Format slint files using Deno

format-slint-deno.ts

const ignore: string[] = [
  // "ui/generated.slint"
];
const dirs = { ui: "ui" };

const whitespaceRE = /^(\s*)(.*?)(\/*|\/\/)?(.*)$/;
const indentBy = "    ";

file: for await (const file of Deno.readDir(dirs.ui)) {
  if (
    file.isFile &&
    file.name.endsWith(".slint") &&
    !ignore.find((ignored) => ignored.endsWith(file.name))
  ) {
    const filename = `${dirs.ui}/${file.name}`;
    const sourceText = await Deno.readTextFile(filename);
    let indentation = 0;
    let changes = 0;
    const formatedLines: string[] = [];
    for (const [line, ln] of sourceText
      .split(/\n/g)
      .map((line, idx) => [line, idx + 1] as const)) {
      const found = whitespaceRE.exec(line);
      if (!found) {
        console.error(
          `Unparsed line ${JSON.stringify(line)}, skipping ${filename}:${ln}`
        );
        continue file;
      }

      const [, _whitespace, beforeComment, hasComment, afterComment] = found;
      if (hasComment && hasComment !== "//") {
        console.error(
          `Unable to handle comments ${JSON.stringify(
            line
          )}, skipping ${filename}:${ln}`
        );
        continue file;
      }

      // console.log({
      //   beforeComment,
      //   hasComment,
      //   afterComment,
      // })

      let rmIndentBy = 0;
      let addIndentBy = 0;
      let closesBy = 0;
      let seenNonCloser = false;
      for (const c of (hasComment ? beforeComment : afterComment).split("")) {
        if (c === "}" || c === ")" || c === "]") {
          rmIndentBy += 1;
          if (!seenNonCloser) {
            closesBy += 1;
          }
        } else {
          seenNonCloser = true;
          if (c === "{" || c === "(" || c === "[") addIndentBy += 1;
        }
      }

      const lineContent = (
        hasComment ? beforeComment + hasComment + afterComment : afterComment
      ).trimStart();
      const modifiedLine = lineContent
        ? indentBy.repeat(indentation - closesBy) + lineContent
        : ""; // empty line is no spaces

      const changeIndentation = addIndentBy - rmIndentBy;
      if (changeIndentation) {
        indentation += changeIndentation;
        // console.error(`Unable to change indentation by (${changeIndentation}) ${JSON.stringify(line)}, skipping ${filename}:${ln}`)
        // continue file
      }

      if (modifiedLine !== line) changes++;
      formatedLines.push(modifiedLine);
    }

    if (changes > 0) {
      const updatedFile = formatedLines.join("\n");
      console.log(`Updates for ${filename}\n`, updatedFile);
      const encoder = new TextEncoder();
      await Deno.writeFile(filename, encoder.encode(updatedFile));
    } else {
      console.log(`No updates for ${filename}`);
    }
  }
}