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lukfluglukflug
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Source code is messy, because this was a quick & dirty thing.
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‎yakjava.bas‎

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dim shared as string labelNames(any)
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dim shared as integer labelNumbers(any)
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dim shared as string lines(any)
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dim shared as string variableName(any)
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dim shared as integer variableValue(any)
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function checkIfValid (nam as string) as integer
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if nam="if" or nam="goto" or nam="print" or nam="true" or nam="false" then
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return false
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end if
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for i as integer=1 to len(nam)
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dim as integer char=asc(mid(nam,i,1))
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if not (char>=asc("A") and char<=asc("Z")) and not (char>=asc("a") and char<=asc("z")) and not (char>=asc("0") and char<=asc("9")) and not mid(nam,i,1)="_" then
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return false
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end if
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next
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return true
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end function
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sub addLabel (label as string, linenum as integer)
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if not checkIfValid(label) then
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print "Error: Line "+str(linenum)+": Invalid label '"+label+"'!"
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system
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end if
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redim preserve labelNames (lbound(labelNames) to ubound(labelNames)+1)
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redim preserve labelNumbers (lbound(labelNames) to ubound(labelNames)+1)
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labelNames(ubound(labelNames))=label
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labelNumbers(ubound(labelNames))=linenum
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end sub
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sub addLine (codeline as string)
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redim preserve lines (lbound(lines) to ubound(lines)+1)
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lines(ubound(lines))=codeline
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end sub
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if command(1)="" then
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print "lukflug's YakJava interpreter Version 0.0.0"
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print "21.07.2020"
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print "Usage: yakjava <code file>"
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system
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end if
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if open(command(1) for input as #1)<>0 then
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print "Fatal: Could not open file '"+command(1)+"'!"
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system
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end if
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dim as integer linenum=0
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while not eof(1)
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linenum+=1
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dim as string fileline,codeline
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input #1,fileline
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dim as integer multispace=false
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for i as integer=1 to len(fileline)
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if mid(fileline,i,1)=" " or mid(fileline,i,1)=chr(9) then
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if not multispace then
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codeline+=" "
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multispace=true
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end if
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else
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codeline+=mid(fileline,i,1)
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multispace=false
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end if
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next
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dim as integer sep=instr(codeline,"//")
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if sep>0 then codeline=mid(codeline,1,sep-1)
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codeline=trim(codeline)
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sep=instr(codeline,":")
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if sep>0 then
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addLabel(trim(mid(codeline,1,sep-1)),linenum)
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codeline=trim(mid(codeline,sep+1))
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end if
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addLine(codeline)
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wend
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close #1
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function replace (byval original as string, oldstr as string, newstr as string) as string
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dim as integer position=1
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while true
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dim as integer location=instr(position,original,oldstr)
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if location>0 then
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original=mid(original,1,location-1)+newstr+mid(original,location+len(oldstr))
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position=location
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else
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exit while
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end if
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wend
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return original
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end function
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function exprEval (byval expr as string) as integer
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for i as integer=lbound(variableName) to ubound(variableName)
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if variableValue(i)=true then
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expr=replace(expr,variableName(i),"true")
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else
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expr=replace(expr,variableName(i),"false")
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end if
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next
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replace(expr," ","")
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while true
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dim as integer oldlen=len(expr)
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' 1. OR
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expr=replace(expr,"true||true","true")
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expr=replace(expr,"true||false","true")
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expr=replace(expr,"false||true","true")
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expr=replace(expr,"false||false","false")
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' 2. AND
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expr=replace(expr,"true&&true","true")
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expr=replace(expr,"true&&false","false")
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expr=replace(expr,"false&&true","false")
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expr=replace(expr,"false&&false","false")
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' 3. XNOR
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expr=replace(expr,"true==true","true")
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expr=replace(expr,"true==false","false")
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expr=replace(expr,"false==true","false")
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expr=replace(expr,"false==false","true")
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' 4. XOR
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expr=replace(expr,"true!=true","false")
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expr=replace(expr,"true!=false","true")
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expr=replace(expr,"false!=true","true")
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expr=replace(expr,"false!=false","false")
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' 5. NOT
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expr=replace(expr,"!true","false")
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expr=replace(expr,"!false","true")
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'6. Parentheses
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expr=replace(expr,"(true)","true")
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expr=replace(expr,"(false)","false")
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' Exit condition
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if expr="true" then
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return true
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elseif expr="false" then
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return false
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end if
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if oldlen=len(expr) then exit while
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wend
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return 1
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end function
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sub addVariable (variable as string, value as integer, linenum as integer)
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if not checkIfValid(variable) then
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print "Error: Line "+str(linenum)+": Invalid variable name '"+variable+"'!"
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system
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end if
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for i as integer=lbound(variableName) to ubound(variableName)
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if variableName(i)=variable then
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variableValue(i)=true
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return
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end if
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next
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redim preserve variableName (lbound(variableName) to ubound(variableName)+1)
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redim preserve variableValue (lbound(variableName) to ubound(variableName)+1)
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variableName(ubound(variableName))=variable
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variableValue(ubound(variableName))=value
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end sub
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function interpretInstruction (linenum as integer, codeline as string) as integer
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if codeline="" then
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elseif mid(codeline,1,3)="if(" or mid(codeline,1,4)="if (" then
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dim as integer separator=0
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dim as integer level=0
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for i as integer=instr(codeline,"(") to len(codeline)
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if mid(codeline,i,1)="(" then
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level+=1
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elseif mid(codeline,i,1)=")" then
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level-=1
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end if
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if level=0 then
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separator=i
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exit for
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end if
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next i
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if separator=0 then
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print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
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system
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end if
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dim as integer condition=exprEval(mid(codeline,instr(codeline,"("),separator-instr(codeline,"(")+1))
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if condition=true then
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interpretInstruction(linenum,trim(mid(codeline,separator+1)))
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elseif condition=false then
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else
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print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
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system
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end if
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elseif mid(codeline,1,5)="goto " then
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for i as integer=lbound(labelNames) to ubound(labelNames)
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if labelNames(i)=mid(codeline,6) then
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return labelNumbers(i)
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end if
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next
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print "Error: Line "+str(linenum)+": Undefined label '"+mid(codeline,6)+"!"
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system
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elseif mid(codeline,1,6)="print " then
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dim as integer value=exprEval(mid(codeline,7))
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if value=true then
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print "true"
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elseif value=false then
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print "false"
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else
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print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
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system
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end if
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else
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dim as integer separator=instr(codeline,"=")
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if separator>0 then
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dim as integer value=exprEval(mid(codeline,separator+1))
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if value=true then
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addVariable(trim(mid(codeline,1,separator-1)),true,linenum)
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elseif value=false then
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addVariable(trim(mid(codeline,1,separator-1)),false,linenum)
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else
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print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
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system
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end if
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else
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print "Error: Line "+str(linenum)+": Syntax error!"
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system
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end if
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end if
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return linenum+1
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end function
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dim as integer counter=1
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while counter<=ubound(lines)+1
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counter=interpretInstruction(counter,lines(counter-1))
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wend

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