config: add "theme" config, track inputs

src/cli/args.zig

@@ -67,6 +67,11 @@ pub fn parse(comptime T: type, alloc: Allocator, dst: *T, iter: anytype) !void {
     };
 
     while (iter.next()) |arg| {
+        // If an _inputs fields exist we keep track of the inputs.
+        if (@hasField(T, "_inputs")) {
+            try dst._inputs.append(arena_alloc, try arena_alloc.dupe(u8, arg));
+        }
+
         // Do manual parsing if we have a hook for it.
         if (@hasDecl(T, "parseManuallyHook")) {
             if (!try dst.parseManuallyHook(arena_alloc, arg, iter)) return;
@@ -381,6 +386,30 @@ test "parse: error tracking" {
     try testing.expect(!data._errors.empty());
 }
 
+test "parse: input tracking" {
+    const testing = std.testing;
+
+    var data: struct {
+        a: []const u8 = "",
+        b: enum { one } = .one,
+
+        _arena: ?ArenaAllocator = null,
+        _errors: ErrorList = .{},
+        _inputs: std.ArrayListUnmanaged([]const u8) = .{},
+    } = .{};
+    defer if (data._arena) |arena| arena.deinit();
+
+    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        testing.allocator,
+        "--what --a=42",
+    );
+    defer iter.deinit();
+    try parse(@TypeOf(data), testing.allocator, &data, &iter);
+    try testing.expect(data._arena != null);
+    try testing.expect(data._inputs.items.len == 2);
+    try testing.expectEqualStrings("--what", data._inputs.items[0]);
+    try testing.expectEqualStrings("--a=42", data._inputs.items[1]);
+}
 test "parseIntoField: ignore underscore-prefixed fields" {
     const testing = std.testing;
     var arena = ArenaAllocator.init(testing.allocator);
@@ -732,6 +761,25 @@ pub fn lineIterator(reader: anytype) LineIterator(@TypeOf(reader)) {
     return .{ .r = reader };
 }
 
+/// An iterator valid for arg parsing from a slice.
+pub const SliceIterator = struct {
+    const Self = @This();
+
+    slice: []const []const u8,
+    idx: usize = 0,
+
+    pub fn next(self: *Self) ?[]const u8 {
+        if (self.idx >= self.slice.len) return null;
+        defer self.idx += 1;
+        return self.slice[self.idx];
+    }
+};
+
+/// Construct a SliceIterator from a slice.
+pub fn sliceIterator(slice: []const []const u8) SliceIterator {
+    return .{ .slice = slice };
+}
+
 test "LineIterator" {
     const testing = std.testing;
     var fbs = std.io.fixedBufferStream(