Re-land r406064 "[GN] Add JSON project writer".

tools/gn/command_gen.cc

Index: tools/gn/command_gen.cc
diff --git a/tools/gn/command_gen.cc b/tools/gn/command_gen.cc
index 3d442745c393970e383074971a14c0f1e33db26d..06b99ca1124d6a63fb92907b190fbe3874dca054 100644
--- a/tools/gn/command_gen.cc
+++ b/tools/gn/command_gen.cc
@@ -11,6 +11,7 @@
 #include "tools/gn/build_settings.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/eclipse_writer.h"
+#include "tools/gn/json_project_writer.h"
 #include "tools/gn/ninja_target_writer.h"
 #include "tools/gn/ninja_writer.h"
 #include "tools/gn/qt_creator_writer.h"
@@ -36,10 +37,14 @@ const char kSwitchIdeValueVs[] = "vs";
 const char kSwitchIdeValueVs2013[] = "vs2013";
 const char kSwitchIdeValueVs2015[] = "vs2015";
 const char kSwitchIdeValueXcode[] = "xcode";
+const char kSwitchIdeValueJson[] = "json";
 const char kSwitchNinjaExtraArgs[] = "ninja-extra-args";
 const char kSwitchRootTarget[] = "root-target";
 const char kSwitchSln[] = "sln";
 const char kSwitchWorkspace[] = "workspace";
+const char kSwitchJsonFileName[] = "json-file-name";
+const char kSwitchJsonIdeScript[] = "json-ide-script";
+const char kSwitchJsonIdeScriptArgs[] = "json-ide-script-args";
 
 // Called on worker thread to write the ninja file.
 void BackgroundDoWrite(const Target* target) {
@@ -113,7 +118,7 @@ void PrintInvalidGeneratedInput(const Builder* builder,
 
   if (generator) {
     err += "but this file was not generated by any dependencies of the " +
-        target_str + ". The target\nthat generates the file is:\n  ";
+           target_str + ". The target\nthat generates the file is:\n  ";
     err += generator->label().GetUserVisibleName(show_toolchains);
   } else {
     err += "but no targets in the build generate that file.";
@@ -166,11 +171,12 @@ bool RunIdeWriter(const std::string& ide,
                   Err* err) {
   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
+  bool quiet = command_line->HasSwitch(switches::kQuiet);
   base::ElapsedTimer timer;
 
   if (ide == kSwitchIdeValueEclipse) {
     bool res = EclipseWriter::RunAndWriteFile(build_settings, builder, err);
-    if (res && !command_line->HasSwitch(switches::kQuiet)) {
+    if (res && !quiet) {
       OutputString("Generating Eclipse settings took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
@@ -189,7 +195,7 @@ bool RunIdeWriter(const std::string& ide,
       filters = command_line->GetSwitchValueASCII(kSwitchFilters);
     bool res = VisualStudioWriter::RunAndWriteFiles(
         build_settings, builder, version, sln_name, filters, err);
-    if (res && !command_line->HasSwitch(switches::kQuiet)) {
+    if (res && !quiet) {
       OutputString("Generating Visual Studio projects took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
@@ -202,7 +208,7 @@ bool RunIdeWriter(const std::string& ide,
         command_line->GetSwitchValueASCII(kSwitchNinjaExtraArgs),
         command_line->GetSwitchValueASCII(kSwitchFilters), build_settings,
         builder, err);
-    if (res && !command_line->HasSwitch(switches::kQuiet)) {
+    if (res && !quiet) {
       OutputString("Generating Xcode projects took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
@@ -214,12 +220,32 @@ bool RunIdeWriter(const std::string& ide,
       root_target = command_line->GetSwitchValueASCII(kSwitchRootTarget);
     bool res = QtCreatorWriter::RunAndWriteFile(build_settings, builder, err,
                                                 root_target);
-    if (res && !command_line->HasSwitch(switches::kQuiet)) {
+    if (res && !quiet) {
       OutputString("Generating QtCreator projects took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
     }
     return res;
+  } else if (ide == kSwitchIdeValueJson) {
+    std::string file_name =
+        command_line->GetSwitchValueASCII(kSwitchJsonFileName);
+    if (file_name.empty())
+      file_name = "project.json";
+    std::string exec_script =
+        command_line->GetSwitchValueASCII(kSwitchJsonIdeScript);
+    std::string exec_script_extra_args =
+        command_line->GetSwitchValueASCII(kSwitchJsonIdeScriptArgs);
+    std::string filters = command_line->GetSwitchValueASCII(kSwitchFilters);
+
+    bool res = JSONProjectWriter::RunAndWriteFiles(
+        build_settings, builder, file_name, exec_script, exec_script_extra_args,
+        filters, quiet, err);
+    if (res && !quiet) {
+      OutputString("Generating JSON projects took " +
+                   base::Int64ToString(timer.Elapsed().InMilliseconds()) +
+                   "ms\n");
+    }
+    return res;
   }
 
   *err = Err(Location(), "Unknown IDE: " + ide);
@@ -229,8 +255,7 @@ bool RunIdeWriter(const std::string& ide,
 }  // namespace
 
 const char kGen[] = "gen";
-const char kGen_HelpShort[] =
-    "gen: Generate ninja files.";
+const char kGen_HelpShort[] = "gen: Generate ninja files.";
 const char kGen_Help[] =
     "gn gen: Generate ninja files.\n"
     "\n"
@@ -259,12 +284,13 @@ const char kGen_Help[] =
     "      \"vs2015\" - Visual Studio 2015 project/solution files.\n"
     "      \"xcode\" - Xcode workspace/solution files.\n"
     "      \"qtcreator\" - QtCreator project files.\n"
+    "      \"json\" - JSON file containing target information\n"
     "\n"
     "  --filters=<path_prefixes>\n"
     "      Semicolon-separated list of label patterns used to limit the set\n"
     "      of generated projects (see \"gn help label_pattern\"). Only\n"
     "      matching targets and their dependencies will be included in the\n"
-    "      solution. Only used for Visual Studio and Xcode.\n"
+    "      solution. Only used for Visual Studio, Xcode and JSON.\n"
     "\n"
     "Visual Studio Flags\n"
     "\n"
@@ -305,7 +331,27 @@ const char kGen_Help[] =
     "  properly define includes/defines for each file individually.\n"
     "  Instead, one set of includes/defines is generated for the entire\n"
     "  project. This works fairly well but may still result in a few indexer\n"
-    "  issues here and there.\n";
+    "  issues here and there.\n"
+    "\n"
+    "Generic JSON Output\n"
+    "\n"
+    "  Dumps target information to JSON file and optionally invokes python\n"
+    "  script on generated file. \n"
+    "  See comments at the beginning of json_project_writer.cc and\n"
+    "  desc_builder.cc for overview of JSON file format.\n"
+    "\n"
+    "  --json-file-name=<json_file_name>\n"
+    "      Overrides default file name (project.json) of generated JSON file.\n"
+    "\n"
+    "  --json-ide-script=<path_to_python_script>\n"
+    "      Executes python script after the JSON file is generated.\n"
+    "      Path can be project absolute (//), system absolute (/) or\n"
+    "      relative, in which case the output directory will be base.\n"
+    "      Path to generated JSON file will be first argument when invoking\n"
+    "      script.\n"
+    "\n"
+    "  --json-ide-script-args=<argument>\n"
+    "      Optional second argument that will passed to executed script.\n";
 
 int RunGen(const std::vector<std::string>& args) {
   base::ElapsedTimer timer;