Custom linter to check the format of the patterns

.github/workflows/lint-patterns.yml

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+# from: https://github.com/marketplace/actions/markdown-linting-action
+name: Pattern Syntax Validation
+
+on:
+  push:
+    branches:
+      - "master"
+  pull_request:
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Problem Matcher for markdownlint-cli
+      uses: xt0rted/markdownlint-problem-matcher@v1
+    - name: Lint pattern files (markdown)
+      uses: avto-dev/markdown-lint@v1
+      with:
+        rules: './lint/pattern-template.js'
+        config: './lint/pattern-template.yml'
+        args: 'patterns/2-structured/*.md patterns/2-structured/project-setup/*.md patterns/3-validated/*.md'

lint/pattern-template.js

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+"use strict";
+
+module.exports = [
+{
+    names: ["PATTERN-TEMPLATE-RULE-001"],
+    description: "h2 headlines and below",
+    tags: ["headings", "headers", "pattern-template"],
+    function: (params, onError) => {
+        params.tokens.filter(function filterToken(token) {
+            return token.type === "heading_open";
+        }).forEach(function forToken(token) {
+            if (token.tag === "h1") {
+                return onError({
+                    lineNumber: token.lineNumber,
+                    detail: "Use of #-headlines (h1) is not allowed in patterns. Please only use ##-headlines (h2) and lower.",
+                    context: token.line
+                });
+            }
+        });
+    }
+},
+{
+    names: ["PATTERN-TEMPLATE-RULE-002"],
+    description: "Standard Headlines",
+    tags: ["headings", "headers", "pattern-template"],
+    function: (params, onError) => {
+        var allowedHeadlines = "Title|Patlet|Problem|Story|Context|Forces|Solutions|Resulting Context|Known Instances|Status|Author(s)|Acknowledgements";
+        var re = new RegExp(`^## (${allowedHeadlines.replace(/(?=[\(\)])/g, '\\')})\\s*$`,"m");
+        // console.log(re);
+
+        params.tokens.filter(function filterToken(token) {
+            return token.type === "heading_open";
+        }).forEach(function forToken(token) {
+            if (token.tag === "h2") {
+                if (re.test(token.line)) {
+                    return;
+                }
+                // if (/^## ()$/m.test(token.line)) {
+                //     return;
+                // }
+
+                return onError({
+                    lineNumber: token.lineNumber,
+                    detail: "Allowed types are: " + allowedHeadlines.replace(/\|/g, ', '),
+                    context: token.line
+                });
+            }
+        });
+    }
+},
+{
+    names: ["PATTERN-TEMPLATE-RULE-003"],
+    description: "Mandatory template sections",
+    tags: ["headings", "headers", "pattern-template"],
+    function: (params, onError) => {
+        var mandatoryHeadlines = {
+          "Title": "Title",
+          "Patlet": "Patlet",
+          "Problem": "Problem",
+          "Context": "Context",
+          "Forces": "Forces",
+          "Solutions": "Solution|Solutions",
+          "Resulting Context": "Resulting Context",
+          "Known Instances": "Known Instances",
+          "Status": "Status",
+          "Author(s)": "Author|Authors|(Author\\(s\\))"
+        };
+
+        var collectedHeadlines = ""
+
+        // collect all h2 headlines
+        // (only the headline text itself, removing markdown sytnax and whitespace)
+        params.tokens.filter(function filterToken(token) {
+            return token.type === "heading_open";
+        }).forEach(function forToken(token) {
+            if (token.tag === "h2") {
+                let re = new RegExp("^## (.*?)\\s*$","m");
+                let matchResult = token.line.match(re);
+
+                if (matchResult != null) {
+                  collectedHeadlines += matchResult[1] + "\n"
+                }
+            }
+        });
+
+        // confirm if all `mandatoryHeadlines` exist exactly once in the `collectedHeadlines`
+        var errorsFound = [];
+
+        let headline;
+        for (headline in mandatoryHeadlines){
+          let pattern = mandatoryHeadlines[headline];
+          let re = new RegExp(`^${pattern}$`,"gm");
+          let matchResult = collectedHeadlines.match(re);
+
+          // TODO as soon as I use the option 'g' in the regexp, it does not return a full match array anymore
+          if (matchResult != null) {
+              if (matchResult.length >= 2 ) {
+                errorsFound.push(`Duplicate headline "${headline}".`);
+              }
+          }
+          else {
+            errorsFound.push(`Required headline "${headline}" is missing.`);
+          }
+        }
+
+        // if any errors were found, raise a linter error
+        if (errorsFound.length > 0) {
+          return onError({
+              lineNumber: 1,
+              detail: errorsFound.join(" ")
+          });
+        }
+    }
+}
+];

lint/pattern-template.yml

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+default: false # excludes all default markdownlint rules
+
+# Custom rules:
+PATTERN-TEMPLATE-RULE-001: true
+# PATTERN-TEMPLATE-RULE-002: true # will likely stop using this in favor of rule 003
+PATTERN-TEMPLATE-RULE-003: true