Merge pull request #84 from ethul/topic/error-handling

Topic/error handling

1 files changed, 145 insertions, 0 deletions

diff --git a/src/to-javascript.js b/src/to-javascript.js
new file mode 100644
index 0000000..b402ad4
--- /dev/null
+++ b/src/to-javascript.js
@@ -0,0 +1,145 @@
+'use strict';
+
+const Promise = require('bluebird');
+
+const fs = Promise.promisifyAll(require('fs'));
+
+const path = require('path');
+
+const jsStringEscape = require('js-string-escape');
+
+const difference = require('lodash.difference');
+
+const debug = require('debug')('purs-loader');
+
+const PsModuleMap = require('./PsModuleMap');
+
+function updatePsModuleMap(psModule) {
+  const options = psModule.options;
+
+  const cache = psModule.cache;
+
+  const filePurs = psModule.srcPath;
+
+  if (!cache.psModuleMap) {
+    debug('module mapping does not exist');
+
+    return PsModuleMap.makeMap(options.src).then(map => {
+      cache.psModuleMap = map;
+      return cache.psModuleMap;
+    });
+  }
+  else {
+    return PsModuleMap.makeMapEntry(filePurs).then(result => {
+      const map = Object.assign(cache.psModuleMap, result);
+
+      cache.psModuleMap = map;
+
+      return cache.psModuleMap;
+    });
+  }
+}
+
+ // Reference the bundle.
+function makeBundleJS(psModule) {
+  const bundleOutput = psModule.options.bundleOutput;
+
+  const name = psModule.name;
+
+  const srcDir = psModule.srcDir;
+
+  const escaped = jsStringEscape(path.relative(srcDir, bundleOutput));
+
+  const result = `module.exports = require("${escaped}")["${name}"]`;
+
+  return result;
+}
+
+// Replace require paths to output files generated by psc with paths
+// to purescript sources, which are then also run through this loader.
+// Additionally, the imports replaced are tracked so that in the event
+// the compiler fails to compile the PureScript source, we can tack on
+// any new imports in order to allow webpack to watch the new files
+// before they have been successfully compiled.
+function makeJS(psModule, psModuleMap, js) {
+  const requireRE = /require\(['"]\.\.\/([\w\.]+)['"]\)/g;
+
+  const foreignRE = /require\(['"]\.\/foreign['"]\)/g;
+
+  const name = psModule.name;
+
+  const imports = psModuleMap[name].imports;
+
+  var replacedImports = [];
+
+  const result = js
+    .replace(requireRE, (m, p1) => {
+      const moduleValue = psModuleMap[p1];
+
+      if (!moduleValue) {
+        debug('module %s was not found in the map, replacing require with null', p1);
+
+        return 'null';
+      }
+      else {
+        const escapedPath = jsStringEscape(moduleValue.src);
+
+        replacedImports.push(p1);
+
+        return `require("${escapedPath}")`;
+      }
+    })
+    .replace(foreignRE, () => {
+      const escapedPath = jsStringEscape(psModuleMap[name].ffi);
+
+      return `require("${escapedPath}")`;
+    })
+  ;
+
+  const additionalImports = difference(imports, replacedImports);
+
+  if (additionalImports.length) {
+    debug('additional imports for %s: %o', name, additionalImports);
+  }
+
+  const additionalImportsResult = additionalImports.map(import_ => {
+    const moduleValue = psModuleMap[import_];
+
+    if (!moduleValue) {
+      debug('module %s was not found in the map, skipping require', import_);
+
+      return null;
+    }
+    else {
+      const escapedPath = jsStringEscape(moduleValue.src);
+
+      return `var ${import_.replace(/\./g, '_')} = require("${escapedPath}")`;
+    }
+  }).filter(a => a !== null).join('\n');
+
+  const result_ = result + (additionalImports.length ? '\n' + additionalImportsResult : '');
+
+  return result_;
+}
+
+module.exports = function toJavaScript(psModule) {
+  const options = psModule.options;
+
+  const cache = psModule.cache;
+
+  const bundlePath = path.resolve(options.bundleOutput);
+
+  const jsPath = cache.bundle ? bundlePath : psModule.jsPath;
+
+  const js = fs.readFileAsync(jsPath, 'utf8').catch(() => '');
+
+  const psModuleMap = updatePsModuleMap(psModule);
+
+  debug('loading JavaScript for %s', psModule.name);
+
+  return Promise.props({js: js, psModuleMap: psModuleMap}).then(result =>
+    options.bundle ?
+      makeBundleJS(psModule) :
+      makeJS(psModule, result.psModuleMap, result.js)
+  );
+};