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-rw-r--r--compiler/expanddefaults.nim131
1 files changed, 131 insertions, 0 deletions
diff --git a/compiler/expanddefaults.nim b/compiler/expanddefaults.nim
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--- /dev/null
+++ b/compiler/expanddefaults.nim
@@ -0,0 +1,131 @@
+#
+#
+#           The Nim Compiler
+#        (c) Copyright 2023 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+import lineinfos, ast, types
+
+proc caseObjDefaultBranch*(obj: PNode; branch: Int128): int =
+  result = 0
+  for i in 1 ..< obj.len:
+    for j in 0 .. obj[i].len - 2:
+      if obj[i][j].kind == nkRange:
+        let x = getOrdValue(obj[i][j][0])
+        let y = getOrdValue(obj[i][j][1])
+        if branch >= x and branch <= y:
+          return i
+      elif getOrdValue(obj[i][j]) == branch:
+        return i
+    if obj[i].len == 1:
+      # else branch
+      return i
+  return 1
+
+template newZero(t: PType; info: TLineInfo; k = nkIntLit): PNode = newNodeIT(k, info, t)
+
+proc expandDefault*(t: PType; info: TLineInfo): PNode
+
+proc expandField(s: PSym; info: TLineInfo): PNode =
+  result = newNodeIT(nkExprColonExpr, info, s.typ)
+  result.add newSymNode(s)
+  result.add expandDefault(s.typ, info)
+
+proc expandDefaultN(n: PNode; info: TLineInfo; res: PNode) =
+  case n.kind
+  of nkRecList:
+    for i in 0..<n.len:
+      expandDefaultN(n[i], info, res)
+  of nkRecCase:
+    res.add expandField(n[0].sym, info)
+    var branch = Zero
+    let constOrNil = n[0].sym.astdef
+    if constOrNil != nil:
+      branch = getOrdValue(constOrNil)
+
+    let selectedBranch = caseObjDefaultBranch(n, branch)
+    let b = lastSon(n[selectedBranch])
+    expandDefaultN b, info, res
+  of nkSym:
+    res.add expandField(n.sym, info)
+  else:
+    discard
+
+proc expandDefaultObj(t: PType; info: TLineInfo; res: PNode) =
+  if t.baseClass != nil:
+    expandDefaultObj(t.baseClass, info, res)
+  expandDefaultN(t.n, info, res)
+
+proc expandDefault(t: PType; info: TLineInfo): PNode =
+  case t.kind
+  of tyInt:     result = newZero(t, info, nkIntLit)
+  of tyInt8:    result = newZero(t, info, nkInt8Lit)
+  of tyInt16:   result = newZero(t, info, nkInt16Lit)
+  of tyInt32:   result = newZero(t, info, nkInt32Lit)
+  of tyInt64:   result = newZero(t, info, nkInt64Lit)
+  of tyUInt:    result = newZero(t, info, nkUIntLit)
+  of tyUInt8:   result = newZero(t, info, nkUInt8Lit)
+  of tyUInt16:  result = newZero(t, info, nkUInt16Lit)
+  of tyUInt32:  result = newZero(t, info, nkUInt32Lit)
+  of tyUInt64:  result = newZero(t, info, nkUInt64Lit)
+  of tyFloat:   result = newZero(t, info, nkFloatLit)
+  of tyFloat32: result = newZero(t, info, nkFloat32Lit)
+  of tyFloat64: result = newZero(t, info, nkFloat64Lit)
+  of tyFloat128: result = newZero(t, info, nkFloat64Lit)
+  of tyChar:    result = newZero(t, info, nkCharLit)
+  of tyBool:    result = newZero(t, info, nkIntLit)
+  of tyEnum:
+    # Could use low(T) here to finally fix old language quirks
+    result = newZero(t, info, nkIntLit)
+  of tyRange:
+    # Could use low(T) here to finally fix old language quirks
+    result = expandDefault(skipModifier t, info)
+  of tyVoid: result = newZero(t, info, nkEmpty)
+  of tySink, tyGenericInst, tyDistinct, tyAlias, tyOwned:
+    result = expandDefault(t.skipModifier, info)
+  of tyOrdinal, tyGenericBody, tyGenericParam, tyInferred, tyStatic:
+    if t.hasElementType:
+      result = expandDefault(t.skipModifier, info)
+    else:
+      result = newZero(t, info, nkEmpty)
+  of tyFromExpr:
+    if t.n != nil and t.n.typ != nil:
+      result = expandDefault(t.n.typ, info)
+    else:
+      result = newZero(t, info, nkEmpty)
+  of tyArray:
+    result = newZero(t, info, nkBracket)
+    let n = toInt64(lengthOrd(nil, t))
+    for i in 0..<n:
+      result.add expandDefault(t.elementType, info)
+  of tyPtr, tyRef, tyProc, tyPointer, tyCstring:
+    result = newZero(t, info, nkNilLit)
+  of tyVar, tyLent:
+    let e = t.elementType
+    if e.skipTypes(abstractInst).kind in {tyOpenArray, tyVarargs}:
+      # skip the modifier, `var openArray` is a (ptr, len) pair too:
+      result = expandDefault(e, info)
+    else:
+      result = newZero(e, info, nkNilLit)
+  of tySet:
+    result = newZero(t, info, nkCurly)
+  of tyObject:
+    result = newNodeIT(nkObjConstr, info, t)
+    result.add newNodeIT(nkType, info, t)
+    expandDefaultObj(t, info, result)
+  of tyTuple:
+    result = newZero(t, info, nkTupleConstr)
+    for it in t.kids:
+      result.add expandDefault(it, info)
+  of tyVarargs, tyOpenArray, tySequence, tyUncheckedArray:
+    result = newZero(t, info, nkBracket)
+  of tyString:
+    result = newZero(t, info, nkStrLit)
+  of tyNone, tyEmpty, tyUntyped, tyTyped, tyTypeDesc,
+     tyNil, tyGenericInvocation, tyError, tyBuiltInTypeClass,
+     tyUserTypeClass, tyUserTypeClassInst, tyCompositeTypeClass,
+     tyAnd, tyOr, tyNot, tyAnything, tyConcept, tyIterable, tyForward:
+    result = newZero(t, info, nkEmpty) # bug indicator