[flang] Add position.{h,cc}.

Original-commit: flang-compiler/f18@78c9c256ba

flang/position.cc

@@ -0,0 +1,7 @@
+#include "position.h"
+
+namespace Fortran {
+std::ostream &operator<<(std::ostream &o, const Position &x) {
+  return o << "(at line " << x.lineNumber() << ", column " << x.column() << ')';
+}
+}  // namespace Fortran

flang/position.h

@@ -0,0 +1,70 @@
+#ifndef FORTRAN_POSITION_H_
+#define FORTRAN_POSITION_H_
+
+// Represents a position in a source file.
+// TODO: Support multiple source files for inclusion and support contextual
+// positions for macro expansions.
+
+#include <ostream>
+
+namespace Fortran {
+
+class Position {
+ public:
+  constexpr Position() = default;
+  constexpr Position(int ln, int col)
+    : lineNumber_{ln}, column_{col} {}
+
+  constexpr int lineNumber() const { return lineNumber_; }
+  constexpr int column() const { return column_; }
+
+  constexpr bool operator<(const Position &that) const {
+    return lineNumber_ < that.lineNumber_ ||
+           (lineNumber_ == that.lineNumber_ &&
+            column_ < that.column_);
+  }
+
+  constexpr bool operator<=(const Position &that) const {
+    return lineNumber_ < that.lineNumber_ ||
+           (lineNumber_ == that.lineNumber_ &&
+            column_ <= that.column_);
+  }
+
+  constexpr bool operator==(const Position &that) const {
+    return lineNumber_ == that.lineNumber_ &&
+           column_ == that.column_;
+  }
+
+  constexpr bool operator!=(const Position &that) const {
+    return !operator==(that);
+  }
+
+  constexpr bool operator>(const Position &that) const {
+    return !operator<=(that);
+  }
+
+  constexpr bool operator>=(const Position &that) const {
+    return !operator<(that);
+  }
+
+  void AdvanceColumn() {
+    ++column_;
+  }
+
+  void TabAdvanceColumn() {
+    column_ = ((column_ + 7) & -8) + 1;
+  }
+
+  void AdvanceLine() {
+    ++lineNumber_;
+    column_ = 1;
+  }
+
+ private:
+  int lineNumber_{1};
+  int column_{1};
+};
+
+std::ostream &operator<<(std::ostream &, const Position &);
+}  // namespace Fortran
+#endif  // FORTRAN_POSITION_H_