hush: add support for ${var/pattern/repl}, conditional on bash compat

function                                             old     new   delta
expand_vars_to_list                                 2386    2833    +447
expand_string_to_string                               69     110     +41
parse_dollar                                         681     721     +40
hush_main                                            963     945     -18
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/1 up/down: 528/-18)           Total: 510 bytes

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/shell/hush_test/hush-vars/var_bash4.tests b/shell/hush_test/hush-vars/var_bash4.tests
new file mode 100755
index 0000000..d547061
--- /dev/null
+++ b/shell/hush_test/hush-vars/var_bash4.tests
@@ -0,0 +1,47 @@
+# This testcase demonstrates that backslashes are treated differently
+# in 1st and 2nd parts of ${var/search/repl}:
+# if quoted ("${var/search/repl}"), and repl contains \a (a non-special char),
+# the backslash in repl stays; if unquoted, backslash is removed.
+# But search part does not act like that: \a is always converted to just a,
+# even in quotes.
+#
+# bash4 (and probably bash3 too): "Quoted:" results are different from
+# unquoted and assignment expansions - they have a backslash before z.
+
+v='a*b\*c'
+echo 'Source:       ' "$v"
+echo 'Replace str:  ' '_\\_\z_'
+
+echo 'Pattern:      ' 'single backslash and star: "replace literal star"'
+r=${v/\*/_\\_\z_}
+echo 'In assignment:' "$r"
+echo 'Unquoted:     ' ${v/\*/_\\_\z_}
+echo 'Quoted:       ' "${v/\*/_\\_\z_}"
+
+echo 'Pattern:      ' 'double backslash and star: "replace backslash and everything after it"'
+r=${v/\\*/_\\_\z_}
+echo 'In assignment:' "$r"
+echo 'Unquoted:     '  ${v/\\*/_\\_\z_}
+echo 'Quoted:       ' "${v/\\*/_\\_\z_}"
+
+echo
+
+v='a\bc'
+echo 'Source:       ' "$v"
+echo 'Replace str:  ' '_\\_\z_'
+
+echo 'Pattern:      ' 'single backslash and b: "replace b"'
+r=${v/\b/_\\_\z_}
+echo 'In assignment:' "$r"
+echo 'Unquoted:     '  ${v/\b/_\\_\z_}
+echo 'Quoted:       ' "${v/\b/_\\_\z_}"
+
+echo 'Pattern:      ' 'double backslash and b: "replace backslash and b"'
+r=${v/\\b/_\\_\z_}
+echo 'In assignment:' "$r"
+echo 'Unquoted:     '  ${v/\\b/_\\_\z_}
+echo 'Quoted:       ' "${v/\\b/_\\_\z_}"
+
+echo
+
+echo Done: $?