1 files changed, 195 insertions, 1 deletions

diff --git a/src/google/protobuf/io/printer.h b/src/google/protobuf/io/printer.h
index f1490bbe..d11745ce 100644
--- a/src/google/protobuf/io/printer.h
+++ b/src/google/protobuf/io/printer.h
@@ -39,6 +39,7 @@
 
 #include <string>
 #include <map>
+#include <vector>
 #include <google/protobuf/stubs/common.h>
 
 namespace google {
@@ -47,6 +48,48 @@ namespace io {
 
 class ZeroCopyOutputStream;     // zero_copy_stream.h
 
+// Records annotations about a Printer's output.
+class LIBPROTOBUF_EXPORT AnnotationCollector {
+ public:
+  // Records that the bytes in file_path beginning with begin_offset and ending
+  // before end_offset are associated with the SourceCodeInfo-style path.
+  virtual void AddAnnotation(size_t begin_offset, size_t end_offset,
+                             const string& file_path,
+                             const std::vector<int>& path) = 0;
+
+  virtual ~AnnotationCollector() {}
+};
+
+// Records annotations about a Printer's output to the given protocol buffer,
+// assuming that the buffer has an ::Annotation message exposing path,
+// source_file, begin and end fields.
+template <typename AnnotationProto>
+class AnnotationProtoCollector : public AnnotationCollector {
+ public:
+  // annotation_proto is the protocol buffer to which new Annotations should be
+  // added. It is not owned by the AnnotationProtoCollector.
+  explicit AnnotationProtoCollector(AnnotationProto* annotation_proto)
+      : annotation_proto_(annotation_proto) {}
+
+  // Override for AnnotationCollector::AddAnnotation.
+  virtual void AddAnnotation(size_t begin_offset, size_t end_offset,
+                             const string& file_path,
+                             const std::vector<int>& path) {
+    typename AnnotationProto::Annotation* annotation =
+        annotation_proto_->add_annotation();
+    for (int i = 0; i < path.size(); ++i) {
+      annotation->add_path(path[i]);
+    }
+    annotation->set_source_file(file_path);
+    annotation->set_begin(begin_offset);
+    annotation->set_end(end_offset);
+  }
+
+ private:
+  // The protocol buffer to which new annotations should be added.
+  AnnotationProto* const annotation_proto_;
+};
+
 // This simple utility class assists in code generation.  It basically
 // allows the caller to define a set of variables and then output some
 // text with variable substitutions.  Example usage:
@@ -61,19 +104,129 @@ class ZeroCopyOutputStream;     // zero_copy_stream.h
 // Printer aggressively enforces correct usage, crashing (with assert failures)
 // in the case of undefined variables in debug builds. This helps greatly in
 // debugging code which uses it.
+//
+// If a Printer is constructed with an AnnotationCollector, it will provide it
+// with annotations that connect the Printer's output to paths that can identify
+// various descriptors.  In the above example, if person_ is a descriptor that
+// identifies Bob, we can associate the output string "My name is Bob." with
+// a source path pointing to that descriptor with:
+//
+//   printer.Annotate("name", person_);
+//
+// The AnnotationCollector will be sent an annotation linking the output range
+// covering "Bob" to the logical path provided by person_.  Tools may use
+// this association to (for example) link "Bob" in the output back to the
+// source file that defined the person_ descriptor identifying Bob.
+//
+// Annotate can only examine variables substituted during the last call to
+// Print.  It is invalid to refer to a variable that was used multiple times
+// in a single Print call.
+//
+// In full generality, one may specify a range of output text using a beginning
+// substitution variable and an ending variable.  The resulting annotation will
+// span from the first character of the substituted value for the beginning
+// variable to the last character of the substituted value for the ending
+// variable.  For example, the Annotate call above is equivalent to this one:
+//
+//   printer.Annotate("name", "name", person_);
+//
+// This is useful if multiple variables combine to form a single span of output
+// that should be annotated with the same source path.  For example:
+//
+//   Printer printer(output, '$');
+//   map<string, string> vars;
+//   vars["first"] = "Alice";
+//   vars["last"] = "Smith";
+//   printer.Print(vars, "My name is $first$ $last$.");
+//   printer.Annotate("first", "last", person_);
+//
+// This code would associate the span covering "Alice Smith" in the output with
+// the person_ descriptor.
+//
+// Note that the beginning variable must come before (or overlap with, in the
+// case of zero-sized substitution values) the ending variable.
+//
+// It is also sometimes useful to use variables with zero-sized values as
+// markers.  This avoids issues with multiple references to the same variable
+// and also allows annotation ranges to span literal text from the Print
+// templates:
+//
+//   Printer printer(output, '$');
+//   map<string, string> vars;
+//   vars["foo"] = "bar";
+//   vars["function"] = "call";
+//   vars["mark"] = "";
+//   printer.Print(vars, "$function$($foo$,$foo$)$mark$");
+//   printer.Annotate("function", "mark", call_);
+//
+// This code associates the span covering "call(bar,bar)" in the output with the
+// call_ descriptor.
+
 class LIBPROTOBUF_EXPORT Printer {
  public:
   // Create a printer that writes text to the given output stream.  Use the
   // given character as the delimiter for variables.
   Printer(ZeroCopyOutputStream* output, char variable_delimiter);
+
+  // Create a printer that writes text to the given output stream.  Use the
+  // given character as the delimiter for variables.  If annotation_collector
+  // is not null, Printer will provide it with annotations about code written
+  // to the stream.  annotation_collector is not owned by Printer.
+  Printer(ZeroCopyOutputStream* output, char variable_delimiter,
+          AnnotationCollector* annotation_collector);
+
   ~Printer();
 
+  // Link a subsitution variable emitted by the last call to Print to the object
+  // described by descriptor.
+  template <typename SomeDescriptor>
+  void Annotate(const char* varname, const SomeDescriptor* descriptor) {
+    Annotate(varname, varname, descriptor);
+  }
+
+  // Link the output range defined by the substitution variables as emitted by
+  // the last call to Print to the object described by descriptor. The range
+  // begins at begin_varname's value and ends after the last character of the
+  // value substituted for end_varname.
+  template <typename SomeDescriptor>
+  void Annotate(const char* begin_varname, const char* end_varname,
+                const SomeDescriptor* descriptor) {
+    if (annotation_collector_ == NULL) {
+      // Annotations aren't turned on for this Printer, so don't pay the cost
+      // of building the location path.
+      return;
+    }
+    std::vector<int> path;
+    descriptor->GetLocationPath(&path);
+    Annotate(begin_varname, end_varname, descriptor->file()->name(), path);
+  }
+
+  // Link a subsitution variable emitted by the last call to Print to the file
+  // with path file_name.
+  void Annotate(const char* varname, const string& file_name) {
+    Annotate(varname, varname, file_name);
+  }
+
+  // Link the output range defined by the substitution variables as emitted by
+  // the last call to Print to the file with path file_name. The range begins
+  // at begin_varname's value and ends after the last character of the value
+  // substituted for end_varname.
+  void Annotate(const char* begin_varname, const char* end_varname,
+                const string& file_name) {
+    if (annotation_collector_ == NULL) {
+      // Annotations aren't turned on for this Printer.
+      return;
+    }
+    std::vector<int> empty_path;
+    Annotate(begin_varname, end_varname, file_name, empty_path);
+  }
+
   // Print some text after applying variable substitutions.  If a particular
   // variable in the text is not defined, this will crash.  Variables to be
   // substituted are identified by their names surrounded by delimiter
   // characters (as given to the constructor).  The variable bindings are
   // defined by the given map.
-  void Print(const map<string, string>& variables, const char* text);
+  void Print(const std::map<string, string>& variables, const char* text);
 
   // Like the first Print(), except the substitutions are given as parameters.
   void Print(const char* text);
@@ -149,16 +302,57 @@ class LIBPROTOBUF_EXPORT Printer {
   bool failed() const { return failed_; }
 
  private:
+  // Link the output range defined by the substitution variables as emitted by
+  // the last call to Print to the object found at the SourceCodeInfo-style path
+  // in a file with path file_path. The range begins at the start of
+  // begin_varname's value and ends after the last character of the value
+  // substituted for end_varname. Note that begin_varname and end_varname
+  // may refer to the same variable.
+  void Annotate(const char* begin_varname, const char* end_varname,
+                const string& file_path, const std::vector<int>& path);
+
+  // Copy size worth of bytes from data to buffer_.
+  void CopyToBuffer(const char* data, int size);
+
   const char variable_delimiter_;
 
   ZeroCopyOutputStream* const output_;
   char* buffer_;
   int buffer_size_;
+  // The current position, in bytes, in the output stream.  This is equivalent
+  // to the total number of bytes that have been written so far.  This value is
+  // used to calculate annotation ranges in the substitutions_ map below.
+  size_t offset_;
 
   string indent_;
   bool at_start_of_line_;
   bool failed_;
 
+  // A map from variable name to [start, end) offsets in the output buffer.
+  // These refer to the offsets used for a variable after the last call to
+  // Print.  If a variable was used more than once, the entry used in
+  // this map is set to a negative-length span.  For singly-used variables, the
+  // start offset is the beginning of the substitution; the end offset is the
+  // last byte of the substitution plus one (such that (end - start) is the
+  // length of the substituted string).
+  std::map<string, std::pair<size_t, size_t> > substitutions_;
+
+  // Keeps track of the keys in substitutions_ that need to be updated when
+  // indents are inserted. These are keys that refer to the beginning of the
+  // current line.
+  std::vector<string> line_start_variables_;
+
+  // Returns true and sets range to the substitution range in the output for
+  // varname if varname was used once in the last call to Print. If varname
+  // was not used, or if it was used multiple times, returns false (and
+  // fails a debug assertion).
+  bool GetSubstitutionRange(const char* varname,
+                            std::pair<size_t, size_t>* range);
+
+  // If non-null, annotation_collector_ is used to store annotations about
+  // generated code.
+  AnnotationCollector* const annotation_collector_;
+
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Printer);
 };