Status: Add SetExplanations() method.

Allow the StatusPrinter::PrintStatus() method to
use an Explanations instance, instead of calling
the global `print_explanations()` method.

Since the rest of Ninja still uses `record_explanation()`
at the moment, keep the old code path until we can get
rid of it as well.

3 files changed, 35 insertions, 5 deletions

diff --git a/src/status.h b/src/status.h
index e38b4e6..29db7c2 100644
--- a/src/status.h
+++ b/src/status.h
@@ -19,6 +19,7 @@
 
 struct BuildConfig;
 struct Edge;
+struct Explanations;
 
 /// Abstract interface to object that tracks the status of a build:
 /// completion fraction, printing updates.
@@ -33,6 +34,11 @@ struct Status {
   virtual void BuildStarted() = 0;
   virtual void BuildFinished() = 0;
 
+  /// Set the Explanations instance to use to report explanations,
+  /// argument can be nullptr if no explanations need to be printed
+  /// (which is the default).
+  virtual void SetExplanations(Explanations*) = 0;
+
   virtual void Info(const char* msg, ...) = 0;
   virtual void Warning(const char* msg, ...) = 0;
   virtual void Error(const char* msg, ...) = 0;
diff --git a/src/status_printer.cc b/src/status_printer.cc
index 577aa93..45854d1 100644
--- a/src/status_printer.cc
+++ b/src/status_printer.cc
@@ -403,11 +403,26 @@ string StatusPrinter::FormatProgressStatus(const char* progress_status_format,
 }
 
 void StatusPrinter::PrintStatus(const Edge* edge, int64_t time_millis) {
-  if (g_explaining) {
-    // Start a new line so that the first explanation does not append to the
-    // status line.
-    printer_.PrintOnNewLine("");
-    print_explanations(stderr, edge);
+  if (explanations_) {
+    // Collect all explanations for the current edge's outputs.
+    std::vector<std::string> explanations;
+    for (Node* output : edge->outputs_) {
+      explanations_->LookupAndAppend(output, &explanations);
+    }
+    if (!explanations.empty()) {
+      // Start a new line so that the first explanation does not append to the
+      // status line.
+      printer_.PrintOnNewLine("");
+      for (const auto& exp : explanations) {
+        fprintf(stderr, "ninja explain: %s\n", exp.c_str());
+      }
+    }
+  } else {
+    // DEPRECATED: Remove this code path once record_explanations() is
+    // no longer used by Ninja.
+    if (g_explaining) {
+      print_explanations(stderr, edge);
+    }
   }
 
   if (config_.verbosity == BuildConfig::QUIET
diff --git a/src/status_printer.h b/src/status_printer.h
index 1681fb8..0fa3a90 100644
--- a/src/status_printer.h
+++ b/src/status_printer.h
@@ -16,6 +16,7 @@
 #include <cstdint>
 #include <queue>
 
+#include "explanations.h"
 #include "line_printer.h"
 #include "status.h"
 
@@ -49,6 +50,11 @@ struct StatusPrinter : Status {
   std::string FormatProgressStatus(const char* progress_status_format,
                                    int64_t time_millis) const;
 
+  /// Set the |explanations_| pointer. Used to implement `-d explain`.
+  void SetExplanations(Explanations* explanations) override {
+    explanations_ = explanations;
+  }
+
  private:
   void PrintStatus(const Edge* edge, int64_t time_millis);
 
@@ -83,6 +89,9 @@ struct StatusPrinter : Status {
   /// Prints progress output.
   LinePrinter printer_;
 
+  /// An optional Explaantions pointer, used to implement `-d explain`.
+  Explanations* explanations_ = nullptr;
+
   /// The custom progress status format to use.
   const char* progress_status_format_;