1 files changed, 64 insertions, 0 deletions
diff --git a/std/node/querystring.ts b/std/node/querystring.ts
index 427183bf0..bed327337 100644
--- a/std/node/querystring.ts
+++ b/std/node/querystring.ts
@@ -4,6 +4,9 @@ interface ParseOptions {
   decodeURIComponent?: (string: string) => string;
   maxKeys?: number;
 }
+export const hexTable = new Array(256);
+for (let i = 0; i < 256; ++i)
+  hexTable[i] = "%" + ((i < 16 ? "0" : "") + i.toString(16)).toUpperCase();
 
 export function parse(
   str: string,
@@ -43,6 +46,67 @@ interface StringifyOptions {
   encodeURIComponent?: (string: string) => string;
 }
 
+export function encodeStr(
+  str: string,
+  noEscapeTable: number[],
+  hexTable: string[]
+): string {
+  const len = str.length;
+  if (len === 0) return "";
+
+  let out = "";
+  let lastPos = 0;
+
+  for (let i = 0; i < len; i++) {
+    let c = str.charCodeAt(i);
+    // ASCII
+    if (c < 0x80) {
+      if (noEscapeTable[c] === 1) continue;
+      if (lastPos < i) out += str.slice(lastPos, i);
+      lastPos = i + 1;
+      out += hexTable[c];
+      continue;
+    }
+
+    if (lastPos < i) out += str.slice(lastPos, i);
+
+    // Multi-byte characters ...
+    if (c < 0x800) {
+      lastPos = i + 1;
+      out += hexTable[0xc0 | (c >> 6)] + hexTable[0x80 | (c & 0x3f)];
+      continue;
+    }
+    if (c < 0xd800 || c >= 0xe000) {
+      lastPos = i + 1;
+      out +=
+        hexTable[0xe0 | (c >> 12)] +
+        hexTable[0x80 | ((c >> 6) & 0x3f)] +
+        hexTable[0x80 | (c & 0x3f)];
+      continue;
+    }
+    // Surrogate pair
+    ++i;
+
+    // This branch should never happen because all URLSearchParams entries
+    // should already be converted to USVString. But, included for
+    // completion's sake anyway.
+    if (i >= len) throw new Deno.errors.InvalidData("invalid URI");
+
+    const c2 = str.charCodeAt(i) & 0x3ff;
+
+    lastPos = i + 1;
+    c = 0x10000 + (((c & 0x3ff) << 10) | c2);
+    out +=
+      hexTable[0xf0 | (c >> 18)] +
+      hexTable[0x80 | ((c >> 12) & 0x3f)] +
+      hexTable[0x80 | ((c >> 6) & 0x3f)] +
+      hexTable[0x80 | (c & 0x3f)];
+  }
+  if (lastPos === 0) return str;
+  if (lastPos < len) return out + str.slice(lastPos);
+  return out;
+}
+
 export function stringify(
   obj: object,
   sep = "&",