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#
#
# The Nimrod Compiler
# (c) Copyright 2013 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module implements destructors.
# special marker values that indicates that we are
# 1) AnalyzingDestructor: currently analyzing the type for destructor
# generation (needed for recursive types)
# 2) DestructorIsTrivial: completed the analysis before and determined
# that the type has a trivial destructor
var analyzingDestructor, destructorIsTrivial: PSym
new(analyzingDestructor)
new(destructorIsTrivial)
var
destructorName = getIdent"destroy_"
destructorParam = getIdent"this_"
destructorPragma = newIdentNode(getIdent"destructor", unknownLineInfo())
rangeDestructorProc*: PSym
proc instantiateDestructor(c: PContext, typ: PType): bool
proc doDestructorStuff(c: PContext, s: PSym, n: PNode) =
let t = s.typ.sons[1].skipTypes({tyVar})
t.destructor = s
# automatically insert calls to base classes' destructors
if n.sons[bodyPos].kind != nkEmpty:
for i in countup(0, t.sonsLen - 1):
# when inheriting directly from object
# there will be a single nil son
if t.sons[i] == nil: continue
if instantiateDestructor(c, t.sons[i]):
n.sons[bodyPos].addSon(newNode(nkCall, t.sym.info, @[
useSym(t.sons[i].destructor),
n.sons[paramsPos][1][0]]))
proc destroyField(c: PContext, field: PSym, holder: PNode): PNode =
if instantiateDestructor(c, field.typ):
result = newNode(nkCall, field.info, @[
useSym(field.typ.destructor),
newNode(nkDotExpr, field.info, @[holder, useSym(field)])])
proc destroyCase(c: PContext, n: PNode, holder: PNode): PNode =
var nonTrivialFields = 0
result = newNode(nkCaseStmt, n.info, @[])
# case x.kind
result.addSon(newNode(nkDotExpr, n.info, @[holder, n.sons[0]]))
for i in countup(1, n.len - 1):
# of A, B:
var caseBranch = newNode(n[i].kind, n[i].info, n[i].sons[0 .. -2])
let recList = n[i].lastSon
var destroyRecList = newNode(nkStmtList, n[i].info, @[])
template addField(f: expr): stmt =
let stmt = destroyField(c, f, holder)
if stmt != nil:
destroyRecList.addSon(stmt)
inc nonTrivialFields
case recList.kind
of nkSym:
addField(recList.sym)
of nkRecList:
for j in countup(0, recList.len - 1):
addField(recList[j].sym)
else:
internalAssert false
caseBranch.addSon(destroyRecList)
result.addSon(caseBranch)
# maybe no fields were destroyed?
if nonTrivialFields == 0:
result = nil
proc generateDestructor(c: PContext, t: PType): PNode =
## generate a destructor for a user-defined object or tuple type
## returns nil if the destructor turns out to be trivial
template addLine(e: expr): stmt =
if result == nil: result = newNode(nkStmtList)
result.addSon(e)
# XXX: This may be true for some C-imported types such as
# Tposix_spawnattr
if t.n == nil or t.n.sons == nil: return
internalAssert t.n.kind == nkRecList
let destructedObj = newIdentNode(destructorParam, unknownLineInfo())
# call the destructods of all fields
for s in countup(0, t.n.sons.len - 1):
case t.n.sons[s].kind
of nkRecCase:
let stmt = destroyCase(c, t.n.sons[s], destructedObj)
if stmt != nil: addLine(stmt)
of nkSym:
let stmt = destroyField(c, t.n.sons[s].sym, destructedObj)
if stmt != nil: addLine(stmt)
else:
internalAssert false
# base classes' destructors will be automatically called by
# semProcAux for both auto-generated and user-defined destructors
proc instantiateDestructor(c: PContext, typ: PType): bool =
# returns true if the type already had a user-defined
# destructor or if the compiler generated a default
# member-wise one
var t = skipTypes(typ, {tyConst, tyMutable})
if t.destructor != nil:
# XXX: This is not entirely correct for recursive types, but we need
# it temporarily to hide the "destroy is already defined" problem
return t.destructor notin [analyzingDestructor, destructorIsTrivial]
case t.kind
of tySequence, tyArray, tyArrayConstr, tyOpenArray, tyVarargs:
if instantiateDestructor(c, t.sons[0]):
if rangeDestructorProc == nil:
rangeDestructorProc = searchInScopes(c, getIdent"nimDestroyRange")
t.destructor = rangeDestructorProc
return true
else:
return false
of tyTuple, tyObject:
t.destructor = analyzingDestructor
let generated = generateDestructor(c, t)
if generated != nil:
internalAssert t.sym != nil
var i = t.sym.info
let fullDef = newNode(nkProcDef, i, @[
newIdentNode(destructorName, i),
emptyNode,
emptyNode,
newNode(nkFormalParams, i, @[
emptyNode,
newNode(nkIdentDefs, i, @[
newIdentNode(destructorParam, i),
useSym(t.sym),
emptyNode]),
]),
newNode(nkPragma, i, @[destructorPragma]),
emptyNode,
generated
])
discard semProc(c, fullDef)
internalAssert t.destructor != nil
return true
else:
t.destructor = destructorIsTrivial
return false
else:
return false
proc insertDestructors(c: PContext,
varSection: PNode): tuple[outer, inner: PNode] =
# Accepts a var or let section.
#
# When a var section has variables with destructors
# the var section is split up and finally blocks are inserted
# immediately after all "destructable" vars
#
# In case there were no destrucable variables, the proc returns
# (nil, nil) and the enclosing stmt-list requires no modifications.
#
# Otherwise, after the try blocks are created, the rest of the enclosing
# stmt-list should be inserted in the most `inner` such block (corresponding
# to the last variable).
#
# `outer` is a statement list that should replace the original var section.
# It will include the new truncated var section followed by the outermost
# try block.
let totalVars = varSection.sonsLen
for j in countup(0, totalVars - 1):
let
varId = varSection[j][0]
varTyp = varId.sym.typ
info = varId.info
if varTyp != nil and instantiateDestructor(c, varTyp) and
sfGlobal notin varId.sym.flags:
var tryStmt = newNodeI(nkTryStmt, info)
if j < totalVars - 1:
var remainingVars = newNodeI(varSection.kind, info)
remainingVars.sons = varSection.sons[(j+1)..(-1)]
let (outer, inner) = insertDestructors(c, remainingVars)
if outer != nil:
tryStmt.addSon(outer)
result.inner = inner
else:
result.inner = newNodeI(nkStmtList, info)
result.inner.addSon(remainingVars)
tryStmt.addSon(result.inner)
else:
result.inner = newNodeI(nkStmtList, info)
tryStmt.addSon(result.inner)
tryStmt.addSon(
newNode(nkFinally, info, @[
semStmt(c, newNode(nkCall, info, @[
useSym(varTyp.destructor),
useSym(varId.sym)]))]))
result.outer = newNodeI(nkStmtList, info)
varSection.sons.setLen(j+1)
result.outer.addSon(varSection)
result.outer.addSon(tryStmt)
return
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