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Merged
sancarn merged 1 commit into from
Dec 9, 2025
Merged

Added for loops and do loops #148

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156 changes: 152 additions & 4 deletions src/stdLambda.cls
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Original file line number Diff line number Diff line change
Expand Up @@ -199,6 +199,7 @@ Private Type TThis
End Type
Private This As TThis

Private InLoop As Boolean



Expand Down Expand Up @@ -470,6 +471,22 @@ Private Function getTokenDefinitions() As TokenDefinition()
i = i + 1: arr(i) = getTokenDefinition("then", "then", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("else", "else", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("end", "end", isKeyword:=True)

'Do Loop
i = i + 1: arr(i) = getTokenDefinition("do", "do", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("until", "until", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("while", "while", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("loop", "loop", isKeyword:=True)

'For Loop
i = i + 1: arr(i) = getTokenDefinition("for", "for", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("to", "to", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("step", "step", isKeyword:=True)
i = i + 1: arr(i) = getTokenDefinition("next", "next", isKeyword:=True)

'Exit keyword
i = i + 1: arr(i) = getTokenDefinition("exit", "exit", isKeyword:=True)

' Brackets
i = i + 1: arr(i) = getTokenDefinition("lBracket", "\(")
i = i + 1: arr(i) = getTokenDefinition("rBracket", "\)")
Expand Down Expand Up @@ -582,7 +599,9 @@ End Sub
'11. Arithmetic (^)
'12. Arithmetic (Unary +, -) (for RHS of power operator) e.g. 2^-1
'13. Flow (if then else)
'14. Value (numbers, $vars, strings, booleans, brackets)
'14. Do (Do Loop)
'15. For(For Loop)
'16. Value (numbers, $vars, strings, booleans, brackets)
'@remark - The order of priority is opposite to the order of evaluation. I.E. Comparrison is evaluated before Logical AND allowing
'expressions such as `1<2 and 2<3` to be evaluated correctly without requiring bracketing. It's important to note however that all
'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)`.
Expand Down Expand Up @@ -799,7 +818,9 @@ Private Sub parseFlowPriority1()
This.stackSize = size

If optConsume("end") Then
Call addOperation(iPush, 0, 1) 'Expressions should always return a value
If InLoop = False Then
Call addOperation(iPush, 0, 1) 'Expressions should always return a value
End If
This.operations(skipElseJumpIndex).value = This.iOperationIndex
Else
Call consume("else")
Expand All @@ -808,6 +829,129 @@ Private Sub parseFlowPriority1()

Call optConsume("end")
End If
Else
Call parseFlowPriority2
End If
End Sub

'Parse loops (do ... {until|while} ... loop{until|while})
Private Sub parseFlowPriority2()
If optConsume("do") Then
Dim LoopEntered As Boolean
If InLoop = False Then LoopEntered = True
InLoop = True
' Do Until|While {Expr}
Dim RepeatLoop As Integer: RepeatLoop = This.iOperationIndex
Dim SkipLoop As Integer: SkipLoop = -1
If optConsume("until") Then
Call parseExpression
SkipLoop = addOperation(iJump_IfTrue, , -1)
ElseIf optConsume("while") Then
Call parseExpression
SkipLoop = addOperation(iJump_IfFalse, , -1)
Else
' Infinite loop
End If

Call parseBlock("loop")
Call consume("loop")

' xxx
' Loop Until|While {expr}
If optConsume("until") Then
Call parseExpression
SkipLoop = addOperation(iJump_IfTrue, , -1)
ElseIf optConsume("while") Then
Call parseExpression
SkipLoop = addOperation(iJump_IfFalse, , -1)
Else
' Loop Ends
End If


' Loop back to start
Call addOperation(iJump_Unconditional, RepeatLoop)
If SkipLoop > -1 Then This.operations(SkipLoop).value = This.iOperationIndex
If LoopEntered Then InLoop = False
Else
Call parseFlowPriority3
End If
End Sub

'Parse for loops (for ... {let} var = lbound to ubound ... {step operator increment} ... next)
Private Sub parseFlowPriority3()
If optConsume("for") Then
Dim LoopEntered As Boolean
If InLoop = False Then LoopEntered = True
InLoop = True
' 1. let index = LowerBound

Dim varName As String: varName = consume("var")
Call consume("equal")
Call parseExpression
Dim IncrementIndex As Long: IncrementIndex = findVariable(varName)
If IncrementIndex >= 0 Then
' If the variable already existed, move the data to that pos on the stack
Call addOperation(iSet_General, IncrementIndex, -1)
Else
' If the variable didn't exist yet, treat this stack pos as its source
Call This.scopes(This.scopeCount).Add(varName, This.stackSize)
IncrementIndex = This.stackSize - 1
If IncrementIndex = 0 Then IncrementIndex = 1 ' Avoid referencing the current operation. | Used when the last added variable was declared in for loop
End If

' Index > UpperBound
' Jump if Condition true
Call addOperation(iAccess_General, IncrementIndex, 1)
Dim RepeatLoop As Long: RepeatLoop = This.iOperationIndex - 1 ' beginning of loop (condition)
If peek("to") Then
This.iTokenIndex = This.iTokenIndex + 1
Else
Call parseBlock("to")
Call consume("to")
End If
Call parseStatement
Dim ConditionIndex As Long: ConditionIndex = addOperation(iComparison_GreaterThan, , -1)
Dim SkipLoop As Integer: SkipLoop = addOperation(iJump_IfTrue, , -1) ' Skip loop

' Setup increment Values
Dim Increment As Long, Operator As IInstruction, Condition As IInstruction
If optConsume("step") Then
If peek("literalNumber") Then
Operator = iArithmetic_Add
Condition = iComparison_GreaterThan
Else
Select Case True
Case optConsume("add"): Operator = iArithmetic_Add: Condition = iComparison_GreaterThan
Case optConsume("subtract"): Operator = iArithmetic_Subtract: Condition = iComparison_LessThan
Case optConsume("multiply"): Operator = iArithmetic_Multiply: Condition = iComparison_GreaterThan
Case optConsume("divide"): Operator = iArithmetic_Divide: Condition = iComparison_LessThan
Case optConsume("power"): Operator = iArithmetic_Power: Condition = iComparison_GreaterThan
End Select
End If
Increment = CLng(consume("literalNumber")) ' TODO add more functionality than just numbers
Else
Increment = 1
Operator = iArithmetic_Add
Condition = iComparison_GreaterThan
End If

This.operations(ConditionIndex).instruction = Condition ' Changes compare-operator of condition according to "step"

' Get rest of loop
' Setup index-incrementation: let index = index Operator Increment
' Setup loop-repeat
Call parseBlock("next")
Call consume("next")

Call addOperation(iAccess_General, IncrementIndex, 1)
Call addOperation(iPush, Increment, 1)
Call addOperation(Operator, , -1)
Call addOperation(iSet_General, IncrementIndex, -1)
Call addOperation(iJump_Unconditional, RepeatLoop, 0)

This.operations(SkipLoop).value = This.iOperationIndex
If LoopEntered Then InLoop = False
Else
Call parseValuePriority1
End If
Expand Down Expand Up @@ -992,8 +1136,12 @@ Private Sub parseAssignment()
Dim offset As Long: offset = findVariable(varName)
If offset >= 0 Then
' If the variable already existed, move the data to that pos on the stack
Call addOperation(iSet_General, offset, -1)
Call addOperation(iAccess_General, offset, 1) ' To keep a return value
If InLoop Then
Call addOperation(iSet_General, offset, -1)
Else
Call addOperation(iSet_General, offset, -1)
Call addOperation(iAccess_General, offset, 1) ' To keep a return value
End If
Else
' If the variable didn't exist yet, treat this stack pos as its source
Call This.scopes(This.scopeCount).add(varName, This.stackSize)
Expand Down