doc,tools: allow stability table to be updated

Keep markers for the stability table so that it can be updated on
subsequent runs of the doc tooling. Only overwrite the files if
they have been changed.

PR-URL: #38048
Fixes: #37886
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>

Author: richardlau

Diff for: doc/api/documentation.md

@@ -50,7 +50,8 @@ modifications occur. To avoid surprises, use of an Experimental feature may need
 a command-line flag. Experimental features may also emit a [warning][].
 
 ## Stability overview
-<!-- STABILITY_OVERVIEW_SLOT -->
+<!-- STABILITY_OVERVIEW_SLOT_BEGIN -->
+<!-- STABILITY_OVERVIEW_SLOT_END -->
 
 ## JSON output
 <!-- YAML

Diff for: tools/doc/stability.js

@@ -14,7 +14,9 @@ const visit = require('unist-util-visit');
 
 const source = `${__dirname}/../../out/doc/api`;
 const data = require(path.join(source, 'all.json'));
-const mark = '<!-- STABILITY_OVERVIEW_SLOT -->';
+const markBegin = '<!-- STABILITY_OVERVIEW_SLOT_BEGIN -->';
+const markEnd = '<!-- STABILITY_OVERVIEW_SLOT_END -->';
+const mark = `${markBegin}(.*)${markEnd}`;
 
 const output = {
   json: path.join(source, 'stability.json'),
@@ -84,28 +86,29 @@ function processStability() {
 
 function updateStabilityMark(file, value, mark) {
   const fd = fs.openSync(file, 'r+');
-  const content = fs.readFileSync(fd);
+  const content = fs.readFileSync(fd, { encoding: 'utf8' });
 
-  // Find the position of the `mark`.
-  const index = content.indexOf(mark);
-
-  // Overwrite the mark with `value` parameter.
-  const offset = fs.writeSync(fd, value, index, 'utf-8');
-
-  // Re-write the end of the file after `value`.
-  fs.writeSync(fd, content, index + mark.length, undefined, index + offset);
+  const replaced = content.replace(mark, value);
+  if (replaced !== content) {
+    fs.writeSync(fd, replaced, 0, 'utf8');
+  }
   fs.closeSync(fd);
 }
 
 const stability = collectStability(data);
 
 // add markdown
 const markdownTable = createMarkdownTable(stability);
-updateStabilityMark(output.docMarkdown, markdownTable, mark);
+updateStabilityMark(output.docMarkdown,
+                    `${markBegin}\n${markdownTable}\n${markEnd}`,
+                    new RegExp(mark, 's'));
 
 // add html table
 const html = createHTML(markdownTable);
-updateStabilityMark(output.docHTML, html, mark);
+updateStabilityMark(output.docHTML, `${markBegin}${html}${markEnd}`,
+                    new RegExp(mark, 's'));
 
 // add json output
-updateStabilityMark(output.docJSON, JSON.stringify(html), JSON.stringify(mark));
+updateStabilityMark(output.docJSON,
+                    JSON.stringify(`${markBegin}${html}${markEnd}`),
+                    new RegExp(JSON.stringify(mark), 's'));