Add rule MD060/table-column-style (fixes #90, fixes #323).

lib/md060.mjs

@@ -0,0 +1,118 @@
+// @ts-check
+
+import { filterByTypes } from "../helpers/micromark-helpers.cjs";
+import { filterByTypesCached } from "./cache.mjs";
+
+/** @typedef {import("micromark-extension-gfm-table")} */
+/** @typedef {import("markdownlint").RuleOnErrorInfo} RuleOnErrorInfo */
+
+/**
+ * Adds a RuleOnErrorInfo object to a list of RuleOnErrorInfo objects.
+ *
+ * @param {RuleOnErrorInfo[]} errors List of errors.
+ * @param {number} lineNumber Line number.
+ * @param {number} column Column number.
+ * @param {string} detail Detail message.
+ */
+function addError(errors, lineNumber, column, detail) {
+  errors.push({
+    lineNumber,
+    detail,
+    "range": [ column, 1 ]
+  });
+}
+
+/** @type {import("markdownlint").Rule} */
+export default {
+  "names": [ "MD060", "table-column-style" ],
+  "description": "Table column style",
+  "tags": [ "table" ],
+  "parser": "micromark",
+  "function": function MD060(params, onError) {
+    const style = String(params.config.style || "any");
+    const styleAlignedAllowed = (style === "any") || (style === "aligned");
+    const styleCompactAllowed = (style === "any") || (style === "compact");
+    const styleTightAllowed = (style === "any") || (style === "tight");
+
+    // Scan all tables/rows
+    const tables = filterByTypesCached([ "table" ]);
+    for (const table of tables) {
+      const rows = filterByTypes(table.children, [ "tableDelimiterRow", "tableRow" ]);
+      const headingRow = rows[0];
+
+      // Determine errors for style "aligned"
+      const errorsIfAligned = [];
+      if (styleAlignedAllowed) {
+        const headingDividerColumns = filterByTypes(headingRow.children, [ "tableCellDivider" ]).map((divider) => divider.startColumn);
+        for (const row of rows.slice(1)) {
+          const remainingHeadingDividerColumns = new Set(headingDividerColumns);
+          const rowDividerColumns = filterByTypes(row.children, [ "tableCellDivider" ]).map((divider) => divider.startColumn);
+          for (const dividerColumn of rowDividerColumns) {
+            if ((remainingHeadingDividerColumns.size > 0) && !remainingHeadingDividerColumns.delete(dividerColumn)) {
+              addError(errorsIfAligned, row.startLine, dividerColumn, "Table pipe does not align with heading for style \"aligned\"");
+            }
+          }
+        }
+      }
+
+      // Determine errors for styles "compact" and "tight"
+      const errorsIfCompact = [];
+      const errorsIfTight = [];
+      if (
+        (styleCompactAllowed || styleTightAllowed) &&
+        !(styleAlignedAllowed && (errorsIfAligned.length === 0))
+      ) {
+        for (const row of rows) {
+          const tokensOfInterest = filterByTypes(row.children, [ "tableCellDivider", "tableContent", "whitespace" ]);
+          for (let i = 0; i < tokensOfInterest.length; i++) {
+            const { startColumn, startLine, type } = tokensOfInterest[i];
+            if (type === "tableCellDivider") {
+              const previous = tokensOfInterest[i - 1];
+              if (previous) {
+                if (previous.type === "whitespace") {
+                  if (previous.text.length !== 1) {
+                    addError(errorsIfCompact, startLine, startColumn, "Table pipe has extra space to the left for style \"compact\"");
+                  }
+                  addError(errorsIfTight, startLine, startColumn, "Table pipe has space to the left for style \"tight\"");
+                } else {
+                  addError(errorsIfCompact, startLine, startColumn, "Table pipe is missing space to the left for style \"compact\"");
+                }
+              }
+              const next = tokensOfInterest[i + 1];
+              if (next) {
+                if (next.type === "whitespace") {
+                  if (next.endColumn !== row.endColumn) {
+                    if (next.text.length !== 1) {
+                      addError(errorsIfCompact, startLine, startColumn, "Table pipe has extra space to the right for style \"compact\"");
+                    }
+                    addError(errorsIfTight, startLine, startColumn, "Table pipe has space to the right for style \"tight\"");
+                  }
+                } else {
+                  addError(errorsIfCompact, startLine, startColumn, "Table pipe is missing space to the right for style \"compact\"");
+                }
+              }
+            }
+          }
+        }
+      }
+
+      // Report errors for whatever (allowed) style has the fewest
+      let errorInfos = errorsIfAligned;
+      if (
+        styleCompactAllowed &&
+        ((errorsIfCompact.length < errorInfos.length) || !styleAlignedAllowed)
+      ) {
+        errorInfos = errorsIfCompact;
+      }
+      if (
+        styleTightAllowed &&
+        ((errorsIfTight.length < errorInfos.length) || (!styleAlignedAllowed && !styleCompactAllowed))
+      ) {
+        errorInfos = errorsIfTight;
+      }
+      for (const errorInfo of errorInfos) {
+        onError(errorInfo);
+      }
+    }
+  }
+};