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WIP implementation of except ExcType as ident syntax. Refs #3691.

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This commit is contained in:
Dominik Picheta 2017-02-01 00:32:56 +01:00
commit e8c46d29cd
4 changed files with 82 additions and 3 deletions
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37
compiler/semstmts.nim
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@ -263,36 +263,67 @@ proc semTry(c: PContext, n: PNode): PNode =
result = n
inc c.p.inTryStmt
checkMinSonsLen(n, 2)
var typ = commonTypeBegin
n.sons[0] = semExprBranchScope(c, n.sons[0])
typ = commonType(typ, n.sons[0].typ)
var check = initIntSet()
var last = sonsLen(n) - 1
for i in countup(1, last):
var a = n.sons[i]
checkMinSonsLen(a, 1)
var length = sonsLen(a)
if a.kind == nkExceptBranch:
# so that ``except [a, b, c]`` is supported:
if length == 2 and a.sons[0].kind == nkBracket:
a.sons[0..0] = a.sons[0].sons
length = a.sonsLen
# Iterate through each exception type in the except branch.
for j in countup(0, length-2):
var typ = semTypeNode(c, a.sons[j], nil)
var typeNode = a.sons[j] # e.g. `Exception`
var symbolNode: PNode = nil # e.g. `foobar`
# Handle the case where the `Exception as foobar` syntax is used.
if typeNode.kind == nkInfix:
typeNode = a.sons[j].sons[1]
symbolNode = a.sons[j].sons[2]
# Resolve the type ident into a PType.
var typ = semTypeNode(c, typeNode, nil)
if not symbolNode.isNil:
# Add the exception ident to the symbol table.
let symbol = newSymG(skLet, symbolNode, c)
symbol.typ = typ.toRef()
addDecl(c, symbol)
# Overwrite symbol in AST with the symbol in the symbol table.
let symNode = newNodeI(nkSym, typeNode.info)
symNode.sym = symbol
a.sons[j].sons[2] = symNode
if typ.kind == tyRef: typ = typ.sons[0]
if typ.kind != tyObject:
localError(a.sons[j].info, errExprCannotBeRaised)
a.sons[j] = newNodeI(nkType, a.sons[j].info)
a.sons[j].typ = typ
let newTypeNode = newNodeI(nkType, typeNode.info)
if symbolNode.isNil:
a.sons[j] = newTypeNode
a.sons[j].typ = typ
else:
a.sons[j].sons[1] = newTypeNode
a.sons[j].sons[1].typ = typ
if containsOrIncl(check, typ.id):
localError(a.sons[j].info, errExceptionAlreadyHandled)
elif a.kind != nkFinally:
illFormedAst(n)
# last child of an nkExcept/nkFinally branch is a statement:
a.sons[length-1] = semExprBranchScope(c, a.sons[length-1])
if a.kind != nkFinally: typ = commonType(typ, a.sons[length-1].typ)
else: dec last
dec c.p.inTryStmt
if isEmptyType(typ) or typ.kind == tyNil:
discardCheck(c, n.sons[0])