gnu.jemacs.swt
Class LineOffsets

java.lang.Object
  gnu.lists.AbstractSequence
      gnu.lists.GapVector
          gnu.jemacs.swt.LineOffsets

All Implemented Interfaces:

Consumable, Sequence, java.lang.Iterable, java.util.Collection, java.util.List

public class LineOffsets
extends GapVector

The purpose of this class is to maintain an ordered set of line offsets for an SwtCharBuffer.

With a LineOffsets instance it's possible to map from the number of a line to the text position where it begins, and back, reasonably fast. (O(1) for line number to line offset, O(log(#lines)) for line offset to line number)

LineOffsets extends GapVector with an U32Vector as base, allowing new line offsets to be inserted quickly during normal text typing.

Instances of SwtCharBuffer should hold an instance LineOffsets class and notify it whenever the it's text changes. The notification happens through the methods:

• textRegionMoved, which should be called when the gap (of SwtCharBuffer) changes (position or size).
• textInserted.
• textDeleted.

TODO: decouple this, using a more general event model.. Assume that lineOffset is an instance of LineOffsets, held by swtCharBuffer an instance of SwtCharBuffer.

Then a value of o at index i in lineOffsets.base means that the line with line number n = (i < lOff.gapStart ? i : i + lOff.gapEnd - lOff.gapStart)

starts at text position p = (o < swtCB.gapStart ? o : o + swtCB.gapEnd - swtCB.gapStart)

Field Summary

static int

minGapSize

Fields inherited from class gnu.lists.GapVector

base, gapEnd, gapStart

Fields inherited from interface gnu.lists.Sequence

ATTRIBUTE_VALUE, BOOLEAN_VALUE, CDATA_VALUE, CHAR_VALUE, COMMENT_VALUE, DOCUMENT_VALUE, DOUBLE_VALUE, EOF_VALUE, eofValue, FLOAT_VALUE, GROUP_VALUE, INT_S16_VALUE, INT_S32_VALUE, INT_S64_VALUE, INT_S8_VALUE, INT_U16_VALUE, INT_U32_VALUE, INT_U64_VALUE, INT_U8_VALUE, OBJECT_VALUE, PRIM_VALUE, PROCESSING_INSTRUCTION_VALUE, TEXT_BYTE_VALUE

Constructor Summary

LineOffsets(int initialSize)

Method Summary

int	countLines(java.lang.String newText)
void	deleteLines(int firstLine, int numberOfLines)
int	index2offset(int index)
void	insertLine(int index, int offSet)
void	insertLines(int index, int[] offsets)
boolean	isLineDelimiter(char c)
int	linesInRange(int startOffset, int endOffset)
int	offset2index(int offset) We seek the line containing a given text offset using a halfing of intervals algorithm.
void	textDeleted(int startOffset, int endOffset)
void	textInserted(int startOffset, java.lang.CharSequence seq)
void	textRegionMoved(int regionStart, int regionEnd, int displacement)
java.lang.String	toString()

Methods inherited from class gnu.lists.GapVector

add, addPos, consumePosRange, createPos, fill, fillPosRange, gapReserve, gapReserve, get, getNextKind, hasNext, isAfterPos, nextIndex, removePosRange, set, shiftGap, size

Methods inherited from class gnu.lists.AbstractSequence

add, addAll, addAll, append, append, append, baseUriOfPos, clear, compare, compare, compare, consume, consumeNext, contains, containsAll, copyPos, createRelativePos, elements, endPos, equals, equals, fill, firstAttributePos, firstChildPos, fromEndIndex, get, getAttribute, getAttributeLength, getContainingSequenceSize, getEffectiveIndex, getIndexDifference, getIterator, getIterator, getIteratorAtPos, getLowBound, getNextTypeName, getNextTypeObject, getPosNext, getPosPrevious, getSize, gotoAttributesStart, gotoChildrenStart, gotoParent, hashCode, hasPrevious, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, nextIndex, nextMatching, nextPos, parentPos, previousPos, rank, releasePos, remove, remove, removeAll, removePos, retainAll, set, setPosNext, setPosPrevious, stableCompare, startPos, subList, subSequence, subSequencePos, toArray, toArray, toString, unsupported

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface gnu.lists.Sequence

elements, isEmpty

Methods inherited from interface java.util.List

add, addAll, addAll, clear, contains, containsAll, equals, hashCode, indexOf, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, retainAll, subList, toArray, toArray

Methods inherited from interface gnu.lists.Consumable

consume

Field Detail

minGapSize

public static final int minGapSize

See Also:

Constant Field Values

Constructor Detail

LineOffsets

public LineOffsets(int initialSize)

Method Detail

insertLine

public void insertLine(int index,
                       int offSet)

index2offset

public int index2offset(int index)

offset2index

public int offset2index(int offset)

We seek the line containing a given text offset using a halfing of intervals algorithm. Therefore the method will use O(log(n)) time, n being the number of lines.

See Also:

StyledTextContent.getLineAtOffset(int)

deleteLines

public void deleteLines(int firstLine,
                        int numberOfLines)

insertLines

public void insertLines(int index,
                        int[] offsets)

toString

public java.lang.String toString()

Overrides:

toString in class AbstractSequence

countLines

public int countLines(java.lang.String newText)

linesInRange

public int linesInRange(int startOffset,
                        int endOffset)

textRegionMoved

public void textRegionMoved(int regionStart,
                            int regionEnd,
                            int displacement)

textInserted

public void textInserted(int startOffset,
                         java.lang.CharSequence seq)

textDeleted

public void textDeleted(int startOffset,
                        int endOffset)

isLineDelimiter

public boolean isLineDelimiter(char c)