Respect original text decorator order (#5207)

src/language-js/loc.js

@@ -2,16 +2,18 @@
 
 const getLast = require("../utils/get-last");
 
-function locStart(node) {
+function locStart(node, opts) {
+  opts = opts || {};
   // Handle nodes with decorators. They should start at the first decorator
   if (
+    !opts.ignoreDecorators &&
     node.declaration &&
     node.declaration.decorators &&
     node.declaration.decorators.length > 0
   ) {
     return locStart(node.declaration.decorators[0]);
   }
-  if (node.decorators && node.decorators.length > 0) {
+  if (!opts.ignoreDecorators && node.decorators && node.decorators.length > 0) {
     return locStart(node.decorators[0]);
   }
 

src/language-js/parser-babylon.js

@@ -4,71 +4,93 @@ const createError = require("../common/parser-create-error");
 const hasPragma = require("./pragma").hasPragma;
 const locFns = require("./loc");
 
+function babylonOptions(extraOptions, extraPlugins) {
+  return Object.assign(
+    {
+      sourceType: "module",
+      allowAwaitOutsideFunction: true,
+      allowImportExportEverywhere: true,
+      allowReturnOutsideFunction: true,
+      allowSuperOutsideMethod: true,
+      plugins: [
+        "jsx",
+        "flow",
+        "doExpressions",
+        "objectRestSpread",
+        "classProperties",
+        "exportDefaultFrom",
+        "exportNamespaceFrom",
+        "asyncGenerators",
+        "functionBind",
+        "functionSent",
+        "dynamicImport",
+        "numericSeparator",
+        "importMeta",
+        "optionalCatchBinding",
+        "optionalChaining",
+        "classPrivateProperties",
+        ["pipelineOperator", { proposal: "minimal" }],
+        "nullishCoalescingOperator",
+        "bigInt",
+        "throwExpressions"
+      ].concat(extraPlugins)
+    },
+    extraOptions
+  );
+}
+
 function parse(text, parsers, opts) {
   // Inline the require to avoid loading all the JS if we don't use it
   const babylon = require("@babel/parser");
 
-  const babylonOptions = {
-    sourceType: "module",
-    allowAwaitOutsideFunction: true,
-    allowImportExportEverywhere: true,
-    allowReturnOutsideFunction: true,
-    allowSuperOutsideMethod: true,
-    plugins: [
-      "jsx",
-      "flow",
-      "doExpressions",
-      "objectRestSpread",
-      "decorators-legacy",
-      "classProperties",
-      "exportDefaultFrom",
-      "exportNamespaceFrom",
-      "asyncGenerators",
-      "functionBind",
-      "functionSent",
-      "dynamicImport",
-      "numericSeparator",
-      "importMeta",
-      "optionalCatchBinding",
-      "optionalChaining",
-      "classPrivateProperties",
-      ["pipelineOperator", { proposal: "minimal" }],
-      "nullishCoalescingOperator",
-      "bigInt",
-      "throwExpressions"
-    ]
-  };
+  const combinations = [
+    babylonOptions({ strictMode: true }, ["decorators-legacy"]),
+    babylonOptions({ strictMode: false }, ["decorators-legacy"]),
+    babylonOptions({ strictMode: true }, [
+      ["decorators", { decoratorsBeforeExport: false }]
+    ]),
+    babylonOptions({ strictMode: false }, [
+      ["decorators", { decoratorsBeforeExport: false }]
+    ])
+  ];
 
   const parseMethod =
     !opts || opts.parser === "babylon" ? "parse" : "parseExpression";
 
   let ast;
   try {
-    ast = babylon[parseMethod](text, babylonOptions);
-  } catch (originalError) {
-    try {
-      ast = babylon[parseMethod](
-        text,
-        Object.assign({}, babylonOptions, { strictMode: false })
-      );
-    } catch (nonStrictError) {
-      throw createError(
-        // babel error prints (l:c) with cols that are zero indexed
-        // so we need our custom error
-        originalError.message.replace(/ \(.*\)/, ""),
-        {
-          start: {
-            line: originalError.loc.line,
-            column: originalError.loc.column + 1
-          }
+    ast = tryCombinations(babylon[parseMethod].bind(null, text), combinations);
+  } catch (error) {
+    throw createError(
+      // babel error prints (l:c) with cols that are zero indexed
+      // so we need our custom error
+      error.message.replace(/ \(.*\)/, ""),
+      {
+        start: {
+          line: error.loc.line,
+          column: error.loc.column + 1
         }
-      );
-    }
+      }
+    );
   }
   delete ast.tokens;
   return ast;
 }
 
+function tryCombinations(fn, combinations) {
+  let error;
+  for (let i = 0; i < combinations.length; i++) {
+    try {
+      return fn(combinations[i]);
+    } catch (_error) {
+      if (!error) {
+        error = _error;
+      }
+    }
+  }
+  throw error;
+}
+
 function parseJson(text, parsers, opts) {
   const ast = parse(text, parsers, Object.assign({}, opts, { parser: "json" }));
 

src/language-js/printer-estree.js

@@ -89,13 +89,19 @@ function genericPrint(path, options, printPath, args) {
     return linesWithoutParens;
   }
 
+  const parentExportDecl = getParentExportDeclaration(path);
   const decorators = [];
   if (
     node.decorators &&
     node.decorators.length > 0 &&
-    // If the parent node is an export declaration, it will be
-    // responsible for printing node.decorators.
-    !getParentExportDeclaration(path)
+    // If the parent node is an export declaration and the decorator
+    // was written before the export, the export will be responsible
+    // for printing the decorators.
+    !(
+      parentExportDecl &&
+      options.locStart(parentExportDecl, { ignoreDecorators: true }) >
+        options.locStart(node.decorators[0])
+    )
   ) {
     const shouldBreak =
       node.type === "ClassDeclaration" ||
@@ -121,10 +127,19 @@ function genericPrint(path, options, printPath, args) {
 
       decorators.push(printPath(decoratorPath), separator);
     }, "decorators");
+
+    if (parentExportDecl) {
+      decorators.unshift(hardline);
+    }
   } else if (
     isExportDeclaration(node) &&
     node.declaration &&
-    node.declaration.decorators
+    node.declaration.decorators &&
+    node.declaration.decorators.length > 0 &&
+    // Only print decorators here if they were written before the export,
+    // otherwise they are printed by the node.declaration
+    options.locStart(node, { ignoreDecorators: true }) >
+      options.locStart(node.declaration.decorators[0])
   ) {
     // Export declarations are responsible for printing any decorators
     // that logically apply to node.declaration.

tests/decorators_export/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,31 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`after_export.js - babylon-verify 1`] = `
+export @decorator class Foo {}
+
+export default @decorator class {}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+export
+@decorator
+class Foo {}
+
+export default
+@decorator
+class {}
+
+`;
+
+exports[`before_export.js - babylon-verify 1`] = `
+@decorator
+export class Foo {}
+
+@decorator
+export default class {}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+@decorator
+export class Foo {}
+
+@decorator
+export default class {}
+
+`;

tests/decorators_export/after_export.js

@@ -0,0 +1,3 @@
+export @decorator class Foo {}
+
+export default @decorator class {}

tests/decorators_export/before_export.js

@@ -0,0 +1,5 @@
+@decorator
+export class Foo {}
+
+@decorator
+export default class {}

tests/decorators_export/jsfmt.spec.js

@@ -0,0 +1,2 @@
+// TypeScript and Flow don't accept decorator after export
+run_spec(__dirname, ["babylon"]);