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clidebugger

A simple command line interface debugger with readline support for Lua 5.1 and 5.2 inspired by RemDebug neglecting its remote facilities. Except for readline support, it's not dependent on anything other than the standard Lua libraries.

Features

Debugger Commands

The following debugger commands are available (as shown by the help command):

help [command]      -- show this list or help for command [F1]
listb               -- lists breakpoints [CTRL+F8]
setb [line file]    -- set a breakpoint to line/file
delb [line file]    -- removes a breakpoint
delallb             -- removes all breakpoints
listw               -- lists watch expressions
setw <exp>          -- adds a new watch expression
delw <index>        -- removes the watch expression at index
delallw             -- removes all watch expressions
ups                 -- list all the upvalue names
locs                -- list all the locals names
vars [depth]        -- list context locals to depth, omitted=1
glob [depth]        -- list globals to depth, omitted=1
what <func>         -- show where <func> is defined (if known)
fenv [depth]        -- list context function env to depth, omitted=1
trace               -- dumps a stack trace
run                 -- run until next breakpoint or watch expression [F9]
over [N]            -- run next N lines, stepping over function calls [F8]
step [N]            -- run next N lines, stepping into function calls [F7]
out [N]             -- run until stepped out of N functions [SHIFT+F8]
exit                -- exits debugger, re-start it using pause()
set [level]         -- set context to stack level, omitted=show
gotoo [line file]   -- step to line in file
show line file X Y  -- show X lines before and Y after line in file [CTRL+RET]
tron [crl]          -- turn trace on for (c)alls, (r)eturns, (l)lines
dump <var> [depth]  -- dump all fields of variable to depth [ALT+F7]
info                -- dumps the complete debug info captured
eval <statement>    -- execute a statement in the current context [ALT+F8]
pon                 -- turn on pause() command
poff                -- turn off pause() command

Readline Support

clidebugger's readline support offers...

  • the line editing features of readline.
  • completion of debugger commands and (some of) its parameters.
  • completion of Lua locals, globals, and upvalues.
  • function and table completions postfixed with ( and [ or ., respectively.
  • completion of filenames via readline's default filename completion, for convenience restricted to directories and files ending in .lua.
  • some command shortcuts if running in a ([u]rxvt-like) terminal, e.g., F8 for step over. See the square bracket-enclosed keys in the Debugger Commands section above for reference.
  • ANSI escape sequence output coloring in some places if running in a terminal, e.g., the show command's source listing indicates the current line of execution by a green *** marker and shows line numbers in an unobtrusive black color.

Future improvements to readline support

  • The what command completion does not (yet) offer completion of local functions as their type cannot be easily inferred at completion time. Implementing this feature requires quite a bit of refactoring (see the source code comments). For the same reason, locals are not postfixed with (, [, or . .
  • A command's optional number or count parameter is generally not offered for completion.
  • Command shortcuts are currently available for [u]rxvt terminals only. Adding support for other terminals is merely a matter of inserting the according key escape sequences for your terminal.

Installation and Usage##

Installation

Just place clidebugger in some directory and add that directory to the LUA_PATH environment variable, e.g.

mkdir $HOME/clidebugger
cd $HOME/clidebugger
git clone https://github.com/stormc/lua-clidebugger.git .
export LUA_PATH=;;$HOME/clidebugger/?.lua

You may want to put the export LUA_PATH=... statement somewhere appropriate in your shell's startup files.

Enjoying readline support requires to compile the Lua C-module libclidebugger.so by running make in $HOME/clidebugger.

Usage Example

Then, insert the following lines into the Lua file to debug

require("debugger")
...
pause("debug time!")

and run the debuggee Lua file which will drop to the debugger shell once the control flow reaches the pause(...) line, e.g.

Lua Debugger
Paused at file ./debugger.lua line 22 (0)
Message: debug time!
Type 'help' for commands
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