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AlmesiAlmesi
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Added for loops and do loops
No implementation of exit keyword as of now. That is because premature leaving of either do, for or fun can result in misaligned stack, which will cause problems down the line.
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‎src/stdLambda.cls‎

Lines changed: 152 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -199,6 +199,7 @@ Private Type TThis
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End Type
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Private This As TThis
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202+
Private InLoop As Boolean
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@@ -470,6 +471,22 @@ Private Function getTokenDefinitions() As TokenDefinition()
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i = i + 1: arr(i) = getTokenDefinition("then", "then", isKeyword:=True)
471472
i = i + 1: arr(i) = getTokenDefinition("else", "else", isKeyword:=True)
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i = i + 1: arr(i) = getTokenDefinition("end", "end", isKeyword:=True)
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'Do Loop
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i = i + 1: arr(i) = getTokenDefinition("do", "do", isKeyword:=True)
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i = i + 1: arr(i) = getTokenDefinition("until", "until", isKeyword:=True)
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i = i + 1: arr(i) = getTokenDefinition("while", "while", isKeyword:=True)
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i = i + 1: arr(i) = getTokenDefinition("loop", "loop", isKeyword:=True)
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'For Loop
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i = i + 1: arr(i) = getTokenDefinition("for", "for", isKeyword:=True)
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i = i + 1: arr(i) = getTokenDefinition("to", "to", isKeyword:=True)
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i = i + 1: arr(i) = getTokenDefinition("step", "step", isKeyword:=True)
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i = i + 1: arr(i) = getTokenDefinition("next", "next", isKeyword:=True)
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'Exit keyword
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i = i + 1: arr(i) = getTokenDefinition("exit", "exit", isKeyword:=True)
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' Brackets
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i = i + 1: arr(i) = getTokenDefinition("lBracket", "\(")
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i = i + 1: arr(i) = getTokenDefinition("rBracket", "\)")
@@ -582,7 +599,9 @@ End Sub
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'11. Arithmetic (^)
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'12. Arithmetic (Unary +, -) (for RHS of power operator) e.g. 2^-1
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'13. Flow (if then else)
585-
'14. Value (numbers, $vars, strings, booleans, brackets)
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'14. Do (Do Loop)
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'15. For(For Loop)
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'16. Value (numbers, $vars, strings, booleans, brackets)
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'@remark - The order of priority is opposite to the order of evaluation. I.E. Comparrison is evaluated before Logical AND allowing
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'expressions such as `1<2 and 2<3` to be evaluated correctly without requiring bracketing. It's important to note however that all
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'comparrisons have the same priority. This means that `1<2<3` will be evaluated as `(1<2)<3` which is not the same as `1<(2<3)`.
@@ -799,7 +818,9 @@ Private Sub parseFlowPriority1()
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This.stackSize = size
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801820
If optConsume("end") Then
802-
Call addOperation(iPush, 0, 1) 'Expressions should always return a value
821+
If InLoop = False Then
822+
Call addOperation(iPush, 0, 1) 'Expressions should always return a value
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End If
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This.operations(skipElseJumpIndex).value = This.iOperationIndex
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Else
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Call consume("else")
@@ -808,6 +829,129 @@ Private Sub parseFlowPriority1()
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Call optConsume("end")
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End If
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Else
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Call parseFlowPriority2
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End If
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End Sub
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'Parse loops (do ... {until|while} ... loop{until|while})
838+
Private Sub parseFlowPriority2()
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If optConsume("do") Then
840+
Dim LoopEntered As Boolean
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If InLoop = False Then LoopEntered = True
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InLoop = True
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' Do Until|While {Expr}
844+
Dim RepeatLoop As Integer: RepeatLoop = This.iOperationIndex
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Dim SkipLoop As Integer: SkipLoop = -1
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If optConsume("until") Then
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Call parseExpression
848+
SkipLoop = addOperation(iJump_IfTrue, , -1)
849+
ElseIf optConsume("while") Then
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Call parseExpression
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SkipLoop = addOperation(iJump_IfFalse, , -1)
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Else
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' Infinite loop
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End If
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Call parseBlock("loop")
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Call consume("loop")
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' xxx
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' Loop Until|While {expr}
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If optConsume("until") Then
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Call parseExpression
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SkipLoop = addOperation(iJump_IfTrue, , -1)
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ElseIf optConsume("while") Then
865+
Call parseExpression
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SkipLoop = addOperation(iJump_IfFalse, , -1)
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Else
868+
' Loop Ends
869+
End If
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' Loop back to start
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Call addOperation(iJump_Unconditional, RepeatLoop)
874+
If SkipLoop > -1 Then This.operations(SkipLoop).value = This.iOperationIndex
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If LoopEntered Then InLoop = False
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Else
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Call parseFlowPriority3
878+
End If
879+
End Sub
880+
881+
'Parse for loops (for ... {let} var = lbound to ubound ... {step operator increment} ... next)
882+
Private Sub parseFlowPriority3()
883+
If optConsume("for") Then
884+
Dim LoopEntered As Boolean
885+
If InLoop = False Then LoopEntered = True
886+
InLoop = True
887+
' 1. let index = LowerBound
888+
889+
Dim varName As String: varName = consume("var")
890+
Call consume("equal")
891+
Call parseExpression
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Dim IncrementIndex As Long: IncrementIndex = findVariable(varName)
893+
If IncrementIndex >= 0 Then
894+
' If the variable already existed, move the data to that pos on the stack
895+
Call addOperation(iSet_General, IncrementIndex, -1)
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Else
897+
' If the variable didn't exist yet, treat this stack pos as its source
898+
Call This.scopes(This.scopeCount).Add(varName, This.stackSize)
899+
IncrementIndex = This.stackSize - 1
900+
If IncrementIndex = 0 Then IncrementIndex = 1 ' Avoid referencing the current operation. | Used when the last added variable was declared in for loop
901+
End If
902+
903+
' Index > UpperBound
904+
' Jump if Condition true
905+
Call addOperation(iAccess_General, IncrementIndex, 1)
906+
Dim RepeatLoop As Long: RepeatLoop = This.iOperationIndex - 1 ' beginning of loop (condition)
907+
If peek("to") Then
908+
This.iTokenIndex = This.iTokenIndex + 1
909+
Else
910+
Call parseBlock("to")
911+
Call consume("to")
912+
End If
913+
Call parseStatement
914+
Dim ConditionIndex As Long: ConditionIndex = addOperation(iComparison_GreaterThan, , -1)
915+
Dim SkipLoop As Integer: SkipLoop = addOperation(iJump_IfTrue, , -1) ' Skip loop
916+
917+
' Setup increment Values
918+
Dim Increment As Long, Operator As IInstruction, Condition As IInstruction
919+
If optConsume("step") Then
920+
If peek("literalNumber") Then
921+
Operator = iArithmetic_Add
922+
Condition = iComparison_GreaterThan
923+
Else
924+
Select Case True
925+
Case optConsume("add"): Operator = iArithmetic_Add: Condition = iComparison_GreaterThan
926+
Case optConsume("subtract"): Operator = iArithmetic_Subtract: Condition = iComparison_LessThan
927+
Case optConsume("multiply"): Operator = iArithmetic_Multiply: Condition = iComparison_GreaterThan
928+
Case optConsume("divide"): Operator = iArithmetic_Divide: Condition = iComparison_LessThan
929+
Case optConsume("power"): Operator = iArithmetic_Power: Condition = iComparison_GreaterThan
930+
End Select
931+
End If
932+
Increment = CLng(consume("literalNumber")) ' TODO add more functionality than just numbers
933+
Else
934+
Increment = 1
935+
Operator = iArithmetic_Add
936+
Condition = iComparison_GreaterThan
937+
End If
938+
939+
This.operations(ConditionIndex).instruction = Condition ' Changes compare-operator of condition according to "step"
940+
941+
' Get rest of loop
942+
' Setup index-incrementation: let index = index Operator Increment
943+
' Setup loop-repeat
944+
Call parseBlock("next")
945+
Call consume("next")
946+
947+
Call addOperation(iAccess_General, IncrementIndex, 1)
948+
Call addOperation(iPush, Increment, 1)
949+
Call addOperation(Operator, , -1)
950+
Call addOperation(iSet_General, IncrementIndex, -1)
951+
Call addOperation(iJump_Unconditional, RepeatLoop, 0)
952+
953+
This.operations(SkipLoop).value = This.iOperationIndex
954+
If LoopEntered Then InLoop = False
811955
Else
812956
Call parseValuePriority1
813957
End If
@@ -992,8 +1136,12 @@ Private Sub parseAssignment()
9921136
Dim offset As Long: offset = findVariable(varName)
9931137
If offset >= 0 Then
9941138
' If the variable already existed, move the data to that pos on the stack
995-
Call addOperation(iSet_General, offset, -1)
996-
Call addOperation(iAccess_General, offset, 1) ' To keep a return value
1139+
If InLoop Then
1140+
Call addOperation(iSet_General, offset, -1)
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Else
1142+
Call addOperation(iSet_General, offset, -1)
1143+
Call addOperation(iAccess_General, offset, 1) ' To keep a return value
1144+
End If
9971145
Else
9981146
' If the variable didn't exist yet, treat this stack pos as its source
9991147
Call This.scopes(This.scopeCount).add(varName, This.stackSize)

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