First version

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

yakjava.bas

@@ -0,0 +1,229 @@
+
+dim shared as string labelNames(any)
+dim shared as integer labelNumbers(any)
+dim shared as string lines(any)
+dim shared as string variableName(any)
+dim shared as integer variableValue(any)
+
+function checkIfValid (nam as string) as integer
+    if nam="if" or nam="goto" or nam="print" or nam="true" or nam="false" then
+        return false
+    end if
+    for i as integer=1 to len(nam)
+        dim as integer char=asc(mid(nam,i,1))
+        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
+            return false
+        end if
+    next
+    return true
+end function
+
+sub addLabel (label as string, linenum as integer)
+    if not checkIfValid(label) then
+        print "Error: Line "+str(linenum)+": Invalid label '"+label+"'!"
+        system
+    end if
+    redim preserve labelNames (lbound(labelNames) to ubound(labelNames)+1)
+    redim preserve labelNumbers (lbound(labelNames) to ubound(labelNames)+1)
+    labelNames(ubound(labelNames))=label
+    labelNumbers(ubound(labelNames))=linenum
+end sub
+
+sub addLine (codeline as string)
+    redim preserve lines (lbound(lines) to ubound(lines)+1)
+    lines(ubound(lines))=codeline
+end sub
+
+if command(1)="" then
+    print "lukflug's YakJava interpreter Version 0.0.0"
+    print "21.07.2020"
+    print "Usage: yakjava <code file>"
+    system
+end if
+
+if open(command(1) for input as #1)<>0 then
+    print "Fatal: Could not open file '"+command(1)+"'!"
+    system
+end if
+
+dim as integer linenum=0
+
+while not eof(1)
+    linenum+=1
+    dim as string fileline,codeline
+    input #1,fileline
+    dim as integer multispace=false
+    for i as integer=1 to len(fileline)
+        if mid(fileline,i,1)=" " or mid(fileline,i,1)=chr(9) then
+            if not multispace then
+                codeline+=" "
+                multispace=true
+            end if
+        else
+            codeline+=mid(fileline,i,1)
+            multispace=false
+        end if
+    next
+
+    dim as integer sep=instr(codeline,"//")
+    if sep>0 then codeline=mid(codeline,1,sep-1)
+    codeline=trim(codeline)
+    sep=instr(codeline,":")
+    if sep>0 then
+        addLabel(trim(mid(codeline,1,sep-1)),linenum)
+        codeline=trim(mid(codeline,sep+1))
+    end if
+    addLine(codeline)
+wend
+
+close #1
+
+function replace (byval original as string, oldstr as string, newstr as string) as string
+    dim as integer position=1
+    while true
+        dim as integer location=instr(position,original,oldstr)
+        if location>0 then
+            original=mid(original,1,location-1)+newstr+mid(original,location+len(oldstr))
+            position=location
+        else
+            exit while
+        end if
+    wend
+    return original
+end function
+
+function exprEval (byval expr as string) as integer
+    for i as integer=lbound(variableName) to ubound(variableName)
+        if variableValue(i)=true then
+            expr=replace(expr,variableName(i),"true")
+        else
+            expr=replace(expr,variableName(i),"false")
+        end if
+    next
+    replace(expr," ","")
+    while true
+        dim as integer oldlen=len(expr)
+        ' 1. OR
+        expr=replace(expr,"true||true","true")
+        expr=replace(expr,"true||false","true")
+        expr=replace(expr,"false||true","true")
+        expr=replace(expr,"false||false","false")
+        ' 2. AND
+        expr=replace(expr,"true&&true","true")
+        expr=replace(expr,"true&&false","false")
+        expr=replace(expr,"false&&true","false")
+        expr=replace(expr,"false&&false","false")
+        ' 3. XNOR
+        expr=replace(expr,"true==true","true")
+        expr=replace(expr,"true==false","false")
+        expr=replace(expr,"false==true","false")
+        expr=replace(expr,"false==false","true")
+        ' 4. XOR
+        expr=replace(expr,"true!=true","false")
+        expr=replace(expr,"true!=false","true")
+        expr=replace(expr,"false!=true","true")
+        expr=replace(expr,"false!=false","false")
+        ' 5. NOT
+        expr=replace(expr,"!true","false")
+        expr=replace(expr,"!false","true")
+        '6. Parentheses
+        expr=replace(expr,"(true)","true")
+        expr=replace(expr,"(false)","false")
+        ' Exit condition
+        if expr="true" then
+            return true
+        elseif expr="false" then
+            return false
+        end if
+        if oldlen=len(expr) then exit while
+    wend
+    return 1
+end function
+
+sub addVariable (variable as string, value as integer, linenum as integer)
+    if not checkIfValid(variable) then
+        print "Error: Line "+str(linenum)+": Invalid variable name '"+variable+"'!"
+        system
+    end if
+    for i as integer=lbound(variableName) to ubound(variableName)
+        if variableName(i)=variable then
+            variableValue(i)=true
+            return
+        end if
+    next
+    redim preserve variableName (lbound(variableName) to ubound(variableName)+1)
+    redim preserve variableValue (lbound(variableName) to ubound(variableName)+1)
+    variableName(ubound(variableName))=variable
+    variableValue(ubound(variableName))=value
+end sub
+
+function interpretInstruction (linenum as integer, codeline as string) as integer
+    if codeline="" then
+    elseif mid(codeline,1,3)="if(" or mid(codeline,1,4)="if (" then
+        dim as integer separator=0
+        dim as integer level=0
+        for i as integer=instr(codeline,"(") to len(codeline)
+            if mid(codeline,i,1)="(" then
+                level+=1
+            elseif mid(codeline,i,1)=")" then
+                level-=1
+            end if
+            if level=0 then
+                separator=i
+                exit for
+            end if
+        next i
+        if separator=0 then
+            print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
+            system
+        end if
+        dim as integer condition=exprEval(mid(codeline,instr(codeline,"("),separator-instr(codeline,"(")+1))
+        if condition=true then
+            interpretInstruction(linenum,trim(mid(codeline,separator+1)))
+        elseif condition=false then
+        else
+            print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
+            system
+        end if
+    elseif mid(codeline,1,5)="goto " then
+        for i as integer=lbound(labelNames) to ubound(labelNames)
+            if labelNames(i)=mid(codeline,6) then
+                return labelNumbers(i)
+            end if
+        next
+        print "Error: Line "+str(linenum)+": Undefined label '"+mid(codeline,6)+"!"
+        system
+    elseif mid(codeline,1,6)="print " then
+        dim as integer value=exprEval(mid(codeline,7))
+        if value=true then
+            print "true"
+        elseif value=false then
+            print "false"
+        else
+            print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
+            system
+        end if
+    else
+        dim as integer separator=instr(codeline,"=")
+        if separator>0 then
+            dim as integer value=exprEval(mid(codeline,separator+1))
+            if value=true then
+                addVariable(trim(mid(codeline,1,separator-1)),true,linenum)
+            elseif value=false then
+                addVariable(trim(mid(codeline,1,separator-1)),false,linenum)
+            else
+                print "Error: Line "+str(linenum)+": Syntax error while parsing expression!"
+                system
+            end if
+        else
+            print "Error: Line "+str(linenum)+": Syntax error!"
+            system
+        end if
+    end if
+    return linenum+1
+end function
+
+dim as integer counter=1
+while counter<=ubound(lines)+1
+    counter=interpretInstruction(counter,lines(counter-1))
+wend