Files
opencloud/vendor/github.com/open-policy-agent/opa/ast/visit.go
2023-04-19 20:24:34 +02:00

784 lines
16 KiB
Go

// Copyright 2016 The OPA Authors. All rights reserved.
// Use of this source code is governed by an Apache2
// license that can be found in the LICENSE file.
package ast
// Visitor defines the interface for iterating AST elements. The Visit function
// can return a Visitor w which will be used to visit the children of the AST
// element v. If the Visit function returns nil, the children will not be
// visited.
// Deprecated: use GenericVisitor or another visitor implementation
type Visitor interface {
Visit(v interface{}) (w Visitor)
}
// BeforeAndAfterVisitor wraps Visitor to provide hooks for being called before
// and after the AST has been visited.
// Deprecated: use GenericVisitor or another visitor implementation
type BeforeAndAfterVisitor interface {
Visitor
Before(x interface{})
After(x interface{})
}
// Walk iterates the AST by calling the Visit function on the Visitor
// v for x before recursing.
// Deprecated: use GenericVisitor.Walk
func Walk(v Visitor, x interface{}) {
if bav, ok := v.(BeforeAndAfterVisitor); !ok {
walk(v, x)
} else {
bav.Before(x)
defer bav.After(x)
walk(bav, x)
}
}
// WalkBeforeAndAfter iterates the AST by calling the Visit function on the
// Visitor v for x before recursing.
// Deprecated: use GenericVisitor.Walk
func WalkBeforeAndAfter(v BeforeAndAfterVisitor, x interface{}) {
Walk(v, x)
}
func walk(v Visitor, x interface{}) {
w := v.Visit(x)
if w == nil {
return
}
switch x := x.(type) {
case *Module:
Walk(w, x.Package)
for i := range x.Imports {
Walk(w, x.Imports[i])
}
for i := range x.Rules {
Walk(w, x.Rules[i])
}
for i := range x.Annotations {
Walk(w, x.Annotations[i])
}
for i := range x.Comments {
Walk(w, x.Comments[i])
}
case *Package:
Walk(w, x.Path)
case *Import:
Walk(w, x.Path)
Walk(w, x.Alias)
case *Rule:
Walk(w, x.Head)
Walk(w, x.Body)
if x.Else != nil {
Walk(w, x.Else)
}
case *Head:
Walk(w, x.Name)
Walk(w, x.Args)
if x.Key != nil {
Walk(w, x.Key)
}
if x.Value != nil {
Walk(w, x.Value)
}
case Body:
for i := range x {
Walk(w, x[i])
}
case Args:
for i := range x {
Walk(w, x[i])
}
case *Expr:
switch ts := x.Terms.(type) {
case *Term, *SomeDecl, *Every:
Walk(w, ts)
case []*Term:
for i := range ts {
Walk(w, ts[i])
}
}
for i := range x.With {
Walk(w, x.With[i])
}
case *With:
Walk(w, x.Target)
Walk(w, x.Value)
case *Term:
Walk(w, x.Value)
case Ref:
for i := range x {
Walk(w, x[i])
}
case *object:
x.Foreach(func(k, vv *Term) {
Walk(w, k)
Walk(w, vv)
})
case *Array:
x.Foreach(func(t *Term) {
Walk(w, t)
})
case Set:
x.Foreach(func(t *Term) {
Walk(w, t)
})
case *ArrayComprehension:
Walk(w, x.Term)
Walk(w, x.Body)
case *ObjectComprehension:
Walk(w, x.Key)
Walk(w, x.Value)
Walk(w, x.Body)
case *SetComprehension:
Walk(w, x.Term)
Walk(w, x.Body)
case Call:
for i := range x {
Walk(w, x[i])
}
case *Every:
if x.Key != nil {
Walk(w, x.Key)
}
Walk(w, x.Value)
Walk(w, x.Domain)
Walk(w, x.Body)
case *SomeDecl:
for i := range x.Symbols {
Walk(w, x.Symbols[i])
}
}
}
// WalkVars calls the function f on all vars under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkVars(x interface{}, f func(Var) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if v, ok := x.(Var); ok {
return f(v)
}
return false
}}
vis.Walk(x)
}
// WalkClosures calls the function f on all closures under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkClosures(x interface{}, f func(interface{}) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
switch x := x.(type) {
case *ArrayComprehension, *ObjectComprehension, *SetComprehension, *Every:
return f(x)
}
return false
}}
vis.Walk(x)
}
// WalkRefs calls the function f on all references under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkRefs(x interface{}, f func(Ref) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if r, ok := x.(Ref); ok {
return f(r)
}
return false
}}
vis.Walk(x)
}
// WalkTerms calls the function f on all terms under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkTerms(x interface{}, f func(*Term) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if term, ok := x.(*Term); ok {
return f(term)
}
return false
}}
vis.Walk(x)
}
// WalkWiths calls the function f on all with modifiers under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkWiths(x interface{}, f func(*With) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if w, ok := x.(*With); ok {
return f(w)
}
return false
}}
vis.Walk(x)
}
// WalkExprs calls the function f on all expressions under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkExprs(x interface{}, f func(*Expr) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if r, ok := x.(*Expr); ok {
return f(r)
}
return false
}}
vis.Walk(x)
}
// WalkBodies calls the function f on all bodies under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkBodies(x interface{}, f func(Body) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if b, ok := x.(Body); ok {
return f(b)
}
return false
}}
vis.Walk(x)
}
// WalkRules calls the function f on all rules under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkRules(x interface{}, f func(*Rule) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if r, ok := x.(*Rule); ok {
stop := f(r)
// NOTE(tsandall): since rules cannot be embedded inside of queries
// we can stop early if there is no else block.
if stop || r.Else == nil {
return true
}
}
return false
}}
vis.Walk(x)
}
// WalkNodes calls the function f on all nodes under x. If the function f
// returns true, AST nodes under the last node will not be visited.
func WalkNodes(x interface{}, f func(Node) bool) {
vis := &GenericVisitor{func(x interface{}) bool {
if n, ok := x.(Node); ok {
return f(n)
}
return false
}}
vis.Walk(x)
}
// GenericVisitor provides a utility to walk over AST nodes using a
// closure. If the closure returns true, the visitor will not walk
// over AST nodes under x.
type GenericVisitor struct {
f func(x interface{}) bool
}
// NewGenericVisitor returns a new GenericVisitor that will invoke the function
// f on AST nodes.
func NewGenericVisitor(f func(x interface{}) bool) *GenericVisitor {
return &GenericVisitor{f}
}
// Walk iterates the AST by calling the function f on the
// GenericVisitor before recursing. Contrary to the generic Walk, this
// does not require allocating the visitor from heap.
func (vis *GenericVisitor) Walk(x interface{}) {
if vis.f(x) {
return
}
switch x := x.(type) {
case *Module:
vis.Walk(x.Package)
for i := range x.Imports {
vis.Walk(x.Imports[i])
}
for i := range x.Rules {
vis.Walk(x.Rules[i])
}
for i := range x.Annotations {
vis.Walk(x.Annotations[i])
}
for i := range x.Comments {
vis.Walk(x.Comments[i])
}
case *Package:
vis.Walk(x.Path)
case *Import:
vis.Walk(x.Path)
vis.Walk(x.Alias)
case *Rule:
vis.Walk(x.Head)
vis.Walk(x.Body)
if x.Else != nil {
vis.Walk(x.Else)
}
case *Head:
vis.Walk(x.Name)
vis.Walk(x.Args)
if x.Key != nil {
vis.Walk(x.Key)
}
if x.Value != nil {
vis.Walk(x.Value)
}
case Body:
for i := range x {
vis.Walk(x[i])
}
case Args:
for i := range x {
vis.Walk(x[i])
}
case *Expr:
switch ts := x.Terms.(type) {
case *Term, *SomeDecl, *Every:
vis.Walk(ts)
case []*Term:
for i := range ts {
vis.Walk(ts[i])
}
}
for i := range x.With {
vis.Walk(x.With[i])
}
case *With:
vis.Walk(x.Target)
vis.Walk(x.Value)
case *Term:
vis.Walk(x.Value)
case Ref:
for i := range x {
vis.Walk(x[i])
}
case *object:
x.Foreach(func(k, v *Term) {
vis.Walk(k)
vis.Walk(x.Get(k))
})
case Object:
x.Foreach(func(k, v *Term) {
vis.Walk(k)
vis.Walk(x.Get(k))
})
case *Array:
x.Foreach(func(t *Term) {
vis.Walk(t)
})
case Set:
xSlice := x.Slice()
for i := range xSlice {
vis.Walk(xSlice[i])
}
case *ArrayComprehension:
vis.Walk(x.Term)
vis.Walk(x.Body)
case *ObjectComprehension:
vis.Walk(x.Key)
vis.Walk(x.Value)
vis.Walk(x.Body)
case *SetComprehension:
vis.Walk(x.Term)
vis.Walk(x.Body)
case Call:
for i := range x {
vis.Walk(x[i])
}
case *Every:
if x.Key != nil {
vis.Walk(x.Key)
}
vis.Walk(x.Value)
vis.Walk(x.Domain)
vis.Walk(x.Body)
case *SomeDecl:
for i := range x.Symbols {
vis.Walk(x.Symbols[i])
}
}
}
// BeforeAfterVisitor provides a utility to walk over AST nodes using
// closures. If the before closure returns true, the visitor will not
// walk over AST nodes under x. The after closure is invoked always
// after visiting a node.
type BeforeAfterVisitor struct {
before func(x interface{}) bool
after func(x interface{})
}
// NewBeforeAfterVisitor returns a new BeforeAndAfterVisitor that
// will invoke the functions before and after AST nodes.
func NewBeforeAfterVisitor(before func(x interface{}) bool, after func(x interface{})) *BeforeAfterVisitor {
return &BeforeAfterVisitor{before, after}
}
// Walk iterates the AST by calling the functions on the
// BeforeAndAfterVisitor before and after recursing. Contrary to the
// generic Walk, this does not require allocating the visitor from
// heap.
func (vis *BeforeAfterVisitor) Walk(x interface{}) {
defer vis.after(x)
if vis.before(x) {
return
}
switch x := x.(type) {
case *Module:
vis.Walk(x.Package)
for i := range x.Imports {
vis.Walk(x.Imports[i])
}
for i := range x.Rules {
vis.Walk(x.Rules[i])
}
for i := range x.Annotations {
vis.Walk(x.Annotations[i])
}
for i := range x.Comments {
vis.Walk(x.Comments[i])
}
case *Package:
vis.Walk(x.Path)
case *Import:
vis.Walk(x.Path)
vis.Walk(x.Alias)
case *Rule:
vis.Walk(x.Head)
vis.Walk(x.Body)
if x.Else != nil {
vis.Walk(x.Else)
}
case *Head:
if len(x.Reference) > 0 {
vis.Walk(x.Reference)
} else {
vis.Walk(x.Name)
if x.Key != nil {
vis.Walk(x.Key)
}
}
vis.Walk(x.Args)
if x.Value != nil {
vis.Walk(x.Value)
}
case Body:
for i := range x {
vis.Walk(x[i])
}
case Args:
for i := range x {
vis.Walk(x[i])
}
case *Expr:
switch ts := x.Terms.(type) {
case *Term, *SomeDecl, *Every:
vis.Walk(ts)
case []*Term:
for i := range ts {
vis.Walk(ts[i])
}
}
for i := range x.With {
vis.Walk(x.With[i])
}
case *With:
vis.Walk(x.Target)
vis.Walk(x.Value)
case *Term:
vis.Walk(x.Value)
case Ref:
for i := range x {
vis.Walk(x[i])
}
case *object:
x.Foreach(func(k, v *Term) {
vis.Walk(k)
vis.Walk(x.Get(k))
})
case Object:
x.Foreach(func(k, v *Term) {
vis.Walk(k)
vis.Walk(x.Get(k))
})
case *Array:
x.Foreach(func(t *Term) {
vis.Walk(t)
})
case Set:
xSlice := x.Slice()
for i := range xSlice {
vis.Walk(xSlice[i])
}
case *ArrayComprehension:
vis.Walk(x.Term)
vis.Walk(x.Body)
case *ObjectComprehension:
vis.Walk(x.Key)
vis.Walk(x.Value)
vis.Walk(x.Body)
case *SetComprehension:
vis.Walk(x.Term)
vis.Walk(x.Body)
case Call:
for i := range x {
vis.Walk(x[i])
}
case *Every:
if x.Key != nil {
vis.Walk(x.Key)
}
vis.Walk(x.Value)
vis.Walk(x.Domain)
vis.Walk(x.Body)
case *SomeDecl:
for i := range x.Symbols {
vis.Walk(x.Symbols[i])
}
}
}
// VarVisitor walks AST nodes under a given node and collects all encountered
// variables. The collected variables can be controlled by specifying
// VarVisitorParams when creating the visitor.
type VarVisitor struct {
params VarVisitorParams
vars VarSet
}
// VarVisitorParams contains settings for a VarVisitor.
type VarVisitorParams struct {
SkipRefHead bool
SkipRefCallHead bool
SkipObjectKeys bool
SkipClosures bool
SkipWithTarget bool
SkipSets bool
}
// NewVarVisitor returns a new VarVisitor object.
func NewVarVisitor() *VarVisitor {
return &VarVisitor{
vars: NewVarSet(),
}
}
// WithParams sets the parameters in params on vis.
func (vis *VarVisitor) WithParams(params VarVisitorParams) *VarVisitor {
vis.params = params
return vis
}
// Vars returns a VarSet that contains collected vars.
func (vis *VarVisitor) Vars() VarSet {
return vis.vars
}
// visit determines if the VarVisitor will recurse into x: if it returns `true`,
// the visitor will _skip_ that branch of the AST
func (vis *VarVisitor) visit(v interface{}) bool {
if vis.params.SkipObjectKeys {
if o, ok := v.(Object); ok {
o.Foreach(func(k, v *Term) {
vis.Walk(v)
})
return true
}
}
if vis.params.SkipRefHead {
if r, ok := v.(Ref); ok {
rSlice := r[1:]
for i := range rSlice {
vis.Walk(rSlice[i])
}
return true
}
}
if vis.params.SkipClosures {
switch v := v.(type) {
case *ArrayComprehension, *ObjectComprehension, *SetComprehension:
return true
case *Expr:
if ev, ok := v.Terms.(*Every); ok {
vis.Walk(ev.Domain)
// We're _not_ walking ev.Body -- that's the closure here
return true
}
}
}
if vis.params.SkipWithTarget {
if v, ok := v.(*With); ok {
vis.Walk(v.Value)
return true
}
}
if vis.params.SkipSets {
if _, ok := v.(Set); ok {
return true
}
}
if vis.params.SkipRefCallHead {
switch v := v.(type) {
case *Expr:
if terms, ok := v.Terms.([]*Term); ok {
termSlice := terms[0].Value.(Ref)[1:]
for i := range termSlice {
vis.Walk(termSlice[i])
}
for i := 1; i < len(terms); i++ {
vis.Walk(terms[i])
}
for i := range v.With {
vis.Walk(v.With[i])
}
return true
}
case Call:
operator := v[0].Value.(Ref)
for i := 1; i < len(operator); i++ {
vis.Walk(operator[i])
}
for i := 1; i < len(v); i++ {
vis.Walk(v[i])
}
return true
case *With:
if ref, ok := v.Target.Value.(Ref); ok {
refSlice := ref[1:]
for i := range refSlice {
vis.Walk(refSlice[i])
}
}
if ref, ok := v.Value.Value.(Ref); ok {
refSlice := ref[1:]
for i := range refSlice {
vis.Walk(refSlice[i])
}
} else {
vis.Walk(v.Value)
}
return true
}
}
if v, ok := v.(Var); ok {
vis.vars.Add(v)
}
return false
}
// Walk iterates the AST by calling the function f on the
// GenericVisitor before recursing. Contrary to the generic Walk, this
// does not require allocating the visitor from heap.
func (vis *VarVisitor) Walk(x interface{}) {
if vis.visit(x) {
return
}
switch x := x.(type) {
case *Module:
vis.Walk(x.Package)
for i := range x.Imports {
vis.Walk(x.Imports[i])
}
for i := range x.Rules {
vis.Walk(x.Rules[i])
}
for i := range x.Comments {
vis.Walk(x.Comments[i])
}
case *Package:
vis.Walk(x.Path)
case *Import:
vis.Walk(x.Path)
vis.Walk(x.Alias)
case *Rule:
vis.Walk(x.Head)
vis.Walk(x.Body)
if x.Else != nil {
vis.Walk(x.Else)
}
case *Head:
if len(x.Reference) > 0 {
vis.Walk(x.Reference)
} else {
vis.Walk(x.Name)
if x.Key != nil {
vis.Walk(x.Key)
}
}
vis.Walk(x.Args)
if x.Value != nil {
vis.Walk(x.Value)
}
case Body:
for i := range x {
vis.Walk(x[i])
}
case Args:
for i := range x {
vis.Walk(x[i])
}
case *Expr:
switch ts := x.Terms.(type) {
case *Term, *SomeDecl, *Every:
vis.Walk(ts)
case []*Term:
for i := range ts {
vis.Walk(ts[i])
}
}
for i := range x.With {
vis.Walk(x.With[i])
}
case *With:
vis.Walk(x.Target)
vis.Walk(x.Value)
case *Term:
vis.Walk(x.Value)
case Ref:
for i := range x {
vis.Walk(x[i])
}
case *object:
x.Foreach(func(k, v *Term) {
vis.Walk(k)
vis.Walk(x.Get(k))
})
case *Array:
x.Foreach(func(t *Term) {
vis.Walk(t)
})
case Set:
xSlice := x.Slice()
for i := range xSlice {
vis.Walk(xSlice[i])
}
case *ArrayComprehension:
vis.Walk(x.Term)
vis.Walk(x.Body)
case *ObjectComprehension:
vis.Walk(x.Key)
vis.Walk(x.Value)
vis.Walk(x.Body)
case *SetComprehension:
vis.Walk(x.Term)
vis.Walk(x.Body)
case Call:
for i := range x {
vis.Walk(x[i])
}
case *Every:
if x.Key != nil {
vis.Walk(x.Key)
}
vis.Walk(x.Value)
vis.Walk(x.Domain)
vis.Walk(x.Body)
case *SomeDecl:
for i := range x.Symbols {
vis.Walk(x.Symbols[i])
}
}
}