feat: connect to spicedb

1 files changed, 790 insertions, 0 deletions

diff --git a/vendor/github.com/authzed/cel-go/cel/library.go b/vendor/github.com/authzed/cel-go/cel/library.go
new file mode 100644
index 0000000..5d6dde4
--- /dev/null
+++ b/vendor/github.com/authzed/cel-go/cel/library.go
@@ -0,0 +1,790 @@
+// Copyright 2020 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 cel
+
+import (
+	"math"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/authzed/cel-go/common/ast"
+	"github.com/authzed/cel-go/common/operators"
+	"github.com/authzed/cel-go/common/overloads"
+	"github.com/authzed/cel-go/common/stdlib"
+	"github.com/authzed/cel-go/common/types"
+	"github.com/authzed/cel-go/common/types/ref"
+	"github.com/authzed/cel-go/common/types/traits"
+	"github.com/authzed/cel-go/interpreter"
+	"github.com/authzed/cel-go/parser"
+)
+
+const (
+	optMapMacro                = "optMap"
+	optFlatMapMacro            = "optFlatMap"
+	hasValueFunc               = "hasValue"
+	optionalNoneFunc           = "optional.none"
+	optionalOfFunc             = "optional.of"
+	optionalOfNonZeroValueFunc = "optional.ofNonZeroValue"
+	valueFunc                  = "value"
+	unusedIterVar              = "#unused"
+)
+
+// Library provides a collection of EnvOption and ProgramOption values used to configure a CEL
+// environment for a particular use case or with a related set of functionality.
+//
+// Note, the ProgramOption values provided by a library are expected to be static and not vary
+// between calls to Env.Program(). If there is a need for such dynamic configuration, prefer to
+// configure these options outside the Library and within the Env.Program() call directly.
+type Library interface {
+	// CompileOptions returns a collection of functional options for configuring the Parse / Check
+	// environment.
+	CompileOptions() []EnvOption
+
+	// ProgramOptions returns a collection of functional options which should be included in every
+	// Program generated from the Env.Program() call.
+	ProgramOptions() []ProgramOption
+}
+
+// SingletonLibrary refines the Library interface to ensure that libraries in this format are only
+// configured once within the environment.
+type SingletonLibrary interface {
+	Library
+
+	// LibraryName provides a namespaced name which is used to check whether the library has already
+	// been configured in the environment.
+	LibraryName() string
+}
+
+// Lib creates an EnvOption out of a Library, allowing libraries to be provided as functional args,
+// and to be linked to each other.
+func Lib(l Library) EnvOption {
+	singleton, isSingleton := l.(SingletonLibrary)
+	return func(e *Env) (*Env, error) {
+		if isSingleton {
+			if e.HasLibrary(singleton.LibraryName()) {
+				return e, nil
+			}
+			e.libraries[singleton.LibraryName()] = true
+		}
+		var err error
+		for _, opt := range l.CompileOptions() {
+			e, err = opt(e)
+			if err != nil {
+				return nil, err
+			}
+		}
+		e.progOpts = append(e.progOpts, l.ProgramOptions()...)
+		return e, nil
+	}
+}
+
+// StdLib returns an EnvOption for the standard library of CEL functions and macros.
+func StdLib() EnvOption {
+	return Lib(stdLibrary{})
+}
+
+// stdLibrary implements the Library interface and provides functional options for the core CEL
+// features documented in the specification.
+type stdLibrary struct{}
+
+// LibraryName implements the SingletonLibrary interface method.
+func (stdLibrary) LibraryName() string {
+	return "cel.lib.std"
+}
+
+// CompileOptions returns options for the standard CEL function declarations and macros.
+func (stdLibrary) CompileOptions() []EnvOption {
+	return []EnvOption{
+		func(e *Env) (*Env, error) {
+			var err error
+			for _, fn := range stdlib.Functions() {
+				existing, found := e.functions[fn.Name()]
+				if found {
+					fn, err = existing.Merge(fn)
+					if err != nil {
+						return nil, err
+					}
+				}
+				e.functions[fn.Name()] = fn
+			}
+			return e, nil
+		},
+		func(e *Env) (*Env, error) {
+			e.variables = append(e.variables, stdlib.Types()...)
+			return e, nil
+		},
+		Macros(StandardMacros...),
+	}
+}
+
+// ProgramOptions returns function implementations for the standard CEL functions.
+func (stdLibrary) ProgramOptions() []ProgramOption {
+	return []ProgramOption{}
+}
+
+// OptionalTypes enable support for optional syntax and types in CEL.
+//
+// The optional value type makes it possible to express whether variables have
+// been provided, whether a result has been computed, and in the future whether
+// an object field path, map key value, or list index has a value.
+//
+// # Syntax Changes
+//
+// OptionalTypes are unlike other CEL extensions because they modify the CEL
+// syntax itself, notably through the use of a `?` preceding a field name or
+// index value.
+//
+// ## Field Selection
+//
+// The optional syntax in field selection is denoted as `obj.?field`. In other
+// words, if a field is set, return `optional.of(obj.field)“, else
+// `optional.none()`. The optional field selection is viral in the sense that
+// after the first optional selection all subsequent selections or indices
+// are treated as optional, i.e. the following expressions are equivalent:
+//
+//	obj.?field.subfield
+//	obj.?field.?subfield
+//
+// ## Indexing
+//
+// Similar to field selection, the optional syntax can be used in index
+// expressions on maps and lists:
+//
+//	list[?0]
+//	map[?key]
+//
+// ## Optional Field Setting
+//
+// When creating map or message literals, if a field may be optionally set
+// based on its presence, then placing a `?` before the field name or key
+// will ensure the type on the right-hand side must be optional(T) where T
+// is the type of the field or key-value.
+//
+// The following returns a map with the key expression set only if the
+// subfield is present, otherwise an empty map is created:
+//
+//	{?key: obj.?field.subfield}
+//
+// ## Optional Element Setting
+//
+// When creating list literals, an element in the list may be optionally added
+// when the element expression is preceded by a `?`:
+//
+//	[a, ?b, ?c] // return a list with either [a], [a, b], [a, b, c], or [a, c]
+//
+// # Optional.Of
+//
+// Create an optional(T) value of a given value with type T.
+//
+//	optional.of(10)
+//
+// # Optional.OfNonZeroValue
+//
+// Create an optional(T) value of a given value with type T if it is not a
+// zero-value. A zero-value the default empty value for any given CEL type,
+// including empty protobuf message types. If the value is empty, the result
+// of this call will be optional.none().
+//
+//	optional.ofNonZeroValue([1, 2, 3]) // optional(list(int))
+//	optional.ofNonZeroValue([]) // optional.none()
+//	optional.ofNonZeroValue(0)  // optional.none()
+//	optional.ofNonZeroValue("") // optional.none()
+//
+// # Optional.None
+//
+// Create an empty optional value.
+//
+// # HasValue
+//
+// Determine whether the optional contains a value.
+//
+//	optional.of(b'hello').hasValue() // true
+//	optional.ofNonZeroValue({}).hasValue() // false
+//
+// # Value
+//
+// Get the value contained by the optional. If the optional does not have a
+// value, the result will be a CEL error.
+//
+//	optional.of(b'hello').value() // b'hello'
+//	optional.ofNonZeroValue({}).value() // error
+//
+// # Or
+//
+// If the value on the left-hand side is optional.none(), the optional value
+// on the right hand side is returned. If the value on the left-hand set is
+// valued, then it is returned. This operation is short-circuiting and will
+// only evaluate as many links in the `or` chain as are needed to return a
+// non-empty optional value.
+//
+//	obj.?field.or(m[?key])
+//	l[?index].or(obj.?field.subfield).or(obj.?other)
+//
+// # OrValue
+//
+// Either return the value contained within the optional on the left-hand side
+// or return the alternative value on the right hand side.
+//
+//	m[?key].orValue("none")
+//
+// # OptMap
+//
+// Apply a transformation to the optional's underlying value if it is not empty
+// and return an optional typed result based on the transformation. The
+// transformation expression type must return a type T which is wrapped into
+// an optional.
+//
+//	msg.?elements.optMap(e, e.size()).orValue(0)
+//
+// # OptFlatMap
+//
+// Introduced in version: 1
+//
+// Apply a transformation to the optional's underlying value if it is not empty
+// and return the result. The transform expression must return an optional(T)
+// rather than type T. This can be useful when dealing with zero values and
+// conditionally generating an empty or non-empty result in ways which cannot
+// be expressed with `optMap`.
+//
+//	msg.?elements.optFlatMap(e, e[?0]) // return the first element if present.
+func OptionalTypes(opts ...OptionalTypesOption) EnvOption {
+	lib := &optionalLib{version: math.MaxUint32}
+	for _, opt := range opts {
+		lib = opt(lib)
+	}
+	return Lib(lib)
+}
+
+type optionalLib struct {
+	version uint32
+}
+
+// OptionalTypesOption is a functional interface for configuring the strings library.
+type OptionalTypesOption func(*optionalLib) *optionalLib
+
+// OptionalTypesVersion configures the version of the optional type library.
+//
+// The version limits which functions are available. Only functions introduced
+// below or equal to the given version included in the library. If this option
+// is not set, all functions are available.
+//
+// See the library documentation to determine which version a function was introduced.
+// If the documentation does not state which version a function was introduced, it can
+// be assumed to be introduced at version 0, when the library was first created.
+func OptionalTypesVersion(version uint32) OptionalTypesOption {
+	return func(lib *optionalLib) *optionalLib {
+		lib.version = version
+		return lib
+	}
+}
+
+// LibraryName implements the SingletonLibrary interface method.
+func (lib *optionalLib) LibraryName() string {
+	return "cel.lib.optional"
+}
+
+// CompileOptions implements the Library interface method.
+func (lib *optionalLib) CompileOptions() []EnvOption {
+	paramTypeK := TypeParamType("K")
+	paramTypeV := TypeParamType("V")
+	optionalTypeV := OptionalType(paramTypeV)
+	listTypeV := ListType(paramTypeV)
+	mapTypeKV := MapType(paramTypeK, paramTypeV)
+
+	opts := []EnvOption{
+		// Enable the optional syntax in the parser.
+		enableOptionalSyntax(),
+
+		// Introduce the optional type.
+		Types(types.OptionalType),
+
+		// Configure the optMap and optFlatMap macros.
+		Macros(ReceiverMacro(optMapMacro, 2, optMap)),
+
+		// Global and member functions for working with optional values.
+		Function(optionalOfFunc,
+			Overload("optional_of", []*Type{paramTypeV}, optionalTypeV,
+				UnaryBinding(func(value ref.Val) ref.Val {
+					return types.OptionalOf(value)
+				}))),
+		Function(optionalOfNonZeroValueFunc,
+			Overload("optional_ofNonZeroValue", []*Type{paramTypeV}, optionalTypeV,
+				UnaryBinding(func(value ref.Val) ref.Val {
+					v, isZeroer := value.(traits.Zeroer)
+					if !isZeroer || !v.IsZeroValue() {
+						return types.OptionalOf(value)
+					}
+					return types.OptionalNone
+				}))),
+		Function(optionalNoneFunc,
+			Overload("optional_none", []*Type{}, optionalTypeV,
+				FunctionBinding(func(values ...ref.Val) ref.Val {
+					return types.OptionalNone
+				}))),
+		Function(valueFunc,
+			MemberOverload("optional_value", []*Type{optionalTypeV}, paramTypeV,
+				UnaryBinding(func(value ref.Val) ref.Val {
+					opt := value.(*types.Optional)
+					return opt.GetValue()
+				}))),
+		Function(hasValueFunc,
+			MemberOverload("optional_hasValue", []*Type{optionalTypeV}, BoolType,
+				UnaryBinding(func(value ref.Val) ref.Val {
+					opt := value.(*types.Optional)
+					return types.Bool(opt.HasValue())
+				}))),
+
+		// Implementation of 'or' and 'orValue' are special-cased to support short-circuiting in the
+		// evaluation chain.
+		Function("or",
+			MemberOverload("optional_or_optional", []*Type{optionalTypeV, optionalTypeV}, optionalTypeV)),
+		Function("orValue",
+			MemberOverload("optional_orValue_value", []*Type{optionalTypeV, paramTypeV}, paramTypeV)),
+
+		// OptSelect is handled specially by the type-checker, so the receiver's field type is used to determine the
+		// optput type.
+		Function(operators.OptSelect,
+			Overload("select_optional_field", []*Type{DynType, StringType}, optionalTypeV)),
+
+		// OptIndex is handled mostly like any other indexing operation on a list or map, so the type-checker can use
+		// these signatures to determine type-agreement without any special handling.
+		Function(operators.OptIndex,
+			Overload("list_optindex_optional_int", []*Type{listTypeV, IntType}, optionalTypeV),
+			Overload("optional_list_optindex_optional_int", []*Type{OptionalType(listTypeV), IntType}, optionalTypeV),
+			Overload("map_optindex_optional_value", []*Type{mapTypeKV, paramTypeK}, optionalTypeV),
+			Overload("optional_map_optindex_optional_value", []*Type{OptionalType(mapTypeKV), paramTypeK}, optionalTypeV)),
+
+		// Index overloads to accommodate using an optional value as the operand.
+		Function(operators.Index,
+			Overload("optional_list_index_int", []*Type{OptionalType(listTypeV), IntType}, optionalTypeV),
+			Overload("optional_map_index_value", []*Type{OptionalType(mapTypeKV), paramTypeK}, optionalTypeV)),
+	}
+	if lib.version >= 1 {
+		opts = append(opts, Macros(ReceiverMacro(optFlatMapMacro, 2, optFlatMap)))
+	}
+	return opts
+}
+
+// ProgramOptions implements the Library interface method.
+func (lib *optionalLib) ProgramOptions() []ProgramOption {
+	return []ProgramOption{
+		CustomDecorator(decorateOptionalOr),
+	}
+}
+
+func optMap(meh MacroExprFactory, target ast.Expr, args []ast.Expr) (ast.Expr, *Error) {
+	varIdent := args[0]
+	varName := ""
+	switch varIdent.Kind() {
+	case ast.IdentKind:
+		varName = varIdent.AsIdent()
+	default:
+		return nil, meh.NewError(varIdent.ID(), "optMap() variable name must be a simple identifier")
+	}
+	mapExpr := args[1]
+	return meh.NewCall(
+		operators.Conditional,
+		meh.NewMemberCall(hasValueFunc, target),
+		meh.NewCall(optionalOfFunc,
+			meh.NewComprehension(
+				meh.NewList(),
+				unusedIterVar,
+				varName,
+				meh.NewMemberCall(valueFunc, meh.Copy(target)),
+				meh.NewLiteral(types.False),
+				meh.NewIdent(varName),
+				mapExpr,
+			),
+		),
+		meh.NewCall(optionalNoneFunc),
+	), nil
+}
+
+func optFlatMap(meh MacroExprFactory, target ast.Expr, args []ast.Expr) (ast.Expr, *Error) {
+	varIdent := args[0]
+	varName := ""
+	switch varIdent.Kind() {
+	case ast.IdentKind:
+		varName = varIdent.AsIdent()
+	default:
+		return nil, meh.NewError(varIdent.ID(), "optFlatMap() variable name must be a simple identifier")
+	}
+	mapExpr := args[1]
+	return meh.NewCall(
+		operators.Conditional,
+		meh.NewMemberCall(hasValueFunc, target),
+		meh.NewComprehension(
+			meh.NewList(),
+			unusedIterVar,
+			varName,
+			meh.NewMemberCall(valueFunc, meh.Copy(target)),
+			meh.NewLiteral(types.False),
+			meh.NewIdent(varName),
+			mapExpr,
+		),
+		meh.NewCall(optionalNoneFunc),
+	), nil
+}
+
+func enableOptionalSyntax() EnvOption {
+	return func(e *Env) (*Env, error) {
+		e.prsrOpts = append(e.prsrOpts, parser.EnableOptionalSyntax(true))
+		return e, nil
+	}
+}
+
+// EnableErrorOnBadPresenceTest enables error generation when a presence test or optional field
+// selection is performed on a primitive type.
+func EnableErrorOnBadPresenceTest(value bool) EnvOption {
+	return features(featureEnableErrorOnBadPresenceTest, value)
+}
+
+func decorateOptionalOr(i interpreter.Interpretable) (interpreter.Interpretable, error) {
+	call, ok := i.(interpreter.InterpretableCall)
+	if !ok {
+		return i, nil
+	}
+	args := call.Args()
+	if len(args) != 2 {
+		return i, nil
+	}
+	switch call.Function() {
+	case "or":
+		if call.OverloadID() != "" && call.OverloadID() != "optional_or_optional" {
+			return i, nil
+		}
+		return &evalOptionalOr{
+			id:  call.ID(),
+			lhs: args[0],
+			rhs: args[1],
+		}, nil
+	case "orValue":
+		if call.OverloadID() != "" && call.OverloadID() != "optional_orValue_value" {
+			return i, nil
+		}
+		return &evalOptionalOrValue{
+			id:  call.ID(),
+			lhs: args[0],
+			rhs: args[1],
+		}, nil
+	default:
+		return i, nil
+	}
+}
+
+// evalOptionalOr selects between two optional values, either the first if it has a value, or
+// the second optional expression is evaluated and returned.
+type evalOptionalOr struct {
+	id  int64
+	lhs interpreter.Interpretable
+	rhs interpreter.Interpretable
+}
+
+// ID implements the Interpretable interface method.
+func (opt *evalOptionalOr) ID() int64 {
+	return opt.id
+}
+
+// Eval evaluates the left-hand side optional to determine whether it contains a value, else
+// proceeds with the right-hand side evaluation.
+func (opt *evalOptionalOr) Eval(ctx interpreter.Activation) ref.Val {
+	// short-circuit lhs.
+	optLHS := opt.lhs.Eval(ctx)
+	optVal, ok := optLHS.(*types.Optional)
+	if !ok {
+		return optLHS
+	}
+	if optVal.HasValue() {
+		return optVal
+	}
+	return opt.rhs.Eval(ctx)
+}
+
+// evalOptionalOrValue selects between an optional or a concrete value. If the optional has a value,
+// its value is returned, otherwise the alternative value expression is evaluated and returned.
+type evalOptionalOrValue struct {
+	id  int64
+	lhs interpreter.Interpretable
+	rhs interpreter.Interpretable
+}
+
+// ID implements the Interpretable interface method.
+func (opt *evalOptionalOrValue) ID() int64 {
+	return opt.id
+}
+
+// Eval evaluates the left-hand side optional to determine whether it contains a value, else
+// proceeds with the right-hand side evaluation.
+func (opt *evalOptionalOrValue) Eval(ctx interpreter.Activation) ref.Val {
+	// short-circuit lhs.
+	optLHS := opt.lhs.Eval(ctx)
+	optVal, ok := optLHS.(*types.Optional)
+	if !ok {
+		return optLHS
+	}
+	if optVal.HasValue() {
+		return optVal.GetValue()
+	}
+	return opt.rhs.Eval(ctx)
+}
+
+type timeUTCLibrary struct{}
+
+func (timeUTCLibrary) CompileOptions() []EnvOption {
+	return timeOverloadDeclarations
+}
+
+func (timeUTCLibrary) ProgramOptions() []ProgramOption {
+	return []ProgramOption{}
+}
+
+// Declarations and functions which enable using UTC on time.Time inputs when the timezone is unspecified
+// in the CEL expression.
+var (
+	utcTZ = types.String("UTC")
+
+	timeOverloadDeclarations = []EnvOption{
+		Function(overloads.TimeGetHours,
+			MemberOverload(overloads.DurationToHours, []*Type{DurationType}, IntType,
+				UnaryBinding(types.DurationGetHours))),
+		Function(overloads.TimeGetMinutes,
+			MemberOverload(overloads.DurationToMinutes, []*Type{DurationType}, IntType,
+				UnaryBinding(types.DurationGetMinutes))),
+		Function(overloads.TimeGetSeconds,
+			MemberOverload(overloads.DurationToSeconds, []*Type{DurationType}, IntType,
+				UnaryBinding(types.DurationGetSeconds))),
+		Function(overloads.TimeGetMilliseconds,
+			MemberOverload(overloads.DurationToMilliseconds, []*Type{DurationType}, IntType,
+				UnaryBinding(types.DurationGetMilliseconds))),
+		Function(overloads.TimeGetFullYear,
+			MemberOverload(overloads.TimestampToYear, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetFullYear(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToYearWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetFullYear),
+			),
+		),
+		Function(overloads.TimeGetMonth,
+			MemberOverload(overloads.TimestampToMonth, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetMonth(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToMonthWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetMonth),
+			),
+		),
+		Function(overloads.TimeGetDayOfYear,
+			MemberOverload(overloads.TimestampToDayOfYear, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetDayOfYear(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToDayOfYearWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(func(ts, tz ref.Val) ref.Val {
+					return timestampGetDayOfYear(ts, tz)
+				}),
+			),
+		),
+		Function(overloads.TimeGetDayOfMonth,
+			MemberOverload(overloads.TimestampToDayOfMonthZeroBased, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetDayOfMonthZeroBased(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToDayOfMonthZeroBasedWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetDayOfMonthZeroBased),
+			),
+		),
+		Function(overloads.TimeGetDate,
+			MemberOverload(overloads.TimestampToDayOfMonthOneBased, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetDayOfMonthOneBased(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToDayOfMonthOneBasedWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetDayOfMonthOneBased),
+			),
+		),
+		Function(overloads.TimeGetDayOfWeek,
+			MemberOverload(overloads.TimestampToDayOfWeek, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetDayOfWeek(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToDayOfWeekWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetDayOfWeek),
+			),
+		),
+		Function(overloads.TimeGetHours,
+			MemberOverload(overloads.TimestampToHours, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetHours(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToHoursWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetHours),
+			),
+		),
+		Function(overloads.TimeGetMinutes,
+			MemberOverload(overloads.TimestampToMinutes, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetMinutes(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToMinutesWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetMinutes),
+			),
+		),
+		Function(overloads.TimeGetSeconds,
+			MemberOverload(overloads.TimestampToSeconds, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetSeconds(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToSecondsWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetSeconds),
+			),
+		),
+		Function(overloads.TimeGetMilliseconds,
+			MemberOverload(overloads.TimestampToMilliseconds, []*Type{TimestampType}, IntType,
+				UnaryBinding(func(ts ref.Val) ref.Val {
+					return timestampGetMilliseconds(ts, utcTZ)
+				}),
+			),
+			MemberOverload(overloads.TimestampToMillisecondsWithTz, []*Type{TimestampType, StringType}, IntType,
+				BinaryBinding(timestampGetMilliseconds),
+			),
+		),
+	}
+)
+
+func timestampGetFullYear(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Year())
+}
+
+func timestampGetMonth(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	// CEL spec indicates that the month should be 0-based, but the Time value
+	// for Month() is 1-based.
+	return types.Int(t.Month() - 1)
+}
+
+func timestampGetDayOfYear(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.YearDay() - 1)
+}
+
+func timestampGetDayOfMonthZeroBased(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Day() - 1)
+}
+
+func timestampGetDayOfMonthOneBased(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Day())
+}
+
+func timestampGetDayOfWeek(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Weekday())
+}
+
+func timestampGetHours(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Hour())
+}
+
+func timestampGetMinutes(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Minute())
+}
+
+func timestampGetSeconds(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Second())
+}
+
+func timestampGetMilliseconds(ts, tz ref.Val) ref.Val {
+	t, err := inTimeZone(ts, tz)
+	if err != nil {
+		return types.NewErr(err.Error())
+	}
+	return types.Int(t.Nanosecond() / 1000000)
+}
+
+func inTimeZone(ts, tz ref.Val) (time.Time, error) {
+	t := ts.(types.Timestamp)
+	val := string(tz.(types.String))
+	ind := strings.Index(val, ":")
+	if ind == -1 {
+		loc, err := time.LoadLocation(val)
+		if err != nil {
+			return time.Time{}, err
+		}
+		return t.In(loc), nil
+	}
+
+	// If the input is not the name of a timezone (for example, 'US/Central'), it should be a numerical offset from UTC
+	// in the format ^(+|-)(0[0-9]|1[0-4]):[0-5][0-9]$. The numerical input is parsed in terms of hours and minutes.
+	hr, err := strconv.Atoi(string(val[0:ind]))
+	if err != nil {
+		return time.Time{}, err
+	}
+	min, err := strconv.Atoi(string(val[ind+1:]))
+	if err != nil {
+		return time.Time{}, err
+	}
+	var offset int
+	if string(val[0]) == "-" {
+		offset = hr*60 - min
+	} else {
+		offset = hr*60 + min
+	}
+	secondsEastOfUTC := int((time.Duration(offset) * time.Minute).Seconds())
+	timezone := time.FixedZone("", secondsEastOfUTC)
+	return t.In(timezone), nil
+}