interpreter.nim
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import streams, strutils, tables import parser type TMinInterpreter* = object stack: TMinStack parser*: TMinParser currSym: TMinValue filename: string debugging: bool TMinOperator* = proc (i: var TMinInterpreter) TMinError* = enum errSystem, errParser, errGeneric, errEmptyStack, errNoQuotation, errUndefined, errIncorrect, errTwoNumbersRequired, errDivisionByZero const ERRORS: array [TMinError, string] = [ "A system error occurred", "A parsing error occurred", "A generic error occurred", "The stack is empty", "Quotation not found on the stack", "Symbol undefined", "Incorrect items on the stack", "Two numbers are required on the stack", "Division by zero" ] var SYMBOLS* = initTable[string, TMinOperator]() proc newMinInterpreter*(debugging = false): TMinInterpreter = var s:TMinStack = newSeq[TMinValue](0) var p:TMinParser var i:TMinInterpreter = TMinInterpreter(filename: "input", parser: p, stack: s, debugging: debugging, currSym: TMinValue(first: 0, last: 0, line: 0, kind: minSymbol, symVal: "")) return i proc error*(i: TMinInterpreter, status: TMinError, message = "") = var msg = if message == "": ERRORS[status] else: message stderr.writeln("$1[$2,$3] `$4`: Error - $5" %[i.filename, $i.currSym.line, $i.currSym.last, i.currSym.symVal, msg]) quit(int(status)) proc open*(i: var TMinInterpreter, stream:PStream, filename: string) = i.filename = filename i.parser.open(stream, filename) proc close*(i: var TMinInterpreter) = i.parser.close(); proc dump*(i: TMinInterpreter): string = var s = "" for item in i.stack: s = s & $item & " " return s.strip proc debug(i: var TMinInterpreter, value: string = "") = if i.debugging: stderr.writeln("DEBUG: " &i.dump & value) proc push*(i: var TMinInterpreter, val: TMinValue) = if val.kind == minSymbol: i.currSym = val i.debug " "&val.symVal if SYMBOLS.hasKey(val.symVal): try: SYMBOLS[val.symVal](i) except: i.error(errSystem, getCurrentExceptionMsg()) else: i.error(errUndefined, "Undefined symbol: '"&val.symVal&"'") else: i.stack.add(val) proc pop*(i: var TMinInterpreter): TMinValue = if i.stack.len > 0: return i.stack.pop else: i.error(errEmptyStack) proc peek*(i: TMinInterpreter): TMinValue = if i.stack.len > 0: return i.stack[i.stack.len-1] else: i.error(errEmptyStack) proc interpret*(i: var TMinInterpreter) = var val: TMinValue while i.parser.token != tkEof: try: val = i.parser.parseMinValue except: i.error errParser, getCurrentExceptionMsg() i.push val |