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Fix double expansions ($$foo)

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Double expansions of variables had the following issues:

* `"$$foo"` threw an error no matter what the value of `$foo` was.
* `set -l foo ''; echo $$foo` threw an error because of the expansion of
  `$foo` to `''`.

With this change, double expansion always works properly. When
double-expanding a multi-valued variable, in a double-quoted string the
first word of the inner expansion is used for the outer expansion, and
outside of a quoted string every word is used for the double-expansion
in each of the arguments.

    > set -l foo bar baz
    > set -l bar one two
    > set -l baz three four
    > echo "$$foo"
    one two baz
    > echo $$foo
    one two three four
This commit is contained in:
Kevin Ballard
2014-08-20 21:19:08 -07:00
parent d0c85471b4
commit 3981b644d6
7 changed files with 153 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
expand.cpp
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@@ -1086,10 +1086,15 @@ static int expand_variables_internal(parser_t &parser, wchar_t * const in, std::
while (1)
{
if (!(in[stop_pos ]))
const wchar_t nc = in[stop_pos];
if (!(nc))
break;
if (!(iswalnum(in[stop_pos]) ||
(wcschr(L"_", in[stop_pos])!= 0)))
if (nc == VARIABLE_EXPAND_EMPTY)
{
stop_pos++;
break;
}
if (!(wcsvarchr(nc)))
break;
stop_pos++;
@@ -1108,7 +1113,15 @@ static int expand_variables_internal(parser_t &parser, wchar_t * const in, std::
}
var_tmp.append(in + start_pos, var_len);
env_var_t var_val = expand_var(var_tmp.c_str());
env_var_t var_val;
if (var_len == 1 && var_tmp[0] == VARIABLE_EXPAND_EMPTY)
{
var_val = env_var_t::missing_var();
}
else
{
var_val = expand_var(var_tmp.c_str());
}
if (! var_val.missing())
{
@@ -1174,7 +1187,18 @@ static int expand_variables_internal(parser_t &parser, wchar_t * const in, std::
{
in[i]=0;
wcstring res = in;
res.push_back(INTERNAL_SEPARATOR);
if (i > 0)
{
if (in[i-1] != VARIABLE_EXPAND_SINGLE)
{
res.push_back(INTERNAL_SEPARATOR);
}
else if (var_item_list.empty() || var_item_list.front().empty())
{
// first expansion is empty, but we need to recursively expand
res.push_back(VARIABLE_EXPAND_EMPTY);
}
}
for (size_t j=0; j<var_item_list.size(); j++)
{
@@ -1204,14 +1228,18 @@ static int expand_variables_internal(parser_t &parser, wchar_t * const in, std::
if (is_ok)
{
wcstring new_in;
new_in.append(in, i);
if (start_pos > 0)
new_in.append(in, start_pos - 1);
// at this point new_in.size() is start_pos - 1
if (start_pos>1 && new_in[start_pos-2]!=VARIABLE_EXPAND)
if (i > 0)
{
new_in.push_back(INTERNAL_SEPARATOR);
if (in[i-1] != VARIABLE_EXPAND)
{
new_in.push_back(INTERNAL_SEPARATOR);
}
else if (next.empty())
{
new_in.push_back(VARIABLE_EXPAND_EMPTY);
}
}
new_in.append(next);
new_in.append(in + stop_pos);
@@ -1243,8 +1271,11 @@ static int expand_variables_internal(parser_t &parser, wchar_t * const in, std::
Expansion to single argument.
*/
wcstring res;
in[i] = 0;
res.append(in);
res.append(in, i);
if (i > 0 && in[i-1] == VARIABLE_EXPAND_SINGLE)
{
res.push_back(VARIABLE_EXPAND_EMPTY);
}
res.append(in + stop_pos);
is_ok &= expand_variables2(parser, res, out, i, errors);