add stop column highlighting support

This change introduces optional marking of the column within a source
line where a thread is stopped.  This marking will show up when the
source code for a thread stop is displayed, when the debug info
knows the column information, and if the optional column marking is
enabled.

There are two separate methods for handling the marking of the stop
column:

* via ANSI terminal codes, which are added inline to the source line
  display.  The default ANSI mark-up is to underline the column.

* via a pure text-based caret that is added in the appropriate column
  in a newly-inserted blank line underneath the source line in
  question.

There are some new options that control how this all works.

* settings set stop-show-column

  This takes one of 4 values:

  * ansi-or-caret: use the ANSI terminal code mechanism if LLDB
    is running with color enabled; if not, use the caret-based,
    pure text method (see the "caret" mode below).

  * ansi: only use the ANSI terminal code mechanism to highlight
    the stop line.  If LLDB is running with color disabled, no
    stop column marking will occur.

  * caret: only use the pure text caret method, which introduces
    a newly-inserted line underneath the current line, where
    the only character in the new line is a caret that highlights
    the stop column in question.

  * none: no stop column marking will be attempted.

* settings set stop-show-column-ansi-prefix

  This is a text format that indicates the ANSI formatting
  code to insert into the stream immediately preceding the
  column where the stop column character will be marked up.
  It defaults to ${ansi.underline}; however, it can contain
  any valid LLDB format codes, e.g.

      ${ansi.fg.red}${ansi.bold}${ansi.underline}

* settings set stop-show-column-ansi-suffix

  This is the text format that specifies the ANSI terminal
  codes to end the markup that was started with the prefix
  described above.  It defaults to: ${ansi.normal}.  This
  should be sufficient for the common cases.

Significant leg-work was done by Adrian Prantl.  (Thanks, Adrian!)

differential review: https://reviews.llvm.org/D20835

reviewers: clayborg, jingham

1 files changed, 140 insertions, 12 deletions

diff --git a/lldb/source/Core/SourceManager.cpp b/lldb/source/Core/SourceManager.cpp
index 6ecd8da33d8..ff0ee7d8246 100644
--- a/lldb/source/Core/SourceManager.cpp
+++ b/lldb/source/Core/SourceManager.cpp
@@ -22,6 +22,7 @@
 #include "lldb/Symbol/Function.h"
 #include "lldb/Symbol/SymbolContext.h"
 #include "lldb/Target/Target.h"
+#include "lldb/Utility/AnsiTerminal.h"
 
 using namespace lldb;
 using namespace lldb_private;
@@ -71,7 +72,10 @@ SourceManager::FileSP SourceManager::GetFile(const FileSpec &file_spec) {
 
   // If file_sp is no good or it points to a non-existent file, reset it.
   if (!file_sp || !file_sp->GetFileSpec().Exists()) {
-    file_sp.reset(new File(file_spec, target_sp.get()));
+    if (target_sp)
+      file_sp.reset(new File(file_spec, target_sp.get()));
+    else
+      file_sp.reset(new File(file_spec, debugger_sp));
 
     if (debugger_sp)
       debugger_sp->GetSourceFileCache().AddSourceFile(file_sp);
@@ -79,8 +83,44 @@ SourceManager::FileSP SourceManager::GetFile(const FileSpec &file_spec) {
   return file_sp;
 }
 
+static bool should_show_stop_column_with_ansi(DebuggerSP debugger_sp) {
+  // We don't use ANSI stop column formatting if we can't lookup values from
+  // the debugger.
+  if (!debugger_sp)
+    return false;
+
+  // We don't use ANSI stop column formatting if the debugger doesn't think
+  // it should be using color.
+  if (!debugger_sp->GetUseColor())
+    return false;
+
+  // We only use ANSI stop column formatting if we're either supposed to show
+  // ANSI where available (which we know we have when we get to this point), or
+  // if we're only supposed to use ANSI.
+  const auto value = debugger_sp->GetStopShowColumn();
+  return ((value == eStopShowColumnAnsiOrCaret) ||
+          (value == eStopShowColumnAnsi));
+}
+
+static bool should_show_stop_column_with_caret(DebuggerSP debugger_sp) {
+  // We don't use text-based stop column formatting if we can't lookup values
+  // from the debugger.
+  if (!debugger_sp)
+    return false;
+
+  // If we're asked to show the first available of ANSI or caret, then
+  // we do show the caret when ANSI is not available.
+  const auto value = debugger_sp->GetStopShowColumn();
+  if ((value == eStopShowColumnAnsiOrCaret) && !debugger_sp->GetUseColor())
+    return true;
+
+  // The only other time we use caret is if we're explicitly asked to show
+  // caret.
+  return value == eStopShowColumnCaret;
+}
+
 size_t SourceManager::DisplaySourceLinesWithLineNumbersUsingLastFile(
-    uint32_t start_line, uint32_t count, uint32_t curr_line,
+    uint32_t start_line, uint32_t count, uint32_t curr_line, uint32_t column,
     const char *current_line_cstr, Stream *s,
     const SymbolContextList *bp_locs) {
   if (count == 0)
@@ -123,7 +163,20 @@ size_t SourceManager::DisplaySourceLinesWithLineNumbersUsingLastFile(
       return_value +=
           s->Printf("%s%2.2s %-4u\t", prefix,
                     line == curr_line ? current_line_cstr : "", line);
-      size_t this_line_size = m_last_file_sp->DisplaySourceLines(line, 0, 0, s);
+      size_t this_line_size = m_last_file_sp->DisplaySourceLines(
+          line, line == curr_line ? column : 0, 0, 0, s);
+      if (column != 0 && line == curr_line &&
+          should_show_stop_column_with_caret(m_debugger_wp.lock())) {
+        // Display caret cursor.
+        std::string src_line;
+        m_last_file_sp->GetLine(line, src_line);
+        return_value += s->Printf("    \t");
+        // Insert a space for every non-tab character in the source line.
+        for (int i = 0; i < column - 1 && i < src_line.length(); ++i)
+          return_value += s->PutChar(src_line[i] == '\t' ? '\t' : ' ');
+        // Now add the caret.
+        return_value += s->Printf("^\n");
+      }
       if (this_line_size == 0) {
         m_last_line = UINT32_MAX;
         break;
@@ -135,8 +188,9 @@ size_t SourceManager::DisplaySourceLinesWithLineNumbersUsingLastFile(
 }
 
 size_t SourceManager::DisplaySourceLinesWithLineNumbers(
-    const FileSpec &file_spec, uint32_t line, uint32_t context_before,
-    uint32_t context_after, const char *current_line_cstr, Stream *s,
+    const FileSpec &file_spec, uint32_t line, uint32_t column,
+    uint32_t context_before, uint32_t context_after,
+    const char *current_line_cstr, Stream *s,
     const SymbolContextList *bp_locs) {
   FileSP file_sp(GetFile(file_spec));
 
@@ -153,7 +207,7 @@ size_t SourceManager::DisplaySourceLinesWithLineNumbers(
     m_last_file_sp = file_sp;
   }
   return DisplaySourceLinesWithLineNumbersUsingLastFile(
-      start_line, count, line, current_line_cstr, s, bp_locs);
+      start_line, count, line, column, current_line_cstr, s, bp_locs);
 }
 
 size_t SourceManager::DisplayMoreWithLineNumbers(
@@ -193,8 +247,9 @@ size_t SourceManager::DisplayMoreWithLineNumbers(
     } else
       m_last_line = 1;
 
+    const uint32_t column = 0;
     return DisplaySourceLinesWithLineNumbersUsingLastFile(
-        m_last_line, m_last_count, UINT32_MAX, "", s, bp_locs);
+        m_last_line, m_last_count, UINT32_MAX, column, "", s, bp_locs);
   }
   return 0;
 }
@@ -272,10 +327,27 @@ void SourceManager::FindLinesMatchingRegex(FileSpec &file_spec,
                                          match_lines);
 }
 
+SourceManager::File::File(const FileSpec &file_spec,
+                          lldb::DebuggerSP debugger_sp)
+    : m_file_spec_orig(file_spec), m_file_spec(file_spec),
+      m_mod_time(file_spec.GetModificationTime()), m_source_map_mod_id(0),
+      m_data_sp(), m_offsets(), m_debugger_wp(debugger_sp) {
+  CommonInitializer(file_spec, nullptr);
+}
+
 SourceManager::File::File(const FileSpec &file_spec, Target *target)
     : m_file_spec_orig(file_spec), m_file_spec(file_spec),
       m_mod_time(file_spec.GetModificationTime()), m_source_map_mod_id(0),
-      m_data_sp(), m_offsets() {
+      m_data_sp(), m_offsets(),
+      m_debugger_wp(target ? target->GetDebugger().shared_from_this()
+                           : DebuggerSP()) {
+  CommonInitializer(file_spec, target);
+}
+
+SourceManager::File::~File() {}
+
+void SourceManager::File::CommonInitializer(const FileSpec &file_spec,
+                                            Target *target) {
   if (!m_mod_time.IsValid()) {
     if (target) {
       m_source_map_mod_id = target->GetSourcePathMap().GetModificationID();
@@ -337,8 +409,6 @@ SourceManager::File::File(const FileSpec &file_spec, Target *target)
     m_data_sp = m_file_spec.ReadFileContents();
 }
 
-SourceManager::File::~File() {}
-
 uint32_t SourceManager::File::GetLineOffset(uint32_t line) {
   if (line == 0)
     return UINT32_MAX;
@@ -418,10 +488,14 @@ void SourceManager::File::UpdateIfNeeded() {
   }
 }
 
-size_t SourceManager::File::DisplaySourceLines(uint32_t line,
+size_t SourceManager::File::DisplaySourceLines(uint32_t line, uint32_t column,
                                                uint32_t context_before,
                                                uint32_t context_after,
                                                Stream *s) {
+  // Nothing to write if there's no stream.
+  if (!s)
+    return 0;
+
   // Sanity check m_data_sp before proceeding.
   if (!m_data_sp)
     return 0;
@@ -440,7 +514,61 @@ size_t SourceManager::File::DisplaySourceLines(uint32_t line,
     if (start_line_offset < end_line_offset) {
       size_t count = end_line_offset - start_line_offset;
       const uint8_t *cstr = m_data_sp->GetBytes() + start_line_offset;
-      bytes_written = s->Write(cstr, count);
+
+      bool displayed_line = false;
+
+      if (column && (column < count)) {
+        auto debugger_sp = m_debugger_wp.lock();
+        if (should_show_stop_column_with_ansi(debugger_sp) && debugger_sp) {
+          // Check if we have any ANSI codes with which to mark this column.
+          // If not, no need to do this work.
+          auto ansi_prefix_entry = debugger_sp->GetStopShowColumnAnsiPrefix();
+          auto ansi_suffix_entry = debugger_sp->GetStopShowColumnAnsiSuffix();
+
+          // We only bother breaking up the line to format the marked column if
+          // there is any marking specified on both sides of the marked column.
+          // In ANSI-terminal-sequence land, there must be a post if there is a
+          // pre format, and vice versa.
+          if (ansi_prefix_entry && ansi_suffix_entry) {
+            // Mark the current column with the desired escape sequence for
+            // formatting the column (e.g. underline, inverse, etc.)
+
+            // First print the part before the column to mark.
+            bytes_written = s->Write(cstr, column - 1);
+
+            // Write the pre escape sequence.
+            const SymbolContext *sc = nullptr;
+            const ExecutionContext *exe_ctx = nullptr;
+            const Address addr = LLDB_INVALID_ADDRESS;
+            ValueObject *valobj = nullptr;
+            const bool function_changed = false;
+            const bool initial_function = false;
+
+            FormatEntity::Format(*ansi_prefix_entry, *s, sc, exe_ctx, &addr,
+                                 valobj, function_changed, initial_function);
+
+            // Write the marked column.
+            bytes_written += s->Write(cstr + column - 1, 1);
+
+            // Write the post escape sequence.
+            FormatEntity::Format(*ansi_suffix_entry, *s, sc, exe_ctx, &addr,
+                                 valobj, function_changed, initial_function);
+
+            // And finish up with the rest of the line.
+            bytes_written += s->Write(cstr + column, count - column);
+
+            // Keep track of the fact that we just wrote the line.
+            displayed_line = true;
+          }
+        }
+      }
+
+      // If we didn't end up displaying the line with ANSI codes for whatever
+      // reason, display it now sans codes.
+      if (!displayed_line)
+        bytes_written = s->Write(cstr, count);
+
+      // Ensure we get an end of line character one way or another.
       if (!is_newline_char(cstr[count - 1]))
         bytes_written += s->EOL();
     }