[src/trunk]: src/distrib/sets Add vis() function, and canonicalise file names...

[apb <apb%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ebc7ebdcc742
branches:  trunk
changeset: 333210:ebc7ebdcc742
user:      apb <apb%NetBSD.org@localhost>
date:      Thu Oct 23 14:19:33 2014 +0000

description:
Add vis() function, and canonicalise file names via vis(unvis($1)).

XXX: The vis() function is very limited, due to the absence of ord()
in NetBSD's awk.

diffstat:

 distrib/sets/join.awk |  65 +++++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 60 insertions(+), 5 deletions(-)

diffs (105 lines):

diff -r 9628188c5e62 -r ebc7ebdcc742 distrib/sets/join.awk
--- a/distrib/sets/join.awk     Thu Oct 23 13:45:41 2014 +0000
+++ b/distrib/sets/join.awk     Thu Oct 23 14:19:33 2014 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: join.awk,v 1.4 2014/10/21 23:15:38 apb Exp $
+#      $NetBSD: join.awk,v 1.5 2014/10/23 14:19:33 apb Exp $
 #
 # Copyright (c) 2002 The NetBSD Foundation, Inc.
 # All rights reserved.
@@ -30,7 +30,8 @@
 # join.awk F1 F2
 #      Similar to join(1), this reads a list of words from F1
 #      and outputs lines in F2 with a first word that is in F1.
-#      Neither file needs to be sorted
+#      The first word is canonicalised via vis(unvis(word))).
+#      Neither file needs to be sorted.
 
 function unvis(s) \
 {
@@ -53,7 +54,7 @@
                        s = substr(s, 3)
                } else if (match(s, "\\\\[0-7][0-7][0-7]") == 1) {
                        # \ooo with three octal digits.
-                       # XXX: use strnum() is that is available
+                       # XXX: use strtonum() when that is available
                        unvis_result = unvis_result "" sprintf("%c", \
                                0+substr(s, 2, 1) * 64 + \
                                0+substr(s, 3, 1) * 8 + \
@@ -72,6 +73,60 @@
        return unvis_result
 }
 
+function vis(s) \
+{
+       # We need to encode backslash, space, and tab, because they
+       # would interfere with scripts that attempt to manipulate
+       # the set files.
+       #
+       # We make no attempt to encode shell special characters
+       # such as " ' $ ( ) { } [ ] < > * ?, because nothing that
+       # parses set files would need that.
+       #
+       # We would like to handle other white space or non-graph
+       # characters, because they may be confusing for human readers,
+       # but they are too difficult to handle in awk without the ord()
+       # function, so we print an error message.
+       #
+       # As of October 2014, no files in the set lists contain
+       # characters that would need any kind of encoding.
+       #
+       vis_result = ""
+       while (length(s) > 0) {
+               vis_pos = match(s, "(\\\\|[[:space:]]|[^[:graph:]])")
+               if (vis_pos == 0) {
+                       vis_result = vis_result "" s
+                       s = ""
+                       break
+               }
+               # copy the part before the next special char
+               vis_result = vis_result "" substr(s, 1, vis_pos - 1)
+               vis_char = substr(s, vis_pos, 1)
+               s = substr(s, vis_pos + 1)
+               # process the special char
+               if (vis_char == "\\") {
+                       # backslash -> double backslash
+                       vis_result = vis_result "\\\\"
+               } else if (vis_char == " ") {
+                       # space -> \040
+                       vis_result = vis_result "\\040"
+               } else if (vis_char == "\t") {
+                       # tab -> \011
+                       vis_result = vis_result "\\011"
+               } else {
+                       # generalised \ooo with three octal digits.
+                       # XXX: I don't know how to do this in awk without ord()
+                       printf "%s: %s:%s: cannot perform vis encoding\n", \
+                               ARGV[0], (FILENAME ? FILENAME : "stdin"), FNR \
+                               >"/dev/stderr"
+                       vis_result = vis_result "" vis_char
+               }
+       }
+       return vis_result
+}
+
+// { $1 = vis(unvis($1)); print }
+
 BEGIN \
 {
        if (ARGC != 3) {
@@ -79,13 +134,13 @@
                exit 1
        }
        while ( (getline < ARGV[1]) > 0) {
-               $1 = unvis($1)
+               $1 = vis(unvis($1))
                words[$1] = $0
        }
        delete ARGV[1]
 }
 
-// { $1 = unvis($1) }
+// { $1 = vis(unvis($1)) }
 
 $1 in words \
 {