Make a script to separate snippets

samtstern · samtstern · commit e618590bb85d · 2020-09-03T17:40:18.000+01:00
diff --git a/scripts/package.json b/scripts/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "scripts",
+  "version": "1.0.0",
+  "description": "Internal repo scripts",
+  "scripts": {
+  },
+  "author": "samstern@google.com",
+  "license": "Apache-2.0"
+}
diff --git a/scripts/separate-snippets.ts b/scripts/separate-snippets.ts
@@ -0,0 +1,137 @@
+import * as cp from "child_process";
+import * as fs from "fs";
+import * as path from "path";
+
+const RE_START_SNIPPET = /\[START\s+([A-Za-z_]+)\s*\]/;
+const RE_END_SNIPPET = /\[END\s+([A-Za-z_]+)\s*\]/;
+// TODO: Handle multiline imports?
+const RE_REQUIRE = /const {(.+?)} = require\((.+?)\)/;
+
+function isBlank(line: string) {
+  return line.trim().length === 0;
+}
+
+/**
+ * Turns a series of source lines into a standalone snippet file by:
+ *   - Converting require statements into top-level imports.
+ *   - Adjusting indentation to left-align all content
+ *   - Removing any blank lines at the starts
+ * @param lines the lines containing the snippet (including START/END comments)
+ */
+function processSnippet(lines: string[]): string {
+  const importLines: string[] = [];
+  const otherLines: string[] = [];
+
+  for (const line of lines) {
+    const requireMatch = line.match(RE_REQUIRE);
+    if (requireMatch) {
+      const asImport = `import {${requireMatch[1]}} from ${requireMatch[2]}`;
+      importLines.push(asImport);
+    } else {
+      otherLines.push(line);
+    }
+  }
+
+  // Adjust indentation of the otherLines so that they're left aligned
+  const nonBlankLines = otherLines.filter((l) => !isBlank(l));
+  const indentSizes = nonBlankLines.map((l) => l.length - l.trimLeft().length);
+  const minIndent = Math.min(...indentSizes);
+
+  const adjustedOtherLines: string[] = [];
+  for (const line of otherLines) {
+    if (isBlank(line)) {
+      adjustedOtherLines.push("");
+    } else {
+      adjustedOtherLines.push(line.substr(minIndent));
+    }
+  }
+
+  // Special case: if the first line after the comments is blank we want to remove it
+  const firstNonComment = adjustedOtherLines.findIndex(
+    (l) => !l.startsWith("//")
+  );
+  if (isBlank(otherLines[firstNonComment])) {
+    adjustedOtherLines.splice(firstNonComment, 1);
+  }
+
+  // TODO: Should we add a preamble?
+  const content = [...importLines, ...adjustedOtherLines].join("\n");
+  return content;
+}
+
+/**
+ * Lists all the files in this repository that should be checked for snippets
+ */
+function listSnippetFiles(): string[] {
+  const output = cp
+    .execSync(
+      'find . -type f -name "*.js" -not -path "*node_modules*" -not -path "./snippets*"'
+    )
+    .toString();
+  return output.split("\n").filter((x) => !isBlank(x));
+}
+
+/**
+ * Collect all the snippets from a file into a map of snippet name to lines.
+ * @param filePath the file path to read.
+ */
+function collectSnippets(filePath: string): { [name: string]: string[] } {
+  const fileContents = fs.readFileSync(filePath).toString();
+  const lines = fileContents.split("\n");
+
+  let currSnippetName = "";
+  let inSnippet = false;
+  const snippetLines: { [name: string]: string[] } = {};
+  for (const line of lines) {
+    const startMatch = line.match(RE_START_SNIPPET);
+    const endMatch = line.match(RE_END_SNIPPET);
+
+    if (startMatch) {
+      inSnippet = true;
+      currSnippetName = startMatch[1];
+      snippetLines[currSnippetName] = [];
+    }
+
+    if (inSnippet) {
+      snippetLines[currSnippetName].push(line);
+    }
+
+    if (endMatch) {
+      if (endMatch[1] !== currSnippetName) {
+        throw new Error(
+          `Snippet ${currSnippetName} in ${filePath} has unmatched START/END tags`
+        );
+      }
+      inSnippet = false;
+    }
+  }
+
+  return snippetLines;
+}
+
+async function main() {
+  const fileNames = listSnippetFiles();
+
+  for (const filePath of fileNames) {
+    const fileSlug = filePath
+      .replace(".js", "")
+      .replace("./", "")
+      .replace(/\./g, "-");
+    const snippetDir = path.join("./snippets", fileSlug);
+
+    console.log(`Processing: ${filePath} --> ${snippetDir}`);
+
+    if (!fs.existsSync(snippetDir)) {
+      fs.mkdirSync(snippetDir, { recursive: true });
+    }
+
+    const snippetLines = collectSnippets(filePath);
+    for (const snippetName in snippetLines) {
+      const filePath = path.join(snippetDir, `${snippetName}.js`);
+      const content = processSnippet(snippetLines[snippetName]);
+      fs.writeFileSync(filePath, content);
+    }
+  }
+}
+
+main();
diff --git a/snippets/README.md b/snippets/README.md
@@ -0,0 +1,3 @@
+# Ignore this folder
+
+This folder contains generated files based on the source in other folders!

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+# Ignore this folder`
	`2`	`+`
	`3`	`+This folder contains generated files based on the source in other folders!`