fix: make expression evaluation in active effects more secure

This commit is contained in:
Johannes Loher 2022-10-31 22:58:04 +01:00
parent 19ba312a44
commit 20ea70d96a
8 changed files with 1222 additions and 1 deletions

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// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT
import { describe, expect, it } from "vitest";
import { defaultEvaluator, Evaluator, mathEvaluator } from "../../src/expression-evaluation/evaluator";
describe("Evaluator", () => {
it("evaluates expressions that only use identifiers according to the given predicate", () => {
// given
const expression = "typeof 'foo' === 'string' ? 42 : null";
// when
const result = defaultEvaluator.evaluate(expression);
// then
expect(result).toEqual(42);
});
it("fails to evaluate expressions that contain identifiers that are not allowed by the predicate", () => {
// given
const expression = "typeof 'foo' === 'string' ? 42 : function (){}";
// when
const evaluate = () => defaultEvaluator.evaluate(expression);
// then
expect(evaluate).toThrowError("'function' is not an allowed identifier.");
});
it("fails to evaluate expressions that contain invalid tokens", () => {
// given
const expression = "1;";
// when
const evaluate = () => defaultEvaluator.evaluate(expression);
// then
expect(evaluate).toThrowError("Invalid or unexpected token (1)");
});
it("fails to evaluate expressions that contain arrow functions", () => {
// given
const expression = "(() => 1)()";
// when
const evaluate = () => defaultEvaluator.evaluate(expression);
// then
expect(evaluate).toThrowError("Invalid or unexpected token (4)");
});
it("makes the given context available", () => {
// given
const context = { floor: Math.floor };
const evaluator = new Evaluator({ context });
const expression = "floor(0.5)";
// when
const result = evaluator.evaluate(expression);
// then
expect(result).toEqual(0);
});
describe("mathEvaluator", () => {
it("makes the given context available", () => {
// given
const expression = "sqrt(sin(PI))";
// when
const result = mathEvaluator.evaluate(expression);
// then
expect(result).toEqual(Math.sqrt(Math.sin(Math.PI)));
});
it("does not give acces to the function constructor", () => {
// given
const expression = "sqrt.constructor";
// when
const evaluate = () => mathEvaluator.evaluate(expression);
// then
expect(evaluate).toThrowError("'constructor' is not an allowed identifier.");
});
});
});

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// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT
import { describe, expect, it } from "vitest";
import { Lexer } from "../../src/expression-evaluation/lexer";
import type { Token } from "../../src/expression-evaluation/grammar";
describe("Lexer", () => {
const singleOperatorTestCases: { input: string; expected: Token[] }[] = [
{
input: "+",
expected: [
{ type: "+", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "-",
expected: [
{ type: "-", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "*",
expected: [
{ type: "*", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "**",
expected: [
{ type: "**", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "/",
expected: [
{ type: "/", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "%",
expected: [
{ type: "%", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "===",
expected: [
{ type: "===", pos: 0 },
{ type: "eof", pos: 3 },
],
},
{
input: "!==",
expected: [
{ type: "!==", pos: 0 },
{ type: "eof", pos: 3 },
],
},
{
input: "==",
expected: [
{ type: "==", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "<",
expected: [
{ type: "<", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "<=",
expected: [
{ type: "<=", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: ">",
expected: [
{ type: ">", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: ">=",
expected: [
{ type: ">=", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "&&",
expected: [
{ type: "&&", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "||",
expected: [
{ type: "||", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "&",
expected: [
{ type: "&", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "|",
expected: [
{ type: "|", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "<<",
expected: [
{ type: "<<", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: ">>>",
expected: [
{ type: ">>>", pos: 0 },
{ type: "eof", pos: 3 },
],
},
{
input: ".",
expected: [
{ type: ".", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "?.",
expected: [
{ type: "?.", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "??",
expected: [
{ type: "??", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "?",
expected: [
{ type: "?", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: ":",
expected: [
{ type: ":", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "(",
expected: [
{ type: "(", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: ")",
expected: [
{ type: ")", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "[",
expected: [
{ type: "[", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "]",
expected: [
{ type: "]", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: ",",
expected: [
{ type: ",", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "{",
expected: [
{ type: "{", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "}",
expected: [
{ type: "}", pos: 0 },
{ type: "eof", pos: 1 },
],
},
];
const singleNumberTestCases: { input: string; expected: Token[] }[] = [
{
input: "1",
expected: [
{ type: "number", symbol: "1", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "42",
expected: [
{ type: "number", symbol: "42", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "42.9",
expected: [
{ type: "number", symbol: "42.9", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: ".9",
expected: [
{ type: "number", symbol: ".9", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "1_1",
expected: [
{ type: "number", symbol: "1_1", pos: 0 },
{ type: "eof", pos: 3 },
],
},
{
input: "10_1",
expected: [
{ type: "number", symbol: "10_1", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "1_1_1",
expected: [
{ type: "number", symbol: "1_1_1", pos: 0 },
{ type: "eof", pos: 5 },
],
},
{
input: ".1_1",
expected: [
{ type: "number", symbol: ".1_1", pos: 0 },
{ type: "eof", pos: 4 },
],
},
];
const invalidNumberTestCases: { input: string; expected: Token[] }[] = [
{ input: "1.1.1", expected: [{ type: "invalid", pos: 0 }] },
{ input: "1__1", expected: [{ type: "invalid", pos: 0 }] },
{ input: "1_", expected: [{ type: "invalid", pos: 0 }] },
{ input: "1._1", expected: [{ type: "invalid", pos: 0 }] },
{ input: "0_1", expected: [{ type: "invalid", pos: 0 }] },
{ input: "00_1", expected: [{ type: "invalid", pos: 0 }] },
];
const singleIdentifierTestCases: { input: string; expected: Token[] }[] = [
{
input: "foo",
expected: [
{ type: "iden", symbol: "foo", pos: 0 },
{ type: "eof", pos: 3 },
],
},
{
input: "_foo",
expected: [
{ type: "iden", symbol: "_foo", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "$foo",
expected: [
{ type: "iden", symbol: "$foo", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "foo1",
expected: [
{ type: "iden", symbol: "foo1", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "_foo1_",
expected: [
{ type: "iden", symbol: "_foo1_", pos: 0 },
{ type: "eof", pos: 6 },
],
},
{
input: "μ",
expected: [
{ type: "iden", symbol: "μ", pos: 0 },
{ type: "eof", pos: 1 },
],
},
{
input: "._1",
expected: [
{ type: ".", pos: 0 },
{ type: "iden", symbol: "_1", pos: 1 },
{ type: "eof", pos: 3 },
],
},
{
input: "true",
expected: [
{ type: "iden", symbol: "true", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "false",
expected: [
{ type: "iden", symbol: "false", pos: 0 },
{ type: "eof", pos: 5 },
],
},
{
input: "null",
expected: [
{ type: "iden", symbol: "null", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "undefined",
expected: [
{ type: "iden", symbol: "undefined", pos: 0 },
{ type: "eof", pos: 9 },
],
},
];
const invalidIdentifierTestCases: { input: string; expected: Token[] }[] = [
{
input: "1foo",
expected: [
{ type: "number", symbol: "1", pos: 0 },
{ type: "iden", symbol: "foo", pos: 1 },
{ type: "eof", pos: 4 },
],
},
{ input: "↓", expected: [{ type: "invalid", pos: 0 }] },
{ input: '"', expected: [{ type: "invalid", pos: 0 }] },
];
const singleStringTestCases: { input: string; expected: Token[] }[] = [
{
input: '""',
expected: [
{ type: "string", symbol: '""', pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: '"foo"',
expected: [
{ type: "string", symbol: '"foo"', pos: 0 },
{ type: "eof", pos: 5 },
],
},
{
input: '"\\""',
expected: [
{ type: "string", symbol: '"\\""', pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: '"\\\'"',
expected: [
{ type: "string", symbol: '"\\\'"', pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "''",
expected: [
{ type: "string", symbol: "''", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "'foo'",
expected: [
{ type: "string", symbol: "'foo'", pos: 0 },
{ type: "eof", pos: 5 },
],
},
{
input: "'\\''",
expected: [
{ type: "string", symbol: "'\\''", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "'\\\"'",
expected: [
{ type: "string", symbol: "'\\\"'", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: "``",
expected: [
{ type: "string", symbol: "``", pos: 0 },
{ type: "eof", pos: 2 },
],
},
{
input: "`foo`",
expected: [
{ type: "string", symbol: "`foo`", pos: 0 },
{ type: "eof", pos: 5 },
],
},
{
input: "`\\``",
expected: [
{ type: "string", symbol: "`\\``", pos: 0 },
{ type: "eof", pos: 4 },
],
},
{
input: '`\\"`',
expected: [
{ type: "string", symbol: '`\\"`', pos: 0 },
{ type: "eof", pos: 4 },
],
},
];
const invalidStringTestCases: { input: string; expected: Token[] }[] = [
{ input: '"', expected: [{ type: "invalid", pos: 0 }] },
{ input: '"\\"', expected: [{ type: "invalid", pos: 0 }] },
{ input: "'", expected: [{ type: "invalid", pos: 0 }] },
{ input: "'\\'", expected: [{ type: "invalid", pos: 0 }] },
];
const whiteSpaceTestCases: { input: string; expected: Token[] }[] = [
{ input: " ", expected: [{ type: "eof", pos: 1 }] },
{ input: " ", expected: [{ type: "eof", pos: 3 }] },
{ input: "\n", expected: [{ type: "eof", pos: 1 }] },
{ input: " \n", expected: [{ type: "eof", pos: 2 }] },
{ input: " ", expected: [{ type: "eof", pos: 1 }] },
];
const complicatedTermTestCases: { input: string; expected: Token[] }[] = [
{
input: "5x",
expected: [
{ type: "number", symbol: "5", pos: 0 },
{ type: "iden", symbol: "x", pos: 1 },
{ type: "eof", pos: 2 },
],
},
{
input: "5*x",
expected: [
{ type: "number", symbol: "5", pos: 0 },
{ type: "*", pos: 1 },
{ type: "iden", symbol: "x", pos: 2 },
{ type: "eof", pos: 3 },
],
},
{
input: "5 * x",
expected: [
{ type: "number", symbol: "5", pos: 0 },
{ type: "*", pos: 2 },
{ type: "iden", symbol: "x", pos: 4 },
{ type: "eof", pos: 5 },
],
},
{
input: "(5 * 5 + 2) / 1.2 === 'foo'",
expected: [
{ type: "(", pos: 0 },
{ type: "number", symbol: "5", pos: 1 },
{ type: "*", pos: 3 },
{ type: "number", symbol: "5", pos: 5 },
{ type: "+", pos: 7 },
{ type: "number", symbol: "2", pos: 9 },
{ type: ")", pos: 10 },
{ type: "/", pos: 12 },
{ type: "number", symbol: "1.2", pos: 14 },
{ type: "===", pos: 18 },
{ type: "string", symbol: "'foo'", pos: 22 },
{ type: "eof", pos: 27 },
],
},
{
input: "(() => {console.log('foo'); return 1;})()",
expected: [
{ type: "(", pos: 0 },
{ type: "(", pos: 1 },
{ type: ")", pos: 2 },
{ type: "invalid", pos: 4 },
],
},
{
input: "(function() {console.log('foo'); return 1;})()",
expected: [
{ type: "(", pos: 0 },
{ type: "iden", symbol: "function", pos: 1 },
{ type: "(", pos: 9 },
{ type: ")", pos: 10 },
{ type: "{", pos: 12 },
{ type: "iden", symbol: "console", pos: 13 },
{ type: ".", pos: 20 },
{ type: "iden", symbol: "log", pos: 21 },
{ type: "(", pos: 24 },
{ type: "string", symbol: "'foo'", pos: 25 },
{ type: ")", pos: 30 },
{ type: "invalid", pos: 31 },
],
},
{
input: "'ranged' === 'ranged'",
expected: [
{ type: "string", symbol: "'ranged'", pos: 0 },
{ type: "===", pos: 9 },
{ type: "string", symbol: "'ranged'", pos: 13 },
{ type: "eof", pos: 21 },
],
},
];
it.each([
...singleOperatorTestCases,
...singleNumberTestCases,
...invalidNumberTestCases,
...singleIdentifierTestCases,
...invalidIdentifierTestCases,
...singleStringTestCases,
...invalidStringTestCases,
...whiteSpaceTestCases,
...complicatedTermTestCases,
])("lexes $input correctly", ({ input, expected }) => {
// when
const result = consume(new Lexer(input));
// then
expect(result).toEqual(expected);
});
});
function consume<T>(iterable: Iterable<T>): T[] {
const result: T[] = [];
for (const value of iterable) {
result.push(value);
}
return result;
}

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@ -0,0 +1,126 @@
// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT
import { describe, expect, it } from "vitest";
import { literals, safeOperators } from "../../src/expression-evaluation/grammar";
import { Validator } from "../../src/expression-evaluation/validator";
describe("Validator", () => {
it("allows identifier according to the given predicate", () => {
// given
const predicate = (identifier: string) => identifier === "true";
const validator = new Validator(predicate);
const input = "true";
// when
const validate = () => validator.validate(input);
// then
expect(validate).not.toThrow();
});
it("disallows identifier according to the given predicate", () => {
// given
const predicate = (identifier: string) => identifier === "false";
const validator = new Validator(predicate);
const input = "true";
// when
const validate = () => validator.validate(input);
// then
expect(validate).toThrowError("'true' is not an allowed identifier");
});
it("allows multiple identifiers according to the given predicate", () => {
// given
const predicate = (identifier: string) => identifier === "true" || identifier === "null";
const validator = new Validator(predicate);
const input = "true null";
// when
const validate = () => validator.validate(input);
// then
expect(validate).not.toThrow();
});
it("allows multiple identifiers in a more complex expression according to the given rule", () => {
// given
const predicate = (identifier: string) => identifier === "true" || identifier === "null";
const validator = new Validator(predicate);
const input = "true === null";
// when
const validate = () => validator.validate(input);
// then
expect(validate).not.toThrow();
});
it("mentions the first not allowed identifier in the thrown errror", () => {
// given
const predicate = (identifier: string) => identifier === "true" || identifier === "null";
const validator = new Validator(predicate);
const input = "true === null && undefined === false";
// when
const validate = () => validator.validate(input);
// then
expect(validate).toThrowError("'undefined' is not an allowed identifier.");
});
it("disallows invalid invalid tokens", () => {
// given
const validator = new Validator();
const input = ";";
// when
const validate = () => validator.validate(input);
// then
expect(validate).toThrowError("Invalid or unexpected token (0)");
});
it("allows a complicated valid expression", () => {
// given
const predicate = (identifier: string) =>
[...safeOperators, ...literals, "floor", "random"].includes(identifier);
const validator = new Validator(predicate);
const input = "typeof (floor(random() * 5) / 2) === 'number' ? 42 : 'foo'";
// when
const validate = () => validator.validate(input);
// then
expect(validate).not.toThrow();
});
it("disallows a complicated expression if it contains a disallowed identifier", () => {
// given
const predicate = (identifier: string) => [...safeOperators, ...literals, "ceil"].includes(identifier);
const validator = new Validator(predicate);
const input = "ceil.constructor('alert(1); return 1;')()";
// when
const validate = () => validator.validate(input);
// then
expect(validate).toThrowError("'constructor' is not an allowed identifier.");
});
it("disallows arrow functions", () => {
// given
const validator = new Validator();
const input = "() => {}";
// when
const validate = () => validator.validate(input);
// then
expect(validate).toThrowError("Invalid or unexpected token (3)");
});
});

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@ -3,6 +3,7 @@
// SPDX-License-Identifier: MIT // SPDX-License-Identifier: MIT
import { DS4Actor } from "./actor/actor"; import { DS4Actor } from "./actor/actor";
import { mathEvaluator } from "./expression-evaluation/evaluator";
import { getGame } from "./helpers"; import { getGame } from "./helpers";
import type { DS4Item } from "./item/item"; import type { DS4Item } from "./item/item";
@ -62,8 +63,9 @@ export class DS4ActiveEffect extends ActiveEffect {
override apply(actor: DS4Actor, change: foundry.data.ActiveEffectData["changes"][number]): unknown { override apply(actor: DS4Actor, change: foundry.data.ActiveEffectData["changes"][number]): unknown {
change.value = Roll.replaceFormulaData(change.value, actor.data); change.value = Roll.replaceFormulaData(change.value, actor.data);
try { try {
change.value = Roll.safeEval(change.value).toString(); change.value = DS4ActiveEffect.safeEval(change.value).toString();
} catch (e) { } catch (e) {
logger.warn(e);
// this is a valid case, e.g., if the effect change simply is a string // this is a valid case, e.g., if the effect change simply is a string
} }
return super.apply(actor, change); return super.apply(actor, change);
@ -104,4 +106,12 @@ export class DS4ActiveEffect extends ActiveEffect {
return this.create(createData, { parent, pack: parent.pack ?? undefined }); return this.create(createData, { parent, pack: parent.pack ?? undefined });
} }
static safeEval(expression: string): number | `${number | boolean}` {
const result = mathEvaluator.evaluate(expression);
if (!Number.isNumeric(result)) {
throw new Error(`mathEvaluator.evaluate produced a non-numeric result from expression "${expression}"`);
}
return result as number | `${number | boolean}`;
}
} }

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@ -0,0 +1,38 @@
// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT
import { Validator } from "./validator";
export class Evaluator<Context extends object> {
context?: Context;
validator: Validator;
constructor({
context,
predicate = Validator.defaultPredicate,
}: { context?: Context; predicate?: (identifier: string) => boolean } = {}) {
let actualPredicate = predicate;
if (context) {
this.context = new Proxy(context, {
has: () => true,
get: (t, k) => (k === Symbol.unscopables ? undefined : t[k as keyof typeof t]),
});
actualPredicate = (identifier: string) =>
predicate(identifier) || Object.getOwnPropertyNames(Math).includes(identifier);
}
this.validator = new Validator(actualPredicate);
}
evaluate(expression: string): unknown {
this.validator.validate(expression);
const body = `with (sandbox) { return ${expression}; }`;
const evaluate = new Function("sandbox", body);
return evaluate(this.context ?? {});
}
}
export const defaultEvaluator = new Evaluator();
export const mathEvaluator = new Evaluator({ context: Math });

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@ -0,0 +1,61 @@
// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT
export type Token = TokenWithSymbol | TokenWithoutSymbol;
export interface TokenWithSymbol {
type: TypeWithSymbol;
symbol: string;
pos: number;
}
interface TokenWithoutSymbol {
type: TypeWithoutSymbol;
pos: number;
}
type TypeWithSymbol = "iden" | "number" | "string";
type TypeWithoutSymbol =
| "+"
| "-"
| "*"
| "**"
| "/"
| "%"
| "==="
| "!=="
| "=="
| "!="
| "<"
| "<="
| ">"
| ">="
| "&&"
| "||"
| "&"
| "|"
| "~"
| "^"
| "<<"
| ">>"
| ">>>"
| "."
| "?."
| "??"
| "!"
| "?"
| ":"
| "("
| ")"
| "["
| "]"
| ","
| "{"
| "}"
| "invalid"
| "eof";
export const literals = ["true", "false", "null", "undefined"];
export const safeOperators = ["in", "instanceof", "typeof", "void"];

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@ -0,0 +1,264 @@
// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT
import type { Token } from "./grammar";
export class Lexer {
constructor(private readonly input: string) {}
*[Symbol.iterator](): Generator<Token, void> {
let pos = 0;
while (true) {
if (this.isWhiteSpace(this.input[pos])) {
pos += 1;
continue;
}
const [token, newPos] = this.getNextToken(pos);
pos = newPos;
yield token;
if (token.type === "eof" || token.type === "invalid") {
break;
}
}
}
private getNextToken(pos: number): [Token, number] {
const current = this.input[pos];
if (current === undefined) {
return [{ type: "eof", pos }, pos];
}
if (this.isOperatorStart(current)) {
return this.getOperator(pos);
}
if (this.isDigit(current)) {
return this.getNumber(pos);
}
if (current === "'" || current === '"' || current === "`") {
return this.getString(pos);
}
if (current === ".") {
const next = this.input[pos + 1];
if (this.isDigit(next)) {
return this.getNumber(pos);
}
return this.getOperator(pos);
}
if (this.isIdentifierStart(current)) {
return this.getIdentifier(pos);
}
return [{ type: "invalid", pos }, pos];
}
private isOperatorStart(char: string) {
const operatorStartChars: (string | undefined)[] = [
"+",
"-",
"*",
"/",
"%",
"=",
"!",
">",
"<",
"&",
"|",
"~",
"^",
"?",
":",
"!",
",",
"(",
")",
"[",
"]",
"{",
"}",
];
return operatorStartChars.includes(char[0]);
}
private getOperator(pos: number): [Token, number] {
const current = this.input[pos];
const next = this.input[pos + 1];
const nextButOne = this.input[pos + 2];
switch (current) {
case "+":
case "-":
case "/":
case "%":
case "~":
case "^":
case ".":
case ":":
case ",":
case "(":
case ")":
case "[":
case "]":
case "{":
case "}": {
return [{ type: current, pos }, pos + 1];
}
case "*": {
if (next === "*") {
return [{ type: "**", pos }, pos + 2];
}
return [{ type: "*", pos }, pos + 1];
}
case "=": {
if (next === "=") {
if (nextButOne === "=") {
return [{ type: "===", pos }, pos + 3];
}
return [{ type: "==", pos }, pos + 2];
}
return [{ type: "invalid", pos }, pos];
}
case "!": {
if (next === "=") {
if (nextButOne === "=") {
return [{ type: "!==", pos }, pos + 3];
}
return [{ type: "!=", pos }, pos + 2];
}
return [{ type: "!", pos }, pos + 1];
}
case ">": {
switch (next) {
case ">": {
if (nextButOne === ">") {
return [{ type: ">>>", pos }, pos + 3];
}
return [{ type: ">>", pos }, pos + 2];
}
case "=": {
return [{ type: ">=", pos }, pos + 2];
}
default: {
return [{ type: ">", pos }, pos + 1];
}
}
}
case "<": {
switch (next) {
case "=": {
return [{ type: "<=", pos }, pos + 2];
}
case "<": {
return [{ type: "<<", pos }, pos + 2];
}
default: {
return [{ type: "<", pos }, pos + 1];
}
}
}
case "&": {
if (next === "&") {
return [{ type: "&&", pos }, pos + 2];
}
return [{ type: "&", pos }, pos + 1];
}
case "|": {
if (next === "|") {
return [{ type: "||", pos }, pos + 2];
}
return [{ type: "|", pos }, pos + 1];
}
case "?": {
switch (next) {
case ".": {
return [{ type: "?.", pos }, pos + 2];
}
case "?": {
return [{ type: "??", pos }, pos + 2];
}
default: {
return [{ type: "?", pos }, pos + 1];
}
}
}
}
return [{ type: "invalid", pos }, pos];
}
private isDigit(char: string | undefined): char is `${number}` {
return /\d/.test(char?.[0] ?? "");
}
private getNumber(pos: number): [Token, number] {
let endPos = pos;
let foundDot = false;
let only0s = false;
while (
this.isDigit(this.input[endPos]) ||
this.input[endPos] === "." ||
(this.input[endPos] === "_" && endPos > pos)
) {
if (this.input[endPos] === ".") {
if (foundDot) {
return [{ type: "invalid", pos }, pos];
}
foundDot = true;
}
if (this.input[endPos] === "0") {
only0s = endPos === pos ? true : only0s;
}
if (
this.input[endPos] === "_" &&
(this.input[endPos - 1] === "_" || this.input[endPos - 1] === "." || only0s)
) {
return [{ type: "invalid", pos }, pos];
}
endPos += 1;
}
if (pos === endPos) {
return [{ type: "invalid", pos }, pos];
}
if (this.input[endPos - 1] === "_") {
return [{ type: "invalid", pos }, pos];
}
return [{ type: "number", symbol: this.input.slice(pos, endPos), pos }, endPos];
}
private isIdentifierStart(char: string | undefined) {
return /[$_\p{ID_Start}]/u.test(char?.[0] ?? "");
}
private isIdentifier(char: string | undefined) {
return /[$\u200c\u200d\p{ID_Continue}]/u.test(char?.[0] ?? "");
}
private getIdentifier(pos: number): [Token, number] {
let endPos = pos;
while (endPos < this.input.length && this.isIdentifier(this.input[endPos])) {
endPos += 1;
}
if (endPos === pos) {
return [{ type: "invalid", pos }, pos];
}
return [{ type: "iden", symbol: this.input.slice(pos, endPos), pos }, endPos];
}
private getString(pos: number): [Token, number] {
const quote = this.input[pos];
let endPos = pos + 1;
let prev = this.input[pos];
while (endPos < this.input.length && (this.input[endPos] !== quote || prev === "\\")) {
prev = this.input[endPos];
endPos += 1;
}
if (endPos === pos || this.input[endPos] !== quote) {
return [{ type: "invalid", pos }, pos];
}
return [{ type: "string", symbol: this.input.slice(pos, endPos + 1), pos }, endPos + 1];
}
private isWhiteSpace(char: string | undefined) {
return /\s/.test(char?.[0] ?? "");
}
}

View file

@ -0,0 +1,30 @@
// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT
import { literals, safeOperators } from "./grammar";
import { Lexer } from "./lexer";
export class Validator {
constructor(private readonly predicate: (identifier: string) => boolean = Validator.defaultPredicate) {}
static readonly defaultPredicate = (identifier: string) => [...literals, ...safeOperators].includes(identifier);
public validate(input: string): void {
const lexer = new Lexer(input);
for (const token of lexer) {
if (token.type === "iden" && !this.predicate(token.symbol)) {
throw new ValidationError(token.symbol);
}
if (token.type === "invalid") {
throw new SyntaxError(`Invalid or unexpected token (${token.pos})`);
}
}
}
}
class ValidationError extends Error {
constructor(identifier: string) {
super(`'${identifier}' is not an allowed identifier.`);
}
}