[meta] Create Workflow to validate WASM Grammar Changes

.github/workflows/validate-wasm-grammar-prs.yml

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+name: Validate WASM Grammar PR Changes
+# Since we now want to enforce the rule that any changes to a WASM grammar binary
+# file, is accompanied by a change to the `parserSource` key within the
+# `grammar.cson` file. This GHA will preform this check for us.
+
+on:
+  pull_request:
+    paths:
+      - '**.wasm'
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout the Latest Code
+      uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+        # Make sure we get all commits, so that we can compare to early commits
+
+    - name: Setup Node
+      uses: actions/setup-node@v3
+      with:
+        node-version: 16
+
+    - name: Install dependencies
+      run: yarn install
+
+    - name: Run Validation Script
+      run: node ./script/validate-wasm-grammar-prs.js

script/validate-wasm-grammar-prs.js

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+/*
+ * This script is called via `validate-wasm-grammar-prs.yml`
+ * It's purpose is to ensure that everytime a `.wasm` file is changed in a PR
+ * That the `parserSource` key of the grammar that uses that specific `.wasm`
+ * file is also updated.
+ * This way we can ensure that the `parserSource` is always accurate, and is
+ * never forgotten about.
+ */
+
+const cp = require("node:child_process");
+const path = require("node:path");
+const fs = require("node:fs");
+const CSON = require("season");
+
+// Change this if you want more logs
+let verbose = true;
+
+// Lets first find our common ancestor commit
+// This lets us determine the commit where the branch or fork departed from
+const commonAncestorCmd = cp.spawnSync("git", [ "merge-base", "origin/master", "HEAD^" ]);
+
+if (commonAncestorCmd.status !== 0 || commonAncestorCmd.stderr.toString().length > 0) {
+  console.error("Git Command has failed!");
+  console.error("'git merge-base origin/master HEAD^'");
+  console.error(commonAncestorCmd.stderr.toString());
+  process.exit(1);
+}
+
+const commit = commonAncestorCmd.stdout.toString().trim();
+
+if (verbose) {
+  console.log(`Common Ancestor Commit: '${commit}'`);
+}
+
+const cmd = cp.spawnSync("git", [ "diff", "--name-only", "-r", "HEAD", commit])
+
+if (cmd.status !== 0 || cmd.stderr.toString().length > 0) {
+  console.error("Git Command has failed!");
+  console.error(`'git diff --name-only -r HEAD ${commit}'`);
+  console.error(cmd.stderr.toString());
+  process.exit(1);
+}
+
+const changedFiles = cmd.stdout.toString().split("\n");
+// This gives us an array of the name and path of every single changed file from the last two commits
+// Now to check if there's any changes we care about.
+
+if (verbose) {
+  console.log("Array of changed files between commits:");
+  console.log(changedFiles);
+}
+
+const wasmFilesChanged = changedFiles.filter(element => element.endsWith(".wasm"));
+
+if (wasmFilesChanged.length === 0) {
+  // No WASM files have been modified. Return success
+  console.log("No WASM files have been changed.");
+  process.exit(0);
+}
+
+// Now for every single wasm file that's been changed, we must validate those changes
+// are also accompanied by a change in the `parserSource` key
+
+for (const wasmFile of wasmFilesChanged) {
+  const wasmPath = path.dirname(wasmFile);
+
+  const files = fs.readdirSync(path.join(wasmPath, ".."));
+  console.log(`Detected changes to: ${wasmFile}`);
+
+  if (verbose) {
+    console.log("Verbose file check details:");
+    console.log(wasmFile);
+    console.log(wasmPath);
+    console.log(files);
+    console.log("\n");
+  }
+
+  for (const file of files) {
+    const filePath = path.join(wasmPath, "..", file);
+    console.log(`Checking: ${filePath}`);
+
+    if (fs.lstatSync(filePath).isFile()) {
+      const contents = CSON.readFileSync(filePath);
+
+      // We now have the contents of one of the grammar files for this specific grammar.
+      // Since each grammar may contain multiple grammar files, we need to ensure
+      // that this particular one is using the tree-sitter wasm file that was
+      // actually changed.
+      const grammarFile = contents.treeSitter?.grammar ?? "";
+
+      if (path.basename(grammarFile) === path.basename(wasmFile)) {
+        // This grammar uses the WASM file that's changed. So we must ensure our key has also changed
+        // Sidenote we use `basename` here, since the `wasmFile` will be
+        // a path relative from the root of the repo, meanwhile `grammarFile`
+        // will be relative from the file itself
+
+        // In order to check the previous state of what the key is, we first must retreive the file prior to this PR
+        const getPrevFile = cp.spawnSync("git", [ "show", `${commit}:./${filePath}` ]);
+
+        if (getPrevFile.status !== 0 || getPrevFile.stderr.toString().length > 0) {
+          // This can fail for two major reasons
+          // 1. The `git show` command has returned an error code other than `0`, failing.
+          // 2. This is a new file, and it failed to find an earlier copy (which didn't exist)
+          // So that we don't fail brand new TreeSitter grammars, we manually check for number 2
+
+          if (getPrevFile.stderr.toString().includes("exists on disk, but not in")) {
+            // Looks like this file is new. Skip this check
+            if (verbose) {
+              console.log("Looks like this file is new. Skipping...");
+            }
+            continue;
+          }
+
+          console.error("Git command failed!");
+          console.error(`'git show ${commit}:./${filePath}'`);
+          console.error(getPrevFile.stderr.toString());
+          process.exit(1);
+        }
+
+        fs.writeFileSync(path.join(wasmPath, "..", `OLD-${file}`), getPrevFile.stdout.toString());
+
+        const oldContents = CSON.readFileSync(path.join(wasmPath, "..", `OLD-${file}`));
+        const oldParserSource = oldContents.treeSitter?.parserSource ?? "";
+        const newParserSource = contents.treeSitter?.parserSource ?? "";
+
+        if (newParserSource.length === 0) {
+          console.error(`Failed to find the new \`parserSource\` within: '${filePath}'`);
+          console.error(contents.treeSitter);
+          process.exit(1);
+        }
+
+        if (oldParserSource == newParserSource) {
+          // The repo and commit is identical! This means it hasn't been updated
+          console.error(`The \`parserSource\` key of '${filePath}' has not been updated!`);
+          console.error(`Current key: ${newParserSource} - Old key: ${oldParserSource}`);
+          process.exit(1);
+        }
+
+        // Else it looks like it has been updated properly
+        console.log(`Validated \`parserSource\` has been updated within '${filePath}' properly.`);
+      } else {
+        if (verbose) {
+          console.log("This grammar file doesn't use a WASM file that's changed (On the current iteration)");
+        }
+      }
+    }
+  }
+}