Hash :
0df60be1
Author :
Date :
2020-11-04T17:18:23
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"use strict";
const { assert } = require('chai');
const PrismLoader = require('./helper/prism-loader');
const { BFS, parseRegex } = require('./helper/util');
const { languages } = require('../components.json');
const { visitRegExpAST } = require('regexpp');
for (const lang in languages) {
if (lang === 'meta') {
continue;
}
describe(`Patterns of '${lang}'`, function () {
const Prism = PrismLoader.createInstance(lang);
testPatterns(Prism);
});
function toArray(value) {
if (Array.isArray(value)) {
return value;
} else if (value != null) {
return [value];
} else {
return [];
}
}
let optional = toArray(languages[lang].optional);
let modify = toArray(languages[lang].modify);
if (optional.length > 0 || modify.length > 0) {
let name = `Patterns of '${lang}'`;
if (optional.length > 0) {
name += ` + optional dependencies '${optional.join("', '")}'`;
}
if (modify.length > 0) {
name += ` + modify dependencies '${modify.join("', '")}'`;
}
describe(name, function () {
const Prism = PrismLoader.createInstance([...optional, ...modify, lang]);
testPatterns(Prism);
});
}
}
/**
* Tests all patterns in the given Prism instance.
*
* @param {any} Prism
*
* @typedef {import("./helper/util").LiteralAST} LiteralAST
* @typedef {import("regexpp/ast").Element} Element
* @typedef {import("regexpp/ast").Pattern} Pattern
*/
function testPatterns(Prism) {
/**
* Invokes the given function on every pattern in `Prism.languages`.
*
* _Note:_ This will aggregate all errors thrown by the given callback and throw an aggregated error at the end
* of the iteration. You can also append any number of errors per callback using the `reportError` function.
*
* @param {(values: ForEachPatternCallbackValue) => void} callback
*
* @typedef ForEachPatternCallbackValue
* @property {RegExp} pattern
* @property {LiteralAST} ast
* @property {string} tokenPath
* @property {string} name
* @property {any} parent
* @property {boolean} lookbehind Whether the first capturing group of the pattern is a Prism lookbehind group.
* @property {{ key: string, value: any }[]} path
* @property {(message: string) => void} reportError
*/
function forEachPattern(callback) {
const errors = [];
BFS(Prism.languages, path => {
const { key, value } = path[path.length - 1];
let tokenPath = 'Prism.languages';
for (const { key } of path) {
if (!key) {
// do nothing
} else if (/^\d+$/.test(key)) {
tokenPath += `[${key}]`;
} else if (/^[a-z]\w*$/i.test(key)) {
tokenPath += `.${key}`;
} else {
tokenPath += `[${JSON.stringify(key)}]`;
}
}
if (Object.prototype.toString.call(value) == '[object RegExp]') {
try {
let ast;
try {
ast = parseRegex(value);
} catch (error) {
throw new SyntaxError(`Invalid RegExp at ${tokenPath}\n\n${error.message}`);
}
const parent = path.length > 1 ? path[path.length - 2].value : undefined;
callback({
pattern: value,
ast,
tokenPath,
name: key,
parent,
path,
lookbehind: key === 'pattern' && parent && !!parent.lookbehind,
reportError: message => errors.push(message)
});
} catch (error) {
errors.push(error);
}
}
});
if (errors.length > 0) {
throw new Error(errors.map(e => String(e.message || e)).join('\n\n'));
}
}
/**
* Invokes the given callback for all capturing groups in the given pattern in left to right order.
*
* @param {Pattern} pattern
* @param {(values: ForEachCapturingGroupCallbackValue) => void} callback
*
* @typedef ForEachCapturingGroupCallbackValue
* @property {import("regexpp/ast").CapturingGroup} group
* @property {number} number Note: Starts at 1.
*/
function forEachCapturingGroup(pattern, callback) {
let number = 0;
visitRegExpAST(pattern, {
onCapturingGroupEnter(node) {
callback({
group: node,
number: ++number
});
}
});
}
/**
* Returns whether the given element will always have zero width meaning that it doesn't consume characters.
*
* @param {Element} element
* @returns {boolean}
*/
function isAlwaysZeroWidth(element) {
switch (element.type) {
case 'Assertion':
// assertions == ^, $, \b, lookarounds
return true;
case 'Quantifier':
return element.max === 0 || isAlwaysZeroWidth(element.element);
case 'CapturingGroup':
case 'Group':
// every element in every alternative has to be of zero length
return element.alternatives.every(alt => alt.elements.every(isAlwaysZeroWidth));
case 'Backreference':
// on if the group referred to is of zero length
return isAlwaysZeroWidth(element.resolved);
default:
return false; // what's left are characters
}
}
/**
* Returns whether the given element will always at the start of the whole match.
*
* @param {Element} element
* @returns {boolean}
*/
function isFirstMatch(element) {
const parent = element.parent;
switch (parent.type) {
case 'Alternative':
// all elements before this element have to of zero length
if (!parent.elements.slice(0, parent.elements.indexOf(element)).every(isAlwaysZeroWidth)) {
return false;
}
const grandParent = parent.parent;
if (grandParent.type === 'Pattern') {
return true;
} else {
return isFirstMatch(grandParent);
}
case 'Quantifier':
if (parent.max >= 2) {
return false;
} else {
return isFirstMatch(parent);
}
default:
throw new Error(`Internal error: The given node should not be a '${element.type}'.`);
}
}
it('- should not match the empty string', function () {
forEachPattern(({ pattern, tokenPath }) => {
// test for empty string
assert.notMatch('', pattern, `${tokenPath}: ${pattern} should not match the empty string.\n\n`
+ `Patterns that do match the empty string can potentially cause infinitely many empty tokens. `
+ `Make sure that all patterns always consume at least one character.`);
});
});
it('- should have a capturing group if lookbehind is set to true', function () {
forEachPattern(({ ast, tokenPath, lookbehind }) => {
if (lookbehind) {
let hasCapturingGroup = false;
forEachCapturingGroup(ast.pattern, () => { hasCapturingGroup = true; });
if (!hasCapturingGroup) {
assert.fail(`${tokenPath}: The pattern is set to 'lookbehind: true' but does not have a capturing group.\n\n`
+ `Prism lookbehind groups use the captured text of the first capturing group to simulate a lookbehind. `
+ `Without a capturing group, a lookbehind is not possible.\n`
+ `To fix this, either add a capturing group for the lookbehind or remove the 'lookbehind' property.`);
}
}
});
});
it('- should not have lookbehind groups that can be preceded by other some characters', function () {
forEachPattern(({ ast, tokenPath, lookbehind }) => {
if (!lookbehind) {
return;
}
forEachCapturingGroup(ast.pattern, ({ group, number }) => {
if (number === 1 && !isFirstMatch(group)) {
assert.fail(`${tokenPath}: The lookbehind group ${group.raw} might be preceded by some characters.\n\n`
+ `Prism assumes that the lookbehind group, if captured, is the first thing matched by the regex. `
+ `If characters might precede the lookbehind group (e.g. /a?(b)c/), then Prism cannot correctly apply the lookbehind correctly in all cases.\n`
+ `To fix this, either remove the preceding characters or include them in the lookbehind group.`);
}
});
});
});
it('- should not have lookbehind groups that only have zero-width alternatives', function () {
forEachPattern(({ ast, tokenPath, lookbehind, reportError }) => {
if (!lookbehind) {
return;
}
forEachCapturingGroup(ast.pattern, ({ group, number }) => {
if (number === 1 && isAlwaysZeroWidth(group)) {
const groupContent = group.raw.substr(1, group.raw.length - 2);
const replacement = group.alternatives.length === 1 ? groupContent : `(?:${groupContent})`;
reportError(`${tokenPath}: The lookbehind group ${group.raw} does not consume characters.\n\n`
+ `Therefor it is not necessary to use a lookbehind group.\n`
+ `To fix this, replace the lookbehind group with ${replacement} and remove the 'lookbehind' property.`);
}
});
});
});
it('- should not have unused capturing groups', function () {
forEachPattern(({ ast, tokenPath, lookbehind, reportError }) => {
forEachCapturingGroup(ast.pattern, ({ group, number }) => {
const isLookbehindGroup = lookbehind && number === 1;
if (group.references.length === 0 && !isLookbehindGroup) {
const fixes = [];
fixes.push(`Make this group a non-capturing group ('(?:...)' instead of '(...)'). (It's usually this option.)`);
fixes.push(`Reference this group with a backreference (use '\\${number}' for this).`);
if (number === 1 && !lookbehind) {
if (isFirstMatch(group)) {
fixes.push(`Add a 'lookbehind: true' declaration.`);
} else {
fixes.push(`Add a 'lookbehind: true' declaration. (This group is not a valid lookbehind group because it can be preceded by some characters.)`);
}
}
reportError(`${tokenPath}: Unused capturing group ${group.raw}.\n\n`
+ `Unused capturing groups generally degrade the performance of regular expressions. `
+ `They might also be a sign that a backreference is incorrect or that a 'lookbehind: true' declaration in missing.\n`
+ `To fix this, do one of the following:\n`
+ fixes.map(f => '- ' + f).join('\n'));
}
});
});
});
it('- should have nice names and aliases', function () {
const niceName = /^[a-z][a-z\d]*(?:-[a-z\d]+)*$/;
function testName(name, desc = 'token name') {
if (!niceName.test(name)) {
assert.fail(`The ${desc} '${name}' does not match ${niceName}.\n\n`
+ `To fix this, choose a name that matches the above regular expression.`);
}
}
forEachPattern(({ name, parent, tokenPath, path }) => {
// token name
let offset = 1;
if (name == 'pattern') { // regex can be inside an object
offset++;
}
if (Array.isArray(path[path.length - 1 - offset].value)) { // regex/regex object can be inside an array
offset++;
}
const patternName = path[path.length - offset].key;
testName(patternName);
// check alias
if (name == 'pattern' && 'alias' in parent) {
const alias = parent.alias;
if (typeof alias === 'string') {
testName(alias, `alias of '${tokenPath}'`);
} else if (Array.isArray(alias)) {
alias.forEach(name => testName(name, `alias of '${tokenPath}'`));
}
}
});
});
it('- should not use octal escapes', function () {
forEachPattern(({ ast, tokenPath, reportError }) => {
visitRegExpAST(ast.pattern, {
onCharacterEnter(node) {
if (/^\\(?:[1-9]|\d{2,})$/.test(node.raw)) {
reportError(`${tokenPath}: Octal escape ${node.raw}.\n\n`
+ `Octal escapes can be confused with backreferences, so please do not use them.\n`
+ `To fix this, use a different escape method. `
+ `Note that this could also be an invalid backreference, so be sure to carefully analyse the pattern.`);
}
}
});
});
});
}