1,
`ifelse(eval($2 > 0), 1, `, ')dnl
array_get(`$1', $2)`'dnl
_show_int_list(`$1', incr($2))'`'dnl
)'dnl
)
dnl Reference: https://en.wikipedia.org/wiki/Insertion_sort#Algorithm
dnl for i = 1 to n-1:
dnl x = varname[i]
dnl j = i
dnl while j > 0 and varname[j-1] > x:
dnl varname[j] = varname[j-1]
dnl j = j - 1
dnl varname[j] = x
define(`insertion_sort',`_insertion_sort_outer(`$1', 1)')
define(`_insertion_sort_outer',
`ifelse(eval($2 < array_get(`$1', `length')), 1,
`_insertion_sort_inner(`$1', $2, array_get(`$1', $2))dnl
_insertion_sort_outer(`$1', incr($2))'dnl
)'dnl
)
define(`_insertion_sort_inner',
`ifelse(eval($2 <= 0), 1, `array_set(`$1', `$2', `$3')',
`ifelse(eval(array_get(`$1', decr($2)) < $3), 1, `array_set(`$1', `$2', `$3')',
`array_set(`$1', $2, array_get(`$1', decr($2)))dnl
_insertion_sort_inner(`$1', decr($2), `$3')'dnl
)'dnl
)'dnl
)
divert(0)dnl
ifelse(eval(ARGC < 1 || len(ARGV1) < 1 || !parse_int_list(`arr', ARGV1)), 1, `show_usage()')dnl
ifelse(eval(array_get(`arr', `length') < 2), 1, `show_usage()')dnl
insertion_sort(`arr')dnl
show_int_list(`arr')
Insertion Sort in M4 was written by:
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