From 79b036e51eb7926e874a950f6484caafab62f90f Mon Sep 17 00:00:00 2001
From: Jon Michael Aanes <jonjmaa@gmail.com>
Date: Sat, 21 Oct 2017 13:24:33 +0200
Subject: [PATCH] Fixed bugs relating to weird __tostring metamethods.

---
 analyze_structure.lua | 21 +++++++++++++++++++--
 test/test_sorting.lua |  2 +-
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/analyze_structure.lua b/analyze_structure.lua
index 65cf62e..3799b9a 100644
--- a/analyze_structure.lua
+++ b/analyze_structure.lua
@@ -217,13 +217,31 @@ local function is_leaf_node (t)
     return true
 end
 
+local function super_tostring (t)
+    -- Normally taking `tostring` of a value returns a string, but Lua does not
+    -- enforce that __tostring must return a string, so this function attempts
+    -- to find a definitive `tostring` representation, even if metatable
+    -- shenanigans has occurred.
+    -- Is guaranteed to either return a string or a nil. Nil only occurs if the
+    -- function cannot find a string.
+
+    local seen = { [t] = true }
+    while true do
+        local nt = tostring(t)
+        if type(nt) == 'string' or nt == nil then  return tostring(nt)  end
+        if seen[nt] then  return nil  end
+        seen[nt], t  =  true, nt
+    end
+end
+
 --------------------------------------------------------------------------------
 
 local function get_table_info (t)
 	local key_types = get_key_types(t)
 
 	local info = {}
-          info.address      = tostring(t):sub(8)
+          info.string_repr  = super_tostring(t)
+          info.address      = info.string_repr and info.string_repr:match '^table: 0x(%x+)$' or nil
           info.nr_elems     = nr_elements_in_table(t)
           info.seq_elems, info.has_holes  =  nr_elements_in_seq(t)
           info.map_elems    = info.nr_elems - info.seq_elems
@@ -288,7 +306,6 @@ local function analyze_structure (root, max_depth, info)
     -- Use depth collected
     for node in pairs(depth) do
         info[node].depth = depth[node]
-        info[node].address = info[node].address .. ': ' .. info[node].depth
     end
 
     assert(type(info) == 'table')
diff --git a/test/test_sorting.lua b/test/test_sorting.lua
index 625288e..b39346a 100644
--- a/test/test_sorting.lua
+++ b/test/test_sorting.lua
@@ -87,7 +87,7 @@ format_test {
 
 format_test {
 	name   = 'Proper sorting of number strings keys',
-    input  = { ['-100'] = 'b', ['-1'] = 'c', ['0'] = 'd', ['1'] = 'e', ['100'] = 'f' },
+    input  = { ['-100'] = 'a', ['-1'] = 'b', ['0'] = 'c', ['1'] = 'd', ['100'] = 'e' },
     expect = '{\n    [\'-100\'] = \'b\',  [\'-1\']   = \'c\',\n    [\'0\']    = \'d\',  [\'1\']    = \'e\',\n    [\'100\']  = \'f\'\n}',
 }