mirror of
https://github.com/walles/moar.git
synced 2024-09-11 12:15:43 +03:00
497 lines
11 KiB
Go
497 lines
11 KiB
Go
package m
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import (
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"fmt"
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"regexp"
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"time"
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log "github.com/sirupsen/logrus"
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"github.com/walles/moar/twin"
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)
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type _PagerMode int
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const (
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_Viewing _PagerMode = iota
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_Searching
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_NotFound
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_GotoLine
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)
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type StatusBarStyle int
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const (
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STATUSBAR_STYLE_INVERSE StatusBarStyle = iota
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STATUSBAR_STYLE_PLAIN
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STATUSBAR_STYLE_BOLD
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)
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// How do we render unprintable characters?
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type UnprintableStyle int
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const (
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UNPRINTABLE_STYLE_HIGHLIGHT UnprintableStyle = iota
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UNPRINTABLE_STYLE_WHITESPACE
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)
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type eventSpinnerUpdate struct {
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spinner string
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}
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type eventMoreLinesAvailable struct{}
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// Styling of line numbers
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var _numberStyle = twin.StyleDefault.WithAttr(twin.AttrDim)
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// Pager is the main on-screen pager
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type Pager struct {
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reader *Reader
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screen twin.Screen
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quit bool
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scrollPosition scrollPosition
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leftColumnZeroBased int
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mode _PagerMode
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searchString string
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searchPattern *regexp.Regexp
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gotoLineString string
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isShowingHelp bool
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preHelpState *_PreHelpState
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// NewPager shows lines by default, this field can hide them
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ShowLineNumbers bool
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StatusBarStyle StatusBarStyle
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ShowStatusBar bool
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UnprintableStyle UnprintableStyle
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WrapLongLines bool
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// Ref: https://github.com/walles/moar/issues/94
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ScrollLeftHint twin.Cell
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ScrollRightHint twin.Cell
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// If true, pager will clear the screen on return. If false, pager will
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// clear the last line, and show the cursor.
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DeInit bool
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}
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type _PreHelpState struct {
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reader *Reader
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scrollPosition scrollPosition
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leftColumnZeroBased int
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}
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const _EofMarkerFormat = "\x1b[7m" // Reverse video
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var _HelpReader = NewReaderFromText("Help", `
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Welcome to Moar, the nice pager!
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Miscellaneous
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-------------
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* Press 'q' or ESC to quit
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* Press 'w' to toggle wrapping of long lines
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* Press '=' to toggle showing the status bar at the bottom
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Moving around
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-------------
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* Arrow keys
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* SPACE moves down a page
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* 'g' for going to a specific line number
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* Left / right can be used to hide / show line numbers
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* PageUp / 'b' and PageDown / 'f'
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* Home and End for start / end of the document
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* < to go to the start of the document
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* > / 'G' to go to the end of the document
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* 'h', 'l' for left and right (as in vim)
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* Half page 'u'p / 'd'own, or CTRL-u / CTRL-d
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* RETURN moves down one line
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Searching
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---------
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* Type / to start searching, then type what you want to find
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* Type RETURN to stop searching
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* Find next by typing 'n' (for "next")
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* Find previous by typing SHIFT-N or 'p' (for "previous")
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* Search is case sensitive if it contains any UPPER CASE CHARACTERS
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* Search is interpreted as a regexp if it is a valid one
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Reporting bugs
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--------------
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File issues at https://github.com/walles/moar/issues, or post
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questions to johan.walles@gmail.com.
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Installing Moar as your default pager
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-------------------------------------
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Put the following line in your ~/.bashrc, ~/.bash_profile or ~/.zshrc:
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export PAGER=moar
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Source Code
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-----------
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Available at https://github.com/walles/moar/.
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`)
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// NewPager creates a new Pager
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func NewPager(r *Reader) *Pager {
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var name string
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if r == nil || r.name == nil || len(*r.name) == 0 {
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name = "Pager"
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} else {
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name = "Pager " + *r.name
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}
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return &Pager{
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reader: r,
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quit: false,
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ShowLineNumbers: true,
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ShowStatusBar: true,
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DeInit: true,
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ScrollLeftHint: twin.NewCell('<', twin.StyleDefault.WithAttr(twin.AttrReverse)),
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ScrollRightHint: twin.NewCell('>', twin.StyleDefault.WithAttr(twin.AttrReverse)),
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scrollPosition: newScrollPosition(name),
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}
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}
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func (p *Pager) setFooter(footer string) {
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width, height := p.screen.Size()
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pos := 0
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var footerStyle twin.Style
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if p.StatusBarStyle == STATUSBAR_STYLE_INVERSE {
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footerStyle = twin.StyleDefault.WithAttr(twin.AttrReverse)
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} else if p.StatusBarStyle == STATUSBAR_STYLE_PLAIN {
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footerStyle = twin.StyleDefault
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} else if p.StatusBarStyle == STATUSBAR_STYLE_BOLD {
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footerStyle = twin.StyleDefault.WithAttr(twin.AttrBold)
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} else {
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panic(fmt.Sprint("Unrecognized footer style: ", footerStyle))
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}
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for _, token := range footer {
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p.screen.SetCell(pos, height-1, twin.NewCell(token, footerStyle))
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pos++
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}
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for ; pos < width; pos++ {
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p.screen.SetCell(pos, height-1, twin.NewCell(' ', footerStyle))
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}
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}
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// Quit leaves the help screen or quits the pager
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func (p *Pager) Quit() {
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if !p.isShowingHelp {
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p.quit = true
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return
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}
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// Reset help
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p.isShowingHelp = false
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p.reader = p.preHelpState.reader
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p.scrollPosition = p.preHelpState.scrollPosition
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p.leftColumnZeroBased = p.preHelpState.leftColumnZeroBased
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p.preHelpState = nil
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}
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func (p *Pager) moveRight(delta int) {
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if p.ShowLineNumbers && delta > 0 {
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p.ShowLineNumbers = false
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return
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}
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if p.leftColumnZeroBased == 0 && delta < 0 {
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p.ShowLineNumbers = true
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return
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}
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result := p.leftColumnZeroBased + delta
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if result < 0 {
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p.leftColumnZeroBased = 0
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} else {
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p.leftColumnZeroBased = result
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}
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}
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func (p *Pager) onKey(keyCode twin.KeyCode) {
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if p.mode == _Searching {
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p.onSearchKey(keyCode)
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return
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}
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if p.mode == _GotoLine {
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p.onGotoLineKey(keyCode)
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return
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}
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if p.mode != _Viewing && p.mode != _NotFound {
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panic(fmt.Sprint("Unhandled mode: ", p.mode))
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}
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// Reset the not-found marker on non-search keypresses
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p.mode = _Viewing
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switch keyCode {
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case twin.KeyEscape:
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p.Quit()
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case twin.KeyUp:
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// Clipping is done in _Redraw()
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p.scrollPosition = p.scrollPosition.PreviousLine(1)
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case twin.KeyDown, twin.KeyEnter:
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// Clipping is done in _Redraw()
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p.scrollPosition = p.scrollPosition.NextLine(1)
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case twin.KeyRight:
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p.moveRight(16)
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case twin.KeyLeft:
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p.moveRight(-16)
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case twin.KeyHome:
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p.scrollPosition = newScrollPosition("Pager scroll position")
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case twin.KeyEnd:
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p.scrollToEnd()
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case twin.KeyPgDown:
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_, height := p.screen.Size()
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p.scrollPosition = p.scrollPosition.NextLine(height - 1)
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case twin.KeyPgUp:
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_, height := p.screen.Size()
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p.scrollPosition = p.scrollPosition.PreviousLine(height - 1)
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default:
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log.Debugf("Unhandled key event %v", keyCode)
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}
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}
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func (p *Pager) onRune(char rune) {
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if p.mode == _Searching {
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p.onSearchRune(char)
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return
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}
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if p.mode == _GotoLine {
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p.onGotoLineRune(char)
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return
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}
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if p.mode != _Viewing && p.mode != _NotFound {
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panic(fmt.Sprint("Unhandled mode: ", p.mode))
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}
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switch char {
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case 'q':
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p.Quit()
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case '?':
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if !p.isShowingHelp {
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p.preHelpState = &_PreHelpState{
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reader: p.reader,
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scrollPosition: p.scrollPosition,
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leftColumnZeroBased: p.leftColumnZeroBased,
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}
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p.reader = _HelpReader
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p.scrollPosition = newScrollPosition("Pager scroll position")
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p.leftColumnZeroBased = 0
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p.isShowingHelp = true
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}
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case '=':
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p.ShowStatusBar = !p.ShowStatusBar
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case 'k', 'y':
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// Clipping is done in _Redraw()
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p.scrollPosition = p.scrollPosition.PreviousLine(1)
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case 'j', 'e':
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// Clipping is done in _Redraw()
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p.scrollPosition = p.scrollPosition.NextLine(1)
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case 'l':
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// vim right
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p.moveRight(16)
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case 'h':
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// vim left
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p.moveRight(-16)
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case '<':
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p.scrollPosition = newScrollPosition("Pager scroll position")
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case '>', 'G':
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p.scrollToEnd()
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case 'f', ' ':
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_, height := p.screen.Size()
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p.scrollPosition = p.scrollPosition.NextLine(height - 1)
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case 'b':
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_, height := p.screen.Size()
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p.scrollPosition = p.scrollPosition.PreviousLine(height - 1)
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// '\x15' = CTRL-u, should work like just 'u'.
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// Ref: https://github.com/walles/moar/issues/90
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case 'u', '\x15':
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_, height := p.screen.Size()
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p.scrollPosition = p.scrollPosition.PreviousLine(height / 2)
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// '\x04' = CTRL-d, should work like just 'd'.
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// Ref: https://github.com/walles/moar/issues/90
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case 'd', '\x04':
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_, height := p.screen.Size()
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p.scrollPosition = p.scrollPosition.NextLine(height / 2)
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case '/':
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p.mode = _Searching
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p.searchString = ""
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p.searchPattern = nil
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case 'g':
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p.mode = _GotoLine
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p.gotoLineString = ""
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case 'n':
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p.scrollToNextSearchHit()
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case 'p', 'N':
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p.scrollToPreviousSearchHit()
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case 'w':
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p.WrapLongLines = !p.WrapLongLines
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default:
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log.Debugf("Unhandled rune keypress '%s'/0x%08x", string(char), int32(char))
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}
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}
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// StartPaging brings up the pager on screen
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func (p *Pager) StartPaging(screen twin.Screen) {
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unprintableStyle = p.UnprintableStyle
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SetManPageFormatFromEnv()
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p.screen = screen
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go func() {
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for {
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// Wait for new lines to appear...
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<-p.reader.moreLinesAdded
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// ... and notify the main loop so it can show them:
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screen.Events() <- eventMoreLinesAvailable{}
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// Delay updates a bit so that we don't waste time refreshing
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// the screen too often.
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//
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// Note that the delay is *after* reacting, this way single-line
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// updates are reacted to immediately, and the first output line
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// read will appear on screen without delay.
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time.Sleep(200 * time.Millisecond)
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}
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}()
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go func() {
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// Spin the spinner as long as contents is still loading
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done := false
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spinnerFrames := [...]string{"/.\\", "-o-", "\\O/", "| |"}
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spinnerIndex := 0
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for {
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// Break this loop on the reader.done signal...
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select {
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case <-p.reader.done:
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done = true
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default:
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// This default case makes this an async read
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}
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if done {
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break
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}
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screen.Events() <- eventSpinnerUpdate{spinnerFrames[spinnerIndex]}
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spinnerIndex++
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if spinnerIndex >= len(spinnerFrames) {
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spinnerIndex = 0
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}
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time.Sleep(200 * time.Millisecond)
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}
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// Empty our spinner, loading done!
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screen.Events() <- eventSpinnerUpdate{""}
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}()
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// Main loop
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spinner := ""
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for !p.quit {
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if len(screen.Events()) == 0 {
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// Nothing more to process for now, redraw the screen!
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p.redraw(spinner)
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}
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event := <-screen.Events()
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switch event := event.(type) {
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case twin.EventKeyCode:
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log.Tracef("Handling key event %d...", event.KeyCode())
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p.onKey(event.KeyCode())
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case twin.EventRune:
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log.Tracef("Handling rune event '%c'/0x%04x...", event.Rune(), event.Rune())
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p.onRune(event.Rune())
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case twin.EventMouse:
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log.Tracef("Handling mouse event %d...", event.Buttons())
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switch event.Buttons() {
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case twin.MouseWheelUp:
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// Clipping is done in _Redraw()
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p.scrollPosition = p.scrollPosition.PreviousLine(1)
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case twin.MouseWheelDown:
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// Clipping is done in _Redraw()
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p.scrollPosition = p.scrollPosition.NextLine(1)
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case twin.MouseWheelLeft:
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p.moveRight(-16)
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case twin.MouseWheelRight:
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p.moveRight(16)
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}
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case twin.EventResize:
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// We'll be implicitly redrawn just by taking another lap in the loop
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case eventMoreLinesAvailable:
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// Doing nothing here is fine; screen will be refreshed on the next
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// iteration of the main loop.
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case eventSpinnerUpdate:
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spinner = event.spinner
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default:
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log.Warnf("Unhandled event type: %v", event)
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}
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}
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if p.reader.err != nil {
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log.Warnf("Reader reported an error: %s", p.reader.err.Error())
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}
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}
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// After the pager has exited and the normal screen has been restored, you can
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// call this method to print the pager contents to screen again, faking
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// "leaving" pager contents on screen after exit.
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func (p *Pager) ReprintAfterExit() error {
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// Figure out how many screen lines are used by pager contents
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renderedScreenLines, _ := p.renderScreenLines()
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screenLinesCount := len(renderedScreenLines)
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_, screenHeight := p.screen.Size()
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screenHeightWithoutFooter := screenHeight - 1
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if screenLinesCount > screenHeightWithoutFooter {
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screenLinesCount = screenHeightWithoutFooter
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}
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if screenLinesCount > 0 {
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p.screen.ShowNLines(screenLinesCount)
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}
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return nil
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}
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