build(antlr): 引入第三方 ANTLR4 runtime/tool 并接入构建

third_party/antlr4-runtime-4.13.2/runtime/src/support/StringUtils.cpp

@@ -0,0 +1,38 @@
+/* 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.
+ */
+
+#include "support/StringUtils.h"
+
+namespace antlrcpp {
+
+  std::string escapeWhitespace(std::string_view in) {
+    std::string out;
+    escapeWhitespace(out, in);
+    out.shrink_to_fit();
+    return out;
+  }
+
+  std::string& escapeWhitespace(std::string& out, std::string_view in) {
+    out.reserve(in.size());  // Best case, no escaping.
+    for (const auto &c : in) {
+      switch (c) {
+        case '\t':
+          out.append("\\t");
+          break;
+        case '\r':
+          out.append("\\r");
+          break;
+        case '\n':
+          out.append("\\n");
+          break;
+        default:
+          out.push_back(c);
+          break;
+      }
+    }
+    return out;
+  }
+
+} // namespace antrlcpp