[LLDB] Add table formatting for register fields

This will be used by the "register info" command to show
the layout of register contents. For example if we have
these fields coming in from XML:
```
<field name="D" start="0" end="7"/>
<field name="C" start="8" end="15"/>
<field name="B" start="16" end="23"/>
<field name="A" start="24" end="31"/>
```
We get:
```
| 31-24 | 23-16 | 15-8 | 7-0 |
|-------|-------|------|-----|
|   A   |   B   |  C   |  D  |
```
Note that this is only the layout, not the values.
For values, use "register read".

The tables' columns are center padded (left bias
if there's an odd padding) and will wrap if the terminal width
is too low.

```
| 31-24 | 23-16 |
|-------|-------|
|   A   |   B   |

| 15-8 | 7-0 |
|------|-----|
|  C   |  D  |
```

This means we match the horizontal format seen in many architecture
manuals but don't spam the user with lots of misaligned text when the
output gets very long.

Reviewed By: jasonmolenda

Differential Revision: https://reviews.llvm.org/D152917

1 files changed, 7 insertions, 0 deletions

diff --git a/lldb/include/lldb/Target/RegisterFlags.h b/lldb/include/lldb/Target/RegisterFlags.h
index 2dd20f9..0b9961e 100644
--- a/lldb/include/lldb/Target/RegisterFlags.h
+++ b/lldb/include/lldb/Target/RegisterFlags.h
@@ -93,6 +93,13 @@ public:
   unsigned GetSize() const { return m_size; }
   void log(Log *log) const;
 
+  /// Produce a text table showing the layout of all the fields. Unamed/padding
+  /// fields will be included, with only their positions shown.
+  /// max_width will be the width in characters of the terminal you are
+  /// going to print the table to. If the table would exceed this width, it will
+  /// be split into many tables as needed.
+  std::string AsTable(uint32_t max_width) const;
+
 private:
   const std::string m_id;
   /// Size in bytes