Programmering i andras ögon?

GraphicsWindow.KeyDown = HandleKey
GraphicsWindow.BackgroundColor = GraphicsWindow.GetColorFromRGB( 253, 252, 251 )

While "True"
  BOXES = 4      ' number of boxes per piece
  BWIDTH = 25    ' box width in pixels
  XOFFSET = 40   ' Screen X offset in pixels of where the board starts
  YOFFSET = 40   ' Screen Y offset in pixels of where the board starts
  CWIDTH = 10    ' Canvas Width, in number of boxes
  CHEIGHT = 20   ' Canvas Height, in number of boxes.
  STARTDELAY = 800
  ENDDELAY = 175
  PREVIEW_xpos = 13
  PREVIEW_ypos = 2
  
  GraphicsWindow.Clear()
  GraphicsWindow.Title = "Small Basic Tetris"
  GraphicsWindow.Height = 580
  GraphicsWindow.Width = 700
  GraphicsWindow.Show()

  SetupTemplates()
  SetupCanvas()
  MainLoop()
  
  GraphicsWindow.ShowMessage( "Game Over", "Small Basic Tetris" )
EndWhile

Sub MainLoop
  template = Text.Append("template", Math.GetRandomNumber(7))

  CreatePiece() ' in: template  ret: h
  nextPiece = h

  end = 0
  sessionDelay = STARTDELAY
  While end = 0
    If sessionDelay > ENDDELAY Then
      sessionDelay = sessionDelay - 1
    EndIf
    
    delay = sessionDelay
    thisPiece = nextPiece
    template = Text.Append("template", Math.GetRandomNumber(7))

    CreatePiece() ' in: template  ret: h
    nextPiece = h
    DrawPreviewPiece()
    
    h = thisPiece    
    
    ypos = 0
    done = 0
    xpos = 3 ' always drop from column 3
    CheckStop() ' in: ypos, xpos, h  ret: done
    If done = 1 Then
      ypos = ypos - 1
      MovePiece()  'in: ypos, xpos, h
      end = 1
    EndIf
    
    yposdelta = 0
    While done = 0 Or yposdelta > 0
      MovePiece()  'in: ypos, xpos, h
      
      ' Delay, but break if the delay get set to 0 if the piece gets dropped
      delayIndex = delay      
      While delayIndex > 0 And delay > 0
        Program.Delay(10)
        delayIndex = delayIndex - 10
      EndWhile  

      If yposdelta > 0 Then
        yposdelta = yposdelta - 1  ' used to create freespin, when the piece is rotated
      Else
        ypos = ypos + 1            ' otherwise, move the piece down.
      EndIf
      
      ' Check if the piece should stop.
      CheckStop() ' in: ypos, xpos, h  ret: done            
    EndWhile
  EndWhile
EndSub

Sub HandleKey
  ' Stop game
  If GraphicsWindow.LastKey = "Escape" Then
    Program.End()
  EndIf

  ' Move piece left
  If GraphicsWindow.LastKey = "Left" Then
    moveDirection = -1
    ValidateMove()  ' in: ypos, xpos, h, moveDirection  ret: invalidMove = 1 or -1 or 2 if move is invalid, otherwise 0
    If invalidMove = 0 Then
      xpos = xpos + moveDirection
    EndIf
    MovePiece()  'in: ypos, xpos, h
  EndIf
  
  ' Move piece right
  If GraphicsWindow.LastKey = "Right" Then
    moveDirection = 1
    ValidateMove()  ' in: ypos, xpos, h, moveDirection  ret: invalidMove = 1 or -1 or 2 if move is invalid, otherwise 0
    If invalidMove = 0 Then
      xpos = xpos + moveDirection
    EndIf
    MovePiece()  'in: ypos, xpos, h
  EndIf
  
  ' Move piece down
  If GraphicsWindow.LastKey = "Down" or GraphicsWindow.LastKey = "Space" Then
    delay = 0
  EndIf
  
  ' Rotate piece
  If GraphicsWindow.LastKey = "Up" Then
    basetemplate = Array.GetValue(h, -1)  ' Array.GetValue(h, -1) = the template name
    template = "temptemplate"
    rotation = "CW"
    CopyPiece()  'in basetemplate, template, rotation

    Array.SetValue(h, -1, template) ' Array.GetValue(h, -1) = the template name
    moveDirection = 0
    ValidateMove()  ' in: ypos, xpos, h, moveDirection  ret: invalidMove = 1 or -1 or 2 if move is invalid, otherwise 0
    
    ' See if it can be moved so that it will rotate.
    xposbk = xpos
    yposdelta = 0
    While yposdelta = 0 And Math.Abs(xposbk - xpos) < 3 ' move up to 3 times only
      ' if the rotation move worked, copy the temp to "rotatedtemplate" and use that from now on
      If invalidMove = 0 Then
        basetemplate = template
        template = "rotatedtemplate"
        Array.SetValue(h, -1, template) ' Array.GetValue(h, -1) = the template name
        rotation = "COPY"
        CopyPiece()  'in basetemplate, template, rotation
        yposdelta = 1 ' Don't move down if we rotate
        MovePiece()  'in: ypos, xpos, h
      ElseIf invalidMove = 2 Then
        ' Don't support shifting piece when hitting another piece to the right or left.
        xpos = 99 ' exit the loop
      Else
        ' if the rotated piece can't be placed, move it left or right and try again.
        xpos = xpos - invalidMove
        ValidateMove()  ' in: ypos, xpos, h, moveDirection  ret: invalidMove = 1 or -1 or 2 if move is invalid, otherwise 0
      EndIf
    EndWhile
        
    If invalidMove <> 0 Then
      xpos = xposbk
      Array.SetValue(h, -1, basetemplate) ' Array.GetValue(h, -1) = the template name
      template = ""
    EndIf      
  EndIf
EndSub


Sub DrawPreviewPiece
  xpos = PREVIEW_xpos
  ypos = PREVIEW_ypos
  h = nextPiece

  XOFFSETBK = XOFFSET
  YOFFSETBK = YOFFSET
  XOFFSET = XOFFSET + Array.GetValue(Array.GetValue(h, -1), "pviewx") ' Array.GetValue(h, -1) = the template name
  YOFFSET = YOFFSET + Array.GetValue(Array.GetValue(h, -1), "pviewy") ' Array.GetValue(h, -1) = the template name
  MovePiece()  'in: ypos, xpos, h

  XOFFSET = XOFFSETBK
  YOFFSET = YOFFSETBK
EndSub

' creates template that's a rotated basetemplate
Sub CopyPiece  'in basetemplate, template, rotation  
  L = Array.GetValue(basetemplate, "dim")
  
  If rotation = "CW" Then
    For i = 0 to BOXES - 1 '      x' = y     y' = L - 1 - x
      v = Array.GetValue(basetemplate, i)

      'x = Math.Floor(v/10)
      'y = Math.Remainder(v, 10)
      
      ' new x and y
      x = (Math.Remainder(v, 10))
      y = (L - 1 - Math.Floor(v/10))
      Array.SetValue(template, i, x * 10 + y)
    EndFor
  ' Count-Cockwise is not currently used
  ElseIf rotation = "CCW" Then
    For i = 0 to BOXES - 1 '      x' = L - 1 - y     y' = x
      v = Array.GetValue(basetemplate, i)
      'x = Math.Floor(v/10)
      'y = Math.Remainder(v, 10)

      ' new x and y
      x = (L - 1 - Math.Remainder(v, 10))
      y = Math.Floor(v/10)
      Array.SetValue(template, i, x * 10 + y)
    EndFor
  ElseIf rotation = "COPY" Then
    For i = 0 to BOXES - 1
      Array.SetValue(template, i, Array.GetValue(basetemplate, i))
    EndFor
  Else
    GraphicsWindow.ShowMessage("invalid parameter", "Error")
    Program.End()
  EndIf
  
  ' Copy the remain properties from basetemplate to template.
  Array.SetValue(template, "color", Array.GetValue(basetemplate, "color"))
  Array.SetValue(template, "dim", Array.GetValue(basetemplate, "dim"))
  Array.SetValue(template, "pviewx", Array.GetValue(basetemplate, "pviewx"))
  Array.SetValue(template, "pviewy", Array.GetValue(basetemplate, "pviewy"))
EndSub
    
Sub CreatePiece ' in: template  ret: h
  ' Create a new handle, representing an arrayName, that will represent the piece
  hcount = hcount + 1
  h = Text.Append("piece", hcount)
  
  Array.SetValue(h, -1, template) ' Array.GetValue(h, -1) = the template name

  GraphicsWindow.PenWidth = 1
  GraphicsWindow.PenColor = "Black"
  GraphicsWindow.BrushColor = Array.GetValue(template, "color")
  
  For i = 0 to BOXES - 1
    s = Shapes.AddRectangle(BWIDTH, BWIDTH)
    Shapes.Move(s, -BWIDTH, -BWIDTH) ' move off screen
    Array.SetValue(h, i, s)
  EndFor
EndSub

Sub MovePiece 'in: ypos, xpos, h.  ypos/xpos is 0-19, representing the top/left box coordinate of the piece on the canvas.  h returned by CreatePiece
  For i = 0 to BOXES - 1
    v = Array.GetValue(Array.GetValue(h, -1), i)  ' Array.GetValue(h, -1) = the template name
    x = Math.Floor(v/10)
    y = Math.Remainder(v, 10)
    
    ' Array.GetValue(h, i) = box for piece h.
    ' xpos/ypos = are topleft of shape.  x/y is the box offset within the shape.
    Shapes.Move(Array.GetValue(h, i), XOFFSET + xpos * BWIDTH + x * BWIDTH, YOFFSET + ypos * BWIDTH + y * BWIDTH)
  EndFor
EndSub

Sub ValidateMove ' in: ypos, xpos, h, moveDirection  ret: invalidMove = 1 or -1 or 2 if move is invalid, otherwise 0
  i = 0
  invalidMove = 0
  While i < BOXES
    v = Array.GetValue(Array.GetValue(h, -1), i)  ' Array.GetValue(h, -1) = the template name

    'x/y is the box offset within the shape.
    x = Math.Floor(v/10)
    y = Math.Remainder(v, 10)
    
    If (x + xpos + moveDirection) < 0 Then
      invalidMove = -1
      i = BOXES ' force getting out of the loop
    EndIf

    If (x + xpos + moveDirection) >= CWIDTH Then
      invalidMove = 1
      i = BOXES ' force getting out of the loop
    EndIf

    If Array.GetValue("c", (x + xpos + moveDirection) + (y + ypos) * CWIDTH) <> "." Then
      invalidMove = 2
      i = BOXES ' force getting out of the loop
    EndIf

    i = i + 1
  EndWhile
EndSub


Sub CheckStop ' in: ypos, xpos, h  ret: done
  done = 0
  i = 0
  While i < BOXES
    v = Array.GetValue(Array.GetValue(h, -1), i)  ' Array.GetValue(h, -1) = the template name

    'x/y is the box offset within the shape.
    x = Math.Floor(v/10)
    y = Math.Remainder(v, 10)
    
    If y + ypos > CHEIGHT Or Array.GetValue("c", (x + xpos) + (y + ypos) * CWIDTH) <> "." Then
      done = 1
      i = BOXES ' force getting out of the loop
    EndIf

    i = i + 1
  EndWhile

  ' If we need to stop the piece, move the box handles to the canvas
  If done = 1 Then
    For i = 0 to BOXES - 1
      v = Array.GetValue(Array.GetValue(h, -1), i)	' Array.GetValue(h, -1) = the template name
      'x = Math.Floor(v/10)
      'y = Math.Remainder(v, 10)      
      Array.SetValue("c", (Math.Floor(v/10) + xpos) + (Math.Remainder(v, 10) + ypos - 1) * CWIDTH, Array.GetValue(h, i))
    EndFor
    
    ' 1 points for every piece successfully dropped
    score = score + 1
    PrintScore()
     
    ' Delete clared lines
    DeleteLines()
  EndIf
EndSub


Sub DeleteLines
  linesCleared = 0
  
  ' Iterate over each row, starting from the bottom
  For y = CHEIGHT - 1 to 0 Step -1  
    
    ' Check to see if the whole row is filled
    x = CWIDTH
    While x = CWIDTH
      x = 0
      While x < CWIDTH
        piece = Array.GetValue("c", x + y * CWIDTH)
        If piece = "." then
          x = CWIDTH
        EndIf
        x = x + 1
      EndWhile
      
      ' if non of them were empty (i.e "."), then remove the line.
      If x = CWIDTH Then
        
        ' Delete the line
        For x1 = 0 to CWIDTH - 1
          Shapes.Remove(Array.GetValue("c", x1 + y * CWIDTH))
        EndFor
        linesCleared = linesCleared + 1
        
        ' Move everything else down one.
        For y1 = y To 1 Step -1
          For x1 = 0 to CWIDTH - 1
            piece = Array.GetValue("c", x1 + (y1 - 1) * CWIDTH)
            Array.SetValue("c", x1 + y1 * CWIDTH, piece)
            Shapes.Move(piece, Shapes.GetLeft(piece), Shapes.GetTop(piece) + BWIDTH)
          EndFor
        EndFor
      EndIf
    EndWhile
  EndFor
  
  If linesCleared > 0 Then
    score = score + 100 * Math.Round(linesCleared * 2.15 - 1)
    PrintScore()
  EndIf
EndSub

Sub SetupCanvas
'    GraphicsWindow.DrawResizedImage( Flickr.GetRandomPicture( "bricks" ), 0, 0, GraphicsWindow.Width, GraphicsWindow.Height)

  
  GraphicsWindow.BrushColor = GraphicsWindow.BackgroundColor
  GraphicsWindow.FillRectangle(XOFFSET, YOFFSET, CWIDTH*BWIDTH, CHEIGHT*BWIDTH)

  Program.Delay(200)
  GraphicsWindow.PenWidth = 1
  GraphicsWindow.PenColor = "Pink"
  For x = 0 To CWIDTH-1
    For y = 0 To CHEIGHT-1
      Array.SetValue("c", x + y * CWIDTH, ".") ' "." indicates spot is free
      GraphicsWindow.DrawRectangle(XOFFSET + x * BWIDTH, YOFFSET + y * BWIDTH, BWIDTH, BWIDTH)
    EndFor
  EndFor

  GraphicsWindow.PenWidth = 4
  GraphicsWindow.PenColor = "Black"
  GraphicsWindow.DrawLine(XOFFSET, YOFFSET, XOFFSET, YOFFSET + CHEIGHT*BWIDTH)
  GraphicsWindow.DrawLine(XOFFSET + CWIDTH*BWIDTH, YOFFSET, XOFFSET + CWIDTH*BWIDTH, YOFFSET + CHEIGHT*BWIDTH)
  GraphicsWindow.DrawLine(XOFFSET, YOFFSET + CHEIGHT*BWIDTH, XOFFSET + CWIDTH*BWIDTH, YOFFSET + CHEIGHT*BWIDTH)
  
  GraphicsWindow.PenColor = "Lime"
  GraphicsWindow.DrawLine(XOFFSET - 4, YOFFSET, XOFFSET - 4, YOFFSET + CHEIGHT*BWIDTH + 6)
  GraphicsWindow.DrawLine(XOFFSET + CWIDTH*BWIDTH + 4, YOFFSET, XOFFSET + CWIDTH*BWIDTH + 4, YOFFSET + CHEIGHT*BWIDTH + 6)
  GraphicsWindow.DrawLine(XOFFSET - 4, YOFFSET + CHEIGHT*BWIDTH + 4, XOFFSET + CWIDTH*BWIDTH + 4, YOFFSET + CHEIGHT*BWIDTH + 4)
  
  GraphicsWindow.PenColor = "Black"
  GraphicsWindow.BrushColor = "Pink"
  x = XOFFSET + PREVIEW_xpos * BWIDTH - BWIDTH
  y = YOFFSET + PREVIEW_ypos * BWIDTH - BWIDTH
  GraphicsWindow.FillRectangle(x, y, BWIDTH * 5, BWIDTH * 6)
  GraphicsWindow.DrawRectangle(x, y, BWIDTH * 5, BWIDTH * 6)
  
  GraphicsWindow.FillRectangle(x - 20, y + 190, 310, 170)
  GraphicsWindow.DrawRectangle(x - 20, y + 190, 310, 170)
  
  GraphicsWindow.BrushColor = "Black"
  GraphicsWindow.FontItalic = "False"
  GraphicsWindow.FontName = "Comic Sans MS"
  GraphicsWindow.FontSize = 16
  GraphicsWindow.DrawText(x, y + 200, "Game control keys:")
  GraphicsWindow.DrawText(x + 25, y + 220, "Left Arrow = Move piece left")
  GraphicsWindow.DrawText(x + 25, y + 240, "Right Arrow = Move piece right")
  GraphicsWindow.DrawText(x + 25, y + 260, "Up Arrow = Rotate piece")
  GraphicsWindow.DrawText(x + 25, y + 280, "Down Arrow = Drop piece")
  GraphicsWindow.DrawText(x, y + 320, "Press  to stop game")

  Program.Delay(200) ' without this delay, the above text will use the fontsize of the score 

  GraphicsWindow.BrushColor = "Black"
  GraphicsWindow.FontName = "Georgia"
  GraphicsWindow.FontItalic = "True"
  GraphicsWindow.FontSize = 36
  GraphicsWindow.DrawText(x - 20, y + 400, "Small Basic Tetris")
  Program.Delay(200) ' without this delay, the above text will use the fontsize of the score 
  GraphicsWindow.FontSize = 16
  GraphicsWindow.DrawText(x - 20, y + 440, "ver.0.1")

  Program.Delay(200) ' without this delay, the above text will use the fontsize of the score 
  score = 0
  PrintScore() 
EndSub


Sub PrintScore
  GraphicsWindow.PenWidth = 4
  GraphicsWindow.BrushColor = "Pink"
  GraphicsWindow.FillRectangle(500, 65, 153, 50)
  GraphicsWindow.BrushColor = "Black"
  GraphicsWindow.DrawRectangle(500, 65, 153, 50)
  GraphicsWindow.FontItalic = "False"
  GraphicsWindow.FontSize = 32
  GraphicsWindow.FontName = "Impact"
  GraphicsWindow.BrushColor = "Black"
  GraphicsWindow.DrawText(505, 70, Text.Append(Text.GetSubText( "00000000", 0, 8 - Text.GetLength( score ) ), score))
EndSub


Sub SetupTemplates
  ' each piece has 4 boxes.
  ' the index of each entry within a piece represents the box number (1-4)
  ' the value of each entry represents to box zero-based box coordinate within the piece: tens place is x, ones place y

  '_X_
  '_X_
  '_XX

  Array.SetValue("template1", 0, 10)
  Array.SetValue("template1", 1, 11)
  Array.SetValue("template1", 2, 12)
  Array.SetValue("template1", 3, 22)
  Array.SetValue("template1", "color", "Yellow")
  Array.SetValue("template1", "dim", 3)
  Array.SetValue("template1", "pviewx", -12)
  Array.SetValue("template1", "pviewy", 12)


  '_X_
  '_X_
  'XX_
  Array.SetValue("template2", 0, 10)
  Array.SetValue("template2", 1, 11)
  Array.SetValue("template2", 2, 12)
  Array.SetValue("template2", 3, 02)
  Array.SetValue("template2", "color", "Magenta")
  Array.SetValue("template2", "dim", 3)
  Array.SetValue("template2", "pviewx", 12)
  Array.SetValue("template2", "pviewy", 12)
  
  
  '_X_
  'XXX
  '_
  Array.SetValue("template3", 0, 10)
  Array.SetValue("template3", 1, 01)
  Array.SetValue("template3", 2, 11)
  Array.SetValue("template3", 3, 21)
  Array.SetValue("template3", "color", "Gray")
  Array.SetValue("template3", "dim", 3)
  Array.SetValue("template3", "pviewx", 0)
  Array.SetValue("template3", "pviewy", 25)
  
  
  'XX_
  'XX_
  '_
  Array.SetValue("template4", 0, 00)
  Array.SetValue("template4", 1, 10)
  Array.SetValue("template4", 2, 01)
  Array.SetValue("template4", 3, 11)
  Array.SetValue("template4", "color", "Cyan")
  Array.SetValue("template4", "dim", 2)
  Array.SetValue("template4", "pviewx", 12)
  Array.SetValue("template4", "pviewy", 25)
  
  
  'XX_
  '_XX
  '_
  Array.SetValue("template5", 0, 00)
  Array.SetValue("template5", 1, 10)
  Array.SetValue("template5", 2, 11)
  Array.SetValue("template5", 3, 21)
  Array.SetValue("template5", "color", "Green")
  Array.SetValue("template5", "dim", 3)
  Array.SetValue("template5", "pviewx", 0)
  Array.SetValue("template5", "pviewy", 25)
  
  
  '_XX
  'XX_
  '_
  Array.SetValue("template6", 0, 10)
  Array.SetValue("template6", 1, 20)
  Array.SetValue("template6", 2, 01)
  Array.SetValue("template6", 3, 11)
  Array.SetValue("template6", "color", "Blue")
  Array.SetValue("template6", "dim", 3)
  Array.SetValue("template6", "pviewx", 0)
  Array.SetValue("template6", "pviewy", 25)
  
  
  '_X
  '_X
  '_X
  '_X
  Array.SetValue("template7", 0, 10)
  Array.SetValue("template7", 1, 11)
  Array.SetValue("template7", 2, 12)
  Array.SetValue("template7", 3, 13)
  Array.SetValue("template7", "color", "Red")
  Array.SetValue("template7", "dim", 4)
  Array.SetValue("template7", "pviewx", 0)
  Array.SetValue("template7", "pviewy", 0)
EndSub

(require 'cl)

(setq ops '(:add (:prio 1  :assoc :left   :repr "+"  :op +)
            :sub (:prio 1  :assoc :left   :repr "-"  :op -)
            :mul (:prio 2  :assoc :left   :repr "*"  :op *)
            :div (:prio 2  :assoc :left   :repr "/"  :op /)
            :pow (:prio 3  :assoc :right  :repr "^"  :op expt)))

(defun op-attr (op attr) (plist-get (plist-get ops op) attr))
(defun op-assoc (op) (op-attr op :assoc))
(defun op-prio (op) (op-attr op :prio))
(defun op-repr (op) (op-attr op :repr))
(defun op-op (op) (op-attr op :op))

(defun ch-type (c)
  (cond ((string-match "[[:space:]]" (string c)) :space)
        ((and (>= c ?0) (<= c ?9)) :number)
        ((or (eq c ?\() (eq c ?\))) :par)
        (t :operator)))

(defun str-to-strtok (str)
  "Turns a string of numbers and operators into a list of tokens
  \"1+2\" -> '(1 + 2)"
  (let ((tokens) (prev-tok :number))
    (dolist (ch (string-to-list str))
      (let ((ct (ch-type ch)))
        (if (not (eq ct :space))
            (progn
              (setq tokens
                    (if (eq prev-tok ct)
                        (cons (concat (car tokens) (string ch))
                              (cdr tokens))
                      (cons (string ch) tokens)))
              (setq prev-tok ct)))))
    (nreverse tokens)))

(defun create-tok (tok)
  "Converts a string into a number or operator keyword, \"+\" -> :add"
  (cond ((string-match "\\`[-+]?[0-9]+\\'" tok) (string-to-number tok))
        ((string-equal tok ")") :rpar)
        ((string-equal tok "(") :lpar)
        (t (let ((result-op))
             (dolist (o ops result-op)
               (if (and (keywordp o)
                        (equal tok (op-repr o)))
                        (setq result-op o)))))))

(defun strtok-to-tok (strtok)
  "Converts a list of string tokens into a list of integers and
   operator keywords, (\"1\" \"+\" \"2\") -> (1 :add 2)"
  (mapcar 'create-tok strtok))

(defun shunting-yard (tokens)
  "Converts from infix to postfix notion, (1 :add 2) -> (1 2 :add)"
  (let ((out) (stack))
    (dolist (tok tokens)
      (cond ((numberp tok) (setq out (cons tok out)))
            ((eq tok :lpar) (setq stack (cons tok stack)))
            ((eq tok :rpar) (while (let ((ts (pop stack)))
                                     (if (eq ts :lpar)
                                         nil
                                       (setq out (cons ts out))))))
            (t (progn (while (let* ((o2 (car stack))
                                    (o2-prio (op-prio o2))
                                    (o1-prio (op-prio tok))
                                    (o1-assoc (op-assoc tok)))
                               (if (and o2
                                        (not (eq o2 :lpar))
                                        (or (and (eq o1-assoc :right)
                                                 (< o1-prio o2-prio))
                                            (and (not (eq o1-assoc :right))
                                                 (<= o1-prio o2-prio))))
                                   (progn (pop stack)
                                          (push o2 out))
                                 nil)))
                      (setq stack (cons tok stack))))))
    (append (nreverse out) stack)))

(defun rpn-to-sexp (tokens)
  "Converts a list of tokens in RPN order to a S-expression,
   (1 2 3 :add :mul) -> (+ 1 (* 2 3))"
  (let ((sexp))
    (car
     (dolist (tok tokens sexp)
       (if (numberp tok)
           (push tok sexp)
         (let ((a (pop sexp))
               (b (pop sexp)))
           (push (list (op-op tok) b a) sexp)))))))

(defun ecalc (str)
  (interactive "M")
  (print (eval (rpn-to-sexp (shunting-yard (strtok-to-tok (str-to-strtok str)))))))