Attach filename property to node.loc when provided.

README.md

@@ -37,6 +37,8 @@ Significant diversions are expected to occur in the future such as streaming, EB
 - **sourceType**: Indicate the mode the code should be parsed in. Can be
   either `"script"` or `"module"`.
 
+- **sourceFilename**: Correlate output AST nodes with their source filename.  Useful when generating code and source maps from the ASTs of multiple input files.
+
 - **plugins**: Array containing the plugins that you want to enable.
 
 ### Example

src/options.js

@@ -3,6 +3,7 @@
 
 export const defaultOptions: {
   sourceType: string,
+  sourceFilename: any,
   allowReturnOutsideFunction: boolean,
   allowImportExportEverywhere: boolean,
   allowSuperOutsideMethod: boolean,
@@ -11,6 +12,8 @@ export const defaultOptions: {
 } = {
   // Source type ("script" or "module") for different semantics
   sourceType: "script",
+  // Source filename.
+  sourceFilename: undefined,
   // When enabled, a return at the top level is not considered an
   // error.
   allowReturnOutsideFunction: false,

src/parser/index.js

@@ -14,6 +14,7 @@ export default class Parser extends Tokenizer {
     this.isReservedWord = reservedWords[6];
     this.input = input;
     this.plugins = this.loadPlugins(this.options.plugins);
+    this.filename = options.sourceFilename;
 
     // If enabled, skip leading hashbang line.
     if (this.state.pos === 0 && this.input[0] === "#" && this.input[1] === "!") {

src/parser/node.js

@@ -6,11 +6,12 @@ import { SourceLocation } from "../util/location";
 const pp = Parser.prototype;
 
 class Node {
-  constructor(pos?: number, loc?: SourceLocation) {
+  constructor(pos?: number, loc?: SourceLocation, filename?: string) {
     this.type = "";
     this.start = pos;
     this.end = 0;
     this.loc = new SourceLocation(loc);
+    if (filename) this.loc.filename = filename;
   }
 
   type: string;
@@ -26,11 +27,11 @@ class Node {
 }
 
 pp.startNode = function () {
-  return new Node(this.state.start, this.state.startLoc);
+  return new Node(this.state.start, this.state.startLoc, this.filename);
 };
 
 pp.startNodeAt = function (pos, loc) {
-  return new Node(pos, loc);
+  return new Node(pos, loc, this.filename);
 };
 
 function finishNodeAt(node, type, pos, loc) {

test/fixtures/core/categorized/filename-specified/actual.js

@@ -0,0 +1 @@
+var node = "shouldHaveFilenameLocProp";

test/fixtures/core/categorized/filename-specified/expected.json

@@ -0,0 +1,109 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 39,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 39
+    },
+    "filename": "path/to/input-file.js"
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 39,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 39
+      },
+      "filename": "path/to/input-file.js"
+    },
+    "sourceType": "script",
+    "body": [
+      {
+        "type": "VariableDeclaration",
+        "start": 0,
+        "end": 39,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 39
+          },
+          "filename": "path/to/input-file.js"
+        },
+        "declarations": [
+          {
+            "type": "VariableDeclarator",
+            "start": 4,
+            "end": 38,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 4
+              },
+              "end": {
+                "line": 1,
+                "column": 38
+              },
+              "filename": "path/to/input-file.js"
+            },
+            "id": {
+              "type": "Identifier",
+              "start": 4,
+              "end": 8,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 4
+                },
+                "end": {
+                  "line": 1,
+                  "column": 8
+                },
+                "filename": "path/to/input-file.js"
+              },
+              "name": "node"
+            },
+            "init": {
+              "type": "StringLiteral",
+              "start": 11,
+              "end": 38,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 11
+                },
+                "end": {
+                  "line": 1,
+                  "column": 38
+                },
+                "filename": "path/to/input-file.js"
+              },
+              "extra": {
+                "rawValue": "shouldHaveFilenameLocProp",
+                "raw": "\"shouldHaveFilenameLocProp\""
+              },
+              "value": "shouldHaveFilenameLocProp"
+            }
+          }
+        ],
+        "kind": "var"
+      }
+    ],
+    "directives": []
+  }
+}

test/fixtures/core/categorized/filename-specified/options.json

@@ -0,0 +1,3 @@
+{
+  "sourceFilename": "path/to/input-file.js"
+}