1 files changed, 63 insertions, 0 deletions
diff --git a/autoload/tools/patch.kak b/autoload/tools/patch.kak
new file mode 100644
index 0000000..a481ff4
--- /dev/null
+++ b/autoload/tools/patch.kak
@@ -0,0 +1,63 @@
+define-command patch -params .. -docstring %{
+    patch [<arguments>]: apply selections in diff to a file
+
+    Given some selections within a unified diff, apply the changed lines in
+    each selection by piping them to "patch <arguments> 1>&2"
+    (or "<arguments> 1>&2" if <arguments> starts with a non-option argument).
+    If successful, the in-buffer diff will be updated to reflect the applied
+    changes.
+    For selections that contain no newline, the entire enclosing diff hunk
+    is applied (unless the cursor is inside a diff header, in which case
+    the entire diff is applied).
+    To revert changes, <arguments> must contain "--reverse" or "-R".
+} %{
+    evaluate-commands -draft -itersel -save-regs aes|^ %{
+        try %{
+            execute-keys <a-k>\n<ret>
+        } catch %{
+            # The selection contains no newline.
+            execute-keys -save-regs '' Z
+            execute-keys <a-l><semicolon><a-?>^diff<ret>
+            try %{
+                execute-keys <a-k>^@@<ret>
+                # If the cursor is in a diff hunk, stage the entire hunk.
+                execute-keys z
+                execute-keys /.*?(?:(?=\n@@)|(?=\ndiff)|(?=\n\n)|\z)<ret>x<semicolon><a-?>^@@<ret>
+            } catch %{
+                # If the cursor is in a diff header, stage the entire diff.
+                execute-keys <a-semicolon>?.*?(?:(?=\ndiff)|(?=\n\n)|\z)<ret>
+            }
+        }
+        # We want to apply only the selected lines. Remember them.
+        execute-keys <a-:>
+        set-register s %val{selection_desc}
+        # Select forward until the end of the last hunk.
+        execute-keys H?.*?(?:(?=\n@@)|(?=\ndiff)|(?=\n\n)|\z)<ret>x
+        # Select backward to the beginning of the first hunk's diff header.
+        execute-keys <a-semicolon><a-L><a-?>^diff<ret>
+        # Move cursor to the beginning so we know the diff's offset within the buffer.
+        execute-keys <a-:><a-semicolon>
+        set-register a %arg{@}
+        set-register e nop
+        set-register | %{
+            # The selected range to apply.
+            IFS=' .,' read min_line _ max_line _ <<-EOF
+            $kak_reg_s
+	EOF
+            min_line=$((min_line - kak_cursor_line + 1))
+            max_line=$((max_line - kak_cursor_line + 1))
+
+            # Since registers are never empty, we get an empty arg even if
+            # there were no args. This does no harm because we pass it to
+            # a shell where it expands to nothing.
+            eval set -- "$kak_quoted_reg_a"
+
+            perl "${kak_runtime}"/rc/tools/patch-range.pl $min_line $max_line "$@" ||
+                echo >$kak_command_fifo "set-register e fail 'patch: failed to apply selections, see *debug* buffer'"
+        }
+        execute-keys |<ret>
+        %reg{e}
+    }
+}
+
+provide-module patch %§§