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⏯ Playground Link

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💻 Code

Reproduction repo: https://github.com/Timeless0911/ast-grep-matcher-performance

Reproduction steps:

• pnpm i
• pnpm build

In Rslib, I use below matcher to find out the import and require statement in DTS files.

const matcher: NapiConfig = {
  rule: {
    kind: "string_fragment",
    any: [
      {
        inside: {
          stopBy: "end",
          kind: "import_statement",
          field: "source",
        },
      },
      {
        inside: {
          stopBy: "end",
          kind: "export_statement",
          field: "source",
        },
      },
      {
        inside: {
          kind: "string",
          inside: {
            kind: "arguments",
            inside: {
              kind: "call_expression",
              has: {
                field: "function",
                regex: "^(import|require)$",
              },
            },
          },
        },
      },
    ],
  },
};

The usage is like below:

const content = await fsP.readFile(dtsFile, 'utf-8');
const sgNode = (await parseAsync('typescript', content)).root();
const matchModule = sgNode.findAll(matcher).map((matchNode) => {
    return {
      n: matchNode.text(),
      s: matchNode.range().start.index,
      e: matchNode.range().end.index,
    };
  });

I found that there are some performance issues when in large files with some inline import/require statements.

🙁 Actual behavior

In repro demo, I use four files to test and the result is as below:

File: ./file/less-import-no-format.d.ts, Time: 228ms
File: ./file/less-import-format.d.ts, Time: 187ms
File: ./file/much-import-no-format.d.ts, Time: 7119ms
File: ./file/much-import-format.d.ts, Time: 2228ms

• less-import-no-format.d.ts: 4161 lines with import statement only in few lines of the head
• less-import-format.d.ts: 11415 lines with formatter applying in less-import-format.d.ts
• much-import-no-format.d.ts: 4161 lines with many import statement in lines

import: import("zod").ZodUnion<[import("zod").ZodString, import("zod").ZodArray<import("zod").ZodString, "many">]>;

• much-import-format.d.ts: 12401 lines with formatter applying in much-import-no-format.d.ts

🙂 Expected behavior

All files without formatter applied be completed in as fast as possible to hundred ms.

Additional information about the issue

Whether or not to format is a factor that I found to affect the time.

In addition, I also divided the matcher into two parts and found that stopBy: "end" is the main reason affecting performance.

{
  inside: {
+ stopBy: "end",
    kind: "import_statement",
    field: "source",
  },
},

I need to match these import/require statements:

import { foo } from "bar";
export { foo } from "bar";
require("bar");
import("bar");

I don't know if you have any suggestions on this issue, many thanks!