chore: import upstream snapshot with attribution

tools/challenge-parser/parser/plugins/add-solution.js

@@ -0,0 +1,63 @@
+const { isEmpty } = require('lodash');
+const { root } = require('mdast-builder');
+const visitChildren = require('unist-util-visit-children');
+
+const { editableRegionMarker, isWorkshop } = require('./add-seed');
+const { getSection } = require('./utils/get-section');
+const { getFileVisitor } = require('./utils/get-file-visitor');
+const { splitOnThematicBreak } = require('./utils/split-on-thematic-break');
+
+function validateMarkers({ value }) {
+  const lines = value.split('\n');
+  if (lines.some(line => line.match(RegExp(editableRegionMarker))))
+    throw Error(
+      '--fcc-editable-region-- should only appear in the --seed-contents--\n' +
+        'section, not in --solutions--'
+    );
+}
+
+function createPlugin() {
+  return function transformer(tree, file) {
+    const solutionArrays = splitOnThematicBreak(
+      getSection(tree, `--solutions--`)
+    );
+    const solutions = [];
+
+    solutionArrays.forEach(nodes => {
+      const solution = {};
+      const solutionTree = root(nodes);
+      const visitForContents = visitChildren(
+        getFileVisitor(solution, 'contents', validateMarkers)
+      );
+
+      visitForContents(solutionTree);
+      if (!isEmpty(solution)) solutions.push(Object.values(solution));
+    });
+
+    if (isWorkshop(file)) {
+      const seedSection = getSection(tree, `--seed--`);
+      const seedContents = getSection(root(seedSection), `--seed-contents--`);
+      let totalMarkers = 0;
+      const seedTree = root(seedContents);
+      seedTree.children.forEach(node => {
+        if (node.value) {
+          const lines = node.value.split('\n');
+          lines.forEach(line => {
+            if (line.trim() === '--fcc-editable-region--') totalMarkers++;
+          });
+        }
+      });
+      if (totalMarkers > 0 && totalMarkers !== 2) {
+        throw Error(
+          `Workshop challenge ${file.path} must have exactly 2 editable region markers`
+        );
+      }
+    }
+    file.data = {
+      ...file.data,
+      solutions: solutions
+    };
+  };
+}
+
+module.exports = createPlugin;