Support sourceType: "unambiguous" parsing

src/index.js

@@ -18,7 +18,27 @@ plugins.jsx = jsxPlugin;
 plugins.typescript = typescriptPlugin;
 
 export function parse(input: string, options?: Options): File {
- return getParser(options, input).parse();
+ if (options && options.sourceType === "unambiguous") {
+ options = Object.assign({}, options);
+ try {
+ options.sourceType = "module";
+ const ast = getParser(options, input).parse();
+
+ // Rather than try to parse as a script first, we opt to parse as a module and convert back
+ // to a script where possible to avoid having to do a full re-parse of the input content.
+ if (!hasModuleSyntax(ast)) ast.program.sourceType = "script";
+ return ast;
+ } catch (moduleError) {
+ try {
+ options.sourceType = "script";
+ return getParser(options, input).parse();
+ } catch (scriptError) {}
+
+ throw moduleError;
+ }
+ } else {
+ return getParser(options, input).parse();
+ }
 }
 
 export function parseExpression(input: string, options?: Options): Expression {
@@ -91,3 +111,16 @@ function getParserClass(
  }
  return cls;
 }
+
+function hasModuleSyntax(ast) {
+ return ast.program.body.some(
+ child =>
+ (child.type === "ImportDeclaration" &&
+ (!child.importKind || child.importKind === "value")) ||
+ (child.type === "ExportNamedDeclaration" &&
+ (!child.exportKind || child.exportKind === "value")) ||
+ (child.type === "ExportAllDeclaration" &&
+ (!child.exportKind || child.exportKind === "value")) ||
+ child.type === "ExportDefaultDeclaration",
+ );
+}

test/fixtures/core/sourcetype-unambiguous/commonjs/actual.js

@@ -0,0 +1 @@
+var foo = require("foo");

test/fixtures/core/sourcetype-unambiguous/commonjs/expected.json

@@ -0,0 +1,138 @@
+{
+ "type": "File",
+ "start": 0,
+ "end": 25,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 0
+ },
+ "end": {
+ "line": 1,
+ "column": 25
+ }
+ },
+ "program": {
+ "type": "Program",
+ "start": 0,
+ "end": 25,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 0
+ },
+ "end": {
+ "line": 1,
+ "column": 25
+ }
+ },
+ "sourceType": "script",
+ "body": [
+ {
+ "type": "VariableDeclaration",
+ "start": 0,
+ "end": 25,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 0
+ },
+ "end": {
+ "line": 1,
+ "column": 25
+ }
+ },
+ "declarations": [
+ {
+ "type": "VariableDeclarator",
+ "start": 4,
+ "end": 24,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 4
+ },
+ "end": {
+ "line": 1,
+ "column": 24
+ }
+ },
+ "id": {
+ "type": "Identifier",
+ "start": 4,
+ "end": 7,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 4
+ },
+ "end": {
+ "line": 1,
+ "column": 7
+ },
+ "identifierName": "foo"
+ },
+ "name": "foo"
+ },
+ "init": {
+ "type": "CallExpression",
+ "start": 10,
+ "end": 24,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 10
+ },
+ "end": {
+ "line": 1,
+ "column": 24
+ }
+ },
+ "callee": {
+ "type": "Identifier",
+ "start": 10,
+ "end": 17,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 10
+ },
+ "end": {
+ "line": 1,
+ "column": 17
+ },
+ "identifierName": "require"
+ },
+ "name": "require"
+ },
+ "arguments": [
+ {
+ "type": "StringLiteral",
+ "start": 18,
+ "end": 23,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 18
+ },
+ "end": {
+ "line": 1,
+ "column": 23
+ }
+ },
+ "extra": {
+ "rawValue": "foo",
+ "raw": "\"foo\""
+ },
+ "value": "foo"
+ }
+ ]
+ }
+ }
+ ],
+ "kind": "var"
+ }
+ ],
+ "directives": []
+ }
+}

test/fixtures/core/sourcetype-unambiguous/commonjs/options.json

@@ -0,0 +1,3 @@
+{
+ "sourceType": "unambiguous"
+}

test/fixtures/core/sourcetype-unambiguous/flow/actual.js

@@ -0,0 +1,3 @@
+import type { Foo } from "bar";
+export type { Foo };
+export type * from "bar";