md055.js

// @ts-check

"use strict";

const { addErrorDetailIf } = require("../helpers");
const { filterByTypes } = require("../helpers/micromark.cjs");
const { filterByTypesCached } = require("./cache");

const whitespaceTypes = new Set([ "linePrefix", "whitespace" ]);
const ignoreWhitespace = (tokens) => tokens.filter(
  (token) => !whitespaceTypes.has(token.type)
);
const firstOrNothing = (items) => items[0];
const lastOrNothing = (items) => items[items.length - 1];
const makeRange = (start, end) => [ start, end - start + 1 ];

// eslint-disable-next-line jsdoc/valid-types
/** @type import("./markdownlint").Rule */
module.exports = {
  "names": [ "MD055", "table-pipe-style" ],
  "description": "Table pipe style",
  "tags": [ "table" ],
  "parser": "micromark",
  "function": function MD055(params, onError) {
    const style = String(params.config.style || "consistent");
    let expectedStyle = style;
    let expectedLeadingPipe =
      ((expectedStyle !== "no_leading_or_trailing") && (expectedStyle !== "trailing_only"));
    let expectedTrailingPipe =
      ((expectedStyle !== "no_leading_or_trailing") && (expectedStyle !== "leading_only"));
    const tables = filterByTypesCached([ "table" ]);
    for (const table of tables) {
      const rows = filterByTypes(
        table.children,
        [ "tableDelimiterRow", "tableRow" ]
      );
      for (const row of rows) {
        // The following uses of first/lastOrNothing lack fallback handling
        // because it seems not to be possible (i.e., 0% coverage)
        const firstCell = firstOrNothing(row.children);
        const leadingToken = firstOrNothing(ignoreWhitespace(firstCell.children));
        const actualLeadingPipe = (leadingToken.type === "tableCellDivider");
        const lastCell = lastOrNothing(row.children);
        const trailingToken = lastOrNothing(ignoreWhitespace(lastCell.children));
        const actualTrailingPipe = (trailingToken.type === "tableCellDivider");
        const actualStyle = actualLeadingPipe ?
          (actualTrailingPipe ? "leading_and_trailing" : "leading_only") :
          (actualTrailingPipe ? "trailing_only" : "no_leading_or_trailing");
        if (expectedStyle === "consistent") {
          expectedStyle = actualStyle;
          expectedLeadingPipe = actualLeadingPipe;
          expectedTrailingPipe = actualTrailingPipe;
        }
        if (actualLeadingPipe !== expectedLeadingPipe) {
          addErrorDetailIf(
            onError,
            firstCell.startLine,
            expectedStyle,
            actualStyle,
            `${expectedLeadingPipe ? "Missing" : "Unexpected"} leading pipe`,
            undefined,
            makeRange(row.startColumn, firstCell.startColumn)
          );
        }
        if (actualTrailingPipe !== expectedTrailingPipe) {
          addErrorDetailIf(
            onError,
            lastCell.endLine,
            expectedStyle,
            actualStyle,
            `${expectedTrailingPipe ? "Missing" : "Unexpected"} trailing pipe`,
            undefined,
            makeRange(lastCell.endColumn - 1, row.endColumn - 1)
          );
        }
      }
    }
  }
};