Allow for clap to parse argument values into types

This changes

- `.flag`, `.option`, `.options` and `.positionals` are now just fields
  you access on the result of `parse` and `parseEx`.
- `clap.ComptimeClap` has been removed.
- `clap.StreamingClap` is now called `clap.streaming.Clap`
- `parse` and `parseEx` now takes a `value_parsers` argument that
  provides the parsers to parse values.
- Remove `helpEx`, `helpFull`, `usageEx` and `usageFull`. They now just
  expect `Id` to have methods for getting the description and value
  texts.

1 files changed, 48 insertions, 0 deletions

diff --git a/clap/parsers.zig b/clap/parsers.zig
new file mode 100644
index 0000000..49b95a9
--- /dev/null
+++ b/clap/parsers.zig
@@ -0,0 +1,48 @@
+const std = @import("std");
+
+const fmt = std.fmt;
+
+pub const default = .{
+    .string = string,
+    .str = string,
+    .u8 = int(u8, 0),
+    .u16 = int(u16, 0),
+    .u32 = int(u32, 0),
+    .u64 = int(u64, 0),
+    .usize = int(usize, 0),
+    .i8 = int(i8, 0),
+    .i16 = int(i16, 0),
+    .i32 = int(i32, 0),
+    .i64 = int(i64, 0),
+    .isize = int(isize, 0),
+    .f32 = float(f32),
+    .f64 = float(f64),
+};
+
+pub fn string(in: []const u8) error{}![]const u8 {
+    return in;
+}
+
+pub fn int(comptime T: type, comptime radix: u8) fn ([]const u8) fmt.ParseIntError!T {
+    return struct {
+        fn parse(in: []const u8) fmt.ParseIntError!T {
+            return fmt.parseInt(T, in, radix);
+        }
+    }.parse;
+}
+
+pub fn float(comptime T: type) fn ([]const u8) fmt.ParseFloatError!T {
+    return struct {
+        fn parse(in: []const u8) fmt.ParseFloatError!T {
+            return fmt.parseFloat(T, in);
+        }
+    }.parse;
+}
+
+fn ReturnType(comptime P: type) type {
+    return @typeInfo(P).Fn.return_type.?;
+}
+
+pub fn Result(comptime P: type) type {
+    return @typeInfo(ReturnType(P)).ErrorUnion.payload;
+}