Implement new line editing "library"

Losing tab complete and text macros, for now.

This new implementation works on an instance of a struct and does
not interact with the rest of catgirl, making it possible to copy
into another project. Unlike existing line editing libraries, this
one is entirely abstract and can be rendered externally.

My goal with this library is to be able to implement vi mode. Since
it operates on struct instances rather than globals, it might also
be possible to give catgirl separate line editing buffers for each
window, which would be a nice UX improvement.

1 files changed, 91 insertions, 0 deletions

diff --git a/edit.h b/edit.h
new file mode 100644
index 0000000..57edfc1
--- /dev/null
+++ b/edit.h
@@ -0,0 +1,91 @@
+/* Copyright (C) 2022  June McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * If you modify this Program, or any covered work, by linking or
+ * combining it with OpenSSL (or a modified version of that library),
+ * containing parts covered by the terms of the OpenSSL License and the
+ * original SSLeay license, the licensors of this Program grant you
+ * additional permission to convey the resulting work. Corresponding
+ * Source for a non-source form of such a combination shall include the
+ * source code for the parts of OpenSSL used as well as that of the
+ * covered work.
+ */
+
+#include <stdbool.h>
+#include <stddef.h>
+
+enum EditMode {
+	EditEmacs,
+};
+
+struct Edit {
+	enum EditMode mode;
+	wchar_t *buf;
+	size_t pos;
+	size_t len;
+	size_t cap;
+	struct {
+		wchar_t *buf;
+		size_t len;
+	} cut;
+	struct {
+		char *buf;
+		size_t pos;
+		size_t len;
+	} mbs;
+};
+
+enum EditFn {
+	EditHead,
+	EditTail,
+	EditPrev,
+	EditNext,
+	EditPrevWord,
+	EditNextWord,
+	EditDeleteHead,
+	EditDeleteTail,
+	EditDeletePrev,
+	EditDeleteNext,
+	EditDeletePrevWord,
+	EditDeleteNextWord,
+	EditPaste,
+	EditTranspose,
+	EditCollapse,
+	EditClear,
+};
+
+// Perform an editing function.
+int editFn(struct Edit *e, enum EditFn fn);
+
+// Perform a vi-mode editing function.
+int editVi(struct Edit *e, wchar_t ch);
+
+// Insert a character at the cursor.
+int editInsert(struct Edit *e, wchar_t ch);
+
+// Convert the buffer to a multi-byte string stored in e->mbs.
+char *editString(struct Edit *e);
+
+// Free all buffers.
+void editFree(struct Edit *e);
+
+// Reserve a range in the buffer.
+int editReserve(struct Edit *e, size_t index, size_t count);
+
+// Copy a range of the buffer into e->cut.
+int editCopy(struct Edit *e, size_t index, size_t count);
+
+// Delete a range from the buffer. If cut is true, copy the deleted portion.
+int editDelete(struct Edit *e, bool cut, size_t index, size_t count);