[flang] Add debug-parser.h.

Original-commit: flang-compiler/f18@e5484d45b4d6ec1e52f79cadcd6979fd9126ff77

diff --git a/flang/debug-parser.h b/flang/debug-parser.h
new file mode 100644 (file)
index 0000000..d7b4e7d
--- /dev/null
+++ b/flang/debug-parser.h
@@ -0,0 +1,37 @@
+#ifndef FORTRAN_DEBUG_PARSER_H_
+#define FORTRAN_DEBUG_PARSER_H_
+
+// Implements the parser with syntax "(YOUR MESSAGE HERE)"_debug for use
+// in temporary modifications to the grammar intended for tracing the
+// flow of the parsers.  Not to be used in production.
+
+#include "basic-parsers.h"
+#include "parse-state.h"
+#include <iostream>
+#include <optional>
+#include <string>
+
+namespace Fortran {
+
+class DebugParser {
+ public:
+  using resultType = Success;
+  constexpr DebugParser(const DebugParser &) = default;
+  constexpr DebugParser(const char *str, size_t n) : str_{str}, length_{n} {}
+  std::optional<Success> Parse(ParseState *state) const {
+    if (auto context = state->context()) {
+      std::cout << *context;
+    }
+    std::cout << state->position() << ' ' << std::string{str_, length_} << '\n';
+    return {Success{}};
+  }
+ private:
+  const char *const str_;
+  size_t length_;
+};
+
+constexpr DebugParser operator""_debug(const char str[], size_t n) {
+  return DebugParser{str, n};
+}
+}  // namespace Fortran
+#endif  // FORTRAN_DEBUG_PARSER_H_