first commit

services/web/webpack-plugins/lezer-grammar-compiler.js

@@ -0,0 +1,60 @@
+const fs = require('fs')
+const path = require('path')
+const modulePath = path.resolve(__dirname, '../scripts/lezer-latex/generate.js')
+
+try {
+  fs.accessSync(modulePath, fs.constants.W_OK)
+  const { compile, grammars } = require(modulePath)
+  const PLUGIN_NAME = 'lezer-grammar-compiler'
+  class LezerGrammarCompilerPlugin {
+    apply(compiler) {
+      for (const grammar of grammars) {
+        compiler.hooks.make.tap(PLUGIN_NAME, compilation => {
+          // Add the grammar file to the file paths watched by webpack
+          compilation.fileDependencies.add(grammar.grammarPath)
+        })
+        compiler.hooks.beforeCompile.tapAsync(
+          PLUGIN_NAME,
+          (_compilation, callback) => {
+            // Check timestamps on grammar and parser files, and re-compile if needed.
+            // (Note: the compiled parser file is watched by webpack, and so will trigger
+            //  a second compilation immediately after. This seems harmless.)
+            if (
+              !fs.existsSync(grammar.parserOutputPath) ||
+              !fs.existsSync(grammar.termsOutputPath)
+            ) {
+              console.log('Parser does not exist, compiling')
+              compile(grammar)
+              return callback()
+            }
+            fs.stat(grammar.grammarPath, (err, grammarStat) => {
+              if (err) {
+                return callback(err)
+              }
+              fs.stat(grammar.parserOutputPath, (err, parserStat) => {
+                if (err) {
+                  return callback(err)
+                }
+                callback()
+                if (grammarStat.mtime > parserStat.mtime) {
+                  console.log(
+                    'Grammar file newer than parser file, re-compiling'
+                  )
+                  compile(grammar)
+                }
+              })
+            })
+          }
+        )
+      }
+    }
+  }
+  module.exports = { LezerGrammarCompilerPlugin }
+} catch {
+  class NoOpPlugin {
+    apply() {
+      console.log('lezer-latex module not present, skipping compile')
+    }
+  }
+  module.exports = { LezerGrammarCompilerPlugin: NoOpPlugin }
+}