Move the line editor into its own file

Trying to make it reusable in other projects.

1 files changed, 288 insertions, 0 deletions

diff --git a/line-editor.c b/line-editor.c
new file mode 100644
index 0000000..708afd4
--- /dev/null
+++ b/line-editor.c
@@ -0,0 +1,288 @@
+/*
+ * line-editor.c: a line editor component for the TUI part of liberty
+ *
+ * Copyright (c) 2017 - 2018, Přemysl Janouch <p@janouch.name>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+// This is here just for IDE code model reasons
+#ifndef HAVE_LIBERTY
+#include "liberty/liberty.c"
+#include "liberty/liberty-tui.c"
+#endif
+
+static void
+row_buffer_append_c (struct row_buffer *self, ucs4_t c, chtype attrs)
+{
+	struct row_char current = { .attrs = attrs, .c = c };
+	struct row_char invalid = { .attrs = attrs, .c = '?', .width = 1 };
+
+	current.width = uc_width (current.c, locale_charset ());
+	if (current.width < 0 || !app_is_character_in_locale (current.c))
+		current = invalid;
+
+	ARRAY_RESERVE (self->chars, 1);
+	self->chars[self->chars_len++] = current;
+	self->total_width += current.width;
+}
+
+// --- Line editor -------------------------------------------------------------
+
+enum line_editor_action
+{
+	LINE_EDITOR_B_CHAR,                 ///< Go back a character
+	LINE_EDITOR_F_CHAR,                 ///< Go forward a character
+	LINE_EDITOR_B_WORD,                 ///< Go back a word
+	LINE_EDITOR_F_WORD,                 ///< Go forward a word
+	LINE_EDITOR_HOME,                   ///< Go to start of line
+	LINE_EDITOR_END,                    ///< Go to end of line
+
+	LINE_EDITOR_B_DELETE,               ///< Delete last character
+	LINE_EDITOR_F_DELETE,               ///< Delete next character
+	LINE_EDITOR_B_KILL_WORD,            ///< Delete last word
+	LINE_EDITOR_B_KILL_LINE,            ///< Delete everything up to BOL
+	LINE_EDITOR_F_KILL_LINE,            ///< Delete everything up to EOL
+};
+
+struct line_editor
+{
+	int point;                          ///< Caret index into line data
+	ucs4_t *line;                       ///< Line data, 0-terminated
+	int *w;                             ///< Codepoint widths, 0-terminated
+	size_t len;                         ///< Editor length
+	size_t alloc;                       ///< Editor allocated
+	char prompt;                        ///< Prompt character
+
+	void (*on_changed) (void);          ///< Callback on text change
+	void (*on_end) (bool);              ///< Callback on abort
+};
+
+static void
+line_editor_free (struct line_editor *self)
+{
+	free (self->line);
+	free (self->w);
+}
+
+/// Notify whomever invoked the editor that it's been either confirmed or
+/// cancelled and clean up editor state
+static void
+line_editor_abort (struct line_editor *self, bool status)
+{
+	self->on_end (status);
+	self->on_changed = NULL;
+
+	free (self->line);
+	self->line = NULL;
+	free (self->w);
+	self->w = NULL;
+	self->alloc = 0;
+	self->len = 0;
+	self->point = 0;
+	self->prompt = 0;
+}
+
+/// Start the line editor; remember to fill in "change" and "end" callbacks
+static void
+line_editor_start (struct line_editor *self, char prompt)
+{
+	self->alloc = 16;
+	self->line = xcalloc (sizeof *self->line, self->alloc);
+	self->w = xcalloc (sizeof *self->w, self->alloc);
+	self->len = 0;
+	self->point = 0;
+	self->prompt = prompt;
+}
+
+static void
+line_editor_changed (struct line_editor *self)
+{
+	self->line[self->len] = 0;
+	self->w[self->len] = 0;
+
+	if (self->on_changed)
+		self->on_changed ();
+}
+
+static void
+line_editor_move (struct line_editor *self, int to, int from, int len)
+{
+	memmove (self->line + to, self->line + from,
+		sizeof *self->line * len);
+	memmove (self->w + to, self->w + from,
+		sizeof *self->w * len);
+}
+
+static void
+line_editor_insert (struct line_editor *self, ucs4_t codepoint)
+{
+	while (self->alloc - self->len < 2 /* inserted + sentinel */)
+	{
+		self->alloc <<= 1;
+		self->line = xreallocarray
+			(self->line, sizeof *self->line, self->alloc);
+		self->w = xreallocarray
+			(self->w, sizeof *self->w, self->alloc);
+	}
+
+	line_editor_move (self, self->point + 1, self->point,
+		self->len - self->point);
+	self->line[self->point] = codepoint;
+	self->w[self->point] = app_is_character_in_locale (codepoint)
+		? uc_width (codepoint, locale_charset ())
+		: 1 /* the replacement question mark */;
+
+	self->point++;
+	self->len++;
+	line_editor_changed (self);
+}
+
+static bool
+line_editor_action (struct line_editor *self, enum line_editor_action action)
+{
+	switch (action)
+	{
+	default:
+		return soft_assert (!"unknown line editor action");
+
+	case LINE_EDITOR_B_CHAR:
+		if (self->point < 1)
+			return false;
+		do self->point--;
+		while (self->point > 0
+			&& !self->w[self->point]);
+		return true;
+	case LINE_EDITOR_F_CHAR:
+		if (self->point + 1 > (int) self->len)
+			return false;
+		do self->point++;
+		while (self->point < (int) self->len
+			&& !self->w[self->point]);
+		return true;
+	case LINE_EDITOR_B_WORD:
+	{
+		if (self->point < 1)
+			return false;
+		int i = self->point;
+		while (i && self->line[--i] == ' ');
+		while (i-- && self->line[i] != ' ');
+		self->point = ++i;
+		return true;
+	}
+	case LINE_EDITOR_F_WORD:
+	{
+		if (self->point + 1 > (int) self->len)
+			return false;
+		int i = self->point;
+		while (i < (int) self->len && self->line[i] != ' ') i++;
+		while (i < (int) self->len && self->line[i] == ' ') i++;
+		self->point = i;
+		return true;
+	}
+	case LINE_EDITOR_HOME:
+		self->point = 0;
+		return true;
+	case LINE_EDITOR_END:
+		self->point = self->len;
+		return true;
+
+	case LINE_EDITOR_B_DELETE:
+	{
+		if (self->point < 1)
+			return false;
+		int len = 1;
+		while (self->point - len > 0
+			&& !self->w[self->point - len])
+			len++;
+		line_editor_move (self, self->point - len, self->point,
+			self->len - self->point);
+		self->len -= len;
+		self->point -= len;
+		line_editor_changed (self);
+		return true;
+	}
+	case LINE_EDITOR_F_DELETE:
+	{
+		if (self->point + 1 > (int) self->len)
+			return false;
+		int len = 1;
+		while (self->point + len < (int) self->len
+			&& !self->w[self->point + len])
+			len++;
+		self->len -= len;
+		line_editor_move (self, self->point, self->point + len,
+			self->len - self->point);
+		line_editor_changed (self);
+		return true;
+	}
+	case LINE_EDITOR_B_KILL_WORD:
+	{
+		if (self->point < 1)
+			return false;
+
+		int i = self->point;
+		while (i && self->line[--i] == ' ');
+		while (i-- && self->line[i] != ' ');
+		i++;
+
+		line_editor_move (self, i, self->point, (self->len - self->point));
+		self->len -= self->point - i;
+		self->point = i;
+		line_editor_changed (self);
+		return true;
+	}
+	case LINE_EDITOR_B_KILL_LINE:
+		self->len -= self->point;
+		line_editor_move (self, 0, self->point, self->len);
+		self->point = 0;
+		line_editor_changed (self);
+		return true;
+	case LINE_EDITOR_F_KILL_LINE:
+		self->len = self->point;
+		line_editor_changed (self);
+		return true;
+	}
+}
+
+static int
+line_editor_write (const struct line_editor *self, struct row_buffer *row,
+	int width, chtype attrs)
+{
+	if (self->prompt)
+	{
+		hard_assert (self->prompt < 127);
+		row_buffer_append_c (row, self->prompt, attrs);
+		width--;
+	}
+
+	int following = 0;
+	for (size_t i = self->point; i < self->len; i++)
+		following += self->w[i];
+
+	int preceding = 0;
+	size_t start = self->point;
+	while (start && preceding < width / 2)
+		preceding += self->w[--start];
+
+	// There can be one extra space at the end of the line but this way we
+	// don't need to care about non-spacing marks following full-width chars
+	while (start && width - preceding - following > 2 /* widest char */)
+		preceding += self->w[--start];
+
+	// XXX: we should also show < > indicators for overflow but it'd probably
+	//   considerably complicate this algorithm
+	for (; start < self->len; start++)
+		row_buffer_append_c (row, self->line[start], attrs);
+	return !!self->prompt + preceding;
+}