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app_vue/node_modules/nth-check/lib/esm/parse.js

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+// Following http://www.w3.org/TR/css3-selectors/#nth-child-pseudo
+// 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.
+ *
+ * @throws An `Error` if parsing fails.
+ * @returns An array containing the integer step size and the integer offset of the nth rule.
+ * @example nthCheck.parse("2n+3"); // returns [2, 3]
+ */
+export function parse(formula) {
+    formula = formula.trim().toLowerCase();
+    if (formula === "even") {
+        return [2, 0];
+    }
+    else if (formula === "odd") {
+        return [2, 1];
+    }
+    // Parse [ ['-'|'+']? INTEGER? {N} [ S* ['-'|'+'] S* INTEGER ]?
+    let idx = 0;
+    let a = 0;
+    let sign = readSign();
+    let number = readNumber();
+    if (idx < formula.length && formula.charAt(idx) === "n") {
+        idx++;
+        a = sign * (number !== null && number !== void 0 ? 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}')`);
+    }
+    return [a, sign * number];
+    function readSign() {
+        if (formula.charAt(idx) === "-") {
+            idx++;
+            return -1;
+        }
+        if (formula.charAt(idx) === "+") {
+            idx++;
+        }
+        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++;
+        }
+    }
+}
+//# sourceMappingURL=parse.js.map