Use "target()" to parse "when" block

`target()` as used in parsing "let" and "if let" implements parsing
nested tuples and structs. But it does not implement parsing literals.

The functions `match_variant()` and `with_parameters()` as used in
parsing "when" blocks do not implement parsing nested structs, but it
implements parsing literals.

This PR combines `match_variant()` and `with_parameters()` into
`target()`, so that all `{%when%}` support nested structs, too.

1 files changed, 10 insertions, 0 deletions

diff --git a/testing/templates/match-option-result-option.html b/testing/templates/match-option-result-option.html
new file mode 100644
index 0000000..25396b6
--- /dev/null
+++ b/testing/templates/match-option-result-option.html
@@ -0,0 +1,10 @@
+{%- match foo -%}
+    {%- when None -%}
+        nothing
+    {%- when Some(Err(err)) -%}
+        err={{err}}
+    {%- when Some(Ok(None)) -%}
+        num=absent
+    {%- when Some(Ok(Some(num))) -%}
+        num={{num}}
+{%- endmatch -%}