all repos — min @ 22a43dc378092f7d1e3c9597afa9b11738867062

A small but practical concatenative programming language.

core/interpreter.nim

 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
import streams, strutils, critbits, os
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",
  "Runtime error",
  "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 delSymbol*(scope: ref MinScope, key: string): bool {.discardable.}=
  if scope.symbols.hasKey(key):
    scope.symbols.excl(key)
    return true
  return false

proc setSymbol*(scope: ref MinScope, key: string, value: MinOperator): bool {.discardable.}=
  result = false
  # check if a symbol already exists in current scope
  if not scope.isNil and scope.symbols.hasKey(key):
    scope.symbols[key] = value
    result = true
  else:
    # Go up the scope chain and attempt to find the symbol
    if not scope.parent.isNil:
      result = scope.parent.setSymbol(key, value)

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

proc newMinInterpreter*(debugging = false): MinInterpreter =
  var st:MinStack = newSeq[MinValue](0)
  var pr:MinParser
  var i:MinInterpreter = MinInterpreter(
    filename: "input", 
    pwd: "",
    parser: pr, 
    stack: st,
    scope: ROOT,
    debugging: debugging, 
    unsafe: false,
    currSym: MinValue(column: 1, line: 1, kind: minSymbol, symVal: "")
  )
  return i

proc copy(i: MinInterpreter, filename = "input"): MinInterpreter =
  result = newMinInterpreter(debugging = i.debugging)
  result.filename = filename
  result.pwd =  filename.parentDir
  result.stack = i.stack
  result.scope = i.scope
  result.currSym = MinValue(column: 1, line: 1, kind: minSymbol, symVal: "")

proc error*(i: MinInterpreter, status: MinError, message = "") =
  var msg = if message == "": ERRORS[status] else: message
  if i.currSym.filename == "":
    stderr.writeLine("`$1`: Error - $2" % [i.currSym.symVal, msg])
  else:
    stderr.writeLine("$1 [$2,$3] `$4`: Error - $5" % [i.currSym.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:
      if i.unsafe:
        symbolProc(i) 
      else:
        try:
          symbolProc(i) 
        except MinRuntimeError:
          stderr.writeLine("$1 [$2,$3]: $4" % [i.currSym.filename, $i.currSym.line, $i.currSym.column, getCurrentExceptionMsg()])
        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]
        i.stack.add(MinValue(kind: minString, strVal: sym))
        if i.unsafe:
          sigilProc(i) 
        else:
          try:
            sigilProc(i) 
          except MinRuntimeError:
            stderr.writeLine("$1 [$2,$3]: $4" % [i.currSym.filename, $i.currSym.line, $i.currSym.column, getCurrentExceptionMsg()])
          except:
            i.error(errSystem, getCurrentExceptionMsg())
      else:
        i.error(errUndefined, "Undefined symbol: '"&val.symVal&"'")
        return
  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 unquote*(i: In, name: string, q: var MinValue) =
  i.newScope(name, q): 
    for v in q.qVal:
      i.push v


proc eval*(i: var MinInterpreter, s: string) =
  let fn = i.filename
  try:
    var i2 = i.copy("eval")
    i2.open(newStringStream(s), "eval")
    discard i2.parser.getToken() 
    i2.interpret()
    i.stack = i2.stack
    i.scope = i2.scope
  except:
    stderr.writeLine getCurrentExceptionMsg()
  finally:
    i.filename = fn

proc load*(i: var MinInterpreter, s: string) =
  let fn = i.filename
  try:
    var i2 = i.copy(s)
    i2.open(newStringStream(s.readFile), s)
    discard i2.parser.getToken() 
    i2.interpret()
    i.stack = i2.stack
    i.scope = i2.scope
  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()