forked from sloum/bombadillo
113 lines
3.3 KiB
Go
113 lines
3.3 KiB
Go
package gopher
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import (
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"errors"
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"fmt"
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)
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//------------------------------------------------\\
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// + + + T Y P E S + + + \\
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//--------------------------------------------------\\
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// The history struct represents the history of the browsing
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// session. It contains the current history position, the
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// length of the active history space (this can be different
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// from the available capacity in the Collection), and a
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// collection array containing View structs representing
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// each page in the current history. In general usage this
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// struct should be initialized via the MakeHistory function.
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type History struct {
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Position int
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Length int
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Collection [20]View
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}
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//------------------------------------------------\\
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// + + + R E C E I V E R S + + + \\
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//--------------------------------------------------\\
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// The "Add" receiver takes a view and adds it to
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// the history struct that called it. "Add" returns
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// nothing. "Add" will shift history down if the max
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// history length would be exceeded, and will reset
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// history length if something is added in the middle.
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func (h *History) Add(v View) {
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v.ParseMap()
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if h.Position == h.Length-1 && h.Length < len(h.Collection) {
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h.Collection[h.Length] = v
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h.Length++
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h.Position++
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} else if h.Position == h.Length-1 && h.Length == 20 {
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for x := 1; x < len(h.Collection); x++ {
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h.Collection[x-1] = h.Collection[x]
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}
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h.Collection[len(h.Collection)-1] = v
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} else {
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h.Position += 1
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h.Length = h.Position + 1
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h.Collection[h.Position] = v
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}
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}
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// The "Get" receiver is called by a history struct
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// and returns a View from the current position, will
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// return an error if history is empty and there is
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// nothing to get.
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func (h History) Get() (*View, error) {
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if h.Position < 0 {
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return nil, errors.New("History is empty, cannot get item from empty history.")
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}
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return &h.Collection[h.Position], nil
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}
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// The "GoBack" receiver is called by a history struct.
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// When called it decrements the current position and
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// displays the content for the View in that position.
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// If history is at position 0, no action is taken.
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func (h *History) GoBack() bool {
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if h.Position > 0 {
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h.Position--
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return true
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}
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fmt.Print("\a")
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return false
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}
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// The "GoForward" receiver is called by a history struct.
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// When called it increments the current position and
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// displays the content for the View in that position.
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// If history is at position len - 1, no action is taken.
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func (h *History) GoForward() bool {
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if h.Position+1 < h.Length {
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h.Position++
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return true
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}
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fmt.Print("\a")
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return false
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}
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// The "DisplayCurrentView" receiver is called by a history
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// struct. It calls the Display receiver for th view struct
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// at the current history position. "DisplayCurrentView" does
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// not return anything, and does nothing if position is less
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// that 0.
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func (h *History) DisplayCurrentView() {
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h.Collection[h.Position].Display()
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}
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//------------------------------------------------\\
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// + + + F U N C T I O N S + + + \\
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//--------------------------------------------------\\
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// Constructor function for History struct.
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// This is used to initialize history position
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// as -1, which is needed. Returns a copy of
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// initialized History struct (does NOT return
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// a pointer to the struct).
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func MakeHistory() History {
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return History{-1, 0, [20]View{}}
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}
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