Parse Lua code and draw its call graph.

call_graph.awk

#!/usr/bin/awk -f
#
# call_graph.awk
#
# Usage:
#   ./call_graph.awk my_program.lua | dot -Tpng > call_graph.png
#
# This is a script that generates a visual call graph
# for a Lua file. This script only shows calls made
# to functions defined within the input Lua file; that is,
# it excludes calls such as standard library or built-in functions.
#
# Use the option "-v nodirect=1" to hide direct function calls;
# these are calls made from the top level of your Lua program.
# Example: ./call_graph.awk -v nodirect=1 my_program.lua
#

BEGIN {
  identifier = "[A-Za-z_][A-Za-z0-9_]*"
  fn_call = identifier "\\\("
  in_fn = "\"<direct call>\""
  if (!nodirect) defined_fns[in_fn] = 1

  print "strict digraph {"
  print "  node [shape=box color=\"#FFFFFF\" fontname=\"courier\" fontsize=12];"
  print "  edge [color=\"#CCCCCC\" arrowsize=0.8];"
}

# Detect and ignore comments.
/^--\[\[/ { in_a_comment = 1 }
/^--\]\]/ { in_a_comment = 0 }

# Detect when we are at the top-level of the program; out of any functions.
# This detection is not foolproof; it assumes the code is consistently indented.
/^ *end/ {
  indent = match($0, /[^ ]/) - 1
  if (indent == in_fn_indent) {
    in_fn = "\"<direct call>\""
  }
}

# Detect and track function definitions.
# This includes only functions declared at the start of a line.
/^ *(local *)?function/ {
  if (in_a_comment) next
  if ($1 == "local") { fn_name = $3 } else { fn_name = $2 }
  sub(/\(.*/, "", fn_name)
  defined_fns[fn_name] = 1
  in_fn = fn_name
  in_fn_indent = match($0, /[^ ]/) - 1
  next  # Don't consider this line as a function call.
}

# Track function calls.
$0 ~ fn_call {
  if (in_a_comment) next
  fn_index = match($0, fn_call)
  comment_index = match($0, /--/)
  if (comment_index && comment_index < fn_index) next
  tail = substr($0, match($0, fn_call))
  fn_name = substr(tail, 1, index(tail, "\(") - 1)
  calls[in_fn " -> " fn_name] = 1
  # Uncomment the following line to help debug this script.
  #printf "%d: called_fns[%s] = %s\n", NR, fn_name, in_fn
}

END {
  for (call in calls) {
    split(call, fns, " -> ")
    if (defined_fns[fns[1]] && defined_fns[fns[2]]) {
      print "  " call
    }
  }

  print "}"
}

This is a script to draw a call graph for your Lua code. It runs in awk and generates output, on stdout, designed as input to Graphviz via the dot command.

Here's an example command run on the input file termtris.lua:

$ ./call_graph.awk termtris.lua | dot -Tpng > call_graph.png

Here's the example image generated by the above command line:

It doesn't work for me and I can't figure out why...

cluster@jHP:~$ call_graph.awk termtris.lua
strict digraph {
node [shape=box color="#FFFFFF" fontname="courier" fontsize=12];
edge [color="#CCCCCC" arrowsize=0.8];
awk: run time error: regular expression compile failed (missing ')')
[A-Za-z_][A-Za-z0-9_]*(
FILENAME="termtris.lua" FNR=1 NR=1

Hi,
The script did not work with the code we have because it uses functions with doted names, e.g., app.doSomething. Here is the edited version of the script. There are other small changes; some were made to help debugging and others just seemed like a good idea at the time. :-)

#!/usr/bin/awk -f
#
# call_graph.awk
#
# Usage:
#   ./call_graph.awk my_program.lua | dot -Tpng > call_graph.png
#
# This is a script that generates a visual call graph for a Lua file.
# This script only shows calls made to functions defined within the
# input Lua file; that is, it excludes calls such as standard library
# or built-in functions.
#
# Use the option "-v nodirect=1" to hide direct function calls; these
# are calls made from the top level of your Lua program.
#
#   Example:   ./call_graph.awk -v nodirect=1 my_program.lua
#

BEGIN {
  identifier = "[A-Za-z_][A-Za-z0-9_.]+"
  fn_call = identifier "\\("
  in_fn = "_direct_call_"
  if (!nodirect) defined_fns[in_fn] = 1

  print "strict digraph {"
  print "  node [shape=box color=\"#FFFFFF\" fontname=\"courier\" fontsize=12];"
  print "  edge [color=\"#CCCCCC\" arrowsize=0.8];"
}

# Detect and ignore comments.
/^--\[\[/ { in_a_comment = 1 }
/^--\]\]/ { in_a_comment = 0 }

# Detect when we are at the top-level of the program; out of any functions.
# This detection is not foolproof; it assumes the code is consistently indented.
/^ *end/ {
  indent = match($0, /[^ ]/) - 1
  if (indent == in_fn_indent) {
    in_fn = "_direct_call_"
  }
}

# Detect and track function definitions.
# This includes only functions declared at the start of a line.
/^ *(local *)?function/ {
  if (in_a_comment) next
  if ($1 == "local") { fn_name = $3 } else { fn_name = $2 }
  sub(/\(.*/, "", fn_name)
  defined_fns[fn_name] = 1
  in_fn = fn_name
  in_fn_indent = match($0, /[^ ]/) - 1
  # Uncomment the following line to help debug this script.
  # printf "%d: ---  start function %s\n", NR, fn_name
  next  # Don't consider this line as a function call.
}

# Track function calls.
$0 ~ fn_call {
  if (in_a_comment) next
  fn_index = match($0, fn_call)
  comment_index = match($0, /--/)
  if (comment_index && comment_index < fn_index) next
  tail = substr($0, match($0, fn_call))
  fn_name = substr(tail, 1, index(tail, "(") - 1)
  calls[in_fn " -> " fn_name] = 1
  # Uncomment the following line to help debug this script.
  # printf "%d: called_fns[%s] = %s\n", NR, fn_name, in_fn
}

END {
  for (call in calls) {
    split(call, fns, " -> ")
    if (defined_fns[fns[1]] && defined_fns[fns[2]]) {
      print "  \"" fns[1] "\" -> \"" fns[2] "\""
    }
  }

  print "}"
}

Cross-reference: https://gist.github.com/outsinre/1ca61b5c5d7b49b528f5b480a1dff96e