Merge remote-tracking branch 'origin/can-builtins-simplify' into list-range

compiler/builtins/bitcode/src/list.zig

@@ -4,6 +4,8 @@ const RocResult = utils.RocResult;
 const mem = std.mem;
 const Allocator = mem.Allocator;
 
+const TAG_WIDTH = 8;
+
 const EqFn = fn (?[*]u8, ?[*]u8) callconv(.C) bool;
 const Opaque = ?[*]u8;
 
@@ -502,6 +504,49 @@ pub fn listWalkBackwards(list: RocList, stepper: Opaque, stepper_caller: Caller2
     utils.decref(std.heap.c_allocator, alignment, list.bytes, data_bytes);
 }
 
+pub fn listWalkUntil(list: RocList, stepper: Opaque, stepper_caller: Caller2, accum: Opaque, alignment: usize, element_width: usize, accum_width: usize, dec: Dec, output: Opaque) callconv(.C) void {
+    // [ Continue a, Stop a ]
+    const CONTINUE: usize = 0;
+
+    if (accum_width == 0) {
+        return;
+    }
+
+    if (list.isEmpty()) {
+        @memcpy(output orelse unreachable, accum orelse unreachable, accum_width);
+        return;
+    }
+
+    const alloc: [*]u8 = @ptrCast([*]u8, std.heap.c_allocator.alloc(u8, TAG_WIDTH + accum_width) catch unreachable);
+
+    @memcpy(alloc + TAG_WIDTH, accum orelse unreachable, accum_width);
+
+    if (list.bytes) |source_ptr| {
+        var i: usize = 0;
+        const size = list.len();
+        while (i < size) : (i += 1) {
+            const element = source_ptr + i * element_width;
+            stepper_caller(stepper, element, alloc + TAG_WIDTH, alloc);
+
+            const usizes: [*]usize = @ptrCast([*]usize, @alignCast(8, alloc));
+            if (usizes[0] != 0) {
+                // decrement refcount of the remaining items
+                i += 1;
+                while (i < size) : (i += 1) {
+                    dec(source_ptr + i * element_width);
+                }
+                break;
+            }
+        }
+    }
+
+    @memcpy(output orelse unreachable, alloc + TAG_WIDTH, accum_width);
+    std.heap.c_allocator.free(alloc[0 .. TAG_WIDTH + accum_width]);
+
+    const data_bytes = list.len() * element_width;
+    utils.decref(std.heap.c_allocator, alignment, list.bytes, data_bytes);
+}
+
 // List.contains : List k, k -> Bool
 pub fn listContains(list: RocList, key: Opaque, key_width: usize, is_eq: EqFn) callconv(.C) bool {
     if (list.bytes) |source_ptr| {

compiler/builtins/bitcode/src/main.zig

@@ -12,6 +12,7 @@ comptime {
     exportListFn(list.listMapWithIndex, "map_with_index");
     exportListFn(list.listKeepIf, "keep_if");
     exportListFn(list.listWalk, "walk");
+    exportListFn(list.listWalkUntil, "walkUntil");
     exportListFn(list.listWalkBackwards, "walk_backwards");
     exportListFn(list.listKeepOks, "keep_oks");
     exportListFn(list.listKeepErrs, "keep_errs");