diff --git a/package-lock.json b/package-lock.json index 925b385c..188f756f 100644 --- a/package-lock.json +++ b/package-lock.json @@ -5,6 +5,7 @@ "requires": true, "packages": { "": { + "name": "nth-check", "version": "2.0.0", "license": "BSD-2-Clause", "dependencies": { @@ -726,7 +727,6 @@ "jest-resolve": "^26.6.2", "jest-util": "^26.6.2", "jest-worker": "^26.6.2", - "node-notifier": "^8.0.0", "slash": "^3.0.0", "source-map": "^0.6.0", "string-length": "^4.0.1", @@ -2228,8 +2228,7 @@ "esprima": "^4.0.1", "estraverse": "^4.2.0", "esutils": "^2.0.2", - "optionator": "^0.8.1", - "source-map": "~0.6.1" + "optionator": "^0.8.1" }, "bin": { "escodegen": "bin/escodegen.js", @@ -3052,9 +3051,9 @@ } }, "node_modules/glob-parent": { - "version": "5.1.1", - "resolved": "https://registry.npmjs.org/glob-parent/-/glob-parent-5.1.1.tgz", - "integrity": "sha512-FnI+VGOpnlGHWZxthPGR+QhR78fuiK0sNLkHQv+bL9fQi57lNNdquIbna/WrfROrolq8GK5Ek6BiMwqL/voRYQ==", + "version": "5.1.2", + "resolved": "https://registry.npmjs.org/glob-parent/-/glob-parent-5.1.2.tgz", + "integrity": "sha512-AOIgSQCepiJYwP3ARnGx+5VnTu2HBYdzbGP45eLw1vr3zB3vZLeyed1sC9hnbcOc9/SrMyM5RPQrkGz4aS9Zow==", "dev": true, "dependencies": { "is-glob": "^4.0.1" @@ -3228,9 +3227,9 @@ } }, "node_modules/hosted-git-info": { - "version": "2.8.8", - "resolved": "https://registry.npmjs.org/hosted-git-info/-/hosted-git-info-2.8.8.tgz", - "integrity": "sha512-f/wzC2QaWBs7t9IYqB4T3sR1xviIViXJRJTWBlx2Gf3g0Xi5vI7Yy4koXQ1c9OYDGHN9sBy1DQ2AB8fqZBWhUg==", + "version": "2.8.9", + "resolved": "https://registry.npmjs.org/hosted-git-info/-/hosted-git-info-2.8.9.tgz", + "integrity": "sha512-mxIDAb9Lsm6DoOJ7xH+5+X4y1LU/4Hi50L9C5sIswK3JzULS4bwk1FvjdBgvYR4bzT4tuUQiC15FE2f5HbLvYw==", "dev": true }, "node_modules/html-encoding-sniffer": { @@ -3858,7 +3857,6 @@ "@types/node": "*", "anymatch": "^3.0.3", "fb-watchman": "^2.0.0", - "fsevents": "^2.1.2", "graceful-fs": "^4.2.4", "jest-regex-util": "^26.0.0", "jest-serializer": "^26.6.2", @@ -4415,9 +4413,9 @@ } }, "node_modules/lodash": { - "version": "4.17.20", - "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.20.tgz", - "integrity": "sha512-PlhdFcillOINfeV7Ni6oF1TAEayyZBoZ8bcshTHqOYJYlrqzRK5hagpagky5o4HfCzzd1TRkXPMFq6cKk9rGmA==", + "version": "4.17.21", + "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz", + "integrity": "sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==", "dev": true }, "node_modules/lodash.memoize": { @@ -5000,9 +4998,9 @@ } }, "node_modules/path-parse": { - 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"version": "7.4.0", - "resolved": "https://registry.npmjs.org/ws/-/ws-7.4.0.tgz", - "integrity": "sha512-kyFwXuV/5ymf+IXhS6f0+eAFvydbaBW3zjpT6hUdAh/hbVjTIB5EHBGi0bPoCLSK2wcuz3BrEkB9LrYv1Nm4NQ==", + "version": "7.5.5", + "resolved": "https://registry.npmjs.org/ws/-/ws-7.5.5.tgz", + "integrity": "sha512-BAkMFcAzl8as1G/hArkxOxq3G7pjUqQ3gzYbLL0/5zNkph70e+lCoxBGnm6AW1+/aiNeV4fnKqZ8m4GZewmH2w==", "dev": true, "requires": {} }, diff --git a/src/parse.ts b/src/parse.ts index 97171a36..5563a038 100644 --- a/src/parse.ts +++ b/src/parse.ts @@ -1,7 +1,9 @@ // Following http://www.w3.org/TR/css3-selectors/#nth-child-pseudo -// [ ['-'|'+']? INTEGER? {N} [ S* ['-'|'+'] S* INTEGER ]? -const RE_NTH_ELEMENT = /^([+-]?\d*n)?\s*(?:([+-]?)\s*(\d+))?$/; +// Whitespace as per https://www.w3.org/TR/selectors-3/#lex is " \t\r\n\f" +const whitespace = new Set([9, 10, 12, 13, 32]); +const ZERO = "0".charCodeAt(0); +const NINE = "9".charCodeAt(0); /** * Parses an expression. @@ -19,24 +21,72 @@ export function parse(formula: string): [a: number, b: number] { return [2, 1]; } - const parsed = formula.match(RE_NTH_ELEMENT); + // Parse [ ['-'|'+']? INTEGER? {N} [ S* ['-'|'+'] S* INTEGER ]? - if (!parsed) { + let idx = 0; + + let a = 0; + let sign = readSign(); + let number = readNumber(); + + if (idx < formula.length && formula.charAt(idx) === "n") { + idx++; + a = sign * (number ?? 1); + + skipWhitespace(); + + if (idx < formula.length) { + sign = readSign(); + skipWhitespace(); + number = readNumber(); + } else { + sign = number = 0; + } + } + + // Throw if there is anything else + if (number === null || idx < formula.length) { throw new Error(`n-th rule couldn't be parsed ('${formula}')`); } - let a; + return [a, sign * number]; - if (parsed[1]) { - a = parseInt(parsed[1], 10); - if (isNaN(a)) { - a = parsed[1].startsWith("-") ? -1 : 1; + function readSign() { + if (formula.charAt(idx) === "-") { + idx++; + return -1; } - } else a = 0; - const b = - (parsed[2] === "-" ? -1 : 1) * - (parsed[3] ? parseInt(parsed[3], 10) : 0); + if (formula.charAt(idx) === "+") { + idx++; + } - return [a, b]; + return 1; + } + + function readNumber() { + const start = idx; + let value = 0; + + while ( + idx < formula.length && + formula.charCodeAt(idx) >= ZERO && + formula.charCodeAt(idx) <= NINE + ) { + value = value * 10 + (formula.charCodeAt(idx) - ZERO); + idx++; + } + + // Return `null` if we didn't read anything. + return idx === start ? null : value; + } + + function skipWhitespace() { + while ( + idx < formula.length && + whitespace.has(formula.charCodeAt(idx)) + ) { + idx++; + } + } }