Nim/compiler/trees.nim

#
#
#           The Nim Compiler
#        (c) Copyright 2012 Andreas Rumpf
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

# tree helper routines

import
  ast, astalgo, lexer, msgs, strutils, wordrecg, idents

proc cyclicTreeAux(n: PNode, visited: var seq[PNode]): bool =
  if n == nil: return
  for v in visited:
    if v == n: return true
  if not (n.kind in {nkEmpty..nkNilLit}):
    visited.add(n)
    for nSon in n.sons:
      if cyclicTreeAux(nSon, visited): return true
    discard visited.pop()

proc cyclicTree*(n: PNode): bool =
  var visited: seq[PNode] = @[]
  cyclicTreeAux(n, visited)

proc exprStructuralEquivalent*(a, b: PNode; strictSymEquality=false): bool =
  if a == b:
    result = true
  elif (a != nil) and (b != nil) and (a.kind == b.kind):
    case a.kind
    of nkSym:
      if strictSymEquality:
        result = a.sym == b.sym
      else:
        # don't go nuts here: same symbol as string is enough:
        result = a.sym.name.id == b.sym.name.id
    of nkIdent: result = a.ident.id == b.ident.id
    of nkCharLit..nkUInt64Lit: result = a.intVal == b.intVal
    of nkFloatLit..nkFloat64Lit: result = a.floatVal == b.floatVal
    of nkStrLit..nkTripleStrLit: result = a.strVal == b.strVal
    of nkCommentStmt: result = a.comment == b.comment
    of nkEmpty, nkNilLit, nkType: result = true
    else:
      if sonsLen(a) == sonsLen(b):
        for i in countup(0, sonsLen(a) - 1):
          if not exprStructuralEquivalent(a.sons[i], b.sons[i],
                                          strictSymEquality): return
        result = true

proc sameTree*(a, b: PNode): bool =
  if a == b:
    result = true
  elif a != nil and b != nil and a.kind == b.kind:
    if a.flags != b.flags: return
    if a.info.line != b.info.line: return
    if a.info.col != b.info.col:
      return                  #if a.info.fileIndex <> b.info.fileIndex then exit;
    case a.kind
    of nkSym:
      # don't go nuts here: same symbol as string is enough:
      result = a.sym.name.id == b.sym.name.id
    of nkIdent: result = a.ident.id == b.ident.id
    of nkCharLit..nkUInt64Lit: result = a.intVal == b.intVal
    of nkFloatLit..nkFloat64Lit: result = a.floatVal == b.floatVal
    of nkStrLit..nkTripleStrLit: result = a.strVal == b.strVal
    of nkEmpty, nkNilLit, nkType: result = true
    else:
      if sonsLen(a) == sonsLen(b):
        for i in countup(0, sonsLen(a) - 1):
          if not sameTree(a.sons[i], b.sons[i]): return
        result = true

proc getMagic*(op: PNode): TMagic =
  case op.kind
  of nkCallKinds:
    case op.sons[0].kind
    of nkSym: result = op.sons[0].sym.magic
    else: result = mNone
  else: result = mNone

proc isConstExpr*(n: PNode): bool =
  const atomKinds = {nkCharLit..nkNilLit} # Char, Int, UInt, Str, Float and Nil literals
  n.kind in atomKinds or nfAllConst in n.flags

proc isCaseObj*(n: PNode): bool =
  if n.kind == nkRecCase: return true
  for i in 0..<safeLen(n):
    if n[i].isCaseObj: return true

proc isDeepConstExpr*(n: PNode): bool =
  case n.kind
  of nkCharLit..nkInt64Lit, nkStrLit..nkTripleStrLit,
      nkFloatLit..nkFloat64Lit, nkNilLit:
    result = true
  of nkExprEqExpr, nkExprColonExpr, nkHiddenStdConv, nkHiddenSubConv:
    result = isDeepConstExpr(n.sons[1])
  of nkCurly, nkBracket, nkPar, nkTupleConstr, nkObjConstr, nkClosure, nkRange:
    for i in ord(n.kind == nkObjConstr) ..< n.len:
      if not isDeepConstExpr(n.sons[i]): return false
    if n.typ.isNil: result = true
    else:
      let t = n.typ.skipTypes({tyGenericInst, tyDistinct, tyAlias, tySink})
      if t.kind in {tyRef, tyPtr}: return false
      if t.kind != tyObject or not isCaseObj(t.n):
        result = true
  else: discard

proc isRange*(n: PNode): bool {.inline.} =
  if n.kind in nkCallKinds:
    let callee = n[0]
    if (callee.kind == nkIdent and callee.ident.id == ord(wDotDot)) or
       (callee.kind == nkSym and callee.sym.name.id == ord(wDotDot)) or
       (callee.kind in {nkClosedSymChoice, nkOpenSymChoice} and
        callee[1].sym.name.id == ord(wDotDot)):
      result = true

proc whichPragma*(n: PNode): TSpecialWord =
  let key = if n.kind in nkPragmaCallKinds and n.len > 0: n.sons[0] else: n
  if key.kind == nkIdent: result = whichKeyword(key.ident)

proc unnestStmts(n, result: PNode) =
  if n.kind == nkStmtList:
    for x in items(n): unnestStmts(x, result)
  elif n.kind notin {nkCommentStmt, nkNilLit}:
    result.add(n)

proc flattenStmts*(n: PNode): PNode =
  result = newNodeI(nkStmtList, n.info)
  unnestStmts(n, result)
  if result.len == 1:
    result = result.sons[0]

proc extractRange*(k: TNodeKind, n: PNode, a, b: int): PNode =
  result = newNodeI(k, n.info, b-a+1)
  for i in 0 .. b-a: result.sons[i] = n.sons[i+a]