Add type checker #237
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| // Copyright 2024-2025 Buf Technologies, Inc. | ||
| // | ||
| // 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. | ||
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| import * as olc from "../gen/dev/cel/expr/overload_const.js"; | ||
| import { _CelChecker } from "./checker.js"; | ||
| import type { Registry } from "@bufbuild/protobuf"; | ||
| import { Namespace } from "../namespace.js"; | ||
| import { Group, Scopes } from "./scopes.js"; | ||
| import type { CelFunc } from "../func.js"; | ||
| import { mergeFuncs } from "../func.js"; | ||
| import type { CelIdent } from "../ident.js"; | ||
| import { | ||
| celConstant, | ||
| celVariable, | ||
| identDeclarationIsEquivalent, | ||
| } from "../ident.js"; | ||
| import { createRegistryWithWKT } from "../registry.js"; | ||
| import { CelScalar, objectType } from "../type.js"; | ||
| import { STD_FUNCS } from "../std/std.js"; | ||
| import { STD_TYPES } from "../std/types.js"; | ||
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| const privateSymbol = Symbol.for("@bufbuild/cel/checker/env"); | ||
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| export enum AggregateLiteralElementType { | ||
| DynElementType = 1, | ||
| HomogenousElementType = 2, | ||
| } | ||
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| /** | ||
| * CEL checker environment. | ||
| * | ||
| * The environment defines the functions and types that are available | ||
| * during CEL expression checking. | ||
| */ | ||
| export interface CelCheckerEnv { | ||
| [privateSymbol]: unknown; | ||
| /** | ||
| * Namespace of the environment. | ||
| */ | ||
| readonly namespace: Namespace | undefined; | ||
| /** | ||
| * The protobuf registry to use. | ||
| */ | ||
| readonly registry: Registry; | ||
| /** | ||
| * The declarations available in this environment. | ||
| */ | ||
| readonly declarations: Scopes; | ||
| /** | ||
| * The aggregate literal element type strategy to use. | ||
| */ | ||
| readonly aggregateLiteralElementType: AggregateLiteralElementType; | ||
| /** | ||
| * The filtered overload ids. | ||
| */ | ||
| readonly filteredOverloadIds: Set<string>; | ||
| /** | ||
| * AddIdents configures the checker with a list of variable declarations. | ||
| * | ||
| * If there are overlapping declarations, the method will error. | ||
| */ | ||
| addIdents(idents: CelIdent[]): void; | ||
| /** | ||
| * AddFunctions configures the checker with a list of function declarations. | ||
| * | ||
| * If there are overlapping declarations, the method will error. | ||
| */ | ||
| addFunctions(funcs: CelFunc[]): void; | ||
| /** | ||
| * LookupIdent returns an identifier in the Env. | ||
| * Returns undefined if no such identifier is found in the Env. | ||
| */ | ||
| lookupIdent(name: string): CelIdent | undefined; | ||
| /** | ||
| * LookupFunction returns a function declaration in the env. | ||
| * Returns undefined if no such function is found in the env. | ||
| */ | ||
| lookupFunction(name: string): CelFunc | undefined; | ||
| /** | ||
| * IsOverloadDisabled returns whether the overloadID is disabled in the current environment. | ||
| */ | ||
| isOverloadDisabled(overloadID: string): boolean; | ||
| /** | ||
| * validatedDeclarations returns a reference to the validated variable and function declaration scope stack. | ||
| */ | ||
| validatedDeclarations(): Scopes; | ||
| /** | ||
| * enterScope creates a new Env instance with a new innermost declaration scope. | ||
| */ | ||
| enterScope(): CelCheckerEnv; | ||
| /** | ||
| * exitScope creates a new Env instance with the nearest outer declaration scope. | ||
| */ | ||
| exitScope(): CelCheckerEnv; | ||
| } | ||
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| export interface CelCheckerEnvOptions { | ||
| /** | ||
| * Namespace of the environment. | ||
| */ | ||
| namespace?: string; | ||
| /** | ||
| * The protobuf registry to use. | ||
| */ | ||
| registry?: Registry; | ||
| /** | ||
| * Additional functions to add. | ||
| * | ||
| * All functions must be unique. This can be used to override any std function. | ||
| */ | ||
| funcs?: CelFunc[]; | ||
| /** | ||
| * Idents available in this environment. | ||
| */ | ||
| idents?: CelIdent[]; | ||
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| /** | ||
| * Whether to enforce homogenous types in aggregate literals. | ||
| */ | ||
| homogenousAggregateLiterals?: boolean; | ||
| /** | ||
| * Whether to allow cross-type numeric comparisons. | ||
| */ | ||
| crossTypeNumericComparisons?: boolean; | ||
|
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There was a problem hiding this comment. As mentioned on the other thread, I'm not convinced we need this flexibility. |
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| } | ||
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| const crossTypeNumericComparisonOverloads = new Set<string>([ | ||
| // double <-> int | uint | ||
| olc.LESS_DOUBLE_INT64, | ||
| olc.LESS_DOUBLE_UINT64, | ||
| olc.LESS_EQUALS_DOUBLE_INT64, | ||
| olc.LESS_EQUALS_DOUBLE_UINT64, | ||
| olc.GREATER_DOUBLE_INT64, | ||
| olc.GREATER_DOUBLE_UINT64, | ||
| olc.GREATER_EQUALS_DOUBLE_INT64, | ||
| olc.GREATER_EQUALS_DOUBLE_UINT64, | ||
| // int <-> double | uint | ||
| olc.LESS_INT64_DOUBLE, | ||
| olc.LESS_INT64_UINT64, | ||
| olc.LESS_EQUALS_INT64_DOUBLE, | ||
| olc.LESS_EQUALS_INT64_UINT64, | ||
| olc.GREATER_INT64_DOUBLE, | ||
| olc.GREATER_INT64_UINT64, | ||
| olc.GREATER_EQUALS_INT64_DOUBLE, | ||
| olc.GREATER_EQUALS_INT64_UINT64, | ||
| // uint <-> double | int | ||
| olc.LESS_UINT64_DOUBLE, | ||
| olc.LESS_UINT64_INT64, | ||
| olc.LESS_EQUALS_UINT64_DOUBLE, | ||
| olc.LESS_EQUALS_UINT64_INT64, | ||
| olc.GREATER_UINT64_DOUBLE, | ||
| olc.GREATER_UINT64_INT64, | ||
| olc.GREATER_EQUALS_UINT64_DOUBLE, | ||
| olc.GREATER_EQUALS_UINT64_INT64, | ||
| ]); | ||
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| export function celCheckerEnv(options?: CelCheckerEnvOptions): CelCheckerEnv { | ||
| const idents = new Map<string, CelIdent>(); | ||
| if (options?.idents) { | ||
| for (const ident of options.idents) { | ||
| idents.set(ident.name, ident); | ||
| } | ||
| } | ||
| for (const ident of STD_TYPES) { | ||
| // TODO: how do other implementations handle this? Can users overwrite std types? | ||
| if (idents.has(ident.name)) { | ||
| continue; | ||
| } | ||
| idents.set(ident.name, ident); | ||
| } | ||
| const funcs = new Map<string, CelFunc>(); | ||
| for (const func of STD_FUNCS.declarations) { | ||
| funcs.set(func.name, func); | ||
| } | ||
| if (options?.funcs) { | ||
| for (const func of options.funcs) { | ||
| funcs.set(func.name, func); | ||
| } | ||
| } | ||
| const declarations = new Scopes(new Group(idents, funcs)); | ||
| declarations.push(); | ||
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| let aggLitElemType = AggregateLiteralElementType.DynElementType; | ||
| if (options?.homogenousAggregateLiterals) { | ||
| aggLitElemType = AggregateLiteralElementType.HomogenousElementType; | ||
| } | ||
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| let filteredOverloadIds = crossTypeNumericComparisonOverloads; | ||
| if (options?.crossTypeNumericComparisons) { | ||
| filteredOverloadIds = new Set<string>(); | ||
| } | ||
| return new _CelCheckerEnv( | ||
| new Namespace(options?.namespace ?? ""), | ||
| options?.registry | ||
| ? createRegistryWithWKT(options.registry) | ||
| : createRegistryWithWKT(), | ||
| declarations, | ||
| aggLitElemType, | ||
| filteredOverloadIds, | ||
| ); | ||
| } | ||
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| class _CelCheckerEnv implements CelCheckerEnv { | ||
| [privateSymbol] = {}; | ||
| constructor( | ||
| public readonly namespace: Namespace, | ||
| public readonly registry: Registry, | ||
| public readonly declarations: Scopes, | ||
| public readonly aggregateLiteralElementType: AggregateLiteralElementType, | ||
| public readonly filteredOverloadIds: Set<string>, | ||
| ) {} | ||
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| /** | ||
| * AddIdents configures the checker with a list of variable declarations. | ||
| * | ||
| * If there are overlapping declarations, the method will error. | ||
| */ | ||
| addIdents(idents: CelIdent[]): void { | ||
| let errMsgs: string[] = []; | ||
| for (const ident of idents) { | ||
| const errMsg = this.#addIdent(ident); | ||
| if (errMsg) { | ||
| errMsgs.push(errMsg); | ||
| } | ||
| } | ||
| if (errMsgs.length > 0) { | ||
| throw new Error(errMsgs.join("\n")); | ||
| } | ||
| } | ||
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| /** | ||
| * AddFunctions configures the checker with a list of function declarations. | ||
| * | ||
| * If there are overlapping declarations, the method will error. | ||
| */ | ||
| addFunctions(funcs: CelFunc[]): void { | ||
| let errMsgs: string[] = []; | ||
| for (const fn of funcs) { | ||
| errMsgs = errMsgs.concat(this.#setFunction(fn)); | ||
| } | ||
| if (errMsgs.length > 0) { | ||
| throw new Error(errMsgs.join("\n")); | ||
| } | ||
| } | ||
|
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There was a problem hiding this comment. Let's eliminate mutation if possible, and require variables and functions to be provided when an environment or scope is created. |
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| /** | ||
| * LookupIdent returns an identifier in the Env. | ||
| * Returns undefined if no such identifier is found in the Env. | ||
| */ | ||
| lookupIdent(name: string): CelIdent | undefined { | ||
|
There was a problem hiding this comment. The compound word |
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| for (const candidate of this.namespace.resolveCandidateNames(name)) { | ||
| const ident = this.declarations.findIdent(candidate); | ||
| if (ident) { | ||
| return ident; | ||
| } | ||
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| // Next try to import the name as a reference to a message type. | ||
| const msg = this.registry.getMessage(candidate); | ||
| if (msg) { | ||
| return celVariable(candidate, objectType(msg)); | ||
| } | ||
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| // Next try to import this as an enum value by splitting the name in a type prefix and | ||
| // the enum inside. | ||
| const lastDot = candidate.lastIndexOf("."); | ||
| if (lastDot !== -1) { | ||
| const enumTypeName = candidate.substring(0, lastDot); | ||
| const enumValueName = candidate.substring(lastDot + 1); | ||
| const enumType = this.registry.getEnum(enumTypeName); | ||
| if (enumType) { | ||
| const enumValueDesc = enumType.values.find( | ||
| (v) => v.name === enumValueName, | ||
| ); | ||
| if (enumValueDesc) { | ||
| return celConstant(candidate, CelScalar.INT, enumValueDesc.number); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| return undefined; | ||
| } | ||
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| /** | ||
| * LookupFunction returns a function declaration in the env. | ||
| * Returns undefined if no such function is found in the env. | ||
| */ | ||
| lookupFunction(name: string): CelFunc | undefined { | ||
| for (const candidate of this.namespace.resolveCandidateNames(name)) { | ||
| const fn = this.declarations.findFunction(candidate); | ||
| if (fn) { | ||
| return fn; | ||
| } | ||
| } | ||
| return undefined; | ||
| } | ||
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| /** | ||
| * setFunction adds the function declaration to the Env. | ||
| * Adds a function decl if one doesn't already exist, then adds all overloads from the Decl. | ||
| * If overload overlaps with an existing overload, adds to the errors in the Env instead. | ||
| */ | ||
| #setFunction(fn: CelFunc): string[] { | ||
| const errMsgs: string[] = []; | ||
| let current = this.declarations.findFunction(fn.name); | ||
| if (!current) { | ||
| current = fn; | ||
| } else { | ||
| current = mergeFuncs(current, fn); | ||
| } | ||
| // TODO: check macros | ||
| // for (const overload of current.overloads) { | ||
| // for _, macro := range parser.AllMacros { | ||
| // if macro.Function() == current.Name() && | ||
| // macro.IsReceiverStyle() == overload.IsMemberFunction() && | ||
| // macro.ArgCount() == len(overload.ArgTypes()) { | ||
| // errMsgs = append(errMsgs, overlappingMacroError(current.Name(), macro.ArgCount())) | ||
| // } | ||
| // } | ||
| // if len(errMsgs) > 0 { | ||
| // return errMsgs | ||
| // } | ||
| // } | ||
| this.declarations.setFunction(current); | ||
| return errMsgs; | ||
| } | ||
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| /** | ||
| * addIdent adds the Decl to the declarations in the Env. | ||
| * Returns a non-empty errorMsg if the identifier is already declared in the scope | ||
| */ | ||
| #addIdent(ident: CelIdent): string | null { | ||
| const current = this.declarations.findIdentInScope(ident.name); | ||
| if (current) { | ||
| if (identDeclarationIsEquivalent(current, ident)) { | ||
| return null; | ||
| } | ||
| return `overlapping identifier for name '${ident.name}'`; | ||
| } | ||
| this.declarations.addIdent(ident); | ||
| return null; | ||
| } | ||
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| /** | ||
| * isOverloadDisabled returns whether the overloadID is disabled in the current environment. | ||
| */ | ||
| isOverloadDisabled(overloadID: string): boolean { | ||
| return this.filteredOverloadIds.has(overloadID); | ||
| } | ||
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| /** | ||
| * validatedDeclarations returns a reference to the validated variable and function declaration scope stack. | ||
| * must be copied before use. | ||
| */ | ||
| validatedDeclarations(): Scopes { | ||
| return this.declarations; | ||
| } | ||
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| /** | ||
| * enterScope creates a new Env instance with a new innermost declaration scope. | ||
| */ | ||
| enterScope(): CelCheckerEnv { | ||
| return new _CelCheckerEnv( | ||
| this.namespace, | ||
| this.registry, | ||
| this.declarations.push(), | ||
| this.aggregateLiteralElementType, | ||
| this.filteredOverloadIds, | ||
| ); | ||
| } | ||
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| /** | ||
| * exitScope creates a new Env instance with the nearest outer declaration scope. | ||
| */ | ||
| exitScope(): CelCheckerEnv { | ||
| return new _CelCheckerEnv( | ||
| this.namespace, | ||
| this.registry, | ||
| this.declarations.pop(), | ||
| this.aggregateLiteralElementType, | ||
| this.filteredOverloadIds, | ||
| ); | ||
| } | ||
| } | ||
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I recognize this may be painful, so feel free to push back (and I'd like to hear @timostamm and/or @srikrsna-buf's thoughts) but I'd like to avoid having multiple "environment" implementations.
cel-gois really hard to work with, in part because for any given noun there are seven different abstractions all related to each other in some convoluted way.For
cel-esif we could follow the rule that "an environment is an environment" I think we'd be better for it.The ontological relationships of "declarations," "scopes," "groups," "namespaces," and "registries" is also going to be a very steep learning curve for the uninitiated. Let's try to narrow the terminology and use the terms very crisply if possible.