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qwen/nodejs/node_modules/axios/lib/helpers/estimateDataURLDecodedBytes.js

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+/**
+ * Estimate decoded byte length of a data:// URL *without* allocating large buffers.
+ * - For base64: compute exact decoded size using length and padding;
+ *               handle %XX at the character-count level (no string allocation).
+ * - For non-base64: use UTF-8 byteLength of the encoded body as a safe upper bound.
+ *
+ * @param {string} url
+ * @returns {number}
+ */
+export default function estimateDataURLDecodedBytes(url) {
+  if (!url || typeof url !== 'string') return 0;
+  if (!url.startsWith('data:')) return 0;
+
+  const comma = url.indexOf(',');
+  if (comma < 0) return 0;
+
+  const meta = url.slice(5, comma);
+  const body = url.slice(comma + 1);
+  const isBase64 = /;base64/i.test(meta);
+
+  if (isBase64) {
+    let effectiveLen = body.length;
+    const len = body.length; // cache length
+
+    for (let i = 0; i < len; i++) {
+      if (body.charCodeAt(i) === 37 /* '%' */ && i + 2 < len) {
+        const a = body.charCodeAt(i + 1);
+        const b = body.charCodeAt(i + 2);
+        const isHex =
+          ((a >= 48 && a <= 57) || (a >= 65 && a <= 70) || (a >= 97 && a <= 102)) &&
+          ((b >= 48 && b <= 57) || (b >= 65 && b <= 70) || (b >= 97 && b <= 102));
+
+        if (isHex) {
+          effectiveLen -= 2;
+          i += 2;
+        }
+      }
+    }
+
+    let pad = 0;
+    let idx = len - 1;
+
+    const tailIsPct3D = (j) =>
+      j >= 2 &&
+      body.charCodeAt(j - 2) === 37 && // '%'
+      body.charCodeAt(j - 1) === 51 && // '3'
+      (body.charCodeAt(j) === 68 || body.charCodeAt(j) === 100); // 'D' or 'd'
+
+    if (idx >= 0) {
+      if (body.charCodeAt(idx) === 61 /* '=' */) {
+        pad++;
+        idx--;
+      } else if (tailIsPct3D(idx)) {
+        pad++;
+        idx -= 3;
+      }
+    }
+
+    if (pad === 1 && idx >= 0) {
+      if (body.charCodeAt(idx) === 61 /* '=' */) {
+        pad++;
+      } else if (tailIsPct3D(idx)) {
+        pad++;
+      }
+    }
+
+    const groups = Math.floor(effectiveLen / 4);
+    const bytes = groups * 3 - (pad || 0);
+    return bytes > 0 ? bytes : 0;
+  }
+
+  return Buffer.byteLength(body, 'utf8');
+}