now is go gettable and updated make file

cmd/micro/cursor.go

@@ -0,0 +1,308 @@
+package main
+
+import (
+	"strings"
+)
+
+// FromCharPos converts from a character position to an x, y position
+func FromCharPos(loc int, buf *Buffer) (int, int) {
+	return FromCharPosStart(0, 0, 0, loc, buf)
+}
+
+// FromCharPosStart converts from a character position to an x, y position, starting at the specified character location
+func FromCharPosStart(startLoc, startX, startY, loc int, buf *Buffer) (int, int) {
+	charNum := startLoc
+	x, y := startX, startY
+
+	lineLen := Count(buf.lines[y]) + 1
+	for charNum+lineLen <= loc {
+		charNum += lineLen
+		y++
+		lineLen = Count(buf.lines[y]) + 1
+	}
+	x = loc - charNum
+
+	return x, y
+}
+
+// ToCharPos converts from an x, y position to a character position
+func ToCharPos(x, y int, buf *Buffer) int {
+	loc := 0
+	for i := 0; i < y; i++ {
+		// + 1 for the newline
+		loc += Count(buf.lines[i]) + 1
+	}
+	loc += x
+	return loc
+}
+
+// The Cursor struct stores the location of the cursor in the view
+// The complicated part about the cursor is storing its location.
+// The cursor must be displayed at an x, y location, but since the buffer
+// uses a rope to store text, to insert text we must have an index. It
+// is also simpler to use character indicies for other tasks such as
+// selection.
+type Cursor struct {
+	v *View
+
+	// The cursor display location
+	x int
+	y int
+
+	// Last cursor x position
+	lastVisualX int
+
+	// The current selection as a range of character numbers (inclusive)
+	curSelection [2]int
+	// The original selection as a range of character numbers
+	// This is used for line and word selection where it is necessary
+	// to know what the original selection was
+	origSelection [2]int
+}
+
+// SetLoc sets the location of the cursor in terms of character number
+// and not x, y location
+// It's just a simple wrapper of FromCharPos
+func (c *Cursor) SetLoc(loc int) {
+	c.x, c.y = FromCharPos(loc, c.v.buf)
+}
+
+// Loc gets the cursor location in terms of character number instead
+// of x, y location
+// It's just a simple wrapper of ToCharPos
+func (c *Cursor) Loc() int {
+	return ToCharPos(c.x, c.y, c.v.buf)
+}
+
+// ResetSelection resets the user's selection
+func (c *Cursor) ResetSelection() {
+	c.curSelection[0] = 0
+	c.curSelection[1] = 0
+}
+
+// HasSelection returns whether or not the user has selected anything
+func (c *Cursor) HasSelection() bool {
+	return c.curSelection[0] != c.curSelection[1]
+}
+
+// DeleteSelection deletes the currently selected text
+func (c *Cursor) DeleteSelection() {
+	if c.curSelection[0] > c.curSelection[1] {
+		c.v.eh.Remove(c.curSelection[1], c.curSelection[0])
+		c.SetLoc(c.curSelection[1])
+	} else {
+		c.v.eh.Remove(c.curSelection[0], c.curSelection[1])
+		c.SetLoc(c.curSelection[0])
+	}
+}
+
+// GetSelection returns the cursor's selection
+func (c *Cursor) GetSelection() string {
+	if c.curSelection[0] > c.curSelection[1] {
+		return string([]rune(c.v.buf.text)[c.curSelection[1]:c.curSelection[0]])
+	}
+	return string([]rune(c.v.buf.text)[c.curSelection[0]:c.curSelection[1]])
+}
+
+// SelectLine selects the current line
+func (c *Cursor) SelectLine() {
+	c.Start()
+	c.curSelection[0] = c.Loc()
+	c.End()
+	c.curSelection[1] = c.Loc()
+
+	c.origSelection = c.curSelection
+}
+
+// AddLineToSelection adds the current line to the selection
+func (c *Cursor) AddLineToSelection() {
+	loc := c.Loc()
+
+	if loc < c.origSelection[0] {
+		c.Start()
+		c.curSelection[0] = c.Loc()
+		c.curSelection[1] = c.origSelection[1]
+	}
+	if loc > c.origSelection[1] {
+		c.End()
+		c.curSelection[1] = c.Loc()
+		c.curSelection[0] = c.origSelection[0]
+	}
+
+	if loc < c.origSelection[1] && loc > c.origSelection[0] {
+		c.curSelection = c.origSelection
+	}
+}
+
+// SelectWord selects the word the cursor is currently on
+func (c *Cursor) SelectWord() {
+	if len(c.v.buf.lines[c.y]) == 0 {
+		return
+	}
+
+	if !IsWordChar(string(c.RuneUnder(c.x))) {
+		loc := c.Loc()
+		c.curSelection[0] = loc
+		c.curSelection[1] = loc + 1
+		c.origSelection = c.curSelection
+		return
+	}
+
+	forward, backward := c.x, c.x
+
+	for backward > 0 && IsWordChar(string(c.RuneUnder(backward-1))) {
+		backward--
+	}
+
+	c.curSelection[0] = ToCharPos(backward, c.y, c.v.buf)
+	c.origSelection[0] = c.curSelection[0]
+
+	for forward < Count(c.v.buf.lines[c.y])-1 && IsWordChar(string(c.RuneUnder(forward+1))) {
+		forward++
+	}
+
+	c.curSelection[1] = ToCharPos(forward, c.y, c.v.buf) + 1
+	c.origSelection[1] = c.curSelection[1]
+}
+
+// AddWordToSelection adds the word the cursor is currently on to the selection
+func (c *Cursor) AddWordToSelection() {
+	loc := c.Loc()
+
+	if loc > c.origSelection[0] && loc < c.origSelection[1] {
+		c.curSelection = c.origSelection
+		return
+	}
+
+	if loc < c.origSelection[0] {
+		backward := c.x
+
+		for backward > 0 && IsWordChar(string(c.RuneUnder(backward-1))) {
+			backward--
+		}
+
+		c.curSelection[0] = ToCharPos(backward, c.y, c.v.buf)
+		c.curSelection[1] = c.origSelection[1]
+	}
+
+	if loc > c.origSelection[1] {
+		forward := c.x
+
+		for forward < Count(c.v.buf.lines[c.y])-1 && IsWordChar(string(c.RuneUnder(forward+1))) {
+			forward++
+		}
+
+		c.curSelection[1] = ToCharPos(forward, c.y, c.v.buf) + 1
+		c.curSelection[0] = c.origSelection[0]
+	}
+}
+
+// RuneUnder returns the rune under the given x position
+func (c *Cursor) RuneUnder(x int) rune {
+	line := []rune(c.v.buf.lines[c.y])
+	if x >= len(line) {
+		x = len(line) - 1
+	} else if x < 0 {
+		x = 0
+	}
+	return line[x]
+}
+
+// Up moves the cursor up one line (if possible)
+func (c *Cursor) Up() {
+	if c.y > 0 {
+		c.y--
+
+		runes := []rune(c.v.buf.lines[c.y])
+		c.x = c.GetCharPosInLine(c.y, c.lastVisualX)
+		if c.x > len(runes) {
+			c.x = len(runes)
+		}
+	}
+}
+
+// Down moves the cursor down one line (if possible)
+func (c *Cursor) Down() {
+	if c.y < len(c.v.buf.lines)-1 {
+		c.y++
+
+		runes := []rune(c.v.buf.lines[c.y])
+		c.x = c.GetCharPosInLine(c.y, c.lastVisualX)
+		if c.x > len(runes) {
+			c.x = len(runes)
+		}
+	}
+}
+
+// Left moves the cursor left one cell (if possible) or to the last line if it is at the beginning
+func (c *Cursor) Left() {
+	if c.Loc() == 0 {
+		return
+	}
+	if c.x > 0 {
+		c.x--
+	} else {
+		c.Up()
+		c.End()
+	}
+	c.lastVisualX = c.GetVisualX()
+}
+
+// Right moves the cursor right one cell (if possible) or to the next line if it is at the end
+func (c *Cursor) Right() {
+	if c.Loc() == c.v.buf.Len() {
+		return
+	}
+	if c.x < Count(c.v.buf.lines[c.y]) {
+		c.x++
+	} else {
+		c.Down()
+		c.Start()
+	}
+	c.lastVisualX = c.GetVisualX()
+}
+
+// End moves the cursor to the end of the line it is on
+func (c *Cursor) End() {
+	c.x = Count(c.v.buf.lines[c.y])
+	c.lastVisualX = c.GetVisualX()
+}
+
+// Start moves the cursor to the start of the line it is on
+func (c *Cursor) Start() {
+	c.x = 0
+	c.lastVisualX = c.GetVisualX()
+}
+
+// GetCharPosInLine gets the char position of a visual x y coordinate (this is necessary because tabs are 1 char but 4 visual spaces)
+func (c *Cursor) GetCharPosInLine(lineNum, visualPos int) int {
+	// Get the tab size
+	tabSize := settings.TabSize
+	// This is the visual line -- every \t replaced with the correct number of spaces
+	visualLine := strings.Replace(c.v.buf.lines[lineNum], "\t", "\t"+Spaces(tabSize-1), -1)
+	if visualPos > Count(visualLine) {
+		visualPos = Count(visualLine)
+	}
+	numTabs := NumOccurences(visualLine[:visualPos], '\t')
+	if visualPos >= (tabSize-1)*numTabs {
+		return visualPos - (tabSize-1)*numTabs
+	}
+	return visualPos / tabSize
+}
+
+// GetVisualX returns the x value of the cursor in visual spaces
+func (c *Cursor) GetVisualX() int {
+	runes := []rune(c.v.buf.lines[c.y])
+	tabSize := settings.TabSize
+	return c.x + NumOccurences(string(runes[:c.x]), '\t')*(tabSize-1)
+}
+
+// Display draws the cursor to the screen at the correct position
+func (c *Cursor) Display() {
+	// Don't draw the cursor if it is out of the viewport or if it has a selection
+	if (c.y-c.v.topline < 0 || c.y-c.v.topline > c.v.height-1) || c.HasSelection() {
+		screen.HideCursor()
+	} else {
+		screen.ShowCursor(c.GetVisualX()+c.v.lineNumOffset-c.v.leftCol, c.y-c.v.topline)
+	}
+}