Rewrite OutputFormattedHelpText in terms of StringRef.

This makes the logic easier to follow and also propagates
StringRef up to the API boundary, which is necessary for
making higher up StringRef API changes.

Differential Revision: https://reviews.llvm.org/D26325

llvm-svn: 286204

1 files changed, 49 insertions, 60 deletions

diff --git a/lldb/source/Interpreter/CommandInterpreter.cpp b/lldb/source/Interpreter/CommandInterpreter.cpp
index e9a702585ae..89ef7fe7760 100644
--- a/lldb/source/Interpreter/CommandInterpreter.cpp
+++ b/lldb/source/Interpreter/CommandInterpreter.cpp
@@ -1104,9 +1104,10 @@ bool CommandInterpreter::RemoveUser(llvm::StringRef alias_name) {
 
 void CommandInterpreter::GetHelp(CommandReturnObject &result,
                                  uint32_t cmd_types) {
-  const char *help_prologue = GetDebugger().GetIOHandlerHelpPrologue();
-  if (help_prologue != NULL) {
-    OutputFormattedHelpText(result.GetOutputStream(), NULL, help_prologue);
+  llvm::StringRef help_prologue(GetDebugger().GetIOHandlerHelpPrologue());
+  if (!help_prologue.empty()) {
+    OutputFormattedHelpText(result.GetOutputStream(), llvm::StringRef(),
+                            help_prologue);
   }
 
   CommandObject::CommandMap::const_iterator pos;
@@ -1121,8 +1122,8 @@ void CommandInterpreter::GetHelp(CommandReturnObject &result,
           (pos->first.compare(0, 1, "_") == 0))
         continue;
 
-      OutputFormattedHelpText(result.GetOutputStream(), pos->first.c_str(),
-                              "--", pos->second->GetHelp(), max_len);
+      OutputFormattedHelpText(result.GetOutputStream(), pos->first, "--",
+                              pos->second->GetHelp(), max_len);
     }
     result.AppendMessage("");
   }
@@ -1138,8 +1139,7 @@ void CommandInterpreter::GetHelp(CommandReturnObject &result,
 
     for (auto alias_pos = m_alias_dict.begin(); alias_pos != m_alias_dict.end();
          ++alias_pos) {
-      OutputFormattedHelpText(result.GetOutputStream(),
-                              alias_pos->first.c_str(), "--",
+      OutputFormattedHelpText(result.GetOutputStream(), alias_pos->first, "--",
                               alias_pos->second->GetHelp(), max_len);
     }
     result.AppendMessage("");
@@ -1151,8 +1151,8 @@ void CommandInterpreter::GetHelp(CommandReturnObject &result,
     result.AppendMessage("");
     max_len = FindLongestCommandWord(m_user_dict);
     for (pos = m_user_dict.begin(); pos != m_user_dict.end(); ++pos) {
-      OutputFormattedHelpText(result.GetOutputStream(), pos->first.c_str(),
-                              "--", pos->second->GetHelp(), max_len);
+      OutputFormattedHelpText(result.GetOutputStream(), pos->first, "--",
+                              pos->second->GetHelp(), max_len);
     }
     result.AppendMessage("");
   }
@@ -2498,79 +2498,68 @@ void CommandInterpreter::SetSynchronous(bool value) {
 }
 
 void CommandInterpreter::OutputFormattedHelpText(Stream &strm,
-                                                 const char *prefix,
-                                                 const char *help_text) {
+                                                 llvm::StringRef prefix,
+                                                 llvm::StringRef help_text) {
   const uint32_t max_columns = m_debugger.GetTerminalWidth();
-  if (prefix == NULL)
-    prefix = "";
 
-  size_t prefix_width = strlen(prefix);
-  size_t line_width_max = max_columns - prefix_width;
-  const char *help_text_end = help_text + strlen(help_text);
-  const char *line_start = help_text;
+  size_t line_width_max = max_columns - prefix.size();
   if (line_width_max < 16)
-    line_width_max = help_text_end - help_text + prefix_width;
-
-  strm.IndentMore(prefix_width);
-  while (line_start < help_text_end) {
-    // Break each line at the first newline or last space/tab before
-    // the maximum number of characters that fit on a line.  Lines with no
-    // natural break are left unbroken to wrap.
-    const char *line_end = help_text_end;
-    const char *line_scan = line_start;
-    const char *line_scan_end = help_text_end;
-    while (line_scan < line_scan_end) {
-      char next = *line_scan;
-      if (next == '\t' || next == ' ') {
-        line_end = line_scan;
-        line_scan_end = line_start + line_width_max;
-      } else if (next == '\n' || next == '\0') {
-        line_end = line_scan;
-        break;
-      }
-      ++line_scan;
-    }
+    line_width_max = help_text.size() + prefix.size();
 
+  strm.IndentMore(prefix.size());
+  bool prefixed_yet = false;
+  while (!help_text.empty()) {
     // Prefix the first line, indent subsequent lines to line up
-    if (line_start == help_text)
-      strm.Write(prefix, prefix_width);
-    else
+    if (!prefixed_yet) {
+      strm << prefix;
+      prefixed_yet = true;
+    } else
       strm.Indent();
-    strm.Write(line_start, line_end - line_start);
+
+    // Never print more than the maximum on one line.
+    llvm::StringRef this_line = help_text.substr(0, line_width_max);
+
+    // Always break on an explicit newline.
+    std::size_t first_newline = this_line.find_first_of("\n");
+
+    // Don't break on space/tab unless the text is too long to fit on one line.
+    std::size_t last_space = llvm::StringRef::npos;
+    if (this_line.size() != help_text.size())
+      last_space = this_line.find_last_of(" \t");
+
+    // Break at whichever condition triggered first.
+    this_line = this_line.substr(0, std::min(first_newline, last_space));
+    strm.PutCString(this_line);
     strm.EOL();
 
-    // When a line breaks at whitespace consume it before continuing
-    line_start = line_end;
-    char next = *line_start;
-    if (next == '\n')
-      ++line_start;
-    else
-      while (next == ' ' || next == '\t')
-        next = *(++line_start);
+    // Remove whitespace / newlines after breaking.
+    help_text = help_text.drop_front(this_line.size()).ltrim();
   }
-  strm.IndentLess(prefix_width);
+  strm.IndentLess(prefix.size());
 }
 
 void CommandInterpreter::OutputFormattedHelpText(Stream &strm,
-                                                 const char *word_text,
-                                                 const char *separator,
-                                                 const char *help_text,
+                                                 llvm::StringRef word_text,
+                                                 llvm::StringRef separator,
+                                                 llvm::StringRef help_text,
                                                  size_t max_word_len) {
   StreamString prefix_stream;
-  prefix_stream.Printf("  %-*s %s ", (int)max_word_len, word_text, separator);
+  prefix_stream.Printf("  %-*s %*s ", (int)max_word_len, word_text.data(),
+                       (int)separator.size(), separator.data());
   OutputFormattedHelpText(strm, prefix_stream.GetData(), help_text);
 }
 
-void CommandInterpreter::OutputHelpText(Stream &strm, const char *word_text,
-                                        const char *separator,
-                                        const char *help_text,
+void CommandInterpreter::OutputHelpText(Stream &strm, llvm::StringRef word_text,
+                                        llvm::StringRef separator,
+                                        llvm::StringRef help_text,
                                         uint32_t max_word_len) {
-  int indent_size = max_word_len + strlen(separator) + 2;
+  int indent_size = max_word_len + separator.size() + 2;
 
   strm.IndentMore(indent_size);
 
   StreamString text_strm;
-  text_strm.Printf("%-*s %s %s", max_word_len, word_text, separator, help_text);
+  text_strm.Printf("%-*s ", (int)max_word_len, word_text.data());
+  text_strm << separator << " " << help_text;
 
   const uint32_t max_columns = m_debugger.GetTerminalWidth();