Allow GN configs to have sub-configs.

tools/gn/command_desc.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 #include <set>
 #include <sstream>
 
 #include "base/command_line.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/config.h"
 #include "tools/gn/config_values_extractors.h"
 #include "tools/gn/deps_iterator.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/item.h"
 #include "tools/gn/label.h"
 #include "tools/gn/runtime_deps.h"
 #include "tools/gn/setup.h"
 #include "tools/gn/standard_out.h"
 #include "tools/gn/substitution_writer.h"
 #include "tools/gn/target.h"
 #include "tools/gn/variables.h"
 
 namespace commands {
 
 namespace {
 
-// The switch for displaying blame.
+// Desc-specific command line switches.
 const char kBlame[] = "blame";
+const char kTree[] = "tree";
 
 // Prints the given directory in a nice way for the user to view.
 std::string FormatSourceDir(const SourceDir& dir) {
 #if defined(OS_WIN)
   // On Windows we fix up system absolute paths to look like native ones.
   // Internally, they'll look like "/C:\foo\bar/"
   if (dir.is_system_absolute()) {
     std::string buf = dir.value();
     if (buf.size() > 3 && buf[2] == ':') {
       buf.erase(buf.begin());  // Erase beginning slash.
@@ skipping 66 matching lines @@
                          indent_level + 1);
     }
   }
 }
 
 void PrintDeps(const Target* target, bool display_header) {
   const base::CommandLine* cmdline = base::CommandLine::ForCurrentProcess();
   Label toolchain_label = target->label().GetToolchainLabel();
 
   // Tree mode is separate.
-  if (cmdline->HasSwitch("tree")) {
+  if (cmdline->HasSwitch(kTree)) {
     if (display_header)
       OutputString("\nDependency tree:\n");
 
     if (cmdline->HasSwitch("all")) {
       // Show all tree deps with no eliding.
       RecursivePrintDeps(target, toolchain_label, nullptr, 1);
     } else {
       // Don't recurse into duplicates.
       std::set<const Target*> seen_targets;
       RecursivePrintDeps(target, toolchain_label, &seen_targets, 1);
@@ skipping 115 matching lines @@
 void PrintTestonly(const Target* target, bool display_header) {
   if (display_header)
     OutputString("\ntestonly:\n");
 
   if (target->testonly())
     OutputString("  true\n");
   else
     OutputString("  false\n");
 }
 
+// Recursively prints subconfigs of a config.
+void PrintSubConfigs(const Config* config, int indent_level) {
+  if (config->configs().empty())
+    return;
+
+  std::string indent(indent_level * 2, ' ');
+  Label toolchain_label = config->label().GetToolchainLabel();
+  for (const auto& pair : config->configs()) {
+    OutputString(
+        indent + pair.label.GetUserVisibleName(toolchain_label) + "\n");
+    PrintSubConfigs(pair.ptr, indent_level + 1);
+  }
+}
+
+// This allows configs stored as either std::vector<LabelConfigPair> or
+// UniqueVector<LabelConfigPair> to be printed.
+template <class VectorType>
 void PrintConfigsVector(const Target* target,
-                        const LabelConfigVector& configs,
+                        const VectorType& configs,
                         const std::string& heading,
                         bool display_header) {
   if (configs.empty())
     return;
 
+  bool tree = base::CommandLine::ForCurrentProcess()->HasSwitch(kTree);
+
   // Don't sort since the order determines how things are processed.
-  if (display_header)
-    OutputString("\n" + heading + " (in order applying):\n");
+  if (display_header) {
+    if (tree)
+      OutputString("\n" + heading + " tree (in order applying):\n");
+    else
+      OutputString("\n" + heading + " (in order applying, try also --tree):\n");
+  }
 
   Label toolchain_label = target->label().GetToolchainLabel();
   for (const auto& config : configs) {
     OutputString("  " + config.label.GetUserVisibleName(toolchain_label) +
                  "\n");
+    if (tree)
+      PrintSubConfigs(config.ptr, 2);  // 2 = start with double-indent.
   }
 }
 
-void PrintConfigsVector(const Target* target,
-                        const UniqueVector<LabelConfigPair>& configs,
-                        const std::string& heading,
-                        bool display_header) {
-  if (configs.empty())
-    return;
-
-  // Don't sort since the order determines how things are processed.
-  if (display_header)
-    OutputString("\n" + heading + " (in order applying):\n");
-
-  Label toolchain_label = target->label().GetToolchainLabel();
-  for (const auto& config : configs) {
-    OutputString("  " + config.label.GetUserVisibleName(toolchain_label) +
-                 "\n");
-  }
-}
-
 void PrintConfigs(const Target* target, bool display_header) {
   PrintConfigsVector(target, target->configs().vector(), "configs",
                      display_header);
 }
 
 void PrintPublicConfigs(const Target* target, bool display_header) {
   PrintConfigsVector(target, target->public_configs(),
                      "public_configs", display_header);
 }
 
@@ skipping 461 matching lines @@
   // so always display them, even for groups and such.
   PrintLibs(target, true);
   PrintLibDirs(target, true);
 
   PrintDeps(target, true);
 
   return 0;
 }
 
 }  // namespace commands