feat(picker): add core trait, types, and builder macro for argument

parsing

Implement the foundational `mingling_picker` library along with its
companion
`mingling_picker_macros` crate. The picker provides:

- `Pickable` trait for parsing types from raw strings
- `PickerResult` enum modeling parse outcomes
- `Picker` struct for storing and indexing command-line arguments
- `PickerRequirement` struct for declarative parameter definitions
- `PickerPattern` family (1..32) of typed pattern structs via the
  `internal_repeat` proc macro
- `req!` proc macro as a succinct builder for `PickerRequirement`

Re-export `mingling_picker::macros::*` from the `mingling` crate when
the
`picker` feature is enabled, replacing the previous wildcard re-export
of
`mingling_macros`.

1 files changed, 29 insertions, 0 deletions

diff --git a/mingling_picker_macros/src/lib.rs b/mingling_picker_macros/src/lib.rs
index 8b13789..a3c93eb 100644
--- a/mingling_picker_macros/src/lib.rs
+++ b/mingling_picker_macros/src/lib.rs
@@ -1 +1,30 @@
+use proc_macro::TokenStream;
 
+mod internal_repeat;
+mod req;
+
+/// Core proc-macro: repeats a template body `count` times.
+///
+/// Internal call signature: `internal_repeat!(count => { template })`
+#[proc_macro]
+pub fn internal_repeat(input: TokenStream) -> TokenStream {
+    internal_repeat::internal_repeat(input)
+}
+
+/// Quick builder for `PickerRequirement`.
+///
+/// # Syntax
+///
+/// ```ignore
+/// use mingling_picker_macros::req;
+///
+/// let basic = req![name: String];
+/// let with_short_name = req![name: String, 'n'];
+/// let with_short_alias = req![name: String, 'n', "alias"];
+/// let positional = req![String];
+/// let positional_with_name = req![String, 'n', "alias"];
+/// ```
+#[proc_macro]
+pub fn req(input: TokenStream) -> TokenStream {
+    req::req(input)
+}