ceph-csi/vendor/github.com/google/cel-go/checker/checker.go

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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package checker defines functions to type-checked a parsed expression
// against a set of identifier and function declarations.
package checker
import (
"fmt"
"reflect"
"github.com/google/cel-go/checker/decls"
"github.com/google/cel-go/common"
"github.com/google/cel-go/common/containers"
"github.com/google/cel-go/common/types/ref"
"google.golang.org/protobuf/proto"
exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
)
type checker struct {
env *Env
errors *typeErrors
mappings *mapping
freeTypeVarCounter int
sourceInfo *exprpb.SourceInfo
types map[int64]*exprpb.Type
references map[int64]*exprpb.Reference
}
// Check performs type checking, giving a typed AST.
// The input is a ParsedExpr proto and an env which encapsulates
// type binding of variables, declarations of built-in functions,
// descriptions of protocol buffers, and a registry for errors.
// Returns a CheckedExpr proto, which might not be usable if
// there are errors in the error registry.
func Check(parsedExpr *exprpb.ParsedExpr,
source common.Source,
env *Env) (*exprpb.CheckedExpr, *common.Errors) {
c := checker{
env: env,
errors: &typeErrors{common.NewErrors(source)},
mappings: newMapping(),
freeTypeVarCounter: 0,
sourceInfo: parsedExpr.GetSourceInfo(),
types: make(map[int64]*exprpb.Type),
references: make(map[int64]*exprpb.Reference),
}
c.check(parsedExpr.GetExpr())
// Walk over the final type map substituting any type parameters either by their bound value or
// by DYN.
m := make(map[int64]*exprpb.Type)
for k, v := range c.types {
m[k] = substitute(c.mappings, v, true)
}
return &exprpb.CheckedExpr{
Expr: parsedExpr.GetExpr(),
SourceInfo: parsedExpr.GetSourceInfo(),
TypeMap: m,
ReferenceMap: c.references,
}, c.errors.Errors
}
func (c *checker) check(e *exprpb.Expr) {
if e == nil {
return
}
switch e.GetExprKind().(type) {
case *exprpb.Expr_ConstExpr:
literal := e.GetConstExpr()
switch literal.GetConstantKind().(type) {
case *exprpb.Constant_BoolValue:
c.checkBoolLiteral(e)
case *exprpb.Constant_BytesValue:
c.checkBytesLiteral(e)
case *exprpb.Constant_DoubleValue:
c.checkDoubleLiteral(e)
case *exprpb.Constant_Int64Value:
c.checkInt64Literal(e)
case *exprpb.Constant_NullValue:
c.checkNullLiteral(e)
case *exprpb.Constant_StringValue:
c.checkStringLiteral(e)
case *exprpb.Constant_Uint64Value:
c.checkUint64Literal(e)
}
case *exprpb.Expr_IdentExpr:
c.checkIdent(e)
case *exprpb.Expr_SelectExpr:
c.checkSelect(e)
case *exprpb.Expr_CallExpr:
c.checkCall(e)
case *exprpb.Expr_ListExpr:
c.checkCreateList(e)
case *exprpb.Expr_StructExpr:
c.checkCreateStruct(e)
case *exprpb.Expr_ComprehensionExpr:
c.checkComprehension(e)
default:
c.errors.ReportError(
c.location(e), "Unrecognized ast type: %v", reflect.TypeOf(e))
}
}
func (c *checker) checkInt64Literal(e *exprpb.Expr) {
c.setType(e, decls.Int)
}
func (c *checker) checkUint64Literal(e *exprpb.Expr) {
c.setType(e, decls.Uint)
}
func (c *checker) checkStringLiteral(e *exprpb.Expr) {
c.setType(e, decls.String)
}
func (c *checker) checkBytesLiteral(e *exprpb.Expr) {
c.setType(e, decls.Bytes)
}
func (c *checker) checkDoubleLiteral(e *exprpb.Expr) {
c.setType(e, decls.Double)
}
func (c *checker) checkBoolLiteral(e *exprpb.Expr) {
c.setType(e, decls.Bool)
}
func (c *checker) checkNullLiteral(e *exprpb.Expr) {
c.setType(e, decls.Null)
}
func (c *checker) checkIdent(e *exprpb.Expr) {
identExpr := e.GetIdentExpr()
// Check to see if the identifier is declared.
if ident := c.env.LookupIdent(identExpr.GetName()); ident != nil {
c.setType(e, ident.GetIdent().GetType())
c.setReference(e, newIdentReference(ident.GetName(), ident.GetIdent().GetValue()))
// Overwrite the identifier with its fully qualified name.
identExpr.Name = ident.GetName()
return
}
c.setType(e, decls.Error)
c.errors.undeclaredReference(
c.location(e), c.env.container.Name(), identExpr.GetName())
}
func (c *checker) checkSelect(e *exprpb.Expr) {
sel := e.GetSelectExpr()
// Before traversing down the tree, try to interpret as qualified name.
qname, found := containers.ToQualifiedName(e)
if found {
ident := c.env.LookupIdent(qname)
if ident != nil {
// We don't check for a TestOnly expression here since the `found` result is
// always going to be false for TestOnly expressions.
// Rewrite the node to be a variable reference to the resolved fully-qualified
// variable name.
c.setType(e, ident.GetIdent().Type)
c.setReference(e, newIdentReference(ident.GetName(), ident.GetIdent().Value))
identName := ident.GetName()
e.ExprKind = &exprpb.Expr_IdentExpr{
IdentExpr: &exprpb.Expr_Ident{
Name: identName,
},
}
return
}
}
// Interpret as field selection, first traversing down the operand.
c.check(sel.GetOperand())
targetType := substitute(c.mappings, c.getType(sel.GetOperand()), false)
// Assume error type by default as most types do not support field selection.
resultType := decls.Error
switch kindOf(targetType) {
case kindMap:
// Maps yield their value type as the selection result type.
mapType := targetType.GetMapType()
resultType = mapType.GetValueType()
case kindObject:
// Objects yield their field type declaration as the selection result type, but only if
// the field is defined.
messageType := targetType
if fieldType, found := c.lookupFieldType(c.location(e), messageType.GetMessageType(), sel.GetField()); found {
resultType = fieldType.Type
}
case kindTypeParam:
// Set the operand type to DYN to prevent assignment to a potentially incorrect type
// at a later point in type-checking. The isAssignable call will update the type
// substitutions for the type param under the covers.
c.isAssignable(decls.Dyn, targetType)
// Also, set the result type to DYN.
resultType = decls.Dyn
default:
// Dynamic / error values are treated as DYN type. Errors are handled this way as well
// in order to allow forward progress on the check.
if isDynOrError(targetType) {
resultType = decls.Dyn
} else {
c.errors.typeDoesNotSupportFieldSelection(c.location(e), targetType)
}
}
if sel.TestOnly {
resultType = decls.Bool
}
c.setType(e, substitute(c.mappings, resultType, false))
}
func (c *checker) checkCall(e *exprpb.Expr) {
// Note: similar logic exists within the `interpreter/planner.go`. If making changes here
// please consider the impact on planner.go and consolidate implementations or mirror code
// as appropriate.
call := e.GetCallExpr()
target := call.GetTarget()
args := call.GetArgs()
fnName := call.GetFunction()
// Traverse arguments.
for _, arg := range args {
c.check(arg)
}
// Regular static call with simple name.
if target == nil {
// Check for the existence of the function.
fn := c.env.LookupFunction(fnName)
if fn == nil {
c.errors.undeclaredReference(
c.location(e), c.env.container.Name(), fnName)
c.setType(e, decls.Error)
return
}
// Overwrite the function name with its fully qualified resolved name.
call.Function = fn.GetName()
// Check to see whether the overload resolves.
c.resolveOverloadOrError(c.location(e), e, fn, nil, args)
return
}
// If a receiver 'target' is present, it may either be a receiver function, or a namespaced
// function, but not both. Given a.b.c() either a.b.c is a function or c is a function with
// target a.b.
//
// Check whether the target is a namespaced function name.
qualifiedPrefix, maybeQualified := containers.ToQualifiedName(target)
if maybeQualified {
maybeQualifiedName := qualifiedPrefix + "." + fnName
fn := c.env.LookupFunction(maybeQualifiedName)
if fn != nil {
// The function name is namespaced and so preserving the target operand would
// be an inaccurate representation of the desired evaluation behavior.
// Overwrite with fully-qualified resolved function name sans receiver target.
call.Target = nil
call.Function = fn.GetName()
c.resolveOverloadOrError(c.location(e), e, fn, nil, args)
return
}
}
// Regular instance call.
c.check(call.Target)
fn := c.env.LookupFunction(fnName)
// Function found, attempt overload resolution.
if fn != nil {
c.resolveOverloadOrError(c.location(e), e, fn, target, args)
return
}
// Function name not declared, record error.
c.errors.undeclaredReference(c.location(e), c.env.container.Name(), fnName)
}
func (c *checker) resolveOverloadOrError(
loc common.Location,
e *exprpb.Expr,
fn *exprpb.Decl, target *exprpb.Expr, args []*exprpb.Expr) {
// Attempt to resolve the overload.
resolution := c.resolveOverload(loc, fn, target, args)
// No such overload, error noted in the resolveOverload call, type recorded here.
if resolution == nil {
c.setType(e, decls.Error)
return
}
// Overload found.
c.setType(e, resolution.Type)
c.setReference(e, resolution.Reference)
}
func (c *checker) resolveOverload(
loc common.Location,
fn *exprpb.Decl, target *exprpb.Expr, args []*exprpb.Expr) *overloadResolution {
var argTypes []*exprpb.Type
if target != nil {
argTypes = append(argTypes, c.getType(target))
}
for _, arg := range args {
argTypes = append(argTypes, c.getType(arg))
}
var resultType *exprpb.Type
var checkedRef *exprpb.Reference
for _, overload := range fn.GetFunction().GetOverloads() {
// Determine whether the overload is currently considered.
if c.env.isOverloadDisabled(overload.GetOverloadId()) {
continue
}
// Ensure the call style for the overload matches.
if (target == nil && overload.GetIsInstanceFunction()) ||
(target != nil && !overload.GetIsInstanceFunction()) {
// not a compatible call style.
continue
}
overloadType := decls.NewFunctionType(overload.ResultType, overload.Params...)
if len(overload.GetTypeParams()) > 0 {
// Instantiate overload's type with fresh type variables.
substitutions := newMapping()
for _, typePar := range overload.GetTypeParams() {
substitutions.add(decls.NewTypeParamType(typePar), c.newTypeVar())
}
overloadType = substitute(substitutions, overloadType, false)
}
candidateArgTypes := overloadType.GetFunction().GetArgTypes()
if c.isAssignableList(argTypes, candidateArgTypes) {
if checkedRef == nil {
checkedRef = newFunctionReference(overload.GetOverloadId())
} else {
checkedRef.OverloadId = append(checkedRef.GetOverloadId(), overload.GetOverloadId())
}
// First matching overload, determines result type.
fnResultType := substitute(c.mappings, overloadType.GetFunction().GetResultType(), false)
if resultType == nil {
resultType = fnResultType
} else if !isDyn(resultType) && !proto.Equal(fnResultType, resultType) {
resultType = decls.Dyn
}
}
}
if resultType == nil {
c.errors.noMatchingOverload(loc, fn.GetName(), argTypes, target != nil)
resultType = decls.Error
return nil
}
return newResolution(checkedRef, resultType)
}
func (c *checker) checkCreateList(e *exprpb.Expr) {
create := e.GetListExpr()
var elemType *exprpb.Type
for _, e := range create.GetElements() {
c.check(e)
elemType = c.joinTypes(c.location(e), elemType, c.getType(e))
}
if elemType == nil {
// If the list is empty, assign free type var to elem type.
elemType = c.newTypeVar()
}
c.setType(e, decls.NewListType(elemType))
}
func (c *checker) checkCreateStruct(e *exprpb.Expr) {
str := e.GetStructExpr()
if str.GetMessageName() != "" {
c.checkCreateMessage(e)
} else {
c.checkCreateMap(e)
}
}
func (c *checker) checkCreateMap(e *exprpb.Expr) {
mapVal := e.GetStructExpr()
var keyType *exprpb.Type
var valueType *exprpb.Type
for _, ent := range mapVal.GetEntries() {
key := ent.GetMapKey()
c.check(key)
keyType = c.joinTypes(c.location(key), keyType, c.getType(key))
c.check(ent.Value)
valueType = c.joinTypes(c.location(ent.Value), valueType, c.getType(ent.Value))
}
if keyType == nil {
// If the map is empty, assign free type variables to typeKey and value type.
keyType = c.newTypeVar()
valueType = c.newTypeVar()
}
c.setType(e, decls.NewMapType(keyType, valueType))
}
func (c *checker) checkCreateMessage(e *exprpb.Expr) {
msgVal := e.GetStructExpr()
// Determine the type of the message.
messageType := decls.Error
decl := c.env.LookupIdent(msgVal.GetMessageName())
if decl == nil {
c.errors.undeclaredReference(
c.location(e), c.env.container.Name(), msgVal.GetMessageName())
return
}
// Ensure the type name is fully qualified in the AST.
msgVal.MessageName = decl.GetName()
c.setReference(e, newIdentReference(decl.GetName(), nil))
ident := decl.GetIdent()
identKind := kindOf(ident.GetType())
if identKind != kindError {
if identKind != kindType {
c.errors.notAType(c.location(e), ident.GetType())
} else {
messageType = ident.GetType().GetType()
if kindOf(messageType) != kindObject {
c.errors.notAMessageType(c.location(e), messageType)
messageType = decls.Error
}
}
}
if isObjectWellKnownType(messageType) {
c.setType(e, getObjectWellKnownType(messageType))
} else {
c.setType(e, messageType)
}
// Check the field initializers.
for _, ent := range msgVal.GetEntries() {
field := ent.GetFieldKey()
value := ent.GetValue()
c.check(value)
fieldType := decls.Error
if t, found := c.lookupFieldType(
c.locationByID(ent.GetId()),
messageType.GetMessageType(),
field); found {
fieldType = t.Type
}
if !c.isAssignable(fieldType, c.getType(value)) {
c.errors.fieldTypeMismatch(
c.locationByID(ent.Id), field, fieldType, c.getType(value))
}
}
}
func (c *checker) checkComprehension(e *exprpb.Expr) {
comp := e.GetComprehensionExpr()
c.check(comp.GetIterRange())
c.check(comp.GetAccuInit())
accuType := c.getType(comp.GetAccuInit())
rangeType := substitute(c.mappings, c.getType(comp.GetIterRange()), false)
var varType *exprpb.Type
switch kindOf(rangeType) {
case kindList:
varType = rangeType.GetListType().GetElemType()
case kindMap:
// Ranges over the keys.
varType = rangeType.GetMapType().GetKeyType()
case kindDyn, kindError, kindTypeParam:
// Set the range type to DYN to prevent assignment to a potentially incorrect type
// at a later point in type-checking. The isAssignable call will update the type
// substitutions for the type param under the covers.
c.isAssignable(decls.Dyn, rangeType)
// Set the range iteration variable to type DYN as well.
varType = decls.Dyn
default:
c.errors.notAComprehensionRange(c.location(comp.GetIterRange()), rangeType)
varType = decls.Error
}
// Create a scope for the comprehension since it has a local accumulation variable.
// This scope will contain the accumulation variable used to compute the result.
c.env = c.env.enterScope()
c.env.Add(decls.NewVar(comp.GetAccuVar(), accuType))
// Create a block scope for the loop.
c.env = c.env.enterScope()
c.env.Add(decls.NewVar(comp.GetIterVar(), varType))
// Check the variable references in the condition and step.
c.check(comp.GetLoopCondition())
c.assertType(comp.GetLoopCondition(), decls.Bool)
c.check(comp.GetLoopStep())
c.assertType(comp.GetLoopStep(), accuType)
// Exit the loop's block scope before checking the result.
c.env = c.env.exitScope()
c.check(comp.GetResult())
// Exit the comprehension scope.
c.env = c.env.exitScope()
c.setType(e, substitute(c.mappings, c.getType(comp.GetResult()), false))
}
// Checks compatibility of joined types, and returns the most general common type.
func (c *checker) joinTypes(loc common.Location,
previous *exprpb.Type,
current *exprpb.Type) *exprpb.Type {
if previous == nil {
return current
}
if c.isAssignable(previous, current) {
return mostGeneral(previous, current)
}
if c.dynAggregateLiteralElementTypesEnabled() {
return decls.Dyn
}
c.errors.typeMismatch(loc, previous, current)
return decls.Error
}
func (c *checker) dynAggregateLiteralElementTypesEnabled() bool {
return c.env.aggLitElemType == dynElementType
}
func (c *checker) newTypeVar() *exprpb.Type {
id := c.freeTypeVarCounter
c.freeTypeVarCounter++
return decls.NewTypeParamType(fmt.Sprintf("_var%d", id))
}
func (c *checker) isAssignable(t1 *exprpb.Type, t2 *exprpb.Type) bool {
subs := isAssignable(c.mappings, t1, t2)
if subs != nil {
c.mappings = subs
return true
}
return false
}
func (c *checker) isAssignableList(l1 []*exprpb.Type, l2 []*exprpb.Type) bool {
subs := isAssignableList(c.mappings, l1, l2)
if subs != nil {
c.mappings = subs
return true
}
return false
}
func (c *checker) lookupFieldType(l common.Location, messageType string, fieldName string) (*ref.FieldType, bool) {
if _, found := c.env.provider.FindType(messageType); !found {
// This should not happen, anyway, report an error.
c.errors.unexpectedFailedResolution(l, messageType)
return nil, false
}
if ft, found := c.env.provider.FindFieldType(messageType, fieldName); found {
return ft, found
}
c.errors.undefinedField(l, fieldName)
return nil, false
}
func (c *checker) setType(e *exprpb.Expr, t *exprpb.Type) {
if old, found := c.types[e.GetId()]; found && !proto.Equal(old, t) {
c.errors.ReportError(c.location(e),
"(Incompatible) Type already exists for expression: %v(%d) old:%v, new:%v", e, e.GetId(), old, t)
return
}
c.types[e.GetId()] = t
}
func (c *checker) getType(e *exprpb.Expr) *exprpb.Type {
return c.types[e.GetId()]
}
func (c *checker) setReference(e *exprpb.Expr, r *exprpb.Reference) {
if old, found := c.references[e.GetId()]; found && !proto.Equal(old, r) {
c.errors.ReportError(c.location(e),
"Reference already exists for expression: %v(%d) old:%v, new:%v", e, e.GetId(), old, r)
return
}
c.references[e.GetId()] = r
}
func (c *checker) assertType(e *exprpb.Expr, t *exprpb.Type) {
if !c.isAssignable(t, c.getType(e)) {
c.errors.typeMismatch(c.location(e), t, c.getType(e))
}
}
type overloadResolution struct {
Reference *exprpb.Reference
Type *exprpb.Type
}
func newResolution(checkedRef *exprpb.Reference, t *exprpb.Type) *overloadResolution {
return &overloadResolution{
Reference: checkedRef,
Type: t,
}
}
func (c *checker) location(e *exprpb.Expr) common.Location {
return c.locationByID(e.GetId())
}
func (c *checker) locationByID(id int64) common.Location {
positions := c.sourceInfo.GetPositions()
var line = 1
if offset, found := positions[id]; found {
col := int(offset)
for _, lineOffset := range c.sourceInfo.GetLineOffsets() {
if lineOffset < offset {
line++
col = int(offset - lineOffset)
} else {
break
}
}
return common.NewLocation(line, col)
}
return common.NoLocation
}
func newIdentReference(name string, value *exprpb.Constant) *exprpb.Reference {
return &exprpb.Reference{Name: name, Value: value}
}
func newFunctionReference(overloads ...string) *exprpb.Reference {
return &exprpb.Reference{OverloadId: overloads}
}