core/interpreter.nim
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import streams, strutils, critbits import types, parser, ../vendor/linenoise const ERRORS: array [MinError, string] = [ "A system error occurred", "A parsing error occurred", "A generic error occurred", "Insufficient items on the stack", "Quotation not found on the stack", "Symbol undefined", "Incorrect items on the stack", "Two numbers are required on the stack", "Division by zero" ] var ROOT*: ref MinScope = new MinScope ROOT.name = "ROOT" proc fullname*(scope: ref MinScope): string = result = scope.name if not scope.parent.isNil: result = scope.parent.fullname & ":" & result proc getSymbol*(scope: ref MinScope, key: string): MinOperator = if scope.symbols.hasKey(key): return scope.symbols[key] elif not scope.parent.isNil: return scope.parent.getSymbol(key) proc setSymbol*(scope: ref MinScope, key: string, value: MinOperator): bool {.discardable.}= result = false # check if a symbol already exists in parent scope if not scope.parent.isNil and scope.parent.symbols.hasKey(key): scope.parent.symbols[key] = value #echo "($1) SET EXISTING SYMBOL: $2" % [scope.parent.fullname, key] return true else: # Go up the scope chain and attempt to find the symbol if not scope.parent.isNil: result = scope.parent.setSymbol(key, value) if not result: # Define local variable #echo "($1) SET LOCAL SYMBOL: $2" % [scope.fullname, key] scope.symbols[key] = value return true proc getSigil*(scope: ref MinScope, key: string): MinOperator = if scope.sigils.hasKey(key): return scope.sigils[key] elif not scope.parent.isNil: return scope.parent.getSigil(key) proc dump*(i: MinInterpreter): string = var s = "" for item in i.stack: s = s & $item & " " return s proc debug*(i: var MinInterpreter, value: MinValue) = if i.debugging: stderr.writeLine("-- " & i.dump & $value) proc debug*(i: var MinInterpreter, value: string) = if i.debugging: stderr.writeLine("-- " & value) template newScope*(i: In, id: string, q: MinValue, body: stmt): stmt {.immediate.}= q.scope = new MinScope q.scope.name = id q.scope.parent = i.scope #i.debug "[scope] " & q.scope.fullname let scope = i.scope i.scope = q.scope body #i.debug "[scope] " & scope.fullname i.scope = scope template newDisposableScope*(i: In, id: string, body: stmt): stmt {.immediate.}= var q = MinValue(kind: minQuotation, qVal: newSeq[MinValue](0)) q.scope = new MinScope q.scope.name = id q.scope.parent = i.scope #i.debug "[scope] " & q.scope.fullname let scope = i.scope i.scope = q.scope body #i.debug "[scope] " & scope.fullname i.scope = scope proc newMinInterpreter*(debugging = false): MinInterpreter = var st:MinStack = newSeq[MinValue](0) var pr:MinParser var i:MinInterpreter = MinInterpreter( filename: "input", parser: pr, stack: st, scope: ROOT, debugging: debugging, currSym: MinValue(column: 1, line: 1, kind: minSymbol, symVal: "") ) return i proc error*(i: MinInterpreter, status: MinError, message = "") = var msg = if message == "": ERRORS[status] else: message if i.filename == "": stderr.writeLine("`$1`: Error - $2" % [i.currSym.symVal, msg]) else: stderr.writeLine("$1 [$2,$3] `$4`: Error - $5" % [i.filename, $i.currSym.line, $i.currSym.column, i.currSym.symVal, msg]) quit(int(status)) proc open*(i: var MinInterpreter, stream:Stream, filename: string) = i.filename = filename i.parser.open(stream, filename) proc close*(i: var MinInterpreter) = i.parser.close(); proc push*(i: var MinInterpreter, val: MinValue) = i.debug val if val.kind == minSymbol: if not i.evaluating: i.currSym = val let symbol = val.symVal let sigil = "" & symbol[0] let symbolProc = i.scope.getSymbol(symbol) if not symbolProc.isNil: try: i.newDisposableScope("<" & symbol & ">"): symbolProc(i) except: i.error(errSystem, getCurrentExceptionMsg()) else: let sigilProc = i.scope.getSigil(sigil) if symbol.len > 1 and not sigilProc.isNil: let sym = symbol[1..symbol.len-1] try: i.stack.add(MinValue(kind: minString, strVal: sym)) sigilProc(i) except: i.error(errSystem, getCurrentExceptionMsg()) else: i.error(errUndefined, "Undefined symbol: '"&val.symVal&"'") else: i.stack.add(val) proc push*(i: var MinInterpreter, q: seq[MinValue]) = for e in q: i.push e proc pop*(i: var MinInterpreter): MinValue = if i.stack.len > 0: return i.stack.pop else: i.error(errEmptyStack) proc peek*(i: MinInterpreter): MinValue = if i.stack.len > 0: return i.stack[i.stack.len-1] else: i.error(errEmptyStack) proc interpret*(i: var MinInterpreter) = var val: MinValue while i.parser.token != tkEof: try: val = i.parser.parseMinValue except: i.error errParser, getCurrentExceptionMsg() i.push val proc eval*(i: var MinInterpreter, s: string) = let fn = i.filename try: i.open(newStringStream(s), "eval") discard i.parser.getToken() i.interpret() except: stderr.writeLine getCurrentExceptionMsg() finally: i.filename = fn proc load*(i: var MinInterpreter, s: string) = let fn = i.filename try: i.open(newStringStream(s.readFile), s) discard i.parser.getToken() i.interpret() except: stderr.writeLine getCurrentExceptionMsg() finally: i.filename = fn proc apply*(i: var MinInterpreter, symbol: string) = i.scope.getSymbol(symbol)(i) proc copystack*(i: var MinInterpreter): MinStack = var s = newSeq[MinValue](0) for i in i.stack: s.add i return s var INTERPRETER* = newMinInterpreter() |