initial commit

src/layout/Framing.zig

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+//! Framing layout for a nested `Layout`s or `Widget`s.
+//!
+//! # Example
+//! ...
+const std = @import("std");
+const terminal = @import("../terminal.zig");
+
+const isTaggedUnion = @import("../event.zig").isTaggedUnion;
+const Error = @import("../event.zig").Error;
+const Key = terminal.Key;
+
+const log = std.log.scoped(.layout_framing);
+
+pub fn Layout(comptime Event: type) type {
+    if (!isTaggedUnion(Event)) {
+        @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
+    }
+    const Element = union(enum) {
+        layout: @import("../layout.zig").Layout(Event),
+        widget: @import("../widget.zig").Widget(Event),
+    };
+    const Events = std.ArrayList(Event);
+    const Contents = std.ArrayList(u8);
+    return struct {
+        size: terminal.Size = undefined,
+        contents: Contents = undefined,
+        element: Element = undefined,
+        events: Events = undefined,
+
+        pub fn init(allocator: std.mem.Allocator, element: Element) @This() {
+            return .{
+                .contents = Contents.init(allocator),
+                .element = element,
+                .events = Events.init(allocator),
+            };
+        }
+
+        pub fn deinit(this: *@This()) void {
+            this.contents.deinit();
+            this.events.deinit();
+            switch ((&this.element).*) {
+                .layout => |*layout| {
+                    layout.deinit();
+                },
+                .widget => |*widget| {
+                    widget.deinit();
+                },
+            }
+        }
+
+        pub fn handle(this: *@This(), event: Event) !*Events {
+            this.events.clearRetainingCapacity();
+            // order is important
+            switch (event) {
+                .resize => |size| {
+                    this.size = size;
+                    // adjust size according to the containing elements
+                    const sub_event = event;
+                    switch ((&this.element).*) {
+                        .layout => |*layout| {
+                            const events = try layout.handle(sub_event);
+                            try this.events.appendSlice(events.items);
+                        },
+                        .widget => |*widget| {
+                            if (widget.handle(sub_event)) |e| {
+                                try this.events.append(e);
+                            }
+                        },
+                    }
+                },
+                else => {
+                    switch ((&this.element).*) {
+                        .layout => |*layout| {
+                            const events = try layout.handle(event);
+                            try this.events.appendSlice(events.items);
+                        },
+                        .widget => |*widget| {
+                            if (widget.handle(event)) |e| {
+                                try this.events.append(e);
+                            }
+                        },
+                    }
+                },
+            }
+            return &this.events;
+        }
+
+        pub fn content(this: *@This()) !*Contents {
+            this.contents.clearRetainingCapacity();
+            // TODO: padding contents accordingly
+            switch ((&this.element).*) {
+                .layout => |*layout| {
+                    const layout_content = try layout.content();
+                    try this.contents.appendSlice(layout_content.items);
+                },
+                .widget => |*widget| {
+                    try this.contents.appendSlice(try widget.content());
+                },
+            }
+            return &this.contents;
+        }
+    };
+}