New simple implementation for YAML serialization

Tiny in size so we don't need to fetch the 80KB yaml package for simple
YAML serializaiton needs in various pages. It's also 8x faster than
yaml package so that's a big plus for debug logging.

lib/common/yaml.ts

@@ -0,0 +1,198 @@
+const LINE_WIDTH = 80;
+const INDENTATION = "  ";
+
+const STRING_RESERVED = new Set([
+  "true",
+  "True",
+  "TRUE",
+  "false",
+  "False",
+  "FALSE",
+  "null",
+  "Null",
+  "NULL",
+]);
+
+function isPrintable(str: string): boolean {
+  return !/[^\t\n\x20-\x7e\x85\u{a0}-\u{d7ff}\u{e000}-\u{fffd}\u{10000}-\u{10ffff}]/u.test(
+    str
+  );
+}
+
+function stringifyKey(str: string): string {
+  if (!str || !isPrintable(str)) return JSON.stringify(str);
+  if (/^[\s-?:,[\]{}#&$!|>'"%@`]|: | #|[\n,[\]{}]|\s$/.test(str))
+    return JSON.stringify(str);
+  return str;
+}
+
+function foldString(str: string): string[] {
+  if (str.length <= LINE_WIDTH) return [str];
+  if (str.startsWith(" ")) return [str];
+  const words = str.split(/(?<=[^ ]) (?=[^ ])/);
+  const lines: string[] = [];
+
+  let idx = 0;
+  let len = 0;
+  for (const [i, word] of words.entries()) {
+    len += word.length + 1;
+    if (len >= LINE_WIDTH && len !== word.length) {
+      lines.push(words.slice(idx, i).join(" "));
+      idx = i;
+      len = 0;
+    }
+  }
+
+  if (idx < words.length) lines.push(words.slice(idx).join(" "));
+
+  return lines;
+}
+
+function stringifyString(str: string, res: string[], prefix1, prefix2): void {
+  if (/^\s*$/.test(str) || STRING_RESERVED.has(str) || !isPrintable(str)) {
+    res.push(prefix1 + JSON.stringify(str));
+    return;
+  }
+
+  if (!prefix2) prefix2 = INDENTATION;
+
+  const lines = str.split("\n");
+  if (lines.length > 1) {
+    let idt = "";
+    let chmp = "-";
+    if ((lines.find((l) => l) || "").startsWith(" "))
+      idt = `${INDENTATION.length}`;
+
+    if (!lines[lines.length - 1]) {
+      lines.pop();
+      if (lines[lines.length - 1]) chmp = "";
+      else chmp = "+";
+    }
+
+    if (/^\s+$/.test(lines[lines.length - 1])) {
+      res.push(prefix1 + JSON.stringify(str));
+      return;
+    }
+
+    let isFolded = false;
+    const folded = lines.map((l) => {
+      const ls = foldString(l);
+      if (ls.length > 1) isFolded = true;
+      return ls;
+    });
+
+    if (!isFolded) {
+      res.push(
+        `${prefix1}|${idt}${chmp}`,
+        ...lines.map((l) => (l ? prefix2 + l : l))
+      );
+      return;
+    }
+
+    res.push(`${prefix1}>${idt}${chmp}`);
+    res.push(...folded[0].map((f) => prefix2 + f));
+    for (let i = 1; i < folded.length; ++i) {
+      const prevLine = folded[i - 1][0];
+      if (prevLine && !folded[i - 1][0].startsWith(" ")) res.push("");
+      res.push(...folded[i].map((f) => prefix2 + f));
+    }
+    return;
+  }
+
+  if (
+    /^[\s-?:,[\]{}#&$!|>'"%@`]|: | #|\s$/.test(str) ||
+    parseFloat(str) === +str
+  ) {
+    res.push(prefix1 + JSON.stringify(str));
+    return;
+  }
+
+  res.push(prefix1 + str);
+}
+
+function stringifyAny(
+  obj: unknown,
+  res: string[],
+  prefix1 = "",
+  prefix2 = ""
+): void {
+  if (obj == null || typeof obj === "number" || typeof obj === "boolean") {
+    res.push(`${prefix1}${obj}`);
+    return;
+  }
+  if (obj instanceof Date) {
+    res.push(`${prefix1}${obj.toJSON()}`);
+    return;
+  }
+
+  if (typeof obj === "string") {
+    stringifyString(obj, res, prefix1, prefix2);
+    return;
+  }
+
+  if (Array.isArray(obj)) {
+    if (!obj.length) {
+      res.push(prefix1 + "[]");
+      return;
+    }
+
+    if (!prefix1 || prefix1.endsWith("- ")) {
+      stringifyAny(obj[0], res, prefix1 + "- ", prefix2 + INDENTATION);
+      prefix1 = prefix2 + "- ";
+      prefix2 = prefix2 + INDENTATION;
+      for (let i = 1; i < obj.length; ++i)
+        stringifyAny(obj[i], res, prefix1, prefix2);
+    } else {
+      res.push(prefix1);
+      prefix1 = prefix2 + "- ";
+      prefix2 = prefix2 + INDENTATION;
+      for (let i = 0; i < obj.length; ++i)
+        stringifyAny(obj[i], res, prefix1, prefix2);
+    }
+    return;
+  }
+
+  const entries = Object.entries(obj);
+
+  if (!entries.length) {
+    res.push(prefix1 + "{}");
+    return;
+  }
+
+  if (!prefix1 || prefix1.endsWith("- ")) {
+    stringifyAny(
+      entries[0][1],
+      res,
+      prefix1 + `${stringifyKey(entries[0][0])}: `,
+      prefix2 + INDENTATION
+    );
+    prefix1 = prefix2;
+    prefix2 = prefix2 + INDENTATION;
+    for (let i = 1; i < entries.length; ++i) {
+      stringifyAny(
+        entries[i][1],
+        res,
+        prefix1 + `${stringifyKey(entries[i][0])}: `,
+        prefix2
+      );
+    }
+  } else {
+    res.push(prefix1);
+    prefix1 = prefix2;
+    prefix2 = prefix2 + INDENTATION;
+    for (let i = 0; i < entries.length; ++i) {
+      stringifyAny(
+        entries[i][1],
+        res,
+        prefix1 + `${stringifyKey(entries[i][0])}: `,
+        prefix2
+      );
+    }
+  }
+}
+
+export function stringify(obj: unknown): string {
+  const lines: string[] = [];
+  stringifyAny(obj, lines);
+  return lines.join("\n") + "\n";
+}