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# Convert tzdata source into a smaller version of itself. 
 
# Contributed by Paul Eggert.  This file is in the public domain. 
 
# This is not a general-purpose converter; it is designed for current tzdata. 
# 'zic' should treat this script's output as if it were identical to 
# this script's input. 
 
 
# Return a new rule name. 
# N_RULE_NAMES keeps track of how many rule names have been generated. 
 
function gen_rule_name(alphabet, base, rule_name, n, digit) 
{ 
  alphabet = "" 
  alphabet = alphabet "ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
  alphabet = alphabet "abcdefghijklmnopqrstuvwxyz" 
  alphabet = alphabet "!$%&'()*+,./:;<=>?@[\\]^_`{|}~" 
  base = length(alphabet) 
  rule_name = "" 
  n = n_rule_names++ 
 
  do { 
    n -= rule_name && n <= base 
    digit = n % base 
    rule_name = substr(alphabet, digit + 1, 1) rule_name 
    n = (n - digit) / base 
  } while (n); 
 
  return rule_name 
} 
 
# Process an input line and save it for later output. 
 
function process_input_line(line, field, end, i, n, startdef) 
{ 
  # Remove comments, normalize spaces, and append a space to each line. 
  sub(/#.*/, "", line) 
  line = line " " 
  gsub(/[\t ]+/, " ", line) 
 
  # Abbreviate keywords.  Do not abbreviate "Link" to just "L", 
  # as pre-2017c zic erroneously diagnoses "Li" as ambiguous. 
  sub(/^Link /, "Li ", line) 
  sub(/^Rule /, "R ", line) 
  sub(/^Zone /, "Z ", line) 
 
  # SystemV rules are not needed. 
  if (line ~ /^R SystemV /) return 
 
  # Replace FooAsia rules with the same rules without "Asia", as they 
  # are duplicates. 
  if (match(line, /[^ ]Asia /)) { 
    if (line ~ /^R /) return 
    line = substr(line, 1, RSTART) substr(line, RSTART + 5) 
  } 
 
  # Abbreviate times. 
  while (match(line, /[: ]0+[0-9]/)) 
    line = substr(line, 1, RSTART) substr(line, RSTART + RLENGTH - 1) 
  while (match(line, /:0[^:]/)) 
    line = substr(line, 1, RSTART - 1) substr(line, RSTART + 2) 
 
  # Abbreviate weekday names.  Do not abbreviate "Sun" and "Sat", as 
  # pre-2017c zic erroneously diagnoses "Su" and "Sa" as ambiguous. 
  while (match(line, / (last)?(Mon|Wed|Fri)[ <>]/)) { 
    end = RSTART + RLENGTH 
    line = substr(line, 1, end - 4) substr(line, end - 1) 
  } 
  while (match(line, / (last)?(Tue|Thu)[ <>]/)) { 
    end = RSTART + RLENGTH 
    line = substr(line, 1, end - 3) substr(line, end - 1) 
  } 
 
  # Abbreviate "max", "only" and month names. 
  # Do not abbreviate "min", as pre-2017c zic erroneously diagnoses "mi" 
  # as ambiguous. 
  gsub(/ max /, " ma ", line) 
  gsub(/ only /, " o ", line) 
  gsub(/ Jan /, " Ja ", line) 
  gsub(/ Feb /, " F ", line) 
  gsub(/ Apr /, " Ap ", line) 
  gsub(/ Aug /, " Au ", line) 
  gsub(/ Sep /, " S ", line) 
  gsub(/ Oct /, " O ", line) 
  gsub(/ Nov /, " N ", line) 
  gsub(/ Dec /, " D ", line) 
 
  # Strip leading and trailing space. 
  sub(/^ /, "", line) 
  sub(/ $/, "", line) 
 
  # Remove unnecessary trailing zero fields. 
  sub(/ 0+$/, "", line) 
 
  # Remove unnecessary trailing days-of-month "1". 
  if (match(line, /[A-Za-z] 1$/)) 
    line = substr(line, 1, RSTART) 
 
  # Remove unnecessary trailing " Ja" (for January). 
  sub(/ Ja$/, "", line) 
 
  n = split(line, field) 
 
  # Abbreviate rule names. 
  i = field[1] == "Z" ? 4 : field[1] == "Li" ? 0 : 2 
  if (i && field[i] ~ /^[^-+0-9]/) { 
    if (!rule[field[i]]) 
      rule[field[i]] = gen_rule_name() 
    field[i] = rule[field[i]] 
  } 
 
  # If this zone supersedes an earlier one, delete the earlier one 
  # from the saved output lines. 
  startdef = "" 
  if (field[1] == "Z") 
    zonename = startdef = field[2] 
  else if (field[1] == "Li") 
    zonename = startdef = field[3] 
  else if (field[1] == "R") 
    zonename = "" 
  if (startdef) { 
    i = zonedef[startdef] 
    if (i) { 
      do 
        output_line[i - 1] = "" 
      while (output_line[i++] ~ /^[-+0-9]/); 
    } 
  } 
  zonedef[zonename] = nout + 1 
 
  # Save the line for later output. 
  line = field[1] 
  for (i = 2; i <= n; i++) 
    line = line " " field[i] 
  output_line[nout++] = line 
} 
 
function output_saved_lines(i) 
{ 
  for (i = 0; i < nout; i++) 
    if (output_line[i]) 
      print output_line[i] 
} 
 
BEGIN { 
  print "# version", version 
  print "# This zic input file is in the public domain." 
} 
 
/^[\t ]*[^#\t ]/ { 
  process_input_line($0) 
} 
 
END { 
  output_saved_lines() 
}