tuples now support default values for fields

nim-lang · Aug 18, 2022 · f0424ff · f0424ff
1 parent 6041db3
commit f0424ff
Show file tree

Hide file tree

Showing 3 changed files with 61 additions and 30 deletions.
diff --git a/compiler/sem.nim b/compiler/sem.nim
@@ -557,6 +557,35 @@ proc defaultNodeField(c: PContext, a: PNode, aTyp: PType): PNode
 
 const defaultFieldsSkipTypes = {tyGenericInst, tyAlias, tySink, tyDistinct}
 
+proc defaultFieldsForTuple(c: PContext, recNode: PNode, hasDefault: var bool): seq[PNode] =
+  case recNode.kind
+  of nkRecList:
+    for field in recNode:
+      result.add defaultFieldsForTuple(c, field, hasDefault)
+  of nkSym:
+    let field = recNode.sym
+    let recType = recNode.typ.skipTypes(defaultFieldsSkipTypes)
+    if field.ast != nil: #Try to use default value
+      hasDefault = true
+      result.add newTree(nkExprColonExpr, recNode, field.ast)
+    elif recType.kind in {tyObject, tyArray, tyTuple}:
+      let asgnExpr = defaultNodeField(c, recNode, recNode.typ)
+      if asgnExpr != nil:
+        hasDefault = true
+        asgnExpr.flags.incl nfUseDefaultField
+        result.add newTree(nkExprColonExpr, recNode, asgnExpr)
+    else:
+      let asgnType = newType(tyTypeDesc, nextTypeId(c.idgen), recType.owner)
+      rawAddSon(asgnType, recType)
+      let asgnExpr = newTree(nkCall,
+                      newSymNode(getSysMagic(c.graph, recNode.info, "zeroDefault", mZeroDefault)),
+                      newNodeIT(nkType, recNode.info, asgnType)
+                    )
+      asgnExpr.flags.incl nfUseDefaultField
+      asgnExpr.typ = recType
+      result.add newTree(nkExprColonExpr, recNode, asgnExpr)
+  else:
+    doAssert false
 
 proc defaultFieldsForTheUninitialized(c: PContext, recNode: PNode): seq[PNode] =
   case recNode.kind
@@ -617,31 +646,13 @@ proc defaultNodeField(c: PContext, a: PNode, aTyp: PType): PNode =
       result.flags.incl nfUseDefaultField
   elif aTypSkip.kind == tyTuple:
     var hasDefault = false
-    var children: seq[PNode]
-    for s in aTypSkip.sons:
-      let child = defaultNodeField(c, a, s)
-      if child != nil:
-        hasDefault = true
-      children.add child
-    if hasDefault:
-      result = newNodeI(nkTupleConstr, a.info)
-      result.typ = aTyp
-      var i = 0
-      while i < children.len:
-        let s = children[i]
-        if s != nil:
-          result.add s
-        else:
-          let asgnType = newType(tyTypeDesc, nextTypeId(c.idgen), aTypSkip[i].owner)
-          rawAddSon(asgnType, aTypSkip[i])
-          let asgnExpr = newTree(nkCall,
-                          newSymNode(getSysMagic(c.graph, a.info, "zeroDefault", mZeroDefault)),
-                          newNodeIT(nkType, a.info, asgnType)
-                        )
-          asgnExpr.flags.incl nfUseDefaultField
-          asgnExpr.typ = aTypSkip[i]
-          result.add asgnExpr
-        inc i
+    if aTypSkip.n != nil:
+      let children = defaultFieldsForTuple(c, aTypSkip.n, hasDefault)
+      if hasDefault and children.len > 0:
+        result = newNodeI(nkTupleConstr, a.info)
+        result.typ = aTyp
+        result.flags.incl nfUseDefaultField
+        result.sons.add children
 
 proc defaultNodeField(c: PContext, a: PNode): PNode =
   result = defaultNodeField(c, a, a.typ)

diff --git a/compiler/semtypes.nim b/compiler/semtypes.nim
@@ -23,7 +23,6 @@ const
   errXExpectsOneTypeParam = "'$1' expects one type parameter"
   errArrayExpectsTwoTypeParams = "array expects two type parameters"
   errInvalidVisibilityX = "invalid visibility: '$1'"
-  errInitHereNotAllowed = "initialization not allowed here"
   errXCannotBeAssignedTo = "'$1' cannot be assigned to"
   errIteratorNotAllowed = "iterators can only be defined at the module's top level"
   errXNeedsReturnType = "$1 needs a return type"
@@ -460,13 +459,19 @@ proc semTuple(c: PContext, n: PNode, prev: PType): PType =
     var a = n[i]
     if (a.kind != nkIdentDefs): illFormedAst(a, c.config)
     checkMinSonsLen(a, 3, c.config)
-    if a[^2].kind != nkEmpty:
+    var hasDefaultField = a[^1].kind != nkEmpty
+    if hasDefaultField:
+      a[^1] = semConstExpr(c, a[^1])
+      typ = a[^1].typ
+    elif a[^2].kind != nkEmpty:
       typ = semTypeNode(c, a[^2], nil)
+      if c.graph.config.isDefined("nimPreviewRangeDefault") and typ.skipTypes(abstractInst).kind == tyRange:
+        a[^1] = newIntNode(nkIntLit, firstOrd(c.config, typ))
+        a[^1].typ = typ
+        hasDefaultField = true
     else:
       localError(c.config, a.info, errTypeExpected)
       typ = errorType(c)
-    if a[^1].kind != nkEmpty:
-      localError(c.config, a[^1].info, errInitHereNotAllowed)
     for j in 0..<a.len - 2:
       var field = newSymG(skField, a[j], c)
       field.typ = typ
@@ -475,7 +480,11 @@ proc semTuple(c: PContext, n: PNode, prev: PType): PType =
       if containsOrIncl(check, field.name.id):
         localError(c.config, a[j].info, "attempt to redefine: '" & field.name.s & "'")
       else:
-        result.n.add newSymNode(field)
+        let fSym = newSymNode(field)
+        if hasDefaultField:
+          fSym.sym.ast = a[^1]
+          fSym.sym.ast.flags.incl nfUseDefaultField
+        result.n.add fSym
         addSonSkipIntLit(result, typ, c.idgen)
       styleCheckDef(c, a[j].info, field)
       onDef(field.info, field)

diff --git a/tests/objects/tobject_default_value.nim b/tests/objects/tobject_default_value.nim
@@ -377,6 +377,17 @@ template main =
 
     doAssert hello[Default]()[^1].id == 1
 
+  block:
+    type
+      Default = tuple
+        id: int = 1
+
+      Default2 = tuple[id: int = 1]
+
+    var x: Default
+    proc hello(): Default2 = discard
+    doAssert hello().id == x.id
+
 
 proc main1 =
   var my = @[1, 2, 3, 4, 5]