[Javascript] Add a case insensitive input stream.

runtime/JavaScript/src/antlr4/CaseInsensitiveInputStream.js

@@ -0,0 +1,54 @@
+//
+/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+ * Use of this file is governed by the BSD 3-clause license that
+ * can be found in the LICENSE.txt file in the project root.
+ */
+//
+
+function CaseInsensitiveInputStream(stream, upper) {
+    this._stream = stream;
+    this._case = upper ? String.toUpperCase : String.toLowerCase;
+    return this;
+}
+
+CaseInsensitiveInputStream.prototype.LA = function (offset) {
+    c = this._stream.LA(i);
+    if (c <= 0) {
+        return c;
+    }
+    return this._case.call(String.fromCodePoint(c))
+};
+
+CaseInsensitiveInputStream.prototype.reset = function() {
+    return this._stream.reset();
+};
+
+CaseInsensitiveInputStream.prototype.consume = function() {
+    return this._stream.consume();
+};
+
+CaseInsensitiveInputStream.prototype.LT = function(offset) {
+    return this._stream.LT(offset);
+};
+
+CaseInsensitiveInputStream.prototype.mark = function() {
+    return this._stream.mark();
+};
+
+CaseInsensitiveInputStream.prototype.release = function(marker) {
+    return this._stream.release(marker);
+};
+
+CaseInsensitiveInputStream.prototype.seek = function(_index) {
+    return this._stream.getText(start, stop);
+};
+
+CaseInsensitiveInputStream.prototype.getText = function(start, stop) {
+    return this._stream.getText(start, stop);
+};
+
+CaseInsensitiveInputStream.prototype.toString = function() {
+    return this._stream.toString();
+};
+
+exports.CaseInsensitiveInputStream = CaseInsensitiveInputStream;

runtime/JavaScript/src/antlr4/CharStreams.js

@@ -5,6 +5,7 @@
  */
 //
 
+var CaseInsensitiveInputStream = require('./CaseInsensitiveInputStream').CaseInsensitiveInputStream;
 var InputStream = require('./InputStream').InputStream;
 
 var isNodeJs = typeof window === 'undefined' && typeof importScripts === 'undefined';
@@ -65,6 +66,14 @@ var CharStreams = {
   fromPathSync: function(path, encoding) {
     var data = fs.readFileSync(path, encoding);
     return new InputStream(data, true);
+  },
+
+  toUpper: function(stream) {
+    return new CaseInsensitiveInputStream(stream, true);
+  },
+
+  toLower: function(stream) {
+    return new CaseInsensitiveInputStream(stream, false);
   }
 };