some work to make 'opt' a first class type

compiler/ast.nim

@@ -404,14 +404,8 @@ type
       # instantiation and prior to this it has the potential to
       # be any type.
 
-    tyFieldAccessor
+    tyOpt
-      # Expressions such as Type.field (valid in contexts such
+      # Builtin optional type
-      # as the `is` operator and magics like `high` and `low`).
-      # Could be lifted to a single argument proc returning the
-      # field value.
-      # sons[0]: type of containing object or tuple
-      # sons[1]: field type
-      # .n: nkDotExpr storing the field name
 
     tyVoid
       # now different from tyEmpty, hurray!
@@ -624,7 +618,7 @@ type
     mSwap, mIsNil, mArrToSeq, mCopyStr, mCopyStrLast,
     mNewString, mNewStringOfCap, mParseBiggestFloat,
     mReset,
-    mArray, mOpenArray, mRange, mSet, mSeq, mVarargs,
+    mArray, mOpenArray, mRange, mSet, mSeq, mOpt, mVarargs,
     mRef, mPtr, mVar, mDistinct, mVoid, mTuple,
     mOrdinal,
     mInt, mInt8, mInt16, mInt32, mInt64,

compiler/canonicalizer.nim

@@ -130,7 +130,7 @@ proc hashType(c: var MD5Context, t: PType) =
     c.hashSym body.sym
     for i in countup(1, sonsLen(t) - 2):
       c.hashType t.sons[i]
-  of tyFromExpr, tyFieldAccessor:
+  of tyFromExpr:
     c.hashTree(t.n)
   of tyArray:
     c.hashTree(t.sons[0].n)

compiler/ccgutils.nim

@@ -100,7 +100,7 @@ proc getUniqueType*(key: PType): PType =
       if result == nil:
         gCanonicalTypes[k] = key
         result = key
-    of tyTypeDesc, tyTypeClasses, tyGenericParam, tyFromExpr, tyFieldAccessor:
+    of tyTypeDesc, tyTypeClasses, tyGenericParam, tyFromExpr:
       if key.isResolvedUserTypeClass:
         return getUniqueType(lastSon(key))
       if key.sym != nil:
@@ -126,7 +126,7 @@ proc getUniqueType*(key: PType): PType =
         result = slowSearch(key, k)
     of tyGenericInvocation, tyGenericBody,
        tyOpenArray, tyArray, tySet, tyRange, tyTuple,
-       tySequence, tyForward, tyVarargs, tyProxy:
+       tySequence, tyForward, tyVarargs, tyProxy, tyOpt:
       # we have to do a slow linear search because types may need
       # to be compared by their structure:
       result = slowSearch(key, k)

compiler/jsgen.nim

@@ -187,12 +187,12 @@ proc mapType(typ: PType): TJSTypeKind =
   of tyBool: result = etyBool
   of tyFloat..tyFloat128: result = etyFloat
   of tySet: result = etyObject # map a set to a table
-  of tyString, tySequence: result = etySeq
+  of tyString, tySequence, tyOpt: result = etySeq
   of tyObject, tyArray, tyTuple, tyOpenArray, tyVarargs:
     result = etyObject
   of tyNil: result = etyNull
   of tyGenericInst, tyGenericParam, tyGenericBody, tyGenericInvocation,
-     tyNone, tyFromExpr, tyForward, tyEmpty, tyFieldAccessor,
+     tyNone, tyFromExpr, tyForward, tyEmpty,
      tyExpr, tyStmt, tyTypeDesc, tyTypeClasses, tyVoid, tyAlias:
     result = etyNone
   of tyInferred:
@@ -927,7 +927,7 @@ proc genAsgnAux(p: PProc, x, y: PNode, noCopyNeeded: bool) =
 
   # we don't care if it's an etyBaseIndex (global) of a string, it's
   # still a string that needs to be copied properly:
-  if x.typ.skipTypes(abstractInst).kind in {tySequence, tyString}:
+  if x.typ.skipTypes(abstractInst).kind in {tySequence, tyOpt, tyString}:
     xtyp = etySeq
   case xtyp
   of etySeq:
@@ -971,7 +971,7 @@ proc genFastAsgn(p: PProc, n: PNode) =
   # See bug #5933. So we try to be more compatible with the C backend semantics
   # here for 'shallowCopy'. This is an educated guess and might require further
   # changes later:
-  let noCopy = n[0].typ.skipTypes(abstractInst).kind in {tySequence, tyString}
+  let noCopy = n[0].typ.skipTypes(abstractInst).kind in {tySequence, tyOpt, tyString}
   genAsgnAux(p, n.sons[0], n.sons[1], noCopyNeeded=noCopy)
 
 proc genSwap(p: PProc, n: PNode) =
@@ -1550,7 +1550,7 @@ proc createVar(p: PProc, typ: PType, indirect: bool): Rope =
       result = putToSeq("[null, 0]", indirect)
     else:
       result = putToSeq("null", indirect)
-  of tySequence, tyString, tyCString, tyPointer, tyProc:
+  of tySequence, tyOpt, tyString, tyCString, tyPointer, tyProc:
     result = putToSeq("null", indirect)
   of tyStatic:
     if t.n != nil:

compiler/semasgn.nim

@@ -185,7 +185,7 @@ proc liftBodyAux(c: var TLiftCtx; t: PType; body, x, y: PNode) =
   case t.kind
   of tyNone, tyEmpty, tyVoid: discard
   of tyPointer, tySet, tyBool, tyChar, tyEnum, tyInt..tyUInt64, tyCString,
-      tyPtr, tyString, tyRef:
+      tyPtr, tyString, tyRef, tyOpt:
     defaultOp(c, t, body, x, y)
   of tyArray, tySequence:
     if tfHasAsgn in t.flags:
@@ -227,7 +227,7 @@ proc liftBodyAux(c: var TLiftCtx; t: PType; body, x, y: PNode) =
      tyTypeDesc, tyGenericInvocation, tyForward:
     internalError(c.info, "assignment requested for type: " & typeToString(t))
   of tyOrdinal, tyRange, tyInferred,
-     tyGenericInst, tyFieldAccessor, tyStatic, tyVar, tyAlias:
+     tyGenericInst, tyStatic, tyVar, tyAlias:
     liftBodyAux(c, lastSon(t), body, x, y)
   of tyUnused, tyUnused0, tyUnused1, tyUnused2: internalError("liftBodyAux")
 

compiler/semexprs.nim

@@ -246,8 +246,7 @@ proc semLowHigh(c: PContext, n: PNode, m: TMagic): PNode =
     localError(n.info, errXExpectsTypeOrValue, opToStr[m])
   else:
     n.sons[1] = semExprWithType(c, n.sons[1], {efDetermineType})
-    var typ = skipTypes(n.sons[1].typ, abstractVarRange +
+    var typ = skipTypes(n.sons[1].typ, abstractVarRange + {tyTypeDesc})
-                                       {tyTypeDesc, tyFieldAccessor})
     case typ.kind
     of tySequence, tyString, tyCString, tyOpenArray, tyVarargs:
       n.typ = getSysType(tyInt)
@@ -255,7 +254,7 @@ proc semLowHigh(c: PContext, n: PNode, m: TMagic): PNode =
       n.typ = typ.sons[0] # indextype
     of tyInt..tyInt64, tyChar, tyBool, tyEnum, tyUInt8, tyUInt16, tyUInt32:
       # do not skip the range!
-      n.typ = n.sons[1].typ.skipTypes(abstractVar + {tyFieldAccessor})
+      n.typ = n.sons[1].typ.skipTypes(abstractVar)
     of tyGenericParam:
       # prepare this for resolving in semtypinst:
       # we must use copyTree here in order to avoid creating a cycle
@@ -279,7 +278,7 @@ proc isOpImpl(c: PContext, n: PNode, flags: TExprFlags): PNode =
     n[1].typ != nil and n[1].typ.kind == tyTypeDesc and
     n[2].kind in {nkStrLit..nkTripleStrLit, nkType}
 
-  let t1 = n[1].typ.skipTypes({tyTypeDesc, tyFieldAccessor})
+  let t1 = n[1].typ.skipTypes({tyTypeDesc})
 
   if n[2].kind in {nkStrLit..nkTripleStrLit}:
     case n[2].strVal.normalize
@@ -1087,9 +1086,6 @@ proc builtinFieldAccess(c: PContext, n: PNode, flags: TExprFlags): PNode =
         if field != nil:
           n.typ = makeTypeDesc(c, field.typ)
           return n
-          #n.typ = newTypeWithSons(c, tyFieldAccessor, @[ty, field.typ])
-          #n.typ.n = copyTree(n)
-          #return n
     else:
       tryReadingGenericParam(ty)
       return

compiler/semstmts.nim

@@ -1234,7 +1234,7 @@ proc semInferredLambda(c: PContext, pt: TIdTable, n: PNode): PNode =
   s.typ = n.typ
   for i in 1..<params.len:
     if params[i].typ.kind in {tyTypeDesc, tyGenericParam,
-                              tyFromExpr, tyFieldAccessor}+tyTypeClasses:
+                              tyFromExpr}+tyTypeClasses:
       localError(params[i].info, "cannot infer type of parameter: " &
                  params[i].sym.name.s)
     #params[i].sym.owner = s

compiler/semtypes.nim

@@ -1592,6 +1592,8 @@ proc processMagicType(c: PContext, m: PSym) =
     setMagicType(m, tySet, 0)
   of mSeq:
     setMagicType(m, tySequence, 0)
+  of mOpt:
+    setMagicType(m, tyOpt, 0)
   of mOrdinal:
     setMagicType(m, tyOrdinal, 0)
     rawAddSon(m.typ, newTypeS(tyNone, c))

compiler/sighashes.nim

@@ -201,7 +201,7 @@ proc hashType(c: var MD5Context, t: PType; flags: set[ConsiderFlag]) =
   of tyRef, tyPtr, tyGenericBody, tyVar:
     c.hashType t.lastSon, flags
     if tfVarIsPtr in t.flags: c &= ".varisptr"
-  of tyFromExpr, tyFieldAccessor:
+  of tyFromExpr:
     c.hashTree(t.n)
   of tyTuple:
     if t.n != nil and CoType notin flags:

compiler/sigmatch.nim

@@ -936,7 +936,7 @@ proc typeRelImpl(c: var TCandidate, f, aOrig: PType,
                                      tfExplicit notin aOrig.flags
 
     aOrig = if useTypeLoweringRuleInTypeClass:
-          aOrig.skipTypes({tyTypeDesc, tyFieldAccessor})
+          aOrig.skipTypes({tyTypeDesc})
         else:
           aOrig
 

compiler/types.nim

@@ -12,9 +12,6 @@
 import
   intsets, ast, astalgo, trees, msgs, strutils, platform, renderer
 
-proc firstOrd*(t: PType): BiggestInt
-proc lastOrd*(t: PType): BiggestInt
-proc lengthOrd*(t: PType): BiggestInt
 type
   TPreferedDesc* = enum
     preferName, preferDesc, preferExported, preferModuleInfo, preferGenericArg
@@ -70,17 +67,6 @@ const
   typedescPtrs* = abstractPtrs + {tyTypeDesc}
   typedescInst* = abstractInst + {tyTypeDesc}
 
-proc containsObject*(t: PType): bool
-proc containsGarbageCollectedRef*(typ: PType): bool
-proc containsHiddenPointer*(typ: PType): bool
-proc canFormAcycle*(typ: PType): bool
-proc isCompatibleToCString*(a: PType): bool
-proc getOrdValue*(n: PNode): BiggestInt
-proc computeSize*(typ: PType): BiggestInt
-proc getSize*(typ: PType): BiggestInt
-proc isPureObject*(typ: PType): bool
-proc invalidGenericInst*(f: PType): bool
-  # for debugging
 type
   TTypeFieldResult* = enum
     frNone,                   # type has no object type field
@@ -92,16 +78,16 @@ proc analyseObjectWithTypeField*(t: PType): TTypeFieldResult
   # made or intializing of the type field suffices or if there is no type field
   # at all in this type.
 
-proc invalidGenericInst(f: PType): bool =
+proc invalidGenericInst*(f: PType): bool =
   result = f.kind == tyGenericInst and lastSon(f) == nil
 
-proc isPureObject(typ: PType): bool =
+proc isPureObject*(typ: PType): bool =
   var t = typ
   while t.kind == tyObject and t.sons[0] != nil:
     t = t.sons[0].skipTypes(skipPtrs)
   result = t.sym != nil and sfPure in t.sym.flags
 
-proc getOrdValue(n: PNode): BiggestInt =
+proc getOrdValue*(n: PNode): BiggestInt =
   case n.kind
   of nkCharLit..nkUInt64Lit: result = n.intVal
   of nkNilLit: result = 0
@@ -116,14 +102,6 @@ proc isIntLit*(t: PType): bool {.inline.} =
 proc isFloatLit*(t: PType): bool {.inline.} =
   result = t.kind == tyFloat and t.n != nil and t.n.kind == nkFloatLit
 
-proc isCompatibleToCString(a: PType): bool =
-  if a.kind == tyArray:
-    if (firstOrd(a.sons[0]) == 0) and
-        (skipTypes(a.sons[0], {tyRange, tyGenericInst, tyAlias}).kind in
-            {tyInt..tyInt64, tyUInt..tyUInt64}) and
-        (a.sons[1].kind == tyChar):
-      result = true
-
 proc getProcHeader*(sym: PSym; prefer: TPreferedDesc = preferName): string =
   result = sym.owner.name.s & '.' & sym.name.s & '('
   var n = sym.typ.n
@@ -252,7 +230,7 @@ proc searchTypeFor(t: PType, predicate: TTypePredicate): bool =
 proc isObjectPredicate(t: PType): bool =
   result = t.kind == tyObject
 
-proc containsObject(t: PType): bool =
+proc containsObject*(t: PType): bool =
   result = searchTypeFor(t, isObjectPredicate)
 
 proc isObjectWithTypeFieldPredicate(t: PType): bool =
@@ -297,7 +275,7 @@ proc isGCRef(t: PType): bool =
   result = t.kind in GcTypeKinds or
     (t.kind == tyProc and t.callConv == ccClosure)
 
-proc containsGarbageCollectedRef(typ: PType): bool =
+proc containsGarbageCollectedRef*(typ: PType): bool =
   # returns true if typ contains a reference, sequence or string (all the
   # things that are garbage-collected)
   result = searchTypeFor(typ, isGCRef)
@@ -312,7 +290,7 @@ proc containsTyRef*(typ: PType): bool =
 proc isHiddenPointer(t: PType): bool =
   result = t.kind in {tyString, tySequence}
 
-proc containsHiddenPointer(typ: PType): bool =
+proc containsHiddenPointer*(typ: PType): bool =
   # returns true if typ contains a string, table or sequence (all the things
   # that need to be copied deeply)
   result = searchTypeFor(typ, isHiddenPointer)
@@ -355,7 +333,7 @@ proc canFormAcycleAux(marker: var IntSet, typ: PType, startId: int): bool =
   of tyProc: result = typ.callConv == ccClosure
   else: discard
 
-proc canFormAcycle(typ: PType): bool =
+proc canFormAcycle*(typ: PType): bool =
   var marker = initIntSet()
   result = canFormAcycleAux(marker, typ, typ.id)
 
@@ -521,7 +499,7 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
   of tyExpr:
     internalAssert t.len == 0
     result = "untyped"
-  of tyFromExpr, tyFieldAccessor:
+  of tyFromExpr:
     result = renderTree(t.n)
   of tyArray:
     if t.sons[0].kind == tyRange:
@@ -532,6 +510,8 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
           typeToString(t.sons[1]) & ']'
   of tySequence:
     result = "seq[" & typeToString(t.sons[0]) & ']'
+  of tyOpt:
+    result = "opt[" & typeToString(t.sons[0]) & ']'
   of tyOrdinal:
     result = "ordinal[" & typeToString(t.sons[0]) & ']'
   of tySet:
@@ -605,7 +585,7 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
     result = typeToStr[t.kind]
   result.addTypeFlags(t)
 
-proc firstOrd(t: PType): BiggestInt =
+proc firstOrd*(t: PType): BiggestInt =
   case t.kind
   of tyBool, tyChar, tySequence, tyOpenArray, tyString, tyVarargs, tyProxy:
     result = 0
@@ -630,7 +610,7 @@ proc firstOrd(t: PType): BiggestInt =
     else:
       assert(t.n.sons[0].kind == nkSym)
       result = t.n.sons[0].sym.position
-  of tyGenericInst, tyDistinct, tyTypeDesc, tyFieldAccessor, tyAlias:
+  of tyGenericInst, tyDistinct, tyTypeDesc, tyAlias:
     result = firstOrd(lastSon(t))
   of tyOrdinal:
     if t.len > 0: result = firstOrd(lastSon(t))
@@ -639,7 +619,7 @@ proc firstOrd(t: PType): BiggestInt =
     internalError("invalid kind for first(" & $t.kind & ')')
     result = 0
 
-proc lastOrd(t: PType): BiggestInt =
+proc lastOrd*(t: PType): BiggestInt =
   case t.kind
   of tyBool: result = 1
   of tyChar: result = 255
@@ -666,7 +646,7 @@ proc lastOrd(t: PType): BiggestInt =
   of tyEnum:
     assert(t.n.sons[sonsLen(t.n) - 1].kind == nkSym)
     result = t.n.sons[sonsLen(t.n) - 1].sym.position
-  of tyGenericInst, tyDistinct, tyTypeDesc, tyFieldAccessor, tyAlias:
+  of tyGenericInst, tyDistinct, tyTypeDesc, tyAlias:
     result = lastOrd(lastSon(t))
   of tyProxy: result = 0
   of tyOrdinal:
@@ -676,7 +656,7 @@ proc lastOrd(t: PType): BiggestInt =
     internalError("invalid kind for last(" & $t.kind & ')')
     result = 0
 
-proc lengthOrd(t: PType): BiggestInt =
+proc lengthOrd*(t: PType): BiggestInt =
   case t.kind
   of tyInt64, tyInt32, tyInt: result = lastOrd(t)
   of tyDistinct: result = lengthOrd(t.sons[0])
@@ -689,6 +669,14 @@ proc lengthOrd(t: PType): BiggestInt =
     else:
       result = lastOrd(t) - firstOrd(t) + 1
 
+proc isCompatibleToCString*(a: PType): bool =
+  if a.kind == tyArray:
+    if (firstOrd(a.sons[0]) == 0) and
+        (skipTypes(a.sons[0], {tyRange, tyGenericInst, tyAlias}).kind in
+            {tyInt..tyInt64, tyUInt..tyUInt64}) and
+        (a.sons[1].kind == tyChar):
+      result = true
+
 # -------------- type equality -----------------------------------------------
 
 type
@@ -989,7 +977,7 @@ proc sameTypeAux(x, y: PType, c: var TSameTypeClosure): bool =
       result = a.sym.position == b.sym.position
   of tyGenericInvocation, tyGenericBody, tySequence,
      tyOpenArray, tySet, tyRef, tyPtr, tyVar,
-     tyArray, tyProc, tyVarargs, tyOrdinal, tyTypeClasses, tyFieldAccessor:
+     tyArray, tyProc, tyVarargs, tyOrdinal, tyTypeClasses, tyOpt:
     cycleCheck()
     if a.kind == tyUserTypeClass and a.n != nil: return a.n == b.n
     result = sameChildrenAux(a, b, c) and sameFlags(a, b)
@@ -1144,7 +1132,7 @@ proc typeAllowedAux(marker: var IntSet, typ: PType, kind: TSymKind,
   of tyTypeClasses:
     if not (tfGenericTypeParam in t.flags or taField notin flags): result = t
   of tyGenericBody, tyGenericParam, tyGenericInvocation,
-     tyNone, tyForward, tyFromExpr, tyFieldAccessor:
+     tyNone, tyForward, tyFromExpr:
     result = t
   of tyNil:
     if kind != skConst: result = t
@@ -1160,7 +1148,7 @@ proc typeAllowedAux(marker: var IntSet, typ: PType, kind: TSymKind,
   of tyOpenArray, tyVarargs:
     if kind != skParam: result = t
     else: result = typeAllowedAux(marker, t.sons[0], skVar, flags)
-  of tySequence:
+  of tySequence, tyOpt:
     if t.sons[0].kind != tyEmpty:
       result = typeAllowedAux(marker, t.sons[0], skVar, flags+{taHeap})
   of tyArray:
@@ -1359,7 +1347,7 @@ proc computeSizeAux(typ: PType, a: var BiggestInt): BiggestInt =
   typ.size = result
   typ.align = int16(a)
 
-proc computeSize(typ: PType): BiggestInt =
+proc computeSize*(typ: PType): BiggestInt =
   var a: BiggestInt = 1
   result = computeSizeAux(typ, a)
 
@@ -1368,7 +1356,7 @@ proc getReturnType*(s: PSym): PType =
   assert s.kind in skProcKinds
   result = s.typ.sons[0]
 
-proc getSize(typ: PType): BiggestInt =
+proc getSize*(typ: PType): BiggestInt =
   result = computeSize(typ)
   if result < 0: internalError("getSize: " & $typ.kind)
 

compiler/vmdeps.nim

@@ -250,6 +250,7 @@ proc mapTypeToAstX(t: PType; info: TLineInfo;
       result = mapTypeToBracket("ref", mRef, t, info)
   of tyVar: result = mapTypeToBracket("var", mVar, t, info)
   of tySequence: result = mapTypeToBracket("seq", mSeq, t, info)
+  of tyOpt: result = mapTypeToBracket("opt", mOpt, t, info)
   of tyProc:
     if inst:
       result = newNodeX(nkProcTy)
@@ -304,7 +305,7 @@ proc mapTypeToAstX(t: PType; info: TLineInfo;
   of tyNot: result = mapTypeToBracket("not", mNot, t, info)
   of tyAnything: result = atomicType("anything", mNone)
   of tyInferred: internalAssert false
-  of tyStatic, tyFromExpr, tyFieldAccessor:
+  of tyStatic, tyFromExpr:
     if inst:
       if t.n != nil: result = t.n.copyTree
       else: result = atomicType("void", mVoid)

lib/core/macros.nim

@@ -97,7 +97,7 @@ type
     ntyError,
     ntyBuiltinTypeClass, ntyUserTypeClass, ntyUserTypeClassInst,
     ntyCompositeTypeClass, ntyInferred, ntyAnd, ntyOr, ntyNot,
-    ntyAnything, ntyStatic, ntyFromExpr, ntyFieldAccessor, ntyVoid
+    ntyAnything, ntyStatic, ntyFromExpr, ntyOpt, ntyVoid
 
   TNimTypeKinds* {.deprecated.} = set[NimTypeKind]
   NimSymKind* = enum