trace: Add JSON output format

Add a new `--trace-format=` flag, to enable the new JSON trace
output format. This new format is easier to parse by machines
than the existing format. This new format also removes the
ambiguity of the whitespace in the "old" format (e.g. is that
whitespace part of a file path, or does it seperate arguments)

1 files changed, 15 insertions, 2 deletions

diff --git a/Source/cmake.h b/Source/cmake.h
index 02de4c1af9..54fdc03732 100644
--- a/Source/cmake.h
+++ b/Source/cmake.h
@@ -113,6 +113,14 @@ public:
     LOG_TRACE
   };
 
+  /** \brief Define supported trace formats **/
+  enum TraceFormat
+  {
+    TRACE_UNDEFINED,
+    TRACE_HUMAN,
+    TRACE_JSON_V1,
+  };
+
   struct GeneratorInfo
   {
     std::string name;
@@ -389,6 +397,7 @@ public:
   LogLevel GetLogLevel() const { return this->MessageLogLevel; }
   void SetLogLevel(LogLevel level) { this->MessageLogLevel = level; }
   static LogLevel StringToLogLevel(const std::string& levelStr);
+  static TraceFormat StringToTraceFormat(const std::string& levelStr);
 
   bool HasCheckInProgress() const
   {
@@ -418,10 +427,12 @@ public:
   void SetShowLogContext(bool b) { this->LogContext = b; }
 
   //! Do we want trace output during the cmake run.
-  bool GetTrace() { return this->Trace; }
+  bool GetTrace() const { return this->Trace; }
   void SetTrace(bool b) { this->Trace = b; }
-  bool GetTraceExpand() { return this->TraceExpand; }
+  bool GetTraceExpand() const { return this->TraceExpand; }
   void SetTraceExpand(bool b) { this->TraceExpand = b; }
+  TraceFormat GetTraceFormat() const { return this->TraceFormatVar; }
+  void SetTraceFormat(TraceFormat f) { this->TraceFormatVar = f; }
   void AddTraceSource(std::string const& file)
   {
     this->TraceOnlyThisSources.push_back(file);
@@ -432,6 +443,7 @@ public:
   }
   cmGeneratedFileStream& GetTraceFile() { return this->TraceFile; }
   void SetTraceFile(std::string const& file);
+  void PrintTraceFormatVersion();
 
   bool GetWarnUninitialized() { return this->WarnUninitialized; }
   void SetWarnUninitialized(bool b) { this->WarnUninitialized = b; }
@@ -579,6 +591,7 @@ private:
   bool DebugOutput = false;
   bool Trace = false;
   bool TraceExpand = false;
+  TraceFormat TraceFormatVar = TRACE_HUMAN;
   cmGeneratedFileStream TraceFile;
   bool WarnUninitialized = false;
   bool WarnUnused = false;