API: Implement buffer_{get,set}_slice

src/api/buffer.c

@@ -1,3 +1,5 @@
+// Much of this code was adapted from 'if_py_both.h' from the original
+// vim source
 #include <stdint.h>
 #include <stdlib.h>
 
@@ -10,6 +12,7 @@
 #include "memory.h"
 #include "misc1.h"
 #include "misc2.h"
+#include "mark.h"
 #include "move.h"
 #include "../window.h"
 #include "undo.h"
@@ -136,20 +139,150 @@ void buffer_set_line(Buffer buffer, int64_t index, Object line, Error *err)
 }
 
 StringArray buffer_get_slice(Buffer buffer,
-    int64_t start,
-    int64_t end,
-    Error *err)
+                             int64_t start,
+                             int64_t end,
+                             bool include_start,
+                             bool include_end,
+                             Error *err)
 {
-  abort();
+  StringArray rv = {.size = 0};
+  buf_T *buf = find_buffer(buffer, err);
+
+  if (!buf) {
+    return rv;
+  }
+
+  start = normalize_index(buf, start) + (include_start ? 0 : 1);
+  end = normalize_index(buf, end) + (include_end ? 1 : 0);
+
+  if (start >= end) {
+    // Return 0-length array
+    return rv;
+  }
+
+  rv.size = end - start;
+  rv.items = xmalloc(sizeof(String) * rv.size);
+
+  for (uint32_t i = 0; i < rv.size; i++) {
+    rv.items[i].data = xstrdup((char *)ml_get_buf(buf, start + i, FALSE));
+    rv.items[i].size = strlen(rv.items[i].data);
+  }
+
+  return rv;
 }
 
 void buffer_set_slice(Buffer buffer,
-    int64_t start,
-    int64_t end,
-    StringArray lines,
-    Error *err)
+                      int64_t start,
+                      int64_t end,
+                      bool include_start,
+                      bool include_end,
+                      StringArray replacement,
+                      Error *err)
 {
-  abort();
+  buf_T *buf = find_buffer(buffer, err);
+
+  if (!buf) {
+    return;
+  }
+
+  start = normalize_index(buf, start) + (include_start ? 0 : 1);
+  end = normalize_index(buf, end) + (include_end ? 1 : 0);
+
+  if (start > end) {
+    set_api_error("start > end", err);
+    return;
+  }
+
+  buf_T *save_curbuf = NULL;
+  win_T *save_curwin = NULL;
+  tabpage_T *save_curtab = NULL;
+  uint32_t new_len = replacement.size;
+  uint32_t old_len = end - start;
+  uint32_t i;
+  int32_t extra = 0; // lines added to text, can be negative
+  char **lines;
+
+  if (new_len == 0) {
+    // avoid allocating zero bytes
+    lines = NULL;
+  } else {
+    lines = xcalloc(sizeof(char *), new_len);
+  }
+
+  for (i = 0; i < new_len; i++) {
+    String l = replacement.items[i];
+    lines[i] = xstrndup(l.data, l.size);
+  }
+
+  try_start();
+  switch_to_win_for_buf(buf, &save_curwin, &save_curtab, &save_curbuf);
+
+  if (u_save(start - 1, end) == FAIL) {
+    set_api_error("Cannot save undo information", err);
+    goto cleanup;
+  }
+
+  // If the size of the range is reducing (ie, new_len < old_len) we
+  // need to delete some old_len. We do this at the start, by
+  // repeatedly deleting line "start".
+  for (i = 0; new_len < old_len && i < old_len - new_len; i++) {
+    if (ml_delete(start, false) == FAIL) {
+      set_api_error("Cannot delete line", err);
+      goto cleanup;
+    }
+  }
+
+  extra -= i;
+
+  // For as long as possible, replace the existing old_len with the
+  // new old_len. This is a more efficient operation, as it requires
+  // less memory allocation and freeing.
+  for (i = 0; i < old_len && i < new_len; i++) {
+    if (ml_replace(start + i, (char_u *)lines[i], false) == FAIL) {
+      set_api_error("Cannot replace line", err);
+      goto cleanup;
+    }
+    // Mark lines that haven't been passed to the buffer as they need
+    // to be freed later
+    lines[i] = NULL;
+  }
+
+  // Now we may need to insert the remaining new old_len
+  while (i < new_len) {
+    if (ml_append(start + i - 1, (char_u *)lines[i], 0, false) == FAIL) {
+      set_api_error("Cannot insert line", err);
+      goto cleanup;
+    }
+    // Same as with replacing
+    lines[i] = NULL;
+    i++;
+    extra++;
+  }
+
+  // Adjust marks. Invalidate any which lie in the
+  // changed range, and move any in the remainder of the buffer.
+  // Only adjust marks if we managed to switch to a window that holds
+  // the buffer, otherwise line numbers will be invalid.
+  if (save_curbuf == NULL) {
+    mark_adjust(start, end - 1, MAXLNUM, extra);
+  }
+
+  changed_lines(start, 0, end, extra);
+
+  if (buf == curbuf) {
+    fix_cursor(start, end, extra);
+  }
+
+cleanup:
+  for (uint32_t i = 0; i < new_len; i++) {
+    if (lines[i] != NULL) {
+      free(lines[i]);
+    }
+  }
+
+  free(lines);
+  restore_win_for_buf(save_curwin, save_curtab, save_curbuf);
+  try_end(err);
 }
 
 Object buffer_get_var(Buffer buffer, String name, Error *err)

src/api/buffer.h

@@ -34,25 +34,34 @@ void buffer_set_line(Buffer buffer, int64_t index, Object line, Error *err);
 ///
 /// @param buffer The buffer handle
 /// @param start The first line index
-/// @param end The last line index(exclusive)
+/// @param end The last line index
+/// @param include_start True if the slice includes the `start` parameter
+/// @param include_end True if the slice includes the `end` parameter
 /// @param[out] err Details of an error that may have occurred
 /// @return An array of lines
 StringArray buffer_get_slice(Buffer buffer,
                              int64_t start,
                              int64_t end,
+                             bool include_start,
+                             bool include_end,
                              Error *err);
 
 /// Replaces a line range on the buffer
 ///
 /// @param buffer The buffer handle
 /// @param start The first line index
-/// @param end The last line index(exclusive)
-/// @param lines An array of lines to use as replacement
+/// @param end The last line index
+/// @param include_start True if the slice includes the `start` parameter
+/// @param include_end True if the slice includes the `end` parameter
+/// @param lines An array of lines to use as replacement(A 0-length array
+///        will simply delete the line range)
 /// @param[out] err Details of an error that may have occurred
 void buffer_set_slice(Buffer buffer,
                       int64_t start,
                       int64_t end,
-                      StringArray lines,
+                      bool include_start,
+                      bool include_end,
+                      StringArray replacement,
                       Error *err);
 
 /// Gets a buffer variable