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Allow switch with something that expands to nothing

Browse source 
Meaning empty variables, command substitutions that don't print
anything.

A switch without an argument

```fish
switch
   case ...
end
```

is still a syntax error, and more than one argument is still a runtime
error.

The none-argument matches either an empty-string `case ''` or a
catch-all `case '*'`.

Fixes #5677.

Fixes #4943.
This commit is contained in:
Fabian Homborg 2019-07-31 14:04:24 +02:00
parent 57ffd18787
commit 6500765256
3 changed files with 75 additions and 3 deletions
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1
CHANGELOG.md
View file

@ -20,6 +20,7 @@
- Local values for `fish_complete_path` and `fish_function_path` are now ignored; only their global values are respected.
- Empty universal variables may now be exported (#5992).
- `string split` had a bug where empty strings would be dropped if the output was only empty strings; this has been fixed (#5987).
- `switch` now allows arguments that expand to nothing, like empty variables (#5677).
### Syntax changes and new commands
- Brace expansion now only takes place if the braces include a "," or a variable expansion, so things like `git reset HEAD@{0}` now work (#5869).

6
src/parse_execution.cpp
View file

@ -478,9 +478,9 @@ parse_execution_result_t parse_execution_context_t::run_switch_statement(
}
}
if (result == parse_execution_success && switch_values_expanded.size() != 1) {
if (result == parse_execution_success && switch_values_expanded.size() > 1) {
result =
report_error(switch_value_n, _(L"switch: Expected exactly one argument, got %lu\n"),
report_error(switch_value_n, _(L"switch: Expected at most one argument, got %lu\n"),
switch_values_expanded.size());
}
@ -488,7 +488,7 @@ parse_execution_result_t parse_execution_context_t::run_switch_statement(
return result;
}
const wcstring &switch_value_expanded = switch_values_expanded.at(0).completion;
const wcstring &switch_value_expanded = switch_values_expanded.size() == 1 ? switch_values_expanded.at(0).completion : L"";
block_t *sb = parser->push_block(block_t::switch_block());

71
tests/checks/switch.fish Normal file
View file

@ -0,0 +1,71 @@
#RUN: %fish -C "set fish %fish" %s
# Check that switch with an argument expanding to nothing still works.
switch $foo
case a
echo a
case ''
echo very little
case '*'
echo Nothin
case ''
echo banana
end
#CHECK: very little
switch (true)
case a
echo a
case ''
echo very little
case '*'
echo Nothin
case ''
echo banana
end
#CHECK: very little
switch (echo)
case a
echo a
case ''
echo very little
case '*'
echo Nothin
case ''
echo banana
end
#CHECK: very little
# Multiple arguments is still an error, we've not decided on good behavior for this.
switch (echo; echo; echo)
case a
echo a
case ""
echo very little
case "*"
echo Nothin
case ""
echo banana
end
#CHECKERR: {{.*/?}}switch.fish (line {{\d+}}): switch: Expected at most one argument, got 3
#CHECKERR:
#CHECKERR: switch (echo; echo; echo)
#CHECKERR: ^
# As is no argument at all.
# Because this is a syntax error, we need to start a sub-fish or we wouldn't execute anything else.
$fish -c '
switch
case a
echo a
case ""
echo very little
case "*"
echo Nothin
case ""
echo banana
end
'
#CHECKERR: fish: 'case' builtin not inside of switch block
#CHECKERR: case a
#CHECKERR: ^