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>

shell/hush_test/hush-vars/var_bash1.right

@@ -0,0 +1,14 @@
+
+
+f
+bcdef
+abcdef
+abcdef
+bcde
+abcd
+abcd
+abcdef
+bcdef
+abcdef
+abcdef
+abcdef

shell/hush_test/hush-vars/var_bash1.tests

@@ -0,0 +1,18 @@
+var=abcdef
+
+echo ${var:7}
+echo ${var:6}
+echo ${var:5}
+echo ${var:1}
+echo ${var:0}
+echo ${var:-1}
+
+echo ${var:1:4}
+echo ${var:0:4}
+echo ${var::4}
+echo ${var:-1:4}
+
+echo ${var:1:7}
+echo ${var:0:7}
+echo ${var::7}
+echo ${var:-1:7}

shell/hush_test/hush-vars/var_bash2.right

@@ -0,0 +1,10 @@
+abc123xcba123
+abx123dcba123
+abx123dxba123
+abcx23dcba123
+abcxxxdcbaxxx
+abx
+xba123
+abx23
+abc23dcba123
+abcdcba

shell/hush_test/hush-vars/var_bash2.tests

@@ -0,0 +1,24 @@
+var=abc123dcba123
+
+echo ${var/d/x}
+echo ${var/c/x}
+echo ${var//c/x}
+echo ${var/[123]/x}
+echo ${var//[123]/x}
+echo ${var/c*/x}
+echo ${var/*c/x}
+
+# must match longest match: result is "abx23"
+echo ${var/c*1/x}
+
+# empty replacement - 2nd slash can be omitted
+echo ${var/[123]}
+echo ${var//[123]}
+
+### ash doesn't support
+### # match only at the beginning:
+### echo ${var/#a/x}
+### echo ${var/#b/x} # should not match
+### echo ${var//#b/x} # should not match
+### # match only at the end:
+### echo ${var/%3/x}

shell/hush_test/hush-vars/var_bash3.right

@@ -0,0 +1,20 @@
+1 a041#c
+2 a041#c
+3 a\041#c
+4 a\041#c
+5 a\041#c
+6 a\041#c
+7 a\041#c
+8 a\041#c
+9 a\041#c
+10 a\c
+11 a\c
+12 a\c
+13 a\\c
+14 a\\c
+15 a\\c
+16 a\tc
+17 a\tc
+18 a\tc
+19 atc
+20 a\tc

shell/hush_test/hush-vars/var_bash3.tests

@@ -0,0 +1,41 @@
+a='abc'
+r=${a//b/\041#}
+echo 1 $r
+echo 2 ${a//b/\041#}
+echo 3 "${a//b/\041#}"
+
+a='abc'
+r=${a//b/\\041#}
+echo 4 $r
+echo 5 ${a//b/\\041#}
+echo 6 "${a//b/\\041#}"
+
+a='abc'
+b='\041#'
+r=${a//b/$b}
+echo 7 $r
+echo 8 ${a//b/$b}
+echo 9 "${a//b/$b}"
+
+a='abc'
+b='\'
+r="${a//b/$b}"
+echo 10 $r
+echo 11 ${a//b/$b}
+echo 12 "${a//b/$b}"
+
+a='abc'
+b='\\'
+r="${a//b/$b}"
+echo 13 $r
+echo 14 ${a//b/$b}
+echo 15 "${a//b/$b}"
+
+a='abc'
+b='\t'
+r="${a//b/$b}"
+echo 16 $r
+echo 17 ${a//b/$b}
+echo 18 "${a//b/$b}"
+echo 19 ${a//b/\t}
+echo 20 "${a//b/\t}"

shell/hush_test/hush-vars/var_bash4.right

@@ -0,0 +1,23 @@
+Source:        a*b\*c
+Replace str:   _\\_\z_
+Pattern:       single backslash and star: "replace literal star"
+In assignment: a_\_z_b\*c
+Unquoted:      a_\_z_b\*c
+Quoted:        a_\_\z_b\*c
+Pattern:       double backslash and star: "replace backslash and everything after it"
+In assignment: a*b_\_z_
+Unquoted:      a*b_\_z_
+Quoted:        a*b_\_\z_
+
+Source:        a\bc
+Replace str:   _\\_\z_
+Pattern:       single backslash and b: "replace b"
+In assignment: a\_\_z_c
+Unquoted:      a\_\_z_c
+Quoted:        a\_\_\z_c
+Pattern:       double backslash and b: "replace backslash and b"
+In assignment: a_\_z_c
+Unquoted:      a_\_z_c
+Quoted:        a_\_\z_c
+
+Done: 0

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: $?

shell/hush_test/hush-vars/var_bash5.right

@@ -0,0 +1,4 @@
+a/
+a/d
+a/e/f
+Done: 0

shell/hush_test/hush-vars/var_bash5.tests

@@ -0,0 +1,11 @@
+# This testcase checks whether slashes in ${v/a/b} are parsed before
+# or after expansions
+
+v='a/b/c'
+s='b/c'
+r='e/f'
+echo "${v/$s}"
+echo "${v/$s/d}"
+echo "${v/$s/$r}"
+
+echo Done: $?