ConfigureLog: Add infrastructure for structured configure event logging

Add infrastructure for a "configure log".  Use YAML for a balance of
machine- and human-readability to records details of configure-time
events in a structured format.

Teach the RunCMake test framework to support matching the configure log.

Issue: #23200

1 files changed, 61 insertions, 0 deletions

diff --git a/Source/cmConfigureLog.h b/Source/cmConfigureLog.h
new file mode 100644
index 0000000..a71fd0c
--- /dev/null
+++ b/Source/cmConfigureLog.h
@@ -0,0 +1,61 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <cm/string_view>
+
+#include "cmsys/FStream.hxx"
+
+namespace Json {
+class StreamWriter;
+}
+
+class cmMakefile;
+
+class cmConfigureLog
+{
+public:
+  cmConfigureLog(std::string logDir);
+  ~cmConfigureLog();
+
+  void WriteBacktrace(cmMakefile const& mf);
+
+  void EnsureInit();
+
+  void BeginEvent(std::string const& kind);
+  void EndEvent();
+
+  void BeginObject(cm::string_view key);
+  void EndObject();
+
+  // TODO other value types
+  void WriteValue(cm::string_view key, std::nullptr_t);
+  void WriteValue(cm::string_view key, bool value);
+  void WriteValue(cm::string_view key, int value);
+  void WriteValue(cm::string_view key, std::string const& value);
+  void WriteValue(cm::string_view key, std::vector<std::string> const& list);
+
+  void WriteTextBlock(cm::string_view key, cm::string_view text);
+  void WriteLiteralTextBlock(cm::string_view key, cm::string_view text);
+
+  void WriteLiteralTextBlock(cm::string_view key, std::string const& text)
+  {
+    this->WriteLiteralTextBlock(key, cm::string_view{ text });
+  }
+
+private:
+  std::string LogDir;
+  cmsys::ofstream Stream;
+  unsigned Indent = 0;
+  bool Opened = false;
+
+  std::unique_ptr<Json::StreamWriter> Encoder;
+
+  cmsys::ofstream& BeginLine();
+  void EndLine();
+  void WriteEscape(unsigned char c);
+};