summary refs log tree commit diff stats
path: root/compiler/nimfix/nimfix.nim
Commit message (Collapse)AuthorAgeFilesLines
* implements a --nep1:on switch to make the compiler enforce the naming ↵Andreas Rumpf2018-06-131-1/+1
| | | | conventions outlined in NEP-1
* options.nim: no global variables anymoreAndreas Rumpf2018-05-131-1/+1
|
* make nimfix compile again (#7708)alaviss2018-04-271-7/+7
|
* removed compiler internal list implementation (#5371)Arne Döring2017-02-221-3/+3
|
* implements module grouping for the import statementAndreas Rumpf2016-12-211-5/+5
|
* make nimfix compile with newer compiler APIAraq2016-12-201-2/+3
|
* Fix few typosFederico Ceratto2016-10-171-1/+1
|
* renamed writeln to writeLine in compilerpatrick dw2015-06-191-1/+1
|
* Hopefully fixes nimsuggest building against the compiler package.Dominik Picheta2015-06-041-6/+8
|
* Happy new year!Guillaume Gelin2015-01-061-1/+1
|
* implemented --bestEffort switch for nimfixAraq2014-12-261-2/+4
|
* documented nimfixAraq2014-11-041-1/+1
|
* nimfix now in its own directory; single file mode now the defaultAraq2014-10-051-0/+106
1'>241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686
#
#
#           The Nimrod Compiler
#        (c) Copyright 2012 Andreas Rumpf
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

# this module folds constants; used by semantic checking phase
# and evaluation phase

import 
  strutils, lists, options, ast, astalgo, trees, treetab, nimsets, times, 
  nversion, platform, math, msgs, os, condsyms, idents, renderer, types,
  commands, magicsys, saturate

proc getConstExpr*(m: PSym, n: PNode): PNode
  # evaluates the constant expression or returns nil if it is no constant
  # expression
proc evalOp*(m: TMagic, n, a, b, c: PNode): PNode
proc leValueConv*(a, b: PNode): bool
proc newIntNodeT*(intVal: BiggestInt, n: PNode): PNode
proc newFloatNodeT*(floatVal: BiggestFloat, n: PNode): PNode
proc newStrNodeT*(strVal: string, n: PNode): PNode

# implementation

proc newIntNodeT(intVal: BiggestInt, n: PNode): PNode =
  case skipTypes(n.typ, abstractVarRange).kind
  of tyInt:
    result = newIntNode(nkIntLit, intVal)
    result.typ = getIntLitType(result)
    # hrm, this is not correct: 1 + high(int) shouldn't produce tyInt64 ...
    #setIntLitType(result)
  of tyChar:
    result = newIntNode(nkCharLit, intVal)
    result.typ = n.typ
  else:
    result = newIntNode(nkIntLit, intVal)
    result.typ = n.typ
  result.info = n.info

proc newFloatNodeT(floatVal: BiggestFloat, n: PNode): PNode = 
  result = newFloatNode(nkFloatLit, floatVal)
  result.typ = n.typ
  result.info = n.info

proc newStrNodeT(strVal: string, n: PNode): PNode = 
  result = newStrNode(nkStrLit, strVal)
  result.typ = n.typ
  result.info = n.info

proc ordinalValToString(a: PNode): string = 
  # because $ has the param ordinal[T], `a` is not necessarily an enum, but an
  # ordinal
  var x = getInt(a)
  
  var t = skipTypes(a.typ, abstractRange)
  case t.kind
  of tyChar: 
    result = $chr(int(x) and 0xff)
  of tyEnum:
    var n = t.n
    for i in countup(0, sonsLen(n) - 1): 
      if n.sons[i].kind != nkSym: InternalError(a.info, "ordinalValToString")
      var field = n.sons[i].sym
      if field.position == x: 
        if field.ast == nil: 
          return field.name.s
        else:
          return field.ast.strVal
    InternalError(a.info, "no symbol for ordinal value: " & $x)
  else:
    result = $x

proc isFloatRange(t: PType): bool {.inline.} =
  result = t.kind == tyRange and t.sons[0].kind in {tyFloat..tyFloat128}

proc isIntRange(t: PType): bool {.inline.} =
  result = t.kind == tyRange and t.sons[0].kind in {
      tyInt..tyInt64, tyUInt8..tyUInt32}

proc pickIntRange(a, b: PType): PType =
  if isIntRange(a): result = a
  elif isIntRange(b): result = b
  else: result = a

proc isIntRangeOrLit(t: PType): bool =
  result = isIntRange(t) or isIntLit(t)

proc pickMinInt(n: PNode): biggestInt =
  if n.kind in {nkIntLit..nkUInt64Lit}:
    result = n.intVal
  elif isIntLit(n.typ):
    result = n.typ.n.intVal
  elif isIntRange(n.typ):
    result = firstOrd(n.typ)
  else:
    InternalError(n.info, "pickMinInt")

proc pickMaxInt(n: PNode): biggestInt =
  if n.kind in {nkIntLit..nkUInt64Lit}:
    result = n.intVal
  elif isIntLit(n.typ):
    result = n.typ.n.intVal
  elif isIntRange(n.typ):
    result = lastOrd(n.typ)
  else:
    InternalError(n.info, "pickMaxInt")

proc makeRange(typ: PType, first, last: biggestInt): PType = 
  var n = newNode(nkRange)
  addSon(n, newIntNode(nkIntLit, min(first, last)))
  addSon(n, newIntNode(nkIntLit, max(first, last)))
  result = newType(tyRange, typ.owner)
  result.n = n
  addSonSkipIntLit(result, skipTypes(typ, {tyRange}))

proc makeRangeF(typ: PType, first, last: biggestFloat): PType =
  var n = newNode(nkRange)
  addSon(n, newFloatNode(nkFloatLit, min(first.float, last.float)))
  addSon(n, newFloatNode(nkFloatLit, max(first.float, last.float)))
  result = newType(tyRange, typ.owner)
  result.n = n
  addSonSkipIntLit(result, skipTypes(typ, {tyRange}))

proc getIntervalType*(m: TMagic, n: PNode): PType =
  # Nimrod requires interval arithmetic for ``range`` types. Lots of tedious
  # work but the feature is very nice for reducing explicit conversions.
  result = n.typ
  
  template commutativeOp(opr: expr) {.immediate.} =
    let a = n.sons[1]
    let b = n.sons[2]
    if isIntRangeOrLit(a.typ) and isIntRangeOrLit(b.typ):
      result = makeRange(pickIntRange(a.typ, b.typ),
                         opr(pickMinInt(a), pickMinInt(b)),
                         opr(pickMaxInt(a), pickMaxInt(b)))
  
  template binaryOp(opr: expr) {.immediate.} =
    let a = n.sons[1]
    let b = n.sons[2]
    if isIntRange(a.typ) and b.kind in {nkIntLit..nkUInt64Lit}:
      result = makeRange(a.typ,
                         opr(pickMinInt(a), pickMinInt(b)),
                         opr(pickMaxInt(a), pickMaxInt(b)))
  
  case m
  of mUnaryMinusI, mUnaryMinusI64:
    let a = n.sons[1].typ
    if isIntRange(a):
      # (1..3) * (-1) == (-3.. -1)
      result = makeRange(a, 0|-|lastOrd(a), 0|-|firstOrd(a))
  of mUnaryMinusF64:
    let a = n.sons[1].typ
    if isFloatRange(a):
      result = makeRangeF(a, -getFloat(a.n.sons[1]),
                             -getFloat(a.n.sons[0]))
  of mAbsF64:
    let a = n.sons[1].typ
    if isFloatRange(a):
      # abs(-5.. 1) == (1..5)
      result = makeRangeF(a, abs(getFloat(a.n.sons[1])),
                             abs(getFloat(a.n.sons[0])))
  of mAbsI, mAbsI64:
    let a = n.sons[1].typ
    if isIntRange(a):
      result = makeRange(a, `|abs|`(getInt(a.n.sons[1])),
                            `|abs|`(getInt(a.n.sons[0])))
  of mSucc:
    let a = n.sons[1].typ
    let b = n.sons[2].typ
    if isIntRange(a) and isIntLit(b):
      # (-5.. 1) + 6 == (-5 + 6)..(-1 + 6)
      result = makeRange(a, pickMinInt(n.sons[1]) |+| pickMinInt(n.sons[2]),
                            pickMaxInt(n.sons[1]) |+| pickMaxInt(n.sons[2]))
  of mPred:
    let a = n.sons[1].typ
    let b = n.sons[2].typ
    if isIntRange(a) and isIntLit(b):
      result = makeRange(a, pickMinInt(n.sons[1]) |-| pickMinInt(n.sons[2]),
                            pickMaxInt(n.sons[1]) |-| pickMaxInt(n.sons[2]))
  of mAddI, mAddI64, mAddU:
    commutativeOp(`|+|`)
  of mMulI, mMulI64, mMulU:
    commutativeOp(`|*|`)
  of mSubI, mSubI64, mSubU:
    binaryOp(`|-|`)
  of mBitandI, mBitandI64:
    var a = n.sons[1]
    var b = n.sons[2]
    # symmetrical:
    if b.kind notin {nkIntLit..nkUInt64Lit}: swap(a, b)
    if b.kind in {nkIntLit..nkUInt64Lit}:
      let x = b.intVal|+|1
      if (x and -x) == x and x >= 0:
        result = makeRange(a.typ, 0, b.intVal)
  of mModU:
    let a = n.sons[1]
    let b = n.sons[2]
    if b.kind in {nkIntLit..nkUInt64Lit}:
      if b.intVal >= 0:
        result = makeRange(a.typ, 0, b.intVal-1)
      else:
        result = makeRange(a.typ, b.intVal+1, 0)
  of mModI, mModI64:
    # so ... if you ever wondered about modulo's signedness; this defines it:
    let a = n.sons[1]
    let b = n.sons[2]
    if b.kind in {nkIntLit..nkUInt64Lit}:
      if b.intVal >= 0:
        result = makeRange(a.typ, -(b.intVal-1), b.intVal-1)
      else:
        result = makeRange(a.typ, b.intVal+1, -(b.intVal+1))
  of mDivI, mDivI64, mDivU:
    binaryOp(`|div|`)
  of mMinI, mMinI64:
    commutativeOp(min)
  of mMaxI, mMaxI64:
    commutativeOp(max)
  else: nil
  
discard """
  mShlI, mShlI64,
  mShrI, mShrI64, mAddF64, mSubF64, mMulF64, mDivF64, mMaxF64, mMinF64
"""

proc evalOp(m: TMagic, n, a, b, c: PNode): PNode = 
  # b and c may be nil
  result = nil
  case m
  of mOrd: result = newIntNodeT(getOrdValue(a), n)
  of mChr: result = newIntNodeT(getInt(a), n)
  of mUnaryMinusI, mUnaryMinusI64: result = newIntNodeT(- getInt(a), n)
  of mUnaryMinusF64: result = newFloatNodeT(- getFloat(a), n)
  of mNot: result = newIntNodeT(1 - getInt(a), n)
  of mCard: result = newIntNodeT(nimsets.cardSet(a), n)
  of mBitnotI, mBitnotI64: result = newIntNodeT(not getInt(a), n)
  of mLengthStr: result = newIntNodeT(len(getStr(a)), n)
  of mLengthArray: result = newIntNodeT(lengthOrd(a.typ), n)
  of mLengthSeq, mLengthOpenArray: result = newIntNodeT(sonsLen(a), n) # BUGFIX
  of mUnaryPlusI, mUnaryPlusI64, mUnaryPlusF64: result = a # throw `+` away
  of mToFloat, mToBiggestFloat: 
    result = newFloatNodeT(toFloat(int(getInt(a))), n)
  of mToInt, mToBiggestInt: result = newIntNodeT(system.toInt(getFloat(a)), n)
  of mAbsF64: result = newFloatNodeT(abs(getFloat(a)), n)
  of mAbsI, mAbsI64: 
    if getInt(a) >= 0: result = a
    else: result = newIntNodeT(- getInt(a), n)
  of mZe8ToI, mZe8ToI64, mZe16ToI, mZe16ToI64, mZe32ToI64, mZeIToI64: 
    # byte(-128) = 1...1..1000_0000'64 --> 0...0..1000_0000'64
    result = newIntNodeT(getInt(a) and (`shl`(1, getSize(a.typ) * 8) - 1), n)
  of mToU8: result = newIntNodeT(getInt(a) and 0x000000FF, n)
  of mToU16: result = newIntNodeT(getInt(a) and 0x0000FFFF, n)
  of mToU32: result = newIntNodeT(getInt(a) and 0x00000000FFFFFFFF'i64, n)
  of mUnaryLt: result = newIntNodeT(getOrdValue(a) - 1, n)
  of mSucc: result = newIntNodeT(getOrdValue(a) + getInt(b), n)
  of mPred: result = newIntNodeT(getOrdValue(a) - getInt(b), n)
  of mAddI, mAddI64: result = newIntNodeT(getInt(a) + getInt(b), n)
  of mSubI, mSubI64: result = newIntNodeT(getInt(a) - getInt(b), n)
  of mMulI, mMulI64: result = newIntNodeT(getInt(a) * getInt(b), n)
  of mMinI, mMinI64: 
    if getInt(a) > getInt(b): result = newIntNodeT(getInt(b), n)
    else: result = newIntNodeT(getInt(a), n)
  of mMaxI, mMaxI64: 
    if getInt(a) > getInt(b): result = newIntNodeT(getInt(a), n)
    else: result = newIntNodeT(getInt(b), n)
  of mShlI, mShlI64: 
    case skipTypes(n.typ, abstractRange).kind
    of tyInt8: result = newIntNodeT(int8(getInt(a)) shl int8(getInt(b)), n)
    of tyInt16: result = newIntNodeT(int16(getInt(a)) shl int16(getInt(b)), n)
    of tyInt32: result = newIntNodeT(int32(getInt(a)) shl int32(getInt(b)), n)
    of tyInt64, tyInt, tyUInt..tyUInt64: 
      result = newIntNodeT(`shl`(getInt(a), getInt(b)), n)
    else: InternalError(n.info, "constant folding for shl")
  of mShrI, mShrI64: 
    case skipTypes(n.typ, abstractRange).kind
    of tyInt8: result = newIntNodeT(int8(getInt(a)) shr int8(getInt(b)), n)
    of tyInt16: result = newIntNodeT(int16(getInt(a)) shr int16(getInt(b)), n)
    of tyInt32: result = newIntNodeT(int32(getInt(a)) shr int32(getInt(b)), n)
    of tyInt64, tyInt, tyUInt..tyUInt64:
      result = newIntNodeT(`shr`(getInt(a), getInt(b)), n)
    else: InternalError(n.info, "constant folding for shr")
  of mDivI, mDivI64: result = newIntNodeT(getInt(a) div getInt(b), n)
  of mModI, mModI64: result = newIntNodeT(getInt(a) mod getInt(b), n)
  of mAddF64: result = newFloatNodeT(getFloat(a) + getFloat(b), n)
  of mSubF64: result = newFloatNodeT(getFloat(a) - getFloat(b), n)
  of mMulF64: result = newFloatNodeT(getFloat(a) * getFloat(b), n)
  of mDivF64: 
    if getFloat(b) == 0.0: 
      if getFloat(a) == 0.0: result = newFloatNodeT(NaN, n)
      else: result = newFloatNodeT(Inf, n)
    else: 
      result = newFloatNodeT(getFloat(a) / getFloat(b), n)
  of mMaxF64: 
    if getFloat(a) > getFloat(b): result = newFloatNodeT(getFloat(a), n)
    else: result = newFloatNodeT(getFloat(b), n)
  of mMinF64: 
    if getFloat(a) > getFloat(b): result = newFloatNodeT(getFloat(b), n)
    else: result = newFloatNodeT(getFloat(a), n)
  of mIsNil: result = newIntNodeT(ord(a.kind == nkNilLit), n)
  of mLtI, mLtI64, mLtB, mLtEnum, mLtCh: 
    result = newIntNodeT(ord(getOrdValue(a) < getOrdValue(b)), n)
  of mLeI, mLeI64, mLeB, mLeEnum, mLeCh: 
    result = newIntNodeT(ord(getOrdValue(a) <= getOrdValue(b)), n)
  of mEqI, mEqI64, mEqB, mEqEnum, mEqCh: 
    result = newIntNodeT(ord(getOrdValue(a) == getOrdValue(b)), n) 
  of mLtF64: result = newIntNodeT(ord(getFloat(a) < getFloat(b)), n)
  of mLeF64: result = newIntNodeT(ord(getFloat(a) <= getFloat(b)), n)
  of mEqF64: result = newIntNodeT(ord(getFloat(a) == getFloat(b)), n) 
  of mLtStr: result = newIntNodeT(ord(getStr(a) < getStr(b)), n)
  of mLeStr: result = newIntNodeT(ord(getStr(a) <= getStr(b)), n)
  of mEqStr: result = newIntNodeT(ord(getStr(a) == getStr(b)), n)
  of mLtU, mLtU64: 
    result = newIntNodeT(ord(`<%`(getOrdValue(a), getOrdValue(b))), n)
  of mLeU, mLeU64: 
    result = newIntNodeT(ord(`<=%`(getOrdValue(a), getOrdValue(b))), n)
  of mBitandI, mBitandI64, mAnd: result = newIntNodeT(a.getInt and b.getInt, n)
  of mBitorI, mBitorI64, mOr: result = newIntNodeT(getInt(a) or getInt(b), n)
  of mBitxorI, mBitxorI64, mXor: result = newIntNodeT(a.getInt xor b.getInt, n)
  of mAddU: result = newIntNodeT(`+%`(getInt(a), getInt(b)), n)
  of mSubU: result = newIntNodeT(`-%`(getInt(a), getInt(b)), n)
  of mMulU: result = newIntNodeT(`*%`(getInt(a), getInt(b)), n)
  of mModU: result = newIntNodeT(`%%`(getInt(a), getInt(b)), n)
  of mDivU: result = newIntNodeT(`/%`(getInt(a), getInt(b)), n)
  of mLeSet: result = newIntNodeT(Ord(containsSets(a, b)), n)
  of mEqSet: result = newIntNodeT(Ord(equalSets(a, b)), n)
  of mLtSet: 
    result = newIntNodeT(Ord(containsSets(a, b) and not equalSets(a, b)), n)
  of mMulSet: 
    result = nimsets.intersectSets(a, b)
    result.info = n.info
  of mPlusSet: 
    result = nimsets.unionSets(a, b)
    result.info = n.info
  of mMinusSet: 
    result = nimsets.diffSets(a, b)
    result.info = n.info
  of mSymDiffSet: 
    result = nimsets.symdiffSets(a, b)
    result.info = n.info
  of mConStrStr: result = newStrNodeT(getStrOrChar(a) & getStrOrChar(b), n)
  of mInSet: result = newIntNodeT(Ord(inSet(a, b)), n)
  of mRepr:
    # BUGFIX: we cannot eval mRepr here for reasons that I forgot.
  of mIntToStr, mInt64ToStr: result = newStrNodeT($(getOrdValue(a)), n)
  of mBoolToStr: 
    if getOrdValue(a) == 0: result = newStrNodeT("false", n)
    else: result = newStrNodeT("true", n)
  of mCopyStr: result = newStrNodeT(substr(getStr(a), int(getOrdValue(b))), n)
  of mCopyStrLast: 
    result = newStrNodeT(substr(getStr(a), int(getOrdValue(b)), 
                                           int(getOrdValue(c))), n)
  of mFloatToStr: result = newStrNodeT($getFloat(a), n)
  of mCStrToStr, mCharToStr: result = newStrNodeT(getStrOrChar(a), n)
  of mStrToStr: result = a
  of mEnumToStr: result = newStrNodeT(ordinalValToString(a), n)
  of mArrToSeq: 
    result = copyTree(a)
    result.typ = n.typ
  of mCompileOption:
    result = newIntNodeT(Ord(commands.testCompileOption(a.getStr, n.info)), n)  
  of mCompileOptionArg:
    result = newIntNodeT(Ord(
      testCompileOptionArg(getStr(a), getStr(b), n.info)), n)
  of mNewString, mNewStringOfCap, 
     mExit, mInc, ast.mDec, mEcho, mSwap, mAppendStrCh, 
     mAppendStrStr, mAppendSeqElem, mSetLengthStr, mSetLengthSeq, 
     mParseExprToAst, mParseStmtToAst, mExpandToAst, mTypeTrait,
     mNLen..mNError, mEqRef, mSlurp, mStaticExec: 
    nil
  of mRand:
    result = newIntNodeT(math.random(a.getInt.int), n)
  else: InternalError(a.info, "evalOp(" & $m & ')')
  
proc getConstIfExpr(c: PSym, n: PNode): PNode = 
  result = nil
  for i in countup(0, sonsLen(n) - 1): 
    var it = n.sons[i]
    case it.kind
    of nkElifExpr: 
      var e = getConstExpr(c, it.sons[0])
      if e == nil: return nil
      if getOrdValue(e) != 0: 
        if result == nil: 
          result = getConstExpr(c, it.sons[1])
          if result == nil: return 
    of nkElseExpr: 
      if result == nil: result = getConstExpr(c, it.sons[0])
    else: internalError(it.info, "getConstIfExpr()")
  
proc partialAndExpr(c: PSym, n: PNode): PNode = 
  # partial evaluation
  result = n
  var a = getConstExpr(c, n.sons[1])
  var b = getConstExpr(c, n.sons[2])
  if a != nil: 
    if getInt(a) == 0: result = a
    elif b != nil: result = b
    else: result = n.sons[2]
  elif b != nil: 
    if getInt(b) == 0: result = b
    else: result = n.sons[1]
  
proc partialOrExpr(c: PSym, n: PNode): PNode = 
  # partial evaluation
  result = n
  var a = getConstExpr(c, n.sons[1])
  var b = getConstExpr(c, n.sons[2])
  if a != nil: 
    if getInt(a) != 0: result = a
    elif b != nil: result = b
    else: result = n.sons[2]
  elif b != nil: 
    if getInt(b) != 0: result = b
    else: result = n.sons[1]
  
proc leValueConv(a, b: PNode): bool = 
  result = false
  case a.kind
  of nkCharLit..nkUInt64Lit: 
    case b.kind
    of nkCharLit..nkUInt64Lit: result = a.intVal <= b.intVal
    of nkFloatLit..nkFloat128Lit: result = a.intVal <= round(b.floatVal)
    else: InternalError(a.info, "leValueConv")
  of nkFloatLit..nkFloat128Lit: 
    case b.kind
    of nkFloatLit..nkFloat128Lit: result = a.floatVal <= b.floatVal
    of nkCharLit..nkUInt64Lit: result = a.floatVal <= toFloat(int(b.intVal))
    else: InternalError(a.info, "leValueConv")
  else: InternalError(a.info, "leValueConv")
  
proc magicCall(m: PSym, n: PNode): PNode =
  if sonsLen(n) <= 1: return

  var s = n.sons[0].sym
  var a = getConstExpr(m, n.sons[1])
  var b, c: PNode
  if a == nil: return 
  if sonsLen(n) > 2: 
    b = getConstExpr(m, n.sons[2])
    if b == nil: return 
    if sonsLen(n) > 3: 
      c = getConstExpr(m, n.sons[3])
      if c == nil: return 
  else: 
    b = nil
  result = evalOp(s.magic, n, a, b, c)
  
proc getAppType(n: PNode): PNode =
  if gGlobalOptions.contains(optGenDynLib):
    result = newStrNodeT("lib", n)
  elif gGlobalOptions.contains(optGenStaticLib):
    result = newStrNodeT("staticlib", n)
  elif gGlobalOptions.contains(optGenGuiApp):
    result = newStrNodeT("gui", n)
  else:
    result = newStrNodeT("console", n)

proc foldConv*(n, a: PNode): PNode = 
  # XXX range checks?
  case skipTypes(n.typ, abstractRange).kind
  of tyInt..tyInt64: 
    case skipTypes(a.typ, abstractRange).kind
    of tyFloat..tyFloat64: result = newIntNodeT(system.toInt(getFloat(a)), n)
    of tyChar: result = newIntNodeT(getOrdValue(a), n)
    else: 
      result = a
      result.typ = n.typ
  of tyFloat..tyFloat64: 
    case skipTypes(a.typ, abstractRange).kind
    of tyInt..tyInt64, tyEnum, tyBool, tyChar: 
      result = newFloatNodeT(toFloat(int(getOrdValue(a))), n)
    else: 
      result = a
      result.typ = n.typ
  of tyOpenArray, tyVarargs, tyProc: 
    nil
  else: 
    result = a
    result.typ = n.typ
  
proc getArrayConstr(m: PSym, n: PNode): PNode =
  if n.kind == nkBracket:
    result = n
  else:
    result = getConstExpr(m, n)
    if result == nil: result = n
  
proc foldArrayAccess(m: PSym, n: PNode): PNode = 
  var x = getConstExpr(m, n.sons[0])
  if x == nil: return
  
  var y = getConstExpr(m, n.sons[1])
  if y == nil: return
  
  var idx = getOrdValue(y)
  case x.kind
  of nkPar: 
    if (idx >= 0) and (idx < sonsLen(x)): 
      result = x.sons[int(idx)]
      if result.kind == nkExprColonExpr: result = result.sons[1]
    else:
      LocalError(n.info, errIndexOutOfBounds)
  of nkBracket, nkMetaNode: 
    if (idx >= 0) and (idx < sonsLen(x)): result = x.sons[int(idx)]
    else: LocalError(n.info, errIndexOutOfBounds)
  of nkStrLit..nkTripleStrLit: 
    result = newNodeIT(nkCharLit, x.info, n.typ)
    if (idx >= 0) and (idx < len(x.strVal)): 
      result.intVal = ord(x.strVal[int(idx)])
    elif idx == len(x.strVal): 
      nil
    else: 
      LocalError(n.info, errIndexOutOfBounds)
  else: nil
  
proc foldFieldAccess(m: PSym, n: PNode): PNode = 
  # a real field access; proc calls have already been transformed
  var x = getConstExpr(m, n.sons[0])
  if x == nil or x.kind != nkPar: return

  var field = n.sons[1].sym
  for i in countup(0, sonsLen(x) - 1): 
    var it = x.sons[i]
    if it.kind != nkExprColonExpr:
      # lookup per index:
      result = x.sons[field.position]
      if result.kind == nkExprColonExpr: result = result.sons[1]
      return
    if it.sons[0].sym.name.id == field.name.id: 
      result = x.sons[i].sons[1]
      return
  localError(n.info, errFieldXNotFound, field.name.s)
  
proc foldConStrStr(m: PSym, n: PNode): PNode = 
  result = newNodeIT(nkStrLit, n.info, n.typ)
  result.strVal = ""
  for i in countup(1, sonsLen(n) - 1): 
    let a = getConstExpr(m, n.sons[i])
    if a == nil: return nil
    result.strVal.add(getStrOrChar(a))
  
proc getConstExpr(m: PSym, n: PNode): PNode = 
  result = nil
  case n.kind
  of nkSym: 
    var s = n.sym
    if s.kind == skEnumField: 
      result = newIntNodeT(s.position, n)
    elif s.kind == skConst: 
      case s.magic
      of mIsMainModule: result = newIntNodeT(ord(sfMainModule in m.flags), n)
      of mCompileDate: result = newStrNodeT(times.getDateStr(), n)
      of mCompileTime: result = newStrNodeT(times.getClockStr(), n)
      of mNimrodVersion: result = newStrNodeT(VersionAsString, n)
      of mNimrodMajor: result = newIntNodeT(VersionMajor, n)
      of mNimrodMinor: result = newIntNodeT(VersionMinor, n)
      of mNimrodPatch: result = newIntNodeT(VersionPatch, n)
      of mCpuEndian: result = newIntNodeT(ord(CPU[targetCPU].endian), n)
      of mHostOS: result = newStrNodeT(toLower(platform.OS[targetOS].name), n)
      of mHostCPU: result = newStrNodeT(platform.CPU[targetCPU].name.toLower, n)
      of mAppType: result = getAppType(n)
      of mNaN: result = newFloatNodeT(NaN, n)
      of mInf: result = newFloatNodeT(Inf, n)
      of mNegInf: result = newFloatNodeT(NegInf, n)
      else:
        if sfFakeConst notin s.flags: result = copyTree(s.ast)
    elif s.kind in {skProc, skMethod}: # BUGFIX
      result = n
  of nkCharLit..nkNilLit: 
    result = copyNode(n)
  of nkIfExpr: 
    result = getConstIfExpr(m, n)
  of nkCall, nkCommand, nkCallStrLit, nkPrefix, nkInfix: 
    if n.sons[0].kind != nkSym: return 
    var s = n.sons[0].sym
    if s.kind != skProc: return 
    try:
      case s.magic
      of mNone:
        return # XXX: if it has no sideEffect, it should be evaluated
      of mSizeOf:
        var a = n.sons[1]
        if computeSize(a.typ) < 0: 
          LocalError(a.info, errCannotEvalXBecauseIncompletelyDefined, 
                     "sizeof")
          result = nil
        elif skipTypes(a.typ, abstractInst).kind in {tyArray,tyObject,tyTuple}:
          result = nil
          # XXX: size computation for complex types is still wrong
        else:
          result = newIntNodeT(getSize(a.typ), n)
      of mLow: 
        result = newIntNodeT(firstOrd(n.sons[1].typ), n)
      of mHigh: 
        if  skipTypes(n.sons[1].typ, abstractVar).kind notin
            {tyOpenArray, tyVarargs, tySequence, tyString}: 
          result = newIntNodeT(lastOrd(skipTypes(n[1].typ, abstractVar)), n)
        else:
          var a = getArrayConstr(m, n.sons[1])
          if a.kind == nkBracket:
            # we can optimize it away: 
            result = newIntNodeT(sonsLen(a)-1, n)
      of mLengthOpenArray:
        var a = getArrayConstr(m, n.sons[1])
        if a.kind == nkBracket:
          # we can optimize it away! This fixes the bug ``len(134)``. 
          result = newIntNodeT(sonsLen(a), n)
        else:
          result = magicCall(m, n)
      of mAstToStr:
        result = newStrNodeT(renderTree(n[1], {renderNoComments}), n)
      of mConStrStr:
        result = foldConStrStr(m, n)
      else:
        result = magicCall(m, n)
    except EOverflow: 
      LocalError(n.info, errOverOrUnderflow)
    except EDivByZero: 
      LocalError(n.info, errConstantDivisionByZero)
  of nkAddr: 
    var a = getConstExpr(m, n.sons[0])
    if a != nil: 
      result = n
      n.sons[0] = a
  of nkBracket: 
    result = copyTree(n)
    for i in countup(0, sonsLen(n) - 1): 
      var a = getConstExpr(m, n.sons[i])
      if a == nil: return nil
      result.sons[i] = a
    incl(result.flags, nfAllConst)
  of nkRange: 
    var a = getConstExpr(m, n.sons[0])
    if a == nil: return 
    var b = getConstExpr(m, n.sons[1])
    if b == nil: return 
    result = copyNode(n)
    addSon(result, a)
    addSon(result, b)
  of nkCurly: 
    result = copyTree(n)
    for i in countup(0, sonsLen(n) - 1): 
      var a = getConstExpr(m, n.sons[i])
      if a == nil: return nil
      result.sons[i] = a
    incl(result.flags, nfAllConst)
  of nkPar: 
    # tuple constructor
    result = copyTree(n)
    if (sonsLen(n) > 0) and (n.sons[0].kind == nkExprColonExpr): 
      for i in countup(0, sonsLen(n) - 1): 
        var a = getConstExpr(m, n.sons[i].sons[1])
        if a == nil: return nil
        result.sons[i].sons[1] = a
    else: 
      for i in countup(0, sonsLen(n) - 1): 
        var a = getConstExpr(m, n.sons[i])
        if a == nil: return nil
        result.sons[i] = a
    incl(result.flags, nfAllConst)
  of nkChckRangeF, nkChckRange64, nkChckRange: 
    var a = getConstExpr(m, n.sons[0])
    if a == nil: return 
    if leValueConv(n.sons[1], a) and leValueConv(a, n.sons[2]): 
      result = a              # a <= x and x <= b
      result.typ = n.typ
    else: 
      LocalError(n.info, errGenerated, `%`(
          msgKindToString(errIllegalConvFromXtoY), 
          [typeToString(n.sons[0].typ), typeToString(n.typ)]))
  of nkStringToCString, nkCStringToString: 
    var a = getConstExpr(m, n.sons[0])
    if a == nil: return 
    result = a
    result.typ = n.typ
  of nkHiddenStdConv, nkHiddenSubConv, nkConv, nkCast: 
    var a = getConstExpr(m, n.sons[1])
    if a == nil: return 
    result = foldConv(n, a)
  of nkBracketExpr: result = foldArrayAccess(m, n)
  of nkDotExpr: result = foldFieldAccess(m, n)
  else:
    nil