@fink/snippet/highlight.js

import { pad_start } from "@fink/std-lib/str.js";
import { split } from "@fink/std-lib/regex.js";
import { map_ac, length, join, drop, take, insert_at } from "@fink/std-lib/iter.js";
import { clamp } from "@fink/std-lib/math.js";
export const default_opts = {
  lines: {
    before: 4,
    after: 3
  }
};

/*
Highlight the `code` snippet at the given location `loc`.

Optionally the number of lines before and after the highlighted
location can be providerd by `options`.
*/
export const highlight_code_loc = (code, loc, options = default_opts) => {
  const {
    start,
    end
  } = loc;
  const {
    lines: {
      before,
      after
    }
  } = options;
  const min = before;
  const lines = split(code, `\n`);
  const max_lines = length(lines);
  const start_line = clamp(0, start.line - before, max_lines - min);
  const insert_line = start.line - start_line;
  const end_line = clamp(0, end.line + after, max_lines);
  const line_num_padding = length(`${end_line}`);
  const underline = pad_start(`^`, 3 + line_num_padding + start.column, ` `);
  {
    let ˆpipe_result_1 = lines;
    ˆpipe_result_1 = drop(start_line)(ˆpipe_result_1);
    ˆpipe_result_1 = take(end_line - start_line)(ˆpipe_result_1);
    ˆpipe_result_1 = map_ac((line, idx = 0) => {
      const line_num = pad_start(`${start_line + idx + 1}`, line_num_padding);
      return [`${line_num}| ${line}`, idx + 1];
    })(ˆpipe_result_1);
    ˆpipe_result_1 = insert_at(insert_line, [underline])(ˆpipe_result_1);
    return ˆpipe_result_1 = join(`\n`)(ˆpipe_result_1);
  }
};