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package analysis
import (
"go/ast"
"go/token"
"go/types"
)
func EscapingObjects(n ast.Node, info *types.Info) []*types.Var {
v := escapeAnalysis{
info: info,
escaping: make(map[*types.Var]bool),
topScope: info.Scopes[n],
bottomScopes: make(map[*types.Scope]bool),
}
ast.Walk(&v, n)
var list []*types.Var
for obj := range v.escaping {
list = append(list, obj)
}
return list
}
type escapeAnalysis struct {
info *types.Info
escaping map[*types.Var]bool
topScope *types.Scope
bottomScopes map[*types.Scope]bool
}
func (v *escapeAnalysis) Visit(node ast.Node) (w ast.Visitor) {
// huge overapproximation
switch n := node.(type) {
case *ast.UnaryExpr:
if n.Op == token.AND {
if _, ok := n.X.(*ast.Ident); ok {
return &escapingObjectCollector{v}
}
}
case *ast.FuncLit:
v.bottomScopes[v.info.Scopes[n.Type]] = true
return &escapingObjectCollector{v}
case *ast.ForStmt:
v.bottomScopes[v.info.Scopes[n.Body]] = true
case *ast.RangeStmt:
v.bottomScopes[v.info.Scopes[n.Body]] = true
}
return v
}
type escapingObjectCollector struct {
analysis *escapeAnalysis
}
func (v *escapingObjectCollector) Visit(node ast.Node) (w ast.Visitor) {
if id, ok := node.(*ast.Ident); ok {
if obj, ok := v.analysis.info.Uses[id].(*types.Var); ok {
for s := obj.Parent(); s != nil; s = s.Parent() {
if s == v.analysis.topScope {
v.analysis.escaping[obj] = true
break
}
if v.analysis.bottomScopes[s] {
break
}
}
}
}
return v
}
|
