fix: change plugin-wasm to expose outputVarIds in the generated module (

#482)

Fixes #481

packages/plugin-wasm/src/plugin.ts

@@ -1,13 +1,16 @@
 // Copyright (c) 2022 Climate Interactive / New Venture Fund
 
-import { existsSync } from 'fs'
+import { existsSync, mkdirSync } from 'fs'
+import { writeFile } from 'fs/promises'
+
 import { basename, dirname, join as joinPath } from 'path'
 
 import { findUp } from 'find-up'
 
-import type { BuildContext, Plugin } from '@sdeverywhere/build'
+import type { BuildContext, ModelSpec, Plugin } from '@sdeverywhere/build'
 
 import type { WasmPluginOptions } from './options'
+import { sdeNameForVensimVarName } from './var-names'
 
 export function wasmPlugin(options?: WasmPluginOptions): Plugin {
   return new WasmPlugin(options)
@@ -16,6 +19,20 @@ export function wasmPlugin(options?: WasmPluginOptions): Plugin {
 class WasmPlugin implements Plugin {
   constructor(private readonly options?: WasmPluginOptions) {}
 
+  async preGenerate(context: BuildContext, modelSpec: ModelSpec): Promise<void> {
+    // Ensure that the build directory exists before we generate a file into it
+    const buildDir = joinPath(context.config.prepDir, 'build')
+    if (!existsSync(buildDir)) {
+      mkdirSync(buildDir, { recursive: true })
+    }
+
+    // Write a file that will be folded into the generated Wasm module
+    const outputVarsFile = joinPath(buildDir, 'processed_outputs.js')
+    const outputVarIds = modelSpec.outputs.map(o => sdeNameForVensimVarName(o.varName))
+    const content = `Module["outputVarIds"] = ${JSON.stringify(outputVarIds)};`
+    await writeFile(outputVarsFile, content)
+  }
+
   async postGenerateC(context: BuildContext, cContent: string): Promise<string> {
     context.log('info', '  Generating WebAssembly module')
 
@@ -99,6 +116,8 @@ async function buildWasm(
   addInput('macros.c')
   addInput('model.c')
   addInput('vensim.c')
+  addArg('--pre-js')
+  addArg('build/processed_outputs.js')
   addArg('-Ibuild')
   addArg('-o')
   addArg(outputJsPath)

packages/plugin-wasm/src/var-names.ts

@@ -0,0 +1,46 @@
+// Copyright (c) 2024 Climate Interactive / New Venture Fund
+
+/**
+ * Helper function that converts a Vensim variable or subscript name
+ * into a valid C identifier as used by SDE.
+ * TODO: Import helper function from `compile` package instead
+ */
+function sdeNameForVensimName(name: string): string {
+  return (
+    '_' +
+    name
+      .trim()
+      .replace(/"/g, '_')
+      .replace(/\s+!$/g, '!')
+      .replace(/\s/g, '_')
+      .replace(/,/g, '_')
+      .replace(/-/g, '_')
+      .replace(/\./g, '_')
+      .replace(/\$/g, '_')
+      .replace(/'/g, '_')
+      .replace(/&/g, '_')
+      .replace(/%/g, '_')
+      .replace(/\//g, '_')
+      .replace(/\|/g, '_')
+      .toLowerCase()
+  )
+}
+
+/**
+ * Helper function that converts a Vensim variable name (possibly containing
+ * subscripts) into a valid C identifier as used by SDE.
+ * TODO: Import helper function from `compile` package instead
+ */
+export function sdeNameForVensimVarName(varName: string): string {
+  const m = varName.match(/([^[]+)(?:\[([^\]]+)\])?/)
+  if (!m) {
+    throw new Error(`Invalid Vensim name: ${varName}`)
+  }
+  let id = sdeNameForVensimName(m[1])
+  if (m[2]) {
+    const subscripts = m[2].split(',').map(x => sdeNameForVensimName(x))
+    id += `[${subscripts.join('][')}]`
+  }
+
+  return id
+}

tests/integration/impl-var-access/run-tests.js

@@ -99,12 +99,23 @@ async function createSynchronousRunner() {
   // fix the generated `wasm-model.js` file so that it works for either ESM or CommonJS.
   global.__dirname = '.'
 
+  // Load the generated Wasm module and verify that it exposes `outputVarIds`
   const wasmModule = await initWasm()
-  const wasmResult = initWasmModelAndBuffers(wasmModule, 1, ['_z', '_d[_a1]'])
+  const actualVarIds = wasmModule.outputVarIds || []
+  const expectedVarIds = ['_z', '_d[_a1]']
+  if (actualVarIds.length !== expectedVarIds.length || !actualVarIds.every((v, i) => v === expectedVarIds[i])) {
+    throw new Error(
+      `Test failed: outputVarIds [${actualVarIds}] in generated Wasm module don't match expected values [${expectedVarIds}]`
+    )
+  }
+
+  // Initialize the synchronous `ModelRunner` that drives the Wasm model
+  const wasmResult = initWasmModelAndBuffers(wasmModule, 1, wasmModule.outputVarIds)
   return createWasmModelRunner(wasmResult)
 }
 
 async function createAsynchronousRunner() {
+  // Initialize the asynchronous `ModelRunner` that drives the Wasm model
   const modelWorkerJs = await readFile(joinPath('sde-prep', 'worker.js'), 'utf8')
   return await spawnAsyncModelRunner({ source: modelWorkerJs })
 }