diff options
| -rw-r--r-- | text.go | 9 |
1 files changed, 8 insertions, 1 deletions
@@ -27,6 +27,9 @@ type Text struct { history History // undo/redo stack } +// Write implements io.Writer, with the side effect of storing written data into a history stack for undo/redo. +// +// If dot has content, it will be replaced by an initial deletion before inserting the bytes. func (t *Text) Write(p []byte) (int, error) { // handle replace if len(t.ReadDot()) > 0 { @@ -44,6 +47,7 @@ func (t *Text) Write(p []byte) (int, error) { return n, nil } +// Delete removes current selection in dot. If dot is empty, it selects the previous rune and deletes that. func (t *Text) Delete() (int, error) { if len(t.ReadDot()) == 0 { t.q0-- @@ -81,6 +85,7 @@ func (t *Text) ReadRune() (r rune, size int, err error) { return } +// UnreadRune returns the rune before the current Seek offset and moves the offset to point to that. This could be called in sequence to scan backwards. func (t *Text) UnreadRune() (r rune, size int, err error) { t.off-- r, size, err = t.ReadRuneAt(t.off) @@ -93,6 +98,8 @@ func (t *Text) UnreadRune() (r rune, size int, err error) { } // ReadRuneAt returns the rune and its size at offset. If the given offset (in byte count) is not a valid rune, it will try to back up until it finds a valid starting point for a rune and return that one. +// +// This is basically a Seek(offset) followed by a ReadRune(), but does not affect the internal offset for future reads.. func (t *Text) ReadRuneAt(offset int) (r rune, size int, err error) { var c byte c, err = t.buf.ByteAt(offset) @@ -147,7 +154,7 @@ func (t *Text) Dot() (int, int) { return t.q0, t.q1 } -// Seek implements io.Seeker and sets the internal offset for next ReadRune(). If the offset is not a valid rune start, it will backup until it finds one. +// Seek implements io.Seeker and sets the internal offset for next ReadRune() or UnreadRune(). If the offset is not a valid rune start, it will backup until it finds one. func (t *Text) Seek(offset, whence int) (int, error) { t.off = offset |