1 files changed, 316 insertions, 0 deletions
diff --git a/vendor/github.com/authzed/cel-go/common/containers/container.go b/vendor/github.com/authzed/cel-go/common/containers/container.go
new file mode 100644
index 0000000..7e3afb6
--- /dev/null
+++ b/vendor/github.com/authzed/cel-go/common/containers/container.go
@@ -0,0 +1,316 @@
+// 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 containers defines types and functions for resolving qualified names within a namespace
+// or type provided to CEL.
+package containers
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/authzed/cel-go/common/ast"
+)
+
+var (
+	// DefaultContainer has an empty container name.
+	DefaultContainer *Container = nil
+
+	// Empty map to search for aliases when needed.
+	noAliases = make(map[string]string)
+)
+
+// NewContainer creates a new Container with the fully-qualified name.
+func NewContainer(opts ...ContainerOption) (*Container, error) {
+	var c *Container
+	var err error
+	for _, opt := range opts {
+		c, err = opt(c)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return c, nil
+}
+
+// Container holds a reference to an optional qualified container name and set of aliases.
+//
+// The program container can be used to simplify variable, function, and type specification within
+// CEL programs and behaves more or less like a C++ namespace. See ResolveCandidateNames for more
+// details.
+type Container struct {
+	name    string
+	aliases map[string]string
+}
+
+// Extend creates a new Container with the existing settings and applies a series of
+// ContainerOptions to further configure the new container.
+func (c *Container) Extend(opts ...ContainerOption) (*Container, error) {
+	if c == nil {
+		return NewContainer(opts...)
+	}
+	// Copy the name and aliases of the existing container.
+	ext := &Container{name: c.Name()}
+	if len(c.aliasSet()) > 0 {
+		aliasSet := make(map[string]string, len(c.aliasSet()))
+		for k, v := range c.aliasSet() {
+			aliasSet[k] = v
+		}
+		ext.aliases = aliasSet
+	}
+	// Apply the new options to the container.
+	var err error
+	for _, opt := range opts {
+		ext, err = opt(ext)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return ext, nil
+}
+
+// Name returns the fully-qualified name of the container.
+//
+// The name may conceptually be a namespace, package, or type.
+func (c *Container) Name() string {
+	if c == nil {
+		return ""
+	}
+	return c.name
+}
+
+// ResolveCandidateNames returns the candidates name of namespaced identifiers in C++ resolution
+// order.
+//
+// Names which shadow other names are returned first. If a name includes a leading dot ('.'),
+// the name is treated as an absolute identifier which cannot be shadowed.
+//
+// Given a container name a.b.c.M.N and a type name R.s, this will deliver in order:
+//
+//	a.b.c.M.N.R.s
+//	a.b.c.M.R.s
+//	a.b.c.R.s
+//	a.b.R.s
+//	a.R.s
+//	R.s
+//
+// If aliases or abbreviations are configured for the container, then alias names will take
+// precedence over containerized names.
+func (c *Container) ResolveCandidateNames(name string) []string {
+	if strings.HasPrefix(name, ".") {
+		qn := name[1:]
+		alias, isAlias := c.findAlias(qn)
+		if isAlias {
+			return []string{alias}
+		}
+		return []string{qn}
+	}
+	alias, isAlias := c.findAlias(name)
+	if isAlias {
+		return []string{alias}
+	}
+	if c.Name() == "" {
+		return []string{name}
+	}
+	nextCont := c.Name()
+	candidates := []string{nextCont + "." + name}
+	for i := strings.LastIndex(nextCont, "."); i >= 0; i = strings.LastIndex(nextCont, ".") {
+		nextCont = nextCont[:i]
+		candidates = append(candidates, nextCont+"."+name)
+	}
+	return append(candidates, name)
+}
+
+// aliasSet returns the alias to fully-qualified name mapping stored in the container.
+func (c *Container) aliasSet() map[string]string {
+	if c == nil || c.aliases == nil {
+		return noAliases
+	}
+	return c.aliases
+}
+
+// findAlias takes a name as input and returns an alias expansion if one exists.
+//
+// If the name is qualified, the first component of the qualified name is checked against known
+// aliases. Any alias that is found in a qualified name is expanded in the result:
+//
+//	alias: R -> my.alias.R
+//	name: R.S.T
+//	output: my.alias.R.S.T
+//
+// Note, the name must not have a leading dot.
+func (c *Container) findAlias(name string) (string, bool) {
+	// If an alias exists for the name, ensure it is searched last.
+	simple := name
+	qualifier := ""
+	dot := strings.Index(name, ".")
+	if dot >= 0 {
+		simple = name[0:dot]
+		qualifier = name[dot:]
+	}
+	alias, found := c.aliasSet()[simple]
+	if !found {
+		return "", false
+	}
+	return alias + qualifier, true
+}
+
+// ContainerOption specifies a functional configuration option for a Container.
+//
+// Note, ContainerOption implementations must be able to handle nil container inputs.
+type ContainerOption func(*Container) (*Container, error)
+
+// Abbrevs configures a set of simple names as abbreviations for fully-qualified names.
+//
+// An abbreviation (abbrev for short) is a simple name that expands to a fully-qualified name.
+// Abbreviations can be useful when working with variables, functions, and especially types from
+// multiple namespaces:
+//
+//	// CEL object construction
+//	qual.pkg.version.ObjTypeName{
+//	   field: alt.container.ver.FieldTypeName{value: ...}
+//	}
+//
+// Only one the qualified names above may be used as the CEL container, so at least one of these
+// references must be a long qualified name within an otherwise short CEL program. Using the
+// following abbreviations, the program becomes much simpler:
+//
+//	// CEL Go option
+//	Abbrevs("qual.pkg.version.ObjTypeName", "alt.container.ver.FieldTypeName")
+//	// Simplified Object construction
+//	ObjTypeName{field: FieldTypeName{value: ...}}
+//
+// There are a few rules for the qualified names and the simple abbreviations generated from them:
+// - Qualified names must be dot-delimited, e.g. `package.subpkg.name`.
+// - The last element in the qualified name is the abbreviation.
+// - Abbreviations must not collide with each other.
+// - The abbreviation must not collide with unqualified names in use.
+//
+// Abbreviations are distinct from container-based references in the following important ways:
+//   - Abbreviations must expand to a fully-qualified name.
+//   - Expanded abbreviations do not participate in namespace resolution.
+//   - Abbreviation expansion is done instead of the container search for a matching identifier.
+//   - Containers follow C++ namespace resolution rules with searches from the most qualified name
+//     to the least qualified name.
+//   - Container references within the CEL program may be relative, and are resolved to fully
+//     qualified names at either type-check time or program plan time, whichever comes first.
+//
+// If there is ever a case where an identifier could be in both the container and as an
+// abbreviation, the abbreviation wins as this will ensure that the meaning of a program is
+// preserved between compilations even as the container evolves.
+func Abbrevs(qualifiedNames ...string) ContainerOption {
+	return func(c *Container) (*Container, error) {
+		for _, qn := range qualifiedNames {
+			ind := strings.LastIndex(qn, ".")
+			if ind <= 0 || ind >= len(qn)-1 {
+				return nil, fmt.Errorf(
+					"invalid qualified name: %s, wanted name of the form 'qualified.name'", qn)
+			}
+			alias := qn[ind+1:]
+			var err error
+			c, err = aliasAs("abbreviation", qn, alias)(c)
+			if err != nil {
+				return nil, err
+			}
+		}
+		return c, nil
+	}
+}
+
+// Alias associates a fully-qualified name with a user-defined alias.
+//
+// In general, Abbrevs is preferred to Alias since the names generated from the Abbrevs option
+// are more easily traced back to source code. The Alias option is useful for propagating alias
+// configuration from one Container instance to another, and may also be useful for remapping
+// poorly chosen protobuf message / package names.
+//
+// Note: all of the rules that apply to Abbrevs also apply to Alias.
+func Alias(qualifiedName, alias string) ContainerOption {
+	return aliasAs("alias", qualifiedName, alias)
+}
+
+func aliasAs(kind, qualifiedName, alias string) ContainerOption {
+	return func(c *Container) (*Container, error) {
+		if len(alias) == 0 || strings.Contains(alias, ".") {
+			return nil, fmt.Errorf(
+				"%s must be non-empty and simple (not qualified): %s=%s", kind, kind, alias)
+		}
+
+		if qualifiedName[0:1] == "." {
+			return nil, fmt.Errorf("qualified name must not begin with a leading '.': %s",
+				qualifiedName)
+		}
+		ind := strings.LastIndex(qualifiedName, ".")
+		if ind <= 0 || ind == len(qualifiedName)-1 {
+			return nil, fmt.Errorf("%s must refer to a valid qualified name: %s",
+				kind, qualifiedName)
+		}
+		aliasRef, found := c.aliasSet()[alias]
+		if found {
+			return nil, fmt.Errorf(
+				"%s collides with existing reference: name=%s, %s=%s, existing=%s",
+				kind, qualifiedName, kind, alias, aliasRef)
+		}
+		if strings.HasPrefix(c.Name(), alias+".") || c.Name() == alias {
+			return nil, fmt.Errorf(
+				"%s collides with container name: name=%s, %s=%s, container=%s",
+				kind, qualifiedName, kind, alias, c.Name())
+		}
+		if c == nil {
+			c = &Container{}
+		}
+		if c.aliases == nil {
+			c.aliases = make(map[string]string)
+		}
+		c.aliases[alias] = qualifiedName
+		return c, nil
+	}
+}
+
+// Name sets the fully-qualified name of the Container.
+func Name(name string) ContainerOption {
+	return func(c *Container) (*Container, error) {
+		if len(name) > 0 && name[0:1] == "." {
+			return nil, fmt.Errorf("container name must not contain a leading '.': %s", name)
+		}
+		if c.Name() == name {
+			return c, nil
+		}
+		if c == nil {
+			return &Container{name: name}, nil
+		}
+		c.name = name
+		return c, nil
+	}
+}
+
+// ToQualifiedName converts an expression AST into a qualified name if possible, with a boolean
+// 'found' value that indicates if the conversion is successful.
+func ToQualifiedName(e ast.Expr) (string, bool) {
+	switch e.Kind() {
+	case ast.IdentKind:
+		id := e.AsIdent()
+		return id, true
+	case ast.SelectKind:
+		sel := e.AsSelect()
+		// Test only expressions are not valid as qualified names.
+		if sel.IsTestOnly() {
+			return "", false
+		}
+		if qual, found := ToQualifiedName(sel.Operand()); found {
+			return qual + "." + sel.FieldName(), true
+		}
+	}
+	return "", false
+}