1 files changed, 101 insertions, 3 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index f7aee16c..33aff840 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -14,6 +14,7 @@ const tracy = @import("tracy.zig");
 pub const panes = @import("panes.zig");
 pub const tagline = @import("tagline.zig");
 pub const exec = @import("exec.zig");
+const recent_files = @import("recent.zig");
 pub const mouse = @import("mouse.zig");
 pub const normal = @import("normal.zig");
 pub const edit = @import("edit.zig");
@@ -447,11 +448,17 @@ test "a compact tagline anchors at its own pane, and both shells step from the s
     try std.testing.expectEqual(@as(u16, 3), gridColAt(p, 3.5 * body_w, body_row, body_w, tag_w));
 }
 
+const recent_path_cap = limits.host_path_cap;
+
 pub const Loc = struct {
     pane: u16,
+    /// 0 once its pane has closed: a file's entry stays, reopened by a
+    /// jump to it from `path_hash`'s recent entry.
     serial: u32,
     line: u32,
     col: u32,
+    /// The file it is in (Wyhash of the path), 0 for a pane with none.
+    path_hash: u64 = 0,
 };
 
 test {
@@ -474,6 +481,7 @@ test {
     _ = @import("draw.zig");
     _ = @import("tag_layer.zig");
     _ = @import("dump.zig"); // its tests ran nowhere before
+    _ = @import("recent.zig");
     _ = @import("Presentation.zig");
     _ = @import("animation.zig");
 }
@@ -4232,6 +4240,10 @@ pub const Options = struct {
     ninep_quic: ?[]const u8 = null,
     mounts: []const filesystem.Mount = &.{},
     config_dir: ?[]const u8 = null,
+    /// Where the list of files opened lately is kept across sessions
+    /// (recent.zig), set by the host that has a state directory; none, it
+    /// lives as long as the session.
+    recent_path: ?[]const u8 = null,
     startup_config_path: ?[]const u8 = null,
     image_allocator: ?std.mem.Allocator = null,
     pdf_allocator: ?std.mem.Allocator = null,
@@ -4298,6 +4310,12 @@ pub const Pardes = struct {
     presentation: Presentation = .{},
 
     active: usize = 0,
+    /// The files opened lately, closed ones too (recent.zig): `Recent`,
+    /// /recent, and the jumplist's way back to a closed pane.
+    recent: recent_files.List = .{},
+    /// The kept list was read (or there was none): only then is it written,
+    /// so a session never writes over one it did not read.
+    recent_loaded: bool = false,
     jumps: [MAX_JUMPS]Loc = undefined,
     njumps: usize = 0,
     jcur: usize = 0,
@@ -4621,6 +4639,7 @@ pub const Pardes = struct {
             },
         }
         p.sync();
+        p.loadRecent();
         exec.applyStartupConfig(p);
         colors.finishThemeInitialization(p);
         p.sync();
@@ -4641,7 +4660,58 @@ pub const Pardes = struct {
         p.col_panes[0][0] = 0;
     }
 
+    /// The recent list's own allocator: it is kept best effort (a file not
+    /// remembered for want of memory is no failure of what opened it), so
+    /// on a host it takes from the process heap, not the editor's, whose
+    /// every failure must be answered.
+    // ponytail: a host heap for a best-effort list; the board's gpa there.
+    pub fn recentGpa(p: *const Pardes) std.mem.Allocator {
+        return if (comptime hosted) std.heap.smp_allocator else p.gpa;
+    }
+
+    /// The kept list of files opened lately, read once at start.
+    fn loadRecent(p: *Pardes) void {
+        const path = p.opts.recent_path orelse return;
+        if (comptime !hosted) return;
+        defer p.recent_loaded = true;
+        const bytes = filesystem.readFile(p.gpa, path) catch return;
+        defer p.gpa.free(bytes);
+        p.recent.read(p.recentGpa(), bytes);
+    }
+
+    /// Written out when it changed, at the end of a step and at the end.
+    pub fn saveRecent(p: *Pardes) void {
+        if (!p.recent.dirty) return;
+        p.recent.dirty = false;
+        const path = p.opts.recent_path orelse return;
+        if (comptime !hosted) return;
+        if (!p.recent_loaded) return;
+        var out: std.Io.Writer.Allocating = .init(p.gpa);
+        defer out.deinit();
+        p.recent.write(&out.writer) catch return;
+        turn.yield();
+        defer turn.back();
+        std.Io.Dir.cwd().writeFile(std.Io.Threaded.global_single_threaded.io(), .{ .sub_path = path, .data = out.written() }) catch {};
+    }
+
+    /// A file pane's path and dot, for the recent list (0 when none).
+    fn recentDot(pane: *const Pane) ?struct { path: []const u8, line: u32, col: u32 } {
+        const f = pane.file orelse return null;
+        if (f.output != null) return null;
+        return .{ .path = f.path, .line = @intCast(@max(0, pane.body.cur_row) + 1), .col = @intCast(@max(0, pane.body.cur_col) + 1) };
+    }
+
+    /// The recent entry a closed jump names, by its path's hash.
+    pub fn recentByHash(p: *const Pardes, hash: u64) ?recent_files.Entry {
+        for (p.recent.entries.items) |e| if (std.hash.Wyhash.hash(0, e.path) == hash) return e;
+        return null;
+    }
+
     pub fn deinit(p: *Pardes) void {
+        // Every file open now is closed with its dot, and the list kept.
+        for (p.panes) |slot| if (slot) |pane| if (recentDot(pane)) |d| p.recent.closed(p.recentGpa(), d.path, d.line, d.col);
+        p.saveRecent();
+        p.recent.deinit(p.recentGpa());
         look.cancelLookHover(p);
         if (p.repl_ask) |ask| p.gpa.free(ask.text);
         for (0..MAX_PANES) |id| p.dropPendingWrite(id);
@@ -4750,6 +4820,9 @@ pub const Pardes = struct {
     }
 
     fn retirePane(p: *Pardes, pane: *Pane) void {
+        // Closed, a file is remembered with its dot: Recent and a jump back
+        // to it reopen it there.
+        if (recentDot(pane)) |d| p.recent.closed(p.recentGpa(), d.path, d.line, d.col);
         const watched = (if (pane.file) |f| f.output == null else false) or pane.hasPdf();
         for (p.panes, 0..) |slot, id| if (slot == pane) {
             if (watched) p.emit(.{ .watch = .{ .pane = @intCast(id), .on = false } });
@@ -5240,6 +5313,7 @@ pub const Pardes = struct {
         f.saved_revision = f.revision;
         f.disk_gone = false;
         ctlfs.events.noteLog(p, .save, pane);
+        p.recent.opened(p.recentGpa(), f.path);
         if (filesystem.localPath(f.path) != null)
             p.emit(.{ .watch = .{ .pane = id, .on = true } });
     }
@@ -6562,9 +6636,15 @@ pub const Pardes = struct {
         var cur: usize = 0;
         for (p.jumps[0..p.njumps], 0..) |j, i| {
             if (i == p.jcur) cur = w; // survives -> lands at w; dies -> the next one does
-            const pane = p.panes[j.pane] orelse continue;
-            if (pane.serial != j.serial) continue;
-            p.jumps[w] = j;
+            var kept = j;
+            const live = if (j.serial == 0) false else if (p.panes[j.pane]) |pane| pane.serial == j.serial else false;
+            // A file's pane closed: its entry stays, closed, while the recent
+            // list knows the file, and a jump to it opens it again.
+            if (!live) {
+                if (j.path_hash == 0 or p.recentByHash(j.path_hash) == null) continue;
+                kept.serial = 0;
+            }
+            p.jumps[w] = kept;
             w += 1;
         }
         p.njumps = w;
@@ -6576,6 +6656,7 @@ pub const Pardes = struct {
             .serial = pane.serial,
             .line = if (pane.pdfPage()) |page| @intCast(page + 1) else if (pane.body.cur_pinned) @intCast(@max(0, pane.body.cur_row) + 1) else 0,
             .col = if (pane.pdfPage() != null) 0 else if (pane.body.cur_pinned) @intCast(@max(0, pane.body.cur_col) + 1) else 0,
+            .path_hash = if (recentDot(pane)) |d| std.hash.Wyhash.hash(0, d.path) else 0,
         };
         if (p.njumps > 0 and p.samePlace(p.jumps[p.jcur], now)) {
             p.jumps[p.jcur] = now; // same visit; the entry IS where you are
@@ -6604,6 +6685,21 @@ pub const Pardes = struct {
         if (p.njumps == 0 or next < 0 or next >= p.njumps) return;
         const j = p.jumps[@intCast(next)];
         if (j.pane >= MAX_PANES) return;
+        // A closed file's entry: opened again at its dot, placed as a look
+        // places it, and the entry is that pane from here on.
+        if (j.serial == 0) {
+            const e = p.recentByHash(j.path_hash) orelse return;
+            var where: [recent_path_cap + 32]u8 = undefined;
+            const loc = std.fmt.bufPrint(&where, "{s}:{d}:{d}", .{ e.path, @max(1, j.line), @max(1, j.col) }) catch return;
+            const from = p.active;
+            look.lookAt(p, from, loc);
+            const opened = p.panes[p.active] orelse return;
+            if (p.active == from) return;
+            p.jumps[@intCast(next)].pane = @intCast(p.active);
+            p.jumps[@intCast(next)].serial = opened.serial;
+            p.jcur = @intCast(next);
+            return;
+        }
         const pane = p.panes[j.pane] orelse return;
         if (pane.serial != j.serial) return;
         if (p.panes[p.active]) |source| look.clearNavigationSelection(p, source);
@@ -6640,6 +6736,8 @@ pub const Pardes = struct {
         if (refused) for (0..p.ncol) |c| if (!layout.columnAtMinimums(p, c)) {
             _ = layout.shareColumn(p, c);
         };
+        // A file opened or closed this step: the kept list follows.
+        p.saveRecent();
         tagline.flattenHeaders(p);
         if (p.header_column != null and p.columnBarHeight() == 0) {
             tagline.exitHeader(p);