Rename window.[ch] to view.[ch]

1 files changed, 898 insertions, 0 deletions

diff --git a/view.c b/view.c
new file mode 100644
index 0000000..73fca17
--- /dev/null
+++ b/view.c
@@ -0,0 +1,898 @@
+/*
+ * Copyright (c) 2014 Marc André Tanner <mat at brain-dump.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * 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.
+ */
+#include <string.h>
+#include <stdlib.h>
+#include <wchar.h>
+#include <ctype.h>
+#include <errno.h>
+#include <regex.h>
+#include "editor.h"
+#include "view.h"
+#include "syntax.h"
+#include "text.h"
+#include "text-motions.h"
+#include "util.h"
+
+typedef struct {            /* cursor position */
+	Filepos pos;        /* in bytes from the start of the file */
+	Filepos lastpos;    /* previous cursor position */
+	int row, col;       /* in terms of zero based screen coordinates */
+	int lastcol;        /* remembered column used when moving across lines */
+	Line *line;         /* screen line on which cursor currently resides */
+	bool highlighted;   /* true e.g. when cursor is on a bracket */
+} Cursor;
+
+struct View {               /* viewable area, showing part of a file */
+	Text *text;         /* underlying text management */
+	UiWin *ui;
+	ViewEvent *events;
+	int width, height;  /* size of display area */
+	Filepos start, end; /* currently displayed area [start, end] in bytes from the start of the file */
+	size_t lines_size;  /* number of allocated bytes for lines (grows only) */
+	Line *lines;        /* view->height number of lines representing view content */
+	Line *topline;      /* top of the view, first line currently shown */
+	Line *lastline;     /* last currently used line, always <= bottomline */
+	Line *bottomline;   /* bottom of view, might be unused if lastline < bottomline */
+	Filerange sel;      /* selected text range in bytes from start of file */
+	Cursor cursor;      /* current cursor position within view */
+	Line *line;         /* used while drawing view content, line where next char will be drawn */
+	int col;            /* used while drawing view content, column where next char will be drawn */
+	Syntax *syntax;     /* syntax highlighting definitions for this view or NULL */
+	int tabwidth;       /* how many spaces should be used to display a tab character */
+};
+
+static void view_clear(View *view);
+static bool view_addch(View *view, Cell *cell);
+static size_t view_cursor_update(View *view);
+/* set/move current cursor position to a given (line, column) pair */
+static size_t view_cursor_set(View *view, Line *line, int col);
+/* move visible viewport n-lines up/down, redraws the view but does not change
+ * cursor position which becomes invalid and should be corrected by either:
+ *
+ *   - view_cursor_to
+ *   - view_cursor_set
+ *
+ * the return value indicates wether the visible area changed.
+ */
+static bool view_viewport_up(View *view, int n);
+static bool view_viewport_down(View *view, int n);
+
+void view_tabwidth_set(View *view, int tabwidth) {
+	view->tabwidth = tabwidth;
+	view_draw(view);
+}
+
+void view_selection_clear(View *view) {
+	view->sel = text_range_empty();
+	view_draw(view);
+	view_cursor_update(view);
+}
+
+/* reset internal view data structures (cell matrix, line offsets etc.) */
+static void view_clear(View *view) {
+	/* calculate line number of first line */
+	// TODO move elsewhere
+	view->topline = view->lines;
+	view->topline->lineno = text_lineno_by_pos(view->text, view->start);
+	view->lastline = view->topline;
+
+	/* reset all other lines */
+	size_t line_size = sizeof(Line) + view->width*sizeof(Cell);
+	size_t end = view->height * line_size;
+	Line *prev = NULL;
+	for (size_t i = 0; i < end; i += line_size) {
+		Line *line = (Line*)(((char*)view->lines) + i);
+		line->width = 0;
+		line->len = 0;
+		line->prev = prev;
+		if (prev)
+			prev->next = line;
+		prev = line;
+	}
+	view->bottomline = prev ? prev : view->topline;
+	view->bottomline->next = NULL;
+	view->line = view->topline;
+	view->col = 0;
+}
+
+Filerange view_selection_get(View *view) {
+	Filerange sel = view->sel;
+	if (sel.start > sel.end) {
+		size_t tmp = sel.start;
+		sel.start = sel.end;
+		sel.end = tmp;
+	}
+	if (!text_range_valid(&sel))
+		return text_range_empty();
+	sel.end = text_char_next(view->text, sel.end);
+	return sel;
+}
+
+void view_selection_set(View *view, Filerange *sel) {
+	Cursor *cursor = &view->cursor;
+	view->sel = *sel;
+	view_draw(view);
+	if (view->ui)
+		view->ui->cursor_to(view->ui, cursor->col, cursor->row);
+}
+
+Filerange view_viewport_get(View *view) {
+	return (Filerange){ .start = view->start, .end = view->end };
+}
+
+/* try to add another character to the view, return whether there was space left */
+static bool view_addch(View *view, Cell *cell) {
+	if (!view->line)
+		return false;
+
+	int width;
+	static Cell empty;
+	size_t lineno = view->line->lineno;
+
+	switch (cell->data[0]) {
+	case '\t':
+		width = view->tabwidth - (view->col % view->tabwidth);
+		for (int w = 0; w < width; w++) {
+			if (view->col + 1 > view->width) {
+				view->line = view->line->next;
+				view->col = 0;
+				if (!view->line)
+					return false;
+				view->line->lineno = lineno;
+			}
+			if (w == 0) {
+				/* first cell of a tab has a length of 1 */
+				view->line->cells[view->col].len = cell->len;
+				view->line->len += cell->len;
+			} else {
+				/* all remaining ones have a lenght of zero */
+				view->line->cells[view->col].len = 0;
+			}
+			/* but all are marked as part of a tabstop */
+			view->line->cells[view->col].width = 1;
+			view->line->cells[view->col].data[0] = ' ';
+			view->line->cells[view->col].data[1] = '\0';
+			view->line->cells[view->col].istab = true;
+			view->line->cells[view->col].attr = cell->attr;
+			view->line->width++;
+			view->col++;
+		}
+		return true;
+	case '\n':
+		cell->width = 1;
+		if (view->col + cell->width > view->width) {
+			view->line = view->line->next;
+			view->col = 0;
+			if (!view->line)
+				return false;
+			view->line->lineno = lineno;
+		}
+		view->line->cells[view->col] = *cell;
+		view->line->len += cell->len;
+		view->line->width += cell->width;
+		for (int i = view->col + 1; i < view->width; i++)
+			view->line->cells[i] = empty;
+
+		view->line = view->line->next;
+		if (view->line)
+			view->line->lineno = lineno + 1;
+		view->col = 0;
+		return true;
+	default:
+		if ((unsigned char)cell->data[0] < 128 && !isprint((unsigned char)cell->data[0])) {
+			/* non-printable ascii char, represent it as ^(char + 64) */
+			*cell = (Cell) {
+				.data = { '^', cell->data[0] + 64, '\0' },
+				.len = 1,
+				.width = 2,
+				.istab = false,
+				.attr = cell->attr,
+			};
+		}
+
+		if (view->col + cell->width > view->width) {
+			for (int i = view->col; i < view->width; i++)
+				view->line->cells[i] = empty;
+			view->line = view->line->next;
+			view->col = 0;
+		}
+
+		if (view->line) {
+			view->line->width += cell->width;
+			view->line->len += cell->len;
+			view->line->lineno = lineno;
+			view->line->cells[view->col] = *cell;
+			view->col++;
+			/* set cells of a character which uses multiple columns */
+			for (int i = 1; i < cell->width; i++)
+				view->line->cells[view->col++] = empty;
+			return true;
+		}
+		return false;
+	}
+}
+
+CursorPos view_cursor_getpos(View *view) {
+	Cursor *cursor = &view->cursor;
+	Line *line = cursor->line;
+	CursorPos pos = { .line = line->lineno, .col = cursor->col };
+	while (line->prev && line->prev->lineno == pos.line) {
+		line = line->prev;
+		pos.col += line->width;
+	}
+	pos.col++;
+	return pos;
+}
+
+/* snyc current cursor position with internal Line/Cell structures */
+static void view_cursor_sync(View *view) {
+	int row = 0, col = 0;
+	size_t cur = view->start, pos = view->cursor.pos;
+	Line *line = view->topline;
+
+	while (line && line != view->lastline && cur < pos) {
+		if (cur + line->len > pos)
+			break;
+		cur += line->len;
+		line = line->next;
+		row++;
+	}
+
+	if (line) {
+		int max_col = MIN(view->width, line->width);
+		while (cur < pos && col < max_col) {
+			cur += line->cells[col].len;
+			/* skip over columns occupied by the same character */
+			while (++col < max_col && line->cells[col].len == 0);
+		}
+	} else {
+		line = view->bottomline;
+		row = view->height - 1;
+	}
+
+	view->cursor.line = line;
+	view->cursor.row = row;
+	view->cursor.col = col;
+}
+
+/* place the cursor according to the screen coordinates in view->{row,col} and
+ * fire user callback. if a selection is active, redraw the view to reflect
+ * its changes. */
+static size_t view_cursor_update(View *view) {
+	Cursor *cursor = &view->cursor;
+	if (view->sel.start != EPOS) {
+		view->sel.end = cursor->pos;
+		view_draw(view);
+	} else if (view->ui && view->syntax) {
+		size_t pos = cursor->pos;
+		size_t pos_match = text_bracket_match_except(view->text, pos, "<>");
+		if (pos != pos_match && view->start <= pos_match && pos_match < view->end) {
+			if (cursor->highlighted)
+				view_draw(view); /* clear active highlighting */
+			cursor->pos = pos_match;
+			view_cursor_sync(view);
+			cursor->line->cells[cursor->col].attr |= A_REVERSE;
+			cursor->pos = pos;
+			view_cursor_sync(view);
+			view->ui->draw_text(view->ui, view->topline);
+			cursor->highlighted = true;
+		} else if (cursor->highlighted) {
+			cursor->highlighted = false;
+			view_draw(view);
+		}
+	}
+	if (cursor->pos != cursor->lastpos)
+		cursor->lastcol = 0;
+	cursor->lastpos = cursor->pos;
+	if (view->ui)
+		view->ui->cursor_to(view->ui, cursor->col, cursor->row);
+	return cursor->pos;
+}
+
+/* move the cursor to the character at pos bytes from the begining of the file.
+ * if pos is not in the current viewport, redraw the view to make it visible */
+void view_cursor_to(View *view, size_t pos) {
+	size_t max = text_size(view->text);
+
+	if (pos > max)
+		pos = max > 0 ? max - 1 : 0;
+
+	if (pos == max && view->end != max) {
+		/* do not display an empty screen when shoviewg the end of the file */
+		view->start = max - 1;
+		view_viewport_up(view, view->height / 2);
+	} else {
+		/* set the start of the viewable region to the start of the line on which
+		 * the cursor should be placed. if this line requires more space than
+		 * available in the view then simply start displaying text at the new
+		 * cursor position */
+		for (int i = 0;  i < 2 && (pos < view->start || pos > view->end); i++) {
+			view->start = i == 0 ? text_line_begin(view->text, pos) : pos;
+			view_draw(view);
+		}
+	}
+
+	view->cursor.pos = pos;
+	view_cursor_sync(view);
+	view_cursor_update(view);
+}
+
+/* redraw the complete with data starting from view->start bytes into the file.
+ * stop once the screen is full, update view->end, view->lastline */
+void view_draw(View *view) {
+	view_clear(view);
+	/* current absolute file position */
+	size_t pos = view->start;
+	/* number of bytes to read in one go */
+	size_t text_len = view->width * view->height;
+	/* current buffer to work with */
+	char text[text_len+1];
+	/* remaining bytes to process in buffer*/
+	size_t rem = text_bytes_get(view->text, pos, text_len, text);
+	/* NUL terminate because regex(3) function expect it */
+	text[rem] = '\0';
+	/* current position into buffer from which to interpret a character */
+	char *cur = text;
+	/* current selection */
+	Filerange sel = view_selection_get(view);
+	/* syntax definition to use */
+	Syntax *syntax = view->syntax;
+	/* matched tokens for each syntax rule */
+	regmatch_t match[syntax ? LENGTH(syntax->rules) : 1][1], *matched = NULL;
+	memset(match, 0, sizeof match);
+	/* default and current curses attributes to use */
+	int default_attrs = COLOR_PAIR(0) | A_NORMAL, attrs = default_attrs;
+
+	while (rem > 0) {
+
+		/* current 'parsed' character' */
+		wchar_t wchar;
+		Cell cell;
+		memset(&cell, 0, sizeof cell);
+	
+		if (syntax) {
+			if (matched && cur >= text + matched->rm_eo) {
+				/* end of current match */
+				matched = NULL;
+				attrs = default_attrs;
+				for (int i = 0; i < LENGTH(syntax->rules); i++) {
+					if (match[i][0].rm_so == -1)
+						continue; /* no match on whole text */
+					/* reset matches which overlap with matched */
+					if (text + match[i][0].rm_so <= cur && cur < text + match[i][0].rm_eo) {
+						match[i][0].rm_so = 0;
+						match[i][0].rm_eo = 0;
+					}
+				}
+			}
+
+			if (!matched) {
+				size_t off = cur - text; /* number of already processed bytes */
+				for (int i = 0; i < LENGTH(syntax->rules); i++) {
+					SyntaxRule *rule = &syntax->rules[i];
+					if (!rule->rule)
+						break;
+					if (match[i][0].rm_so == -1)
+						continue; /* no match on whole text */
+					if (off >= (size_t)match[i][0].rm_eo) {
+						/* past match, continue search from current position */
+						if (regexec(&rule->regex, cur, 1, match[i], 0) ||
+						    match[i][0].rm_so == match[i][0].rm_eo) {
+							match[i][0].rm_so = -1;
+							match[i][0].rm_eo = -1;
+							continue;
+						}
+						match[i][0].rm_so += off;
+						match[i][0].rm_eo += off;
+					}
+
+					if (text + match[i][0].rm_so <= cur && cur < text + match[i][0].rm_eo) {
+						/* within matched expression */
+						matched = &match[i][0];
+						attrs = rule->color->attr;
+						break; /* first match views */
+					}
+				}
+			}
+		}
+
+		size_t len = mbrtowc(&wchar, cur, rem, NULL);
+		if (len == (size_t)-1 && errno == EILSEQ) {
+			/* ok, we encountered an invalid multibyte sequence,
+			 * replace it with the Unicode Replacement Character
+			 * (FFFD) and skip until the start of the next utf8 char */
+			for (len = 1; rem > len && !ISUTF8(cur[len]); len++);
+			cell = (Cell){ .data = "\xEF\xBF\xBD", .len = len, .width = 1, .istab = false };
+		} else if (len == (size_t)-2) {
+			/* not enough bytes available to convert to a
+			 * wide character. advance file position and read
+			 * another junk into buffer.
+			 */
+			rem = text_bytes_get(view->text, pos, text_len, text);
+			text[rem] = '\0';
+			cur = text;
+			continue;
+		} else if (len == 0) {
+			/* NUL byte encountered, store it and continue */
+			cell = (Cell){ .data = "\x00", .len = 1, .width = 0, .istab = false };
+		} else {
+			for (size_t i = 0; i < len; i++)
+				cell.data[i] = cur[i];
+			cell.data[len] = '\0';
+			cell.istab = false;
+			cell.len = len;
+			cell.width = wcwidth(wchar);
+			if (cell.width == -1)
+				cell.width = 1;
+		}
+
+		if (cur[0] == '\r' && rem > 1 && cur[1] == '\n') {
+			/* convert views style newline \r\n into a single char with len = 2 */
+			cell = (Cell){ .data = "\n", .len = 2, .width = 1, .istab = false };
+		}
+
+		cell.attr = attrs;
+		if (sel.start <= pos && pos < sel.end)
+			cell.attr |= A_REVERSE;
+		if (!view_addch(view, &cell))
+			break;
+
+ 		rem -= cell.len;
+		cur += cell.len;
+		pos += cell.len;
+	}
+
+	/* set end of vieviewg region */
+	view->end = pos;
+	view->lastline = view->line ? view->line : view->bottomline;
+	view->lastline->next = NULL;
+	view_cursor_sync(view);
+	if (view->ui)
+		view->ui->draw_text(view->ui, view->topline);
+	if (sel.start != EPOS && view->events && view->events->selection)
+		view->events->selection(view->events->data, &sel);
+}
+
+bool view_resize(View *view, int width, int height) {
+	size_t lines_size = height*(sizeof(Line) + width*sizeof(Cell));
+	if (lines_size > view->lines_size) {
+		Line *lines = realloc(view->lines, lines_size);
+		if (!lines)
+			return false;
+		view->lines = lines;
+		view->lines_size = lines_size;
+	}
+	view->width = width;
+	view->height = height;
+	if (view->lines)
+		memset(view->lines, 0, view->lines_size);
+	view_draw(view);
+	return true;
+}
+
+int view_height_get(View *view) {
+	return view->height;
+}
+
+void view_free(View *view) {
+	if (!view)
+		return;
+	free(view->lines);
+	free(view);
+}
+
+void view_reload(View *view, Text *text) {
+	view->text = text;
+	view_selection_clear(view);
+	view_cursor_to(view, 0);
+	if (view->ui)
+		view->ui->reload(view->ui, text);
+}
+
+View *view_new(Text *text, ViewEvent *events) {
+	if (!text)
+		return NULL;
+	View *view = calloc(1, sizeof(View));
+	if (!view)
+		return NULL;
+	view->text = text;
+	view->events = events;
+	view->tabwidth = 8;
+	
+	if (!view_resize(view, 1, 1)) {
+		view_free(view);
+		return NULL;
+	}
+	view_selection_clear(view);
+	view_cursor_to(view, 0);
+
+	return view;
+}
+
+void view_ui(View *view, UiWin* ui) {
+	view->ui = ui;
+}
+size_t view_char_prev(View *view) {
+	Cursor *cursor = &view->cursor;
+	Line *line = cursor->line;
+
+	do {
+		if (cursor->col == 0) {
+			if (!line->prev)
+				return cursor->pos;
+			cursor->line = line = line->prev;
+			cursor->col = MIN(line->width, view->width - 1);
+			cursor->row--;
+		} else {
+			cursor->col--;
+		}
+	} while (line->cells[cursor->col].len == 0);
+
+	cursor->pos -= line->cells[cursor->col].len;
+	return view_cursor_update(view);
+}
+
+size_t view_char_next(View *view) {
+	Cursor *cursor = &view->cursor;
+	Line *line = cursor->line;
+
+	do {
+		cursor->pos += line->cells[cursor->col].len;
+		if ((line->width == view->width && cursor->col == view->width - 1) ||
+		    cursor->col == line->width) {
+			if (!line->next)
+				return cursor->pos;
+			cursor->line = line = line->next;
+			cursor->row++;
+			cursor->col = 0;
+		} else {
+			cursor->col++;
+		}
+	} while (line->cells[cursor->col].len == 0);
+
+	return view_cursor_update(view);
+}
+
+static size_t view_cursor_set(View *view, Line *line, int col) {
+	int row = 0;
+	size_t pos = view->start;
+	Cursor *cursor = &view->cursor;
+	/* get row number and file offset at start of the given line */
+	for (Line *cur = view->topline; cur && cur != line; cur = cur->next) {
+		pos += cur->len;
+		row++;
+	}
+
+	/* for characters which use more than 1 column, make sure we are on the left most */
+	while (col > 0 && line->cells[col].len == 0)
+		col--;
+	while (col < line->width && line->cells[col].istab)
+		col++;
+
+	/* calculate offset within the line */
+	for (int i = 0; i < col; i++)
+		pos += line->cells[i].len;
+
+	cursor->col = col;
+	cursor->row = row;
+	cursor->pos = pos;
+	cursor->line = line;
+
+	view_cursor_update(view);
+
+	return pos;
+}
+
+static bool view_viewport_down(View *view, int n) {
+	Line *line;
+	if (view->end == text_size(view->text))
+		return false;
+	if (n >= view->height) {
+		view->start = view->end;
+	} else {
+		for (line = view->topline; line && n > 0; line = line->next, n--)
+			view->start += line->len;
+	}
+	view_draw(view);
+	return true;
+}
+
+static bool view_viewport_up(View *view, int n) {
+	/* scrolling up is somewhat tricky because we do not yet know where
+	 * the lines start, therefore scan backwards but stop at a reasonable
+	 * maximum in case we are dealing with a file without any newlines
+	 */
+	if (view->start == 0)
+		return false;
+	size_t max = view->width * view->height;
+	char c;
+	Iterator it = text_iterator_get(view->text, view->start - 1);
+
+	if (!text_iterator_byte_get(&it, &c))
+		return false;
+	size_t off = 0;
+	/* skip newlines immediately before display area */
+	if (c == '\n' && text_iterator_byte_prev(&it, &c))
+		off++;
+	if (c == '\r' && text_iterator_byte_prev(&it, &c))
+		off++;
+	do {
+		if (c == '\n' && --n == 0)
+			break;
+		if (++off > max)
+			break;
+	} while (text_iterator_byte_prev(&it, &c));
+	if (c == '\r')
+		off++;
+	view->start -= off;
+	view_draw(view);
+	return true;
+}
+
+void view_redraw_top(View *view) {
+	Line *line = view->cursor.line;
+	for (Line *cur = view->topline; cur && cur != line; cur = cur->next)
+		view->start += cur->len;
+	view_draw(view);
+	view_cursor_to(view, view->cursor.pos);
+}
+
+void view_redraw_center(View *view) {
+	int center = view->height / 2;
+	size_t pos = view->cursor.pos;
+	for (int i = 0; i < 2; i++) {
+		int linenr = 0;
+		Line *line = view->cursor.line;
+		for (Line *cur = view->topline; cur && cur != line; cur = cur->next)
+			linenr++;
+		if (linenr < center) {
+			view_slide_down(view, center - linenr);
+			continue;
+		}
+		for (Line *cur = view->topline; cur && cur != line && linenr > center; cur = cur->next) {
+			view->start += cur->len;
+			linenr--;
+		}
+		break;
+	}
+	view_draw(view);
+	view_cursor_to(view, pos);
+}
+
+void view_redraw_bottom(View *view) {
+	Line *line = view->cursor.line;
+	if (line == view->lastline)
+		return;
+	int linenr = 0;
+	size_t pos = view->cursor.pos;
+	for (Line *cur = view->topline; cur && cur != line; cur = cur->next)
+		linenr++;
+	view_slide_down(view, view->height - linenr - 1);
+	view_cursor_to(view, pos);
+}
+
+size_t view_slide_up(View *view, int lines) {
+	Cursor *cursor = &view->cursor;
+	if (view_viewport_down(view, lines)) {
+		if (cursor->line == view->topline)
+			view_cursor_set(view, view->topline, cursor->col);
+		else
+			view_cursor_to(view, cursor->pos);
+	} else {
+		view_screenline_down(view);
+	}
+	return cursor->pos;
+}
+
+size_t view_slide_down(View *view, int lines) {
+	Cursor *cursor = &view->cursor;
+	if (view_viewport_up(view, lines)) {
+		if (cursor->line == view->lastline)
+			view_cursor_set(view, view->lastline, cursor->col);
+		else
+			view_cursor_to(view, cursor->pos);
+	} else {
+		view_screenline_up(view);
+	}
+	return cursor->pos;
+}
+
+size_t view_scroll_up(View *view, int lines) {
+	Cursor *cursor = &view->cursor;
+	if (view_viewport_up(view, lines)) {
+		Line *line = cursor->line < view->lastline ? cursor->line : view->lastline;
+		view_cursor_set(view, line, view->cursor.col);
+	} else {
+		view_cursor_to(view, 0);
+	}
+	return cursor->pos;
+}
+
+size_t view_scroll_down(View *view, int lines) {
+	Cursor *cursor = &view->cursor;
+	if (view_viewport_down(view, lines)) {
+		Line *line = cursor->line > view->topline ? cursor->line : view->topline;
+		view_cursor_set(view, line, cursor->col);
+	} else {
+		view_cursor_to(view, text_size(view->text));
+	}
+	return cursor->pos;
+}
+
+size_t view_line_up(View *view) {
+	Cursor *cursor = &view->cursor;
+	if (cursor->line->prev && cursor->line->prev->prev &&
+	    cursor->line->lineno != cursor->line->prev->lineno &&
+	    cursor->line->prev->lineno != cursor->line->prev->prev->lineno)
+		return view_screenline_up(view);
+	size_t bol = text_line_begin(view->text, cursor->pos);
+	size_t prev = text_line_prev(view->text, bol);
+	size_t pos = text_line_offset(view->text, prev, cursor->pos - bol);
+	view_cursor_to(view, pos);
+	return cursor->pos;
+}
+
+size_t view_line_down(View *view) {
+	Cursor *cursor = &view->cursor;
+	if (!cursor->line->next || cursor->line->next->lineno != cursor->line->lineno)
+		return view_screenline_down(view);
+	size_t bol = text_line_begin(view->text, cursor->pos);
+	size_t next = text_line_next(view->text, bol);
+	size_t pos = text_line_offset(view->text, next, cursor->pos - bol);
+	view_cursor_to(view, pos);
+	return cursor->pos;
+}
+
+size_t view_screenline_up(View *view) {
+	Cursor *cursor = &view->cursor;
+	int lastcol = cursor->lastcol;
+	if (!lastcol)
+		lastcol = cursor->col;
+	if (!cursor->line->prev)
+		view_scroll_up(view, 1);
+	if (cursor->line->prev)
+		view_cursor_set(view, cursor->line->prev, lastcol);
+	cursor->lastcol = lastcol;
+	return cursor->pos;
+}
+
+size_t view_screenline_down(View *view) {
+	Cursor *cursor = &view->cursor;
+	int lastcol = cursor->lastcol;
+	if (!lastcol)
+		lastcol = cursor->col;
+	if (!cursor->line->next && cursor->line == view->bottomline)
+		view_scroll_down(view, 1);
+	if (cursor->line->next)
+		view_cursor_set(view, cursor->line->next, lastcol);
+	cursor->lastcol = lastcol;
+	return cursor->pos;
+}
+
+size_t view_screenline_begin(View *view) {
+	return view_cursor_set(view, view->cursor.line, 0);
+}
+
+size_t view_screenline_middle(View *view) {
+	Cursor *cursor = &view->cursor;
+	return view_cursor_set(view, cursor->line, cursor->line->width / 2);
+}
+
+size_t view_screenline_end(View *view) {
+	Cursor *cursor = &view->cursor;
+	int col = cursor->line->width - 1;
+	return view_cursor_set(view, cursor->line, col >= 0 ? col : 0);
+}
+
+size_t view_delete_key(View *view) {
+	Cursor *cursor = &view->cursor;
+	Line *line = cursor->line;
+	size_t len = line->cells[cursor->col].len;
+	text_delete(view->text, cursor->pos, len);
+	view_draw(view);
+	view_cursor_to(view, cursor->pos);
+	return cursor->pos;
+}
+
+size_t view_backspace_key(View *view) {
+	Cursor *cursor = &view->cursor;
+	if (view->start == cursor->pos) {
+		if (view->start == 0)
+			return cursor->pos;
+		/* if we are on the top left most position in the view
+		 * first scroll up so that the to be deleted character is
+		 * visible then proceed as normal */
+		size_t pos = cursor->pos;
+		view_viewport_up(view, 1);
+		view_cursor_to(view, pos);
+	}
+	view_char_prev(view);
+	size_t pos = cursor->pos;
+	size_t len = cursor->line->cells[cursor->col].len;
+	text_delete(view->text, pos, len);
+	view_draw(view);
+	view_cursor_to(view, pos);
+	return pos;
+}
+
+size_t view_insert_key(View *view, const char *c, size_t len) {
+	size_t pos = view->cursor.pos;
+	text_insert(view->text, pos, c, len);
+	if (view->cursor.line == view->bottomline && memchr(c, '\n', len))
+		view_viewport_down(view, 1);
+	else
+		view_draw(view);
+	pos += len;
+	view_cursor_to(view, pos);
+	return pos;
+}
+
+size_t view_replace_key(View *view, const char *c, size_t len) {
+	Cursor *cursor = &view->cursor;
+	Line *line = cursor->line;
+	size_t pos = cursor->pos;
+	/* do not overwrite new line which would merge the two lines */
+	if (line->cells[cursor->col].data[0] != '\n') {
+		size_t oldlen = line->cells[cursor->col].len;
+		text_delete(view->text, pos, oldlen);
+	}
+	text_insert(view->text, pos, c, len);
+	if (cursor->line == view->bottomline && memchr(c, '\n', len))
+		view_viewport_down(view, 1);
+	else
+		view_draw(view);
+	pos += len;
+	view_cursor_to(view, pos);
+	return pos;
+}
+
+size_t view_cursor_get(View *view) {
+	return view->cursor.pos;
+}
+
+const Line *view_lines_get(View *view) {
+	return view->topline;
+}
+
+void view_scroll_to(View *view, size_t pos) {
+	while (pos < view->start && view_viewport_up(view, 1));
+	while (pos > view->end && view_viewport_down(view, 1));
+	view_cursor_to(view, pos);
+}
+
+void view_selection_start(View *view) {
+	if (view->sel.start != EPOS && view->sel.end != EPOS)
+		return;
+	size_t pos = view_cursor_get(view);
+	view->sel.start = view->sel.end = pos;
+	view_draw(view);
+	view_cursor_to(view, pos);
+}
+
+void view_syntax_set(View *view, Syntax *syntax) {
+	view->syntax = syntax;
+}
+
+Syntax *view_syntax_get(View *view) {
+	return view->syntax;
+}
+
+size_t view_screenline_goto(View *view, int n) {
+	size_t pos = view->start;
+	for (Line *line = view->topline; --n > 0 && line != view->lastline; line = line->next)
+		pos += line->len;
+	return pos;
+}