Annotation of src/share/zoneinfo/zishrink.awk, Revision 1.2
1.1 millert 1: # Convert tzdata source into a smaller version of itself.
2:
3: # Contributed by Paul Eggert. This file is in the public domain.
4:
5: # This is not a general-purpose converter; it is designed for current tzdata.
6: # 'zic' should treat this script's output as if it were identical to
7: # this script's input.
8:
9: # Record a hash N for the new name NAME, checking for collisions.
10:
11: function record_hash(n, name)
12: {
13: if (used_hashes[n]) {
14: printf "# ! collision: %s %s\n", used_hashes[n], name
15: exit 1
16: }
17: used_hashes[n] = name
18: }
19:
20: # Return a shortened rule name representing NAME,
21: # and record this relationship to the hash table.
22:
23: function gen_rule_name(name, \
24: n)
25: {
26: # Use a simple mnemonic: the first two letters.
27: n = substr(name, 1, 2)
28: record_hash(n, name)
29: # printf "# %s = %s\n", n, name
30: return n
31: }
32:
33: function prehash_rule_names( \
34: name)
35: {
36: # Rule names are not part of the tzdb API, so substitute shorter
37: # ones. Shortening them consistently from one release to the next
38: # simplifies comparison of the output. That being said, the
39: # 1-letter names below are not standardized in any way, and can
40: # change arbitrarily from one release to the next, as the main goal
41: # here is compression not comparison.
42:
43: # Abbreviating these rules names to one letter saved the most space
44: # circa 2018e.
45: rule["Arg"] = "A"
46: rule["Brazil"] = "B"
47: rule["Canada"] = "C"
48: rule["Denmark"] = "D"
49: rule["EU"] = "E"
50: rule["France"] = "F"
51: rule["GB-Eire"] = "G"
52: rule["Halifax"] = "H"
53: rule["Italy"] = "I"
54: rule["Jordan"] = "J"
55: rule["Egypt"] = "K" # "Kemet" in ancient Egyptian
56: rule["Libya"] = "L"
57: rule["Morocco"] = "M"
58: rule["Neth"] = "N"
59: rule["Poland"] = "O" # arbitrary
60: rule["Palestine"] = "P"
61: rule["Cuba"] = "Q" # Its start sounds like "Q".
62: rule["Russia"] = "R"
63: rule["Syria"] = "S"
64: rule["Turkey"] = "T"
65: rule["Uruguay"] = "U"
66: rule["Vincennes"] = "V"
67: rule["Winn"] = "W"
68: rule["Mongol"] = "X" # arbitrary
69: rule["NT_YK"] = "Y"
70: rule["Zion"] = "Z"
71: rule["Austria"] = "a"
72: rule["Belgium"] = "b"
73: rule["C-Eur"] = "c"
74: rule["Algeria"] = "d" # country code DZ
75: rule["E-Eur"] = "e"
76: rule["Taiwan"] = "f" # Formosa
77: rule["Greece"] = "g"
78: rule["Hungary"] = "h"
79: rule["Iran"] = "i"
80: rule["StJohns"] = "j"
81: rule["Chatham"] = "k" # arbitrary
82: rule["Lebanon"] = "l"
83: rule["Mexico"] = "m"
84: rule["Tunisia"] = "n" # country code TN
85: rule["Moncton"] = "o" # arbitrary
86: rule["Port"] = "p"
87: rule["Albania"] = "q" # arbitrary
88: rule["Regina"] = "r"
89: rule["Spain"] = "s"
90: rule["Toronto"] = "t"
91: rule["US"] = "u"
92: rule["Louisville"] = "v" # ville
93: rule["Iceland"] = "w" # arbitrary
94: rule["Chile"] = "x" # arbitrary
95: rule["Para"] = "y" # country code PY
96: rule["Romania"] = "z" # arbitrary
97: rule["Macau"] = "_" # arbitrary
98:
99: # Use ISO 3166 alpha-2 country codes for remaining names that are countries.
100: # This is more systematic, and avoids collisions (e.g., Malta and Moldova).
101: rule["Armenia"] = "AM"
102: rule["Aus"] = "AU"
103: rule["Azer"] = "AZ"
104: rule["Barb"] = "BB"
105: rule["Dhaka"] = "BD"
106: rule["Bulg"] = "BG"
107: rule["Bahamas"] = "BS"
108: rule["Belize"] = "BZ"
109: rule["Swiss"] = "CH"
110: rule["Cook"] = "CK"
111: rule["PRC"] = "CN"
112: rule["Cyprus"] = "CY"
113: rule["Czech"] = "CZ"
114: rule["Germany"] = "DE"
115: rule["DR"] = "DO"
116: rule["Ecuador"] = "EC"
117: rule["Finland"] = "FI"
118: rule["Fiji"] = "FJ"
119: rule["Falk"] = "FK"
120: rule["Ghana"] = "GH"
121: rule["Guat"] = "GT"
122: rule["Hond"] = "HN"
123: rule["Haiti"] = "HT"
124: rule["Eire"] = "IE"
125: rule["Iraq"] = "IQ"
126: rule["Japan"] = "JP"
127: rule["Kyrgyz"] = "KG"
128: rule["ROK"] = "KR"
129: rule["Latvia"] = "LV"
130: rule["Lux"] = "LX"
131: rule["Moldova"] = "MD"
132: rule["Malta"] = "MT"
133: rule["Mauritius"] = "MU"
134: rule["Namibia"] = "NA"
135: rule["Nic"] = "NI"
136: rule["Norway"] = "NO"
137: rule["Peru"] = "PE"
138: rule["Phil"] = "PH"
139: rule["Pakistan"] = "PK"
140: rule["Sudan"] = "SD"
141: rule["Salv"] = "SV"
142: rule["Tonga"] = "TO"
143: rule["Vanuatu"] = "VU"
144:
145: # Avoid collisions.
146: rule["Detroit"] = "Dt" # De = Denver
147:
148: for (name in rule) {
149: record_hash(rule[name], name)
150: }
151: }
152:
153: function make_line(n, field, \
154: f, r)
155: {
156: r = field[1]
157: for (f = 2; f <= n; f++)
158: r = r " " field[f]
159: return r
160: }
161:
162: # Process the input line LINE and save it for later output.
163:
164: function process_input_line(line, \
1.2 ! millert 165: f, field, end, n, outline, r, \
1.1 millert 166: linkline, ruleline, zoneline)
167: {
168: # Remove comments, normalize spaces, and append a space to each line.
169: sub(/#.*/, "", line)
170: line = line " "
171: gsub(/[\t ]+/, " ", line)
172:
173: # Abbreviate keywords and determine line type.
174: linkline = sub(/^Link /, "L ", line)
175: ruleline = sub(/^Rule /, "R ", line)
176: zoneline = sub(/^Zone /, "Z ", line)
177:
178: # Replace FooAsia rules with the same rules without "Asia", as they
179: # are duplicates.
180: if (match(line, /[^ ]Asia /)) {
181: if (ruleline) return
182: line = substr(line, 1, RSTART) substr(line, RSTART + 5)
183: }
184:
185: # Abbreviate times.
186: while (match(line, /[: ]0+[0-9]/))
187: line = substr(line, 1, RSTART) substr(line, RSTART + RLENGTH - 1)
188: while (match(line, /:0[^:]/))
189: line = substr(line, 1, RSTART - 1) substr(line, RSTART + 2)
190:
191: # Abbreviate weekday names.
192: while (match(line, / (last)?(Mon|Wed|Fri)[ <>]/)) {
193: end = RSTART + RLENGTH
194: line = substr(line, 1, end - 4) substr(line, end - 1)
195: }
196: while (match(line, / (last)?(Sun|Tue|Thu|Sat)[ <>]/)) {
197: end = RSTART + RLENGTH
198: line = substr(line, 1, end - 3) substr(line, end - 1)
199: }
200:
201: # Abbreviate "max", "min", "only" and month names.
1.2 ! millert 202: # Although "max" and "min" can both be abbreviated to just "m",
! 203: # the longer forms "ma" and "mi" are needed with zic 2023d and earlier.
! 204: gsub(/ max /, dataform == "vanguard" ? " m " : " ma ", line)
! 205: gsub(/ min /, dataform == "vanguard" ? " m " : " mi ", line)
1.1 millert 206: gsub(/ only /, " o ", line)
207: gsub(/ Jan /, " Ja ", line)
208: gsub(/ Feb /, " F ", line)
209: gsub(/ Apr /, " Ap ", line)
210: gsub(/ Aug /, " Au ", line)
211: gsub(/ Sep /, " S ", line)
212: gsub(/ Oct /, " O ", line)
213: gsub(/ Nov /, " N ", line)
214: gsub(/ Dec /, " D ", line)
215:
216: # Strip leading and trailing space.
217: sub(/^ /, "", line)
218: sub(/ $/, "", line)
219:
220: # Remove unnecessary trailing zero fields.
221: sub(/ 0+$/, "", line)
222:
223: # Remove unnecessary trailing days-of-month "1".
224: if (match(line, /[A-Za-z] 1$/))
225: line = substr(line, 1, RSTART)
226:
227: # Remove unnecessary trailing " Ja" (for January).
228: sub(/ Ja$/, "", line)
229:
230: n = split(line, field)
231:
232: # Record which rule names are used, and generate their abbreviations.
233: f = zoneline ? 4 : linkline || ruleline ? 0 : 2
234: r = field[f]
235: if (r ~ /^[^-+0-9]/) {
236: rule_used[r] = 1
237: }
238:
239: if (zoneline)
240: zonename = startdef = field[2]
241: else if (linkline)
242: zonename = startdef = field[3]
243: else if (ruleline)
244: zonename = ""
245:
1.2 ! millert 246: # Save the information for later output.
! 247: outline = make_line(n, field)
! 248: if (ruleline)
! 249: rule_output_line[nrule_out++] = outline
! 250: else if (linkline) {
! 251: # In vanguard format with Gawk, links are output sorted by destination.
! 252: if (dataform == "vanguard" && PROCINFO["version"])
! 253: linkdef[zonename] = field[2]
! 254: else
! 255: link_output_line[nlink_out++] = outline
! 256: }else
! 257: zonedef[zonename] = (zoneline ? "" : zonedef[zonename] "\n") outline
1.1 millert 258: }
259:
260: function omit_unused_rules( \
261: i, field)
262: {
1.2 ! millert 263: for (i = 0; i < nrule_out; i++) {
! 264: split(rule_output_line[i], field)
! 265: if (!rule_used[field[2]])
! 266: rule_output_line[i] = ""
1.1 millert 267: }
268: }
269:
270: function abbreviate_rule_names( \
1.2 ! millert 271: abbr, f, field, i, n, newdef, newline, r, \
! 272: zoneline, zonelines, zonename)
1.1 millert 273: {
1.2 ! millert 274: for (i = 0; i < nrule_out; i++) {
! 275: n = split(rule_output_line[i], field)
1.1 millert 276: if (n) {
1.2 ! millert 277: r = field[2]
1.1 millert 278: if (r ~ /^[^-+0-9]/) {
279: abbr = rule[r]
280: if (!abbr) {
281: rule[r] = abbr = gen_rule_name(r)
282: }
1.2 ! millert 283: field[2] = abbr
! 284: rule_output_line[i] = make_line(n, field)
1.1 millert 285: }
286: }
287: }
1.2 ! millert 288: for (zonename in zonedef) {
! 289: zonelines = split(zonedef[zonename], zoneline, /\n/)
! 290: newdef = ""
! 291: for (i = 1; i <= zonelines; i++) {
! 292: newline = zoneline[i]
! 293: n = split(newline, field)
! 294: f = i == 1 ? 4 : 2
! 295: r = rule[field[f]]
! 296: if (r) {
! 297: field[f] = r
! 298: newline = make_line(n, field)
! 299: }
! 300: newdef = (newdef ? newdef "\n" : "") newline
! 301: }
! 302: zonedef[zonename] = newdef
! 303: }
1.1 millert 304: }
305:
306: function output_saved_lines( \
1.2 ! millert 307: i, zonename)
1.1 millert 308: {
1.2 ! millert 309: for (i = 0; i < nrule_out; i++)
! 310: if (rule_output_line[i])
! 311: print rule_output_line[i]
! 312:
! 313: # When using gawk, output zones sorted by name.
! 314: # This makes the output a bit more compressible.
! 315: PROCINFO["sorted_in"] = "@ind_str_asc"
! 316: for (zonename in zonedef)
! 317: print zonedef[zonename]
! 318:
! 319: if (nlink_out)
! 320: for (i = 0; i < nlink_out; i++)
! 321: print link_output_line[i]
! 322: else {
! 323: # When using gawk, output links sorted by destination.
! 324: # This also helps compressibility a bit.
! 325: PROCINFO["sorted_in"] = "@val_type_asc"
! 326: for (zonename in linkdef)
! 327: printf "L %s %s\n", linkdef[zonename], zonename
! 328: }
1.1 millert 329: }
330:
331: BEGIN {
332: # Files that the output normally depends on.
333: default_dep["africa"] = 1
334: default_dep["antarctica"] = 1
335: default_dep["asia"] = 1
336: default_dep["australasia"] = 1
337: default_dep["backward"] = 1
338: default_dep["etcetera"] = 1
339: default_dep["europe"] = 1
340: default_dep["factory"] = 1
341: default_dep["northamerica"] = 1
342: default_dep["southamerica"] = 1
343: default_dep["ziguard.awk"] = 1
344: default_dep["zishrink.awk"] = 1
345:
346: # Output a version string from 'version' and related configuration variables
347: # supported by tzdb's Makefile. If you change the makefile or any other files
348: # that affect the output of this script, you should append '-SOMETHING'
349: # to the contents of 'version', where SOMETHING identifies what was changed.
350:
351: ndeps = split(deps, dep)
352: ddeps = ""
353: for (i = 1; i <= ndeps; i++) {
354: if (default_dep[dep[i]]) {
355: default_dep[dep[i]]++
356: } else {
357: ddeps = ddeps " " dep[i]
358: }
359: }
360: for (d in default_dep) {
361: if (default_dep[d] == 1) {
362: ddeps = ddeps " !" d
363: }
364: }
365: print "# version", version
366: if (dataform != "main") {
367: print "# dataform", dataform
368: }
369: if (redo != "posix_right") {
370: print "# redo " redo
371: }
372: if (ddeps) {
373: print "# ddeps" ddeps
374: }
375: print "# This zic input file is in the public domain."
376:
377: prehash_rule_names()
378: }
379:
380: /^[\t ]*[^#\t ]/ {
381: process_input_line($0)
382: }
383:
384: END {
385: omit_unused_rules()
386: abbreviate_rule_names()
387: output_saved_lines()
388: }
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