Add some missing string-to-enum-to-string convertors.

LoggingTypeToString
StringtoLoggingType
DumpFormatTypeToString
StringtoDumpFormatType

Fixes https://github.com/ceres-solver/ceres-solver/issues/470

Change-Id: Ic7eb98dada008c869a686fbdf2c7ff9ab81dad54

include/ceres/types.h

diff --git a/include/ceres/types.h b/include/ceres/types.h
index d01e921..4473ad5 100644
--- a/include/ceres/types.h
+++ b/include/ceres/types.h
@@ -498,6 +498,12 @@
     std::string value,
     NumericDiffMethodType* type);
 
+CERES_EXPORT const char* LoggingTypeToString(LoggingType type);
+CERES_EXPORT bool StringtoLoggingType(std::string value, LoggingType* type);
+
+CERES_EXPORT const char* DumpFormatTypeToString(DumpFormatType type);
+CERES_EXPORT bool StringtoDumpFormatType(std::string value, LoggingType* type);
+
 CERES_EXPORT const char* TerminationTypeToString(TerminationType type);
 
 CERES_EXPORT bool IsSchurType(LinearSolverType type);

internal/ceres/types.cc

diff --git a/internal/ceres/types.cc b/internal/ceres/types.cc
index 932ec7d..4691414 100644
--- a/internal/ceres/types.cc
+++ b/internal/ceres/types.cc
@@ -336,6 +336,39 @@
   }
 }
 
+const char* LoggingTypeToString(LoggingType type) {
+  switch (type) {
+    CASESTR(SILENT);
+    CASESTR(PER_MINIMIZER_ITERATION);
+    default:
+      return "UNKNOWN";
+  }
+}
+
+bool StringtoLoggingType(std::string value, LoggingType* type) {
+  UpperCase(&value);
+  STRENUM(SILENT);
+  STRENUM(PER_MINIMIZER_ITERATION);
+  return false;
+}
+
+
+const char* DumpFormatTypeToString(DumpFormatType type) {
+   switch (type) {
+    CASESTR(CONSOLE);
+    CASESTR(TEXTFILE);
+    default:
+      return "UNKNOWN";
+  }
+}
+
+bool StringtoDumpFormatType(std::string value, DumpFormatType* type) {
+  UpperCase(&value);
+  STRENUM(CONSOLE);
+  STRENUM(TEXTFILE);
+  return false;
+}
+
 #undef CASESTR
 #undef STRENUM