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cmd/compile: simplify noding const declarations

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By grouping all the logic into constDecl, we're able to get rid of the
lastconst and lasttype globals, and simplify the logic slightly. Still
clunky, but much easier to reason about.

Change-Id: I446696c31084b3bfc1fd5d3651655a81ddd159ab
Reviewed-on: https://go-review.googlesource.com/36023
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Matthew Dempsky 2017-01-31 16:31:11 -08:00
parent 1cbc5aa529
commit b761b07bf9
3 changed files with 52 additions and 69 deletions
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76
src/cmd/compile/internal/gc/noder.go
View file

@ -117,9 +117,7 @@ func (p *noder) node() {
}
func (p *noder) decls(decls []syntax.Decl) (l []*Node) {
var lastConstGroup *syntax.Group
var lastConstRHS []*Node
var iotaVal int64
var cs constState
for _, decl := range decls {
p.lineno(decl)
@ -131,23 +129,7 @@ func (p *noder) decls(decls []syntax.Decl) (l []*Node) {
l = append(l, p.varDecl(decl)...)
case *syntax.ConstDecl:
// Tricky to handle golang.org/issue/15550 correctly.
if decl.Group == nil || decl.Group != lastConstGroup {
iotaVal = 0
lastConstRHS = nil
}
lastconst = lastConstRHS
l = append(l, p.constDecl(decl, iotaVal)...)
lastConstRHS = lastconst
lastconst = nil
iotaVal++
lastConstGroup = decl.Group
l = append(l, p.constDecl(decl, &cs)...)
case *syntax.TypeDecl:
l = append(l, p.typeDecl(decl))
@ -222,16 +204,62 @@ func (p *noder) varDecl(decl *syntax.VarDecl) []*Node {
return variter(names, typ, exprs)
}
func (p *noder) constDecl(decl *syntax.ConstDecl, iotaVal int64) []*Node {
type constState struct {
group *syntax.Group
typ *Node
values []*Node
iota int64
}
func (p *noder) constDecl(decl *syntax.ConstDecl, cs *constState) []*Node {
if decl.Group == nil || decl.Group != cs.group {
*cs = constState{
group: decl.Group,
}
}
names := p.declNames(decl.NameList)
typ := p.typeExprOrNil(decl.Type)
var exprs []*Node
var values []*Node
if decl.Values != nil {
exprs = p.exprList(decl.Values)
values = p.exprList(decl.Values)
cs.typ, cs.values = typ, values
} else {
if typ != nil {
yyerror("const declaration cannot have type without expression")
}
typ, values = cs.typ, cs.values
}
return constiter(names, typ, exprs, iotaVal)
var nn []*Node
for i, n := range names {
if i >= len(values) {
yyerror("missing value in const declaration")
break
}
v := values[i]
if decl.Values == nil {
v = treecopy(v, n.Pos)
}
n.Op = OLITERAL
declare(n, dclcontext)
n.Name.Param.Ntype = typ
n.Name.Defn = v
n.SetIota(cs.iota)
nn = append(nn, p.nod(decl, ODCLCONST, n, nil))
}
if len(values) > len(names) {
yyerror("extra expression in const declaration")
}
cs.iota++
return nn
}
func (p *noder) typeDecl(decl *syntax.TypeDecl) *Node {