public interface LineMap
LineMap
is an interface for accessing the line structure information of a TextBuffer
. This allows clients to determine the line that an offset is on, the starting and ending offset of a specific line, and the total number of lines in the TextBuffer
.
Client Usage Notes:
LineMap
as well as specified by the client. For example, if there are 5 lines in the buffer, the lines will be numbered 0 through 4, while getLineCount()
will return 5 lines.
Clients must take this into account as line numbers reported through UI components to end users typically start from 1.
getLineStartOffset(int)
are inclusive, while end offsets returned from getLineEndOffset(int)
are exclusive.
For example, if the first line of the buffer contains "abcd" followed by a newline (\n), then the start offset of the line will be 0, while the end offset will be 5. The length of the line (including line terminators) will always be the end offset minus the start offset.
getLineFromOffset(int)
, the offset given has a forward bias. In the above example, offset 5 occurs between the newline (\n) of line 0 and the first character of line 1. Since the bias is to the right, getLineFromOffset( 5 )
will return line 1, not 0.LineMap
tracks the underlying text buffer, it will be modified when the text buffer is modified. To ensure data consistency (and program stability), clients must be sure to acquire at least a read lock on the buffer while accessing the LineMap
. This is just a documented policy, and is not enforced programmatically in order to not affect performance.TextBuffer
Modifier and Type | Method and Description |
---|---|
int |
getLineCount()
Fetches the number of lines in this
TextBuffer . |
int |
getLineEndOffset(int line)
Given a specified line, returns the offset from the beginning of a
TextBuffer that the line ends at. |
int |
getLineFromOffset(int offset)
Given an offset from the beginning of the underlying
TextBuffer , fetches the line number containing that offset using a Forward bias. |
int |
getLineStartOffset(int line)
Given a specified line, returns the offset from the beginning of the
TextBuffer for the start of the line. |
TextBuffer |
getTextBuffer()
Fetches the underlying
TextBuffer of this line map. |
TextBuffer getTextBuffer()
TextBuffer
of this line map.int getLineCount()
TextBuffer
. For example, a 5-line TextBuffer
has lines 0 through 4.TextBuffer
int getLineFromOffset(int offset)
TextBuffer
, fetches the line number containing that offset using a Forward bias. This means if line A starts with offset B, and previous line A-1 ends with offset B, getLineFromOffset(B)
will return line A.int getLineStartOffset(int line)
TextBuffer
for the start of the line.line
- a line in the TextBuffer
int getLineEndOffset(int line)
TextBuffer
that the line ends at.line
- a line in the TextBuffer
the
- ending offset of the specified line