API: Context

9 files changed, 717 insertions, 101 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index dbe3b66fd5..3fd50ffaf8 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -21,6 +21,7 @@
 #include "nvim/lua/executor.h"
 #include "nvim/vim.h"
 #include "nvim/buffer.h"
+#include "nvim/context.h"
 #include "nvim/file_search.h"
 #include "nvim/highlight.h"
 #include "nvim/window.h"
@@ -1268,6 +1269,63 @@ Dictionary nvim_get_color_map(void)
   return colors;
 }
 
+/// Gets a map of the current editor state.
+///
+/// @param  types  Context types ("regs", "jumps", "buflist", "gvars", ...)
+///                to gather, or NIL for all.
+///
+/// @return map of global context
+Dictionary nvim_get_context(Array types)
+  FUNC_API_SINCE(6)
+{
+  int int_types = 0;
+  if (types.size == 1 && types.items[0].type == kObjectTypeNil) {
+    int_types = kCtxAll;
+  } else {
+    for (size_t i = 0; i < types.size; i++) {
+      if (types.items[i].type == kObjectTypeString) {
+        const char *const current = types.items[i].data.string.data;
+        if (strequal(current, "regs")) {
+          int_types |= kCtxRegs;
+        } else if (strequal(current, "jumps")) {
+          int_types |= kCtxJumps;
+        } else if (strequal(current, "buflist")) {
+          int_types |= kCtxBuflist;
+        } else if (strequal(current, "gvars")) {
+          int_types |= kCtxGVars;
+        }
+      }
+    }
+  }
+
+  Context ctx = CONTEXT_INIT;
+  ctx_save(&ctx, int_types);
+  Dictionary dict = ctx_to_dict(&ctx);
+  ctx_free(&ctx);
+  return dict;
+}
+
+/// Sets the current editor state to that in given context dictionary.
+///
+/// @param ctx_dict  Context dictionary.
+Object nvim_load_context(Dictionary dict)
+  FUNC_API_SINCE(6)
+{
+  Context ctx = CONTEXT_INIT;
+
+  int save_did_emsg = did_emsg;
+  did_emsg = false;
+
+  ctx_from_dict(dict, &ctx);
+  if (!did_emsg) {
+    ctx_restore(&ctx, kCtxAll);
+  }
+
+  ctx_free(&ctx);
+
+  did_emsg = save_did_emsg;
+  return (Object)OBJECT_INIT;
+}
 
 /// Gets the current mode. |mode()|
 /// "blocking" is true if Nvim is waiting for input.
diff --git a/src/nvim/context.c b/src/nvim/context.c
new file mode 100644
index 0000000000..09f2d7bd76
--- /dev/null
+++ b/src/nvim/context.c
@@ -0,0 +1,317 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
+// Context: snapshot of the entire editor state as one big object/map
+
+#include "nvim/context.h"
+#include "nvim/eval/encode.h"
+#include "nvim/option.h"
+#include "nvim/shada.h"
+#include "nvim/api/private/helpers.h"
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "context.c.generated.h"
+#endif
+
+int kCtxAll = (kCtxRegs | kCtxJumps | kCtxBuflist | kCtxGVars);
+
+static ContextVec ctx_stack = KV_INITIAL_VALUE;
+
+/// Clears and frees the context stack
+void free_ctx_stack(void)
+{
+  for (size_t i = 0; i < kv_size(ctx_stack); i++) {
+    ctx_free(&kv_A(ctx_stack, i));
+  }
+  kv_destroy(ctx_stack);
+}
+
+/// Returns the size of the context stack.
+size_t ctx_size(void)
+{
+  return kv_size(ctx_stack);
+}
+
+/// Returns pointer to Context object with given zero-based index from the top
+/// of context stack or NULL if index is out of bounds.
+Context *ctx_get(size_t index)
+{
+  if (index < kv_size(ctx_stack)) {
+    return &kv_Z(ctx_stack, index);
+  }
+  return NULL;
+}
+
+/// Free resources used by Context object.
+///
+/// param[in]  ctx  pointer to Context object to free.
+void ctx_free(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (ctx->regs.data) {
+    msgpack_sbuffer_destroy(&ctx->regs);
+  }
+  if (ctx->jumps.data) {
+    msgpack_sbuffer_destroy(&ctx->jumps);
+  }
+  if (ctx->buflist.data) {
+    msgpack_sbuffer_destroy(&ctx->buflist);
+  }
+  if (ctx->gvars.data) {
+    msgpack_sbuffer_destroy(&ctx->gvars);
+  }
+}
+
+/// Saves the editor state to a context.
+///
+/// If "context" is NULL, pushes context on context stack.
+/// Use "flags" to select particular types of context.
+///
+/// @param  ctx    Save to this context, or push on context stack if NULL.
+/// @param  flags  Flags, see ContextTypeFlags enum.
+void ctx_save(Context *ctx, const int flags)
+{
+  if (ctx == NULL) {
+    kv_push(ctx_stack, CONTEXT_INIT);
+    ctx = &kv_last(ctx_stack);
+  }
+
+  if (flags & kCtxRegs) {
+    ctx_save_regs(ctx);
+  }
+  if (flags & kCtxJumps) {
+    ctx_save_jumps(ctx);
+  }
+  if (flags & kCtxBuflist) {
+    ctx_save_buflist(ctx);
+  }
+  if (flags & kCtxGVars) {
+    ctx_save_gvars(ctx);
+  }
+}
+
+/// Restores the editor state from a context.
+///
+/// If "context" is NULL, pops context from context stack.
+/// Use "flags" to select particular types of context.
+///
+/// @param  ctx    Restore from this context. Pop from context stack if NULL.
+/// @param  flags  Flags, see ContextTypeFlags enum.
+///
+/// @return true on success, false otherwise (i.e.: empty context stack).
+bool ctx_restore(Context *ctx, const int flags)
+{
+  bool free_ctx = false;
+  if (ctx == NULL) {
+    if (ctx_stack.size == 0) {
+      return false;
+    }
+    ctx = &kv_pop(ctx_stack);
+    free_ctx = true;
+  }
+
+  char_u *op_shada;
+  get_option_value((char_u *)"shada", NULL, &op_shada, OPT_GLOBAL);
+  set_option_value("shada", 0L, "!,'100,%", OPT_GLOBAL);
+
+  if (flags & kCtxRegs) {
+    ctx_restore_regs(ctx);
+  }
+  if (flags & kCtxJumps) {
+    ctx_restore_jumps(ctx);
+  }
+  if (flags & kCtxBuflist) {
+    ctx_restore_buflist(ctx);
+  }
+  if (flags & kCtxGVars) {
+    ctx_restore_gvars(ctx);
+  }
+
+  if (free_ctx) {
+    ctx_free(ctx);
+  }
+
+  set_option_value("shada", 0L, (char *)op_shada, OPT_GLOBAL);
+  xfree(op_shada);
+
+  return true;
+}
+
+/// Saves the global registers to a context.
+///
+/// @param  ctx    Save to this context.
+static inline void ctx_save_regs(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  msgpack_sbuffer_init(&ctx->regs);
+  shada_encode_regs(&ctx->regs);
+}
+
+/// Restores the global registers from a context.
+///
+/// @param  ctx   Restore from this context.
+static inline void ctx_restore_regs(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  shada_read_sbuf(&ctx->regs, kShaDaWantInfo | kShaDaForceit);
+}
+
+/// Saves the jumplist to a context.
+///
+/// @param  ctx  Save to this context.
+static inline void ctx_save_jumps(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  msgpack_sbuffer_init(&ctx->jumps);
+  shada_encode_jumps(&ctx->jumps);
+}
+
+/// Restores the jumplist from a context.
+///
+/// @param  ctx  Restore from this context.
+static inline void ctx_restore_jumps(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  shada_read_sbuf(&ctx->jumps, kShaDaWantInfo | kShaDaForceit);
+}
+
+/// Saves the buffer list to a context.
+///
+/// @param  ctx  Save to this context.
+static inline void ctx_save_buflist(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  msgpack_sbuffer_init(&ctx->buflist);
+  shada_encode_buflist(&ctx->buflist);
+}
+
+/// Restores the buffer list from a context.
+///
+/// @param  ctx  Restore from this context.
+static inline void ctx_restore_buflist(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  shada_read_sbuf(&ctx->buflist, kShaDaWantInfo | kShaDaForceit);
+}
+
+/// Saves global variables to a context.
+///
+/// @param  ctx  Save to this context.
+static inline void ctx_save_gvars(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  msgpack_sbuffer_init(&ctx->gvars);
+  shada_encode_gvars(&ctx->gvars);
+}
+
+/// Restores global variables from a context.
+///
+/// @param  ctx  Restore from this context.
+static inline void ctx_restore_gvars(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  shada_read_sbuf(&ctx->gvars, kShaDaWantInfo | kShaDaForceit);
+}
+
+/// Convert msgpack_sbuffer to readfile()-style array.
+///
+/// @param[in]  sbuf  msgpack_sbuffer to convert.
+///
+/// @return readfile()-style array representation of "sbuf".
+static inline Array sbuf_to_array(msgpack_sbuffer sbuf)
+{
+  list_T *const list = tv_list_alloc(kListLenMayKnow);
+  tv_list_append_string(list, "", 0);
+  if (sbuf.size > 0) {
+    encode_list_write(list, sbuf.data, sbuf.size);
+  }
+
+  typval_T list_tv = (typval_T) {
+    .v_lock = VAR_UNLOCKED,
+    .v_type = VAR_LIST,
+    .vval.v_list = list
+  };
+
+  Array array = vim_to_object(&list_tv).data.array;
+  tv_clear(&list_tv);
+  return array;
+}
+
+/// Convert readfile()-style array to msgpack_sbuffer.
+///
+/// @param[in]  array  readfile()-style array to convert.
+///
+/// @return msgpack_sbuffer with conversion result.
+static inline msgpack_sbuffer array_to_sbuf(Array array)
+{
+  msgpack_sbuffer sbuf;
+  msgpack_sbuffer_init(&sbuf);
+
+  typval_T list_tv;
+  Error err = ERROR_INIT;
+  object_to_vim(ARRAY_OBJ(array), &list_tv, &err);
+
+  if (!encode_vim_list_to_buf(list_tv.vval.v_list, &sbuf.size, &sbuf.data)) {
+    EMSG(_("E474: Failed to convert list to msgpack string buffer"));
+  }
+  sbuf.alloc = sbuf.size;
+
+  tv_clear(&list_tv);
+  api_clear_error(&err);
+  return sbuf;
+}
+
+/// Converts Context to Dictionary representation.
+///
+/// @param[in]  ctx  Context to convert.
+///
+/// @return Dictionary representing "ctx".
+Dictionary ctx_to_dict(Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  assert(ctx != NULL);
+
+  Dictionary rv = ARRAY_DICT_INIT;
+
+  PUT(rv, "regs", ARRAY_OBJ(sbuf_to_array(ctx->regs)));
+  PUT(rv, "jumps", ARRAY_OBJ(sbuf_to_array(ctx->jumps)));
+  PUT(rv, "buflist", ARRAY_OBJ(sbuf_to_array(ctx->buflist)));
+  PUT(rv, "gvars", ARRAY_OBJ(sbuf_to_array(ctx->gvars)));
+
+  return rv;
+}
+
+/// Converts Dictionary representation of Context back to Context object.
+///
+/// @param[in]   dict  Context Dictionary representation.
+/// @param[out]  ctx   Context object to store conversion result into.
+///
+/// @return types of included context items.
+int ctx_from_dict(Dictionary dict, Context *ctx)
+  FUNC_ATTR_NONNULL_ALL
+{
+  assert(ctx != NULL);
+
+  int types = 0;
+  for (size_t i = 0; i < dict.size; i++) {
+    KeyValuePair item = dict.items[i];
+    if (item.value.type != kObjectTypeArray) {
+      continue;
+    }
+    if (strequal(item.key.data, "regs")) {
+      types |= kCtxRegs;
+      ctx->regs = array_to_sbuf(item.value.data.array);
+    } else if (strequal(item.key.data, "jumps")) {
+      types |= kCtxJumps;
+      ctx->jumps = array_to_sbuf(item.value.data.array);
+    } else if (strequal(item.key.data, "buflist")) {
+      types |= kCtxBuflist;
+      ctx->buflist = array_to_sbuf(item.value.data.array);
+    } else if (strequal(item.key.data, "gvars")) {
+      types |= kCtxGVars;
+      ctx->gvars = array_to_sbuf(item.value.data.array);
+    }
+  }
+
+  return types;
+}
diff --git a/src/nvim/context.h b/src/nvim/context.h
new file mode 100644
index 0000000000..4e641adeda
--- /dev/null
+++ b/src/nvim/context.h
@@ -0,0 +1,42 @@
+#ifndef NVIM_CONTEXT_H
+#define NVIM_CONTEXT_H
+
+#include <msgpack.h>
+#include "nvim/api/private/defs.h"
+#include "nvim/lib/kvec.h"
+
+typedef struct {
+  msgpack_sbuffer regs;     ///< Registers.
+  msgpack_sbuffer jumps;    ///< Jumplist.
+  msgpack_sbuffer buflist;  ///< Buffer list.
+  msgpack_sbuffer gvars;    ///< Global variables.
+} Context;
+typedef kvec_t(Context) ContextVec;
+
+#define MSGPACK_SBUFFER_INIT (msgpack_sbuffer) { \
+  .size = 0, \
+  .data = NULL, \
+  .alloc = 0, \
+}
+
+#define CONTEXT_INIT (Context) { \
+  .regs = MSGPACK_SBUFFER_INIT, \
+  .jumps = MSGPACK_SBUFFER_INIT, \
+  .buflist = MSGPACK_SBUFFER_INIT, \
+  .gvars = MSGPACK_SBUFFER_INIT, \
+}
+
+typedef enum {
+  kCtxRegs = 1,       ///< Registers
+  kCtxJumps = 2,      ///< Jumplist
+  kCtxBuflist = 4,    ///< Buffer list
+  kCtxGVars = 8,      ///< Global variables
+} ContextTypeFlags;
+
+extern int kCtxAll;
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "context.h.generated.h"
+#endif
+
+#endif  // NVIM_CONTEXT_H
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 0b943cedc7..cd89a22db3 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -303,15 +303,6 @@ typedef struct {
   list_T      *fi_list;         /* list being used */
 } forinfo_T;
 
-/*
- * enum used by var_flavour()
- */
-typedef enum {
-  VAR_FLAVOUR_DEFAULT,          /* doesn't start with uppercase */
-  VAR_FLAVOUR_SESSION,          /* starts with uppercase, some lower */
-  VAR_FLAVOUR_SHADA             /* all uppercase */
-} var_flavour_T;
-
 /* values for vv_flags: */
 #define VV_COMPAT       1       /* compatible, also used without "v:" */
 #define VV_RO           2       /* read-only */
@@ -5261,7 +5252,7 @@ bool garbage_collect(bool testing)
       yankreg_T reg;
       char name = NUL;
       bool is_unnamed = false;
-      reg_iter = op_register_iter(reg_iter, &name, &reg, &is_unnamed);
+      reg_iter = op_global_reg_iter(reg_iter, &name, &reg, &is_unnamed);
       if (name != NUL) {
         ABORTING(set_ref_dict)(reg.additional_data, copyID);
       }
@@ -15618,7 +15609,7 @@ free_lstval:
 
   if (set_unnamed) {
     // Discard the result. We already handle the error case.
-    if (op_register_set_previous(regname)) { }
+    if (op_reg_set_previous(regname)) { }
   }
 }
 
@@ -23278,7 +23269,7 @@ dictitem_T *find_var_in_scoped_ht(const char *name, const size_t namelen,
 /// @return Pointer that needs to be passed to next `var_shada_iter` invocation
 ///         or NULL to indicate that iteration is over.
 const void *var_shada_iter(const void *const iter, const char **const name,
-                           typval_T *rettv)
+                           typval_T *rettv, var_flavour_T flavour)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ARG(2, 3)
 {
   const hashitem_T *hi;
@@ -23289,7 +23280,7 @@ const void *var_shada_iter(const void *const iter, const char **const name,
     hi = globvarht.ht_array;
     while ((size_t) (hi - hifirst) < hinum
            && (HASHITEM_EMPTY(hi)
-               || var_flavour(hi->hi_key) != VAR_FLAVOUR_SHADA)) {
+               || !(var_flavour(hi->hi_key) & flavour))) {
       hi++;
     }
     if ((size_t) (hi - hifirst) == hinum) {
@@ -23301,7 +23292,7 @@ const void *var_shada_iter(const void *const iter, const char **const name,
   *name = (char *)TV_DICT_HI2DI(hi)->di_key;
   tv_copy(&TV_DICT_HI2DI(hi)->di_tv, rettv);
   while ((size_t)(++hi - hifirst) < hinum) {
-    if (!HASHITEM_EMPTY(hi) && var_flavour(hi->hi_key) == VAR_FLAVOUR_SHADA) {
+    if (!HASHITEM_EMPTY(hi) && (var_flavour(hi->hi_key) & flavour)) {
       return hi;
     }
   }
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index 149dae688e..abe032a96e 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -24,6 +24,13 @@ EXTERN ufunc_T dumuf;
 #define HIKEY2UF(p)  ((ufunc_T *)(p - offsetof(ufunc_T, uf_name)))
 #define HI2UF(hi)    HIKEY2UF((hi)->hi_key)
 
+/// enum used by var_flavour()
+typedef enum {
+  VAR_FLAVOUR_DEFAULT = 1,   // doesn't start with uppercase
+  VAR_FLAVOUR_SESSION = 2,   // starts with uppercase, some lower
+  VAR_FLAVOUR_SHADA   = 4    // all uppercase
+} var_flavour_T;
+
 /// Defines for Vim variables
 typedef enum {
     VV_COUNT,
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 3736004527..9f357575d0 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -1213,8 +1213,8 @@ void cleanup_jumplist(win_T *wp, bool loadfiles)
 
   // When pointer is below last jump, remove the jump if it matches the current
   // line.  This avoids useless/phantom jumps. #9805
-  if (wp->w_jumplistlen
-      && wp->w_jumplistidx == wp->w_jumplistlen) {
+  if (loadfiles  // otherwise (i.e.: Shada), last entry should be kept
+      && wp->w_jumplistlen && wp->w_jumplistidx == wp->w_jumplistlen) {
     const xfmark_T *fm_last = &wp->w_jumplist[wp->w_jumplistlen - 1];
     if (fm_last->fmark.fnum == curbuf->b_fnum
         && fm_last->fmark.mark.lnum == wp->w_cursor.lnum) {
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index 40c96eb333..a1f2a2f1b6 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -3516,8 +3516,8 @@ void ex_display(exarg_T *eap)
  * display a string for do_dis()
  * truncate at end of screen line
  */
-static void 
-dis_msg (
+static void
+dis_msg(
     char_u *p,
     int skip_esc                       /* if TRUE, ignore trailing ESC */
 )
@@ -3857,8 +3857,8 @@ static int same_leader(linenr_T lnum, int leader1_len, char_u *leader1_flags, in
 /*
  * Implementation of the format operator 'gq'.
  */
-void 
-op_format (
+void
+op_format(
     oparg_T *oap,
     int keep_cursor                        /* keep cursor on same text char */
 )
@@ -3937,8 +3937,8 @@ void op_formatexpr(oparg_T *oap)
     op_format(oap, FALSE);
 }
 
-int 
-fex_format (
+int
+fex_format(
     linenr_T lnum,
     long count,
     int c                  /* character to be inserted */
@@ -3980,8 +3980,8 @@ fex_format (
  * Lines after the cursor line are saved for undo, caller must have saved the
  * first line.
  */
-void 
-format_lines (
+void
+format_lines(
     linenr_T line_count,
     int avoid_fex                          /* don't use 'formatexpr' */
 )
@@ -5892,33 +5892,45 @@ static inline bool reg_empty(const yankreg_T *const reg)
               && *(reg->y_array[0]) == NUL));
 }
 
-/// Iterate over registerrs
+/// Iterate over global registers.
+///
+/// @see op_register_iter
+const void *op_global_reg_iter(const void *const iter, char *const name,
+                               yankreg_T *const reg, bool *is_unnamed)
+  FUNC_ATTR_NONNULL_ARG(2, 3, 4) FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  return op_reg_iter(iter, y_regs, name, reg, is_unnamed);
+}
+
+/// Iterate over registers `regs`.
 ///
 /// @param[in]   iter      Iterator. Pass NULL to start iteration.
+/// @param[in]   regs      Registers list to be iterated.
 /// @param[out]  name      Register name.
 /// @param[out]  reg       Register contents.
 ///
-/// @return Pointer that needs to be passed to next `op_register_iter` call or
+/// @return Pointer that must be passed to next `op_register_iter` call or
 ///         NULL if iteration is over.
-const void *op_register_iter(const void *const iter, char *const name,
-                             yankreg_T *const reg, bool *is_unnamed)
-  FUNC_ATTR_NONNULL_ARG(2, 3) FUNC_ATTR_WARN_UNUSED_RESULT
+const void *op_reg_iter(const void *const iter, const yankreg_T *const regs,
+                        char *const name, yankreg_T *const reg,
+                        bool *is_unnamed)
+  FUNC_ATTR_NONNULL_ARG(3, 4, 5) FUNC_ATTR_WARN_UNUSED_RESULT
 {
   *name = NUL;
   const yankreg_T *iter_reg = (iter == NULL
-                               ? &(y_regs[0])
-                               : (const yankreg_T *const) iter);
-  while (iter_reg - &(y_regs[0]) < NUM_SAVED_REGISTERS && reg_empty(iter_reg)) {
+                               ? &(regs[0])
+                               : (const yankreg_T *const)iter);
+  while (iter_reg - &(regs[0]) < NUM_SAVED_REGISTERS && reg_empty(iter_reg)) {
     iter_reg++;
   }
-  if (iter_reg - &(y_regs[0]) == NUM_SAVED_REGISTERS || reg_empty(iter_reg)) {
+  if (iter_reg - &(regs[0]) == NUM_SAVED_REGISTERS || reg_empty(iter_reg)) {
     return NULL;
   }
-  int iter_off = (int)(iter_reg - &(y_regs[0]));
+  int iter_off = (int)(iter_reg - &(regs[0]));
   *name = (char)get_register_name(iter_off);
   *reg = *iter_reg;
   *is_unnamed = (iter_reg == y_previous);
-  while (++iter_reg - &(y_regs[0]) < NUM_SAVED_REGISTERS) {
+  while (++iter_reg - &(regs[0]) < NUM_SAVED_REGISTERS) {
     if (!reg_empty(iter_reg)) {
       return (void *) iter_reg;
     }
@@ -5927,7 +5939,7 @@ const void *op_register_iter(const void *const iter, char *const name,
 }
 
 /// Get a number of non-empty registers
-size_t op_register_amount(void)
+size_t op_reg_amount(void)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   size_t ret = 0;
@@ -5946,7 +5958,7 @@ size_t op_register_amount(void)
 /// @param[in]  is_unnamed  Whether to set the unnamed regiseter to reg
 ///
 /// @return true on success, false on failure.
-bool op_register_set(const char name, const yankreg_T reg, bool is_unnamed)
+bool op_reg_set(const char name, const yankreg_T reg, bool is_unnamed)
 {
   int i = op_reg_index(name);
   if (i == -1) {
@@ -5966,7 +5978,7 @@ bool op_register_set(const char name, const yankreg_T reg, bool is_unnamed)
 /// @param[in]  name  Register name.
 ///
 /// @return Pointer to the register contents or NULL.
-const yankreg_T *op_register_get(const char name)
+const yankreg_T *op_reg_get(const char name)
 {
   int i = op_reg_index(name);
   if (i == -1) {
@@ -5980,7 +5992,7 @@ const yankreg_T *op_register_get(const char name)
 /// @param[in]  name  Register name.
 ///
 /// @return true on success, false on failure.
-bool op_register_set_previous(const char name)
+bool op_reg_set_previous(const char name)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   int i = op_reg_index(name);
diff --git a/src/nvim/shada.c b/src/nvim/shada.c
index 4aafc669dc..d23985ca86 100644
--- a/src/nvim/shada.c
+++ b/src/nvim/shada.c
@@ -151,15 +151,6 @@ KHASH_SET_INIT_STR(strset)
 /// Callback function for add_search_pattern
 typedef void (*SearchPatternGetter)(SearchPattern *);
 
-/// Flags for shada_read_file and children
-typedef enum {
-  kShaDaWantInfo = 1,       ///< Load non-mark information
-  kShaDaWantMarks = 2,      ///< Load local file marks and change list
-  kShaDaForceit = 4,        ///< Overwrite info already read
-  kShaDaGetOldfiles = 8,    ///< Load v:oldfiles.
-  kShaDaMissingError = 16,  ///< Error out when os_open returns -ENOENT.
-} ShaDaReadFileFlags;
-
 /// Possible ShaDa entry types
 ///
 /// @warning Enum values are part of the API and must not be altered.
@@ -1328,13 +1319,13 @@ static void shada_read(ShaDaReadDef *const sd_reader, const int flags)
           break;
         }
         if (!force) {
-          const yankreg_T *const reg = op_register_get(cur_entry.data.reg.name);
+          const yankreg_T *const reg = op_reg_get(cur_entry.data.reg.name);
           if (reg == NULL || reg->timestamp >= cur_entry.timestamp) {
             shada_free_shada_entry(&cur_entry);
             break;
           }
         }
-        if (!op_register_set(cur_entry.data.reg.name, (yankreg_T) {
+        if (!op_reg_set(cur_entry.data.reg.name, (yankreg_T) {
           .y_array = (char_u **)cur_entry.data.reg.contents,
           .y_size = cur_entry.data.reg.contents_size,
           .y_type = cur_entry.data.reg.type,
@@ -2496,7 +2487,7 @@ static inline void shada_initialize_registers(WriteMergerState *const wms,
     yankreg_T reg;
     char name = NUL;
     bool is_unnamed = false;
-    reg_iter = op_register_iter(reg_iter, &name, &reg, &is_unnamed);
+    reg_iter = op_global_reg_iter(reg_iter, &name, &reg, &is_unnamed);
     if (name == NUL) {
       break;
     }
@@ -2552,6 +2543,19 @@ static inline void replace_numbered_mark(WriteMergerState *const wms,
   wms->numbered_marks[idx].data.data.filemark.name = (char)('0' + (int)idx);
 }
 
+/// Find buffers ignored due to their location.
+///
+/// @param[out]  removable_bufs  Cache of buffers ignored due to their location.
+static inline void find_removable_bufs(khash_t(bufset) *removable_bufs)
+{
+  FOR_ALL_BUFFERS(buf) {
+    if (buf->b_ffname != NULL && shada_removable((char *)buf->b_ffname)) {
+      int kh_ret;
+      (void)kh_put(bufset, removable_bufs, (uintptr_t)buf, &kh_ret);
+    }
+  }
+}
+
 /// Write ShaDa file
 ///
 /// @param[in]  sd_writer  Structure containing file writer definition.
@@ -2621,12 +2625,7 @@ static ShaDaWriteResult shada_write(ShaDaWriteDef *const sd_writer,
     set_last_cursor(wp);
   }
 
-  FOR_ALL_BUFFERS(buf) {
-    if (buf->b_ffname != NULL && shada_removable((char *) buf->b_ffname)) {
-      int kh_ret;
-      (void) kh_put(bufset, &removable_bufs, (uintptr_t) buf, &kh_ret);
-    }
-  }
+  find_removable_bufs(&removable_bufs);
 
   // Write header
   if (shada_pack_entry(packer, (ShadaEntry) {
@@ -2673,7 +2672,7 @@ static ShaDaWriteResult shada_write(ShaDaWriteDef *const sd_writer,
     do {
       typval_T vartv;
       const char *name = NULL;
-      var_iter = var_shada_iter(var_iter, &name, &vartv);
+      var_iter = var_shada_iter(var_iter, &name, &vartv, VAR_FLAVOUR_SHADA);
       if (name == NULL) {
         break;
       }
@@ -2737,49 +2736,7 @@ static ShaDaWriteResult shada_write(ShaDaWriteDef *const sd_writer,
   }
 
   // Initialize jump list
-  const void *jump_iter = NULL;
-  cleanup_jumplist(curwin, false);
-  setpcmark();
-  do {
-    xfmark_T fm;
-    jump_iter = mark_jumplist_iter(jump_iter, curwin, &fm);
-
-    if (fm.fmark.mark.lnum == 0) {
-      iemsgf("ShaDa: mark lnum zero (ji:%p, js:%p, len:%i)",
-             (void *)jump_iter, (void *)&curwin->w_jumplist[0],
-             curwin->w_jumplistlen);
-      continue;
-    }
-    const buf_T *const buf = (fm.fmark.fnum == 0
-                              ? NULL
-                              : buflist_findnr(fm.fmark.fnum));
-    if (buf != NULL
-        ? in_bufset(&removable_bufs, buf)
-        : fm.fmark.fnum != 0) {
-      continue;
-    }
-    const char *const fname = (char *) (fm.fmark.fnum == 0
-                                        ? (fm.fname == NULL ? NULL : fm.fname)
-                                        : buf->b_ffname);
-    if (fname == NULL) {
-      continue;
-    }
-    wms->jumps[wms->jumps_size++] = (PossiblyFreedShadaEntry) {
-      .can_free_entry = false,
-      .data = {
-        .type = kSDItemJump,
-        .timestamp = fm.fmark.timestamp,
-        .data = {
-          .filemark = {
-            .name = NUL,
-            .mark = fm.fmark.mark,
-            .fname = (char *) fname,
-            .additional_data = fm.fmark.additional_data,
-          }
-        }
-      }
-    };
-  } while (jump_iter != NULL);
+  wms->jumps_size = shada_init_jumps(wms->jumps, &removable_bufs);
 
   // Initialize global marks
   if (dump_global_marks) {
@@ -4117,3 +4074,224 @@ static bool shada_removable(const char *name)
   xfree(new_name);
   return retval;
 }
+
+/// Initialize ShaDa jumplist entries.
+///
+/// @param[in,out]  jumps           Array of ShaDa entries to set.
+/// @param[in]      removable_bufs  Cache of buffers ignored due to their
+///                                 location.
+///
+/// @return number of jumplist entries
+static inline size_t shada_init_jumps(
+    PossiblyFreedShadaEntry *jumps, khash_t(bufset) *const removable_bufs)
+{
+  // Initialize jump list
+  size_t jumps_size = 0;
+  const void *jump_iter = NULL;
+  setpcmark();
+  cleanup_jumplist(curwin, false);
+  do {
+    xfmark_T fm;
+    jump_iter = mark_jumplist_iter(jump_iter, curwin, &fm);
+
+    if (fm.fmark.mark.lnum == 0) {
+      iemsgf("ShaDa: mark lnum zero (ji:%p, js:%p, len:%i)",
+             (void *)jump_iter, (void *)&curwin->w_jumplist[0],
+             curwin->w_jumplistlen);
+      continue;
+    }
+    const buf_T *const buf = (fm.fmark.fnum == 0
+                              ? NULL
+                              : buflist_findnr(fm.fmark.fnum));
+    if (buf != NULL
+        ? in_bufset(removable_bufs, buf)
+        : fm.fmark.fnum != 0) {
+      continue;
+    }
+    const char *const fname = (char *) (fm.fmark.fnum == 0
+                                        ? (fm.fname == NULL ? NULL : fm.fname)
+                                        : buf->b_ffname);
+    if (fname == NULL) {
+      continue;
+    }
+    jumps[jumps_size++] = (PossiblyFreedShadaEntry) {
+      .can_free_entry = false,
+      .data = {
+        .type = kSDItemJump,
+        .timestamp = fm.fmark.timestamp,
+        .data = {
+          .filemark = {
+            .name = NUL,
+            .mark = fm.fmark.mark,
+            .fname = (char *) fname,
+            .additional_data = fm.fmark.additional_data,
+          }
+        }
+      }
+    };
+  } while (jump_iter != NULL);
+  return jumps_size;
+}
+
+/// Write registers ShaDa entries in given msgpack_sbuffer.
+///
+/// @param[in]  sbuf  target msgpack_sbuffer to write to.
+void shada_encode_regs(msgpack_sbuffer *const sbuf)
+  FUNC_ATTR_NONNULL_ALL
+{
+  WriteMergerState wms;
+  shada_initialize_registers(&wms, -1);
+  msgpack_packer packer;
+  msgpack_packer_init(&packer, sbuf, msgpack_sbuffer_write);
+  for (size_t i = 0; i < ARRAY_SIZE(wms.registers); i++) {
+    if (wms.registers[i].data.type == kSDItemRegister) {
+      shada_pack_pfreed_entry(&packer, wms.registers[i], 0);
+    }
+  }
+}
+
+/// Write jumplist ShaDa entries in given msgpack_sbuffer.
+///
+/// @param[in]  sbuf            target msgpack_sbuffer to write to.
+void shada_encode_jumps(msgpack_sbuffer *const sbuf)
+  FUNC_ATTR_NONNULL_ALL
+{
+  khash_t(bufset) removable_bufs = KHASH_EMPTY_TABLE(bufset);
+  find_removable_bufs(&removable_bufs);
+  PossiblyFreedShadaEntry jumps[JUMPLISTSIZE];
+  size_t jumps_size = shada_init_jumps(jumps, &removable_bufs);
+  msgpack_packer packer;
+  msgpack_packer_init(&packer, sbuf, msgpack_sbuffer_write);
+  for (size_t i = 0; i < jumps_size; i++) {
+    shada_pack_pfreed_entry(&packer, jumps[i], 0);
+  }
+}
+
+/// Write buffer list ShaDa entry in given msgpack_sbuffer.
+///
+/// @param[in]  sbuf            target msgpack_sbuffer to write to.
+void shada_encode_buflist(msgpack_sbuffer *const sbuf)
+  FUNC_ATTR_NONNULL_ALL
+{
+  khash_t(bufset) removable_bufs = KHASH_EMPTY_TABLE(bufset);
+  find_removable_bufs(&removable_bufs);
+  ShadaEntry buflist_entry = shada_get_buflist(&removable_bufs);
+  msgpack_packer packer;
+  msgpack_packer_init(&packer, sbuf, msgpack_sbuffer_write);
+  shada_pack_entry(&packer, buflist_entry, 0);
+  xfree(buflist_entry.data.buffer_list.buffers);
+}
+
+/// Write global variables ShaDa entries in given msgpack_sbuffer.
+///
+/// @param[in]  sbuf            target msgpack_sbuffer to write to.
+void shada_encode_gvars(msgpack_sbuffer *const sbuf)
+  FUNC_ATTR_NONNULL_ALL
+{
+  msgpack_packer packer;
+  msgpack_packer_init(&packer, sbuf, msgpack_sbuffer_write);
+  const void *var_iter = NULL;
+  const Timestamp cur_timestamp = os_time();
+  do {
+    typval_T vartv;
+    const char *name = NULL;
+    var_iter = var_shada_iter(
+        var_iter, &name, &vartv,
+        VAR_FLAVOUR_DEFAULT | VAR_FLAVOUR_SESSION | VAR_FLAVOUR_SHADA);
+    if (name == NULL) {
+      break;
+    }
+    if (vartv.v_type != VAR_FUNC && vartv.v_type != VAR_PARTIAL) {
+      typval_T tgttv;
+      tv_copy(&vartv, &tgttv);
+      shada_pack_entry(&packer, (ShadaEntry) {
+        .type = kSDItemVariable,
+        .timestamp = cur_timestamp,
+        .data = {
+          .global_var = {
+            .name = (char *)name,
+            .value = tgttv,
+            .additional_elements = NULL,
+          }
+        }
+      }, 0);
+      tv_clear(&tgttv);
+    }
+    tv_clear(&vartv);
+  } while (var_iter != NULL);
+}
+
+/// Wrapper for reading from msgpack_sbuffer.
+///
+/// @return number of bytes read.
+static ptrdiff_t read_sbuf(ShaDaReadDef *const sd_reader, void *const dest,
+                           const size_t size)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  msgpack_sbuffer *sbuf = (msgpack_sbuffer *)sd_reader->cookie;
+  const uintmax_t bytes_read = MIN(size, sbuf->size - sd_reader->fpos);
+  if (bytes_read < size) {
+    sd_reader->eof = true;
+  }
+  memcpy(dest, sbuf->data + sd_reader->fpos, (size_t)bytes_read);
+  sd_reader->fpos += bytes_read;
+  return (ptrdiff_t)bytes_read;
+}
+
+/// Wrapper for read that ignores bytes read from msgpack_sbuffer.
+///
+/// Used for skipping.
+///
+/// @param[in,out]  sd_reader  ShaDaReadDef with msgpack_sbuffer.
+/// @param[in]      offset     Amount of bytes to skip.
+///
+/// @return FAIL in case of failure, OK in case of success. May set
+///         sd_reader->eof.
+static int sd_sbuf_reader_skip_read(ShaDaReadDef *const sd_reader,
+                                    const size_t offset)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  msgpack_sbuffer *sbuf = (msgpack_sbuffer *)sd_reader->cookie;
+  const uintmax_t bytes_skipped = MIN(offset, sbuf->size - sd_reader->fpos);
+  if (bytes_skipped < offset) {
+    sd_reader->eof = true;
+    return FAIL;
+  }
+  sd_reader->fpos += offset;
+  return OK;
+}
+
+/// Prepare ShaDaReadDef with msgpack_sbuffer for reading.
+///
+/// @param[in]   sbuf       msgpack_sbuffer to read from.
+/// @param[out]  sd_reader  Location where reader structure will be saved.
+static void open_shada_sbuf_for_reading(const msgpack_sbuffer *const sbuf,
+                                        ShaDaReadDef *sd_reader)
+  FUNC_ATTR_NONNULL_ALL
+{
+  *sd_reader = (ShaDaReadDef) {
+    .read = &read_sbuf,
+    .close = NULL,
+    .skip = &sd_sbuf_reader_skip_read,
+    .error = NULL,
+    .eof = false,
+    .fpos = 0,
+    .cookie = (void *)sbuf,
+  };
+}
+
+/// Read ShaDa from msgpack_sbuffer.
+///
+/// @param[in]  file   msgpack_sbuffer to read from.
+/// @param[in]  flags  Flags, see ShaDaReadFileFlags enum.
+void shada_read_sbuf(msgpack_sbuffer *const sbuf, const int flags)
+  FUNC_ATTR_NONNULL_ALL
+{
+  assert(sbuf != NULL);
+  if (sbuf->data == NULL) {
+    return;
+  }
+  ShaDaReadDef sd_reader;
+  open_shada_sbuf_for_reading(sbuf, &sd_reader);
+  shada_read(&sd_reader, flags);
+}
diff --git a/src/nvim/shada.h b/src/nvim/shada.h
index 49986ac1c1..2a945a06bc 100644
--- a/src/nvim/shada.h
+++ b/src/nvim/shada.h
@@ -1,6 +1,17 @@
 #ifndef NVIM_SHADA_H
 #define NVIM_SHADA_H
 
+#include <msgpack.h>
+
+/// Flags for shada_read_file and children
+typedef enum {
+  kShaDaWantInfo = 1,       ///< Load non-mark information
+  kShaDaWantMarks = 2,      ///< Load local file marks and change list
+  kShaDaForceit = 4,        ///< Overwrite info already read
+  kShaDaGetOldfiles = 8,    ///< Load v:oldfiles.
+  kShaDaMissingError = 16,  ///< Error out when os_open returns -ENOENT.
+} ShaDaReadFileFlags;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "shada.h.generated.h"
 #endif