From 0c8ee616823ebcafd3db440932182217badd2101 Mon Sep 17 00:00:00 2001
From: Tobias Ulmer <tu@emlix.com>
Date: Wed, 26 Jun 2019 17:51:44 +0200
Subject: [PATCH] environment: bugfix for set() and iter()

Both problems behaved in a deterministic way and didn't produce
problematic EnvID changes

set() failed on duplicate vars, inserting the same var more than once
into the sorted table

iter() was using next(), which is not guaranteed to follow the table
in numerical order

Unit tests have been added for this issue.

Signed-off-by: Tobias Ulmer <tu@emlix.com>
---
 local/environment.lua | 37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/local/environment.lua b/local/environment.lua
index f321f7d..bd439ac 100644
--- a/local/environment.lua
+++ b/local/environment.lua
@@ -38,7 +38,6 @@ function environment.new()
     env.seqid = environment_seqid
     environment_seqid = environment_seqid + 1
     env.dict = {}
-    env.sorted = {}
     return env
 end
 
@@ -49,12 +48,9 @@ end
 -- @return env as passed in the first parameter
 function environment.set(env, var, val)
     assertIsTable(env)
-    assertIsTable(env.sorted)
     assertIsStringN(var)
     assertIsString(val)
     env.dict[var] = val
-    table.insert(env.sorted, var)
-    table.sort(env.sorted)
     return env
 end
 
@@ -62,7 +58,6 @@ end
 -- @param env environment
 function environment.envid(env)
     assertIsTable(env)
-    assertIsTable(env.sorted)
     local eid
     local hc = hash.hash_start()
     for var, val in env:iter() do
@@ -80,16 +75,12 @@ end
 -- @return environment as merged from env and merge
 function environment.merge(env, merge, override)
     assertIsTable(env)
-    assertIsTable(env.sorted)
     assertIsTable(merge)
-    assertIsTable(merge.sorted)
     assertIsBoolean(override)
-    for i, var in ipairs(merge.sorted) do
-        if not env.dict[var] then
-            table.insert(env.sorted, var)
-        end
+
+    for var, val in pairs(merge.dict) do
         if not env.dict[var] or override then
-            env.dict[var] = merge.dict[var]
+            env.dict[var] = val
         end
     end
     return env
@@ -99,14 +90,20 @@ end
 -- @param env environment
 function environment.iter(env)
     assertIsTable(env)
-    assertIsTable(env.sorted)
-    local index = nil
-    local function _iter(t)
-        local var
-        index, var = next(t, index)
-        return var, env.dict[var]
+
+    local sorted = {}
+    local index = 0
+
+    for var, _ in pairs(env.dict) do
+        table.insert(sorted, var)
+    end
+    table.sort(sorted)
+
+    local function _iter()
+        index = index + 1
+        return sorted[index], env.dict[sorted[index]]
     end
-    return _iter, env.sorted
+    return _iter
 end
 
 --- return a (copy of the) dictionary
@@ -114,7 +111,6 @@ end
 -- @return a copy of the dictionary representing the environment
 function environment.get_dict(env)
     assertIsTable(env)
-    assertIsTable(env.sorted)
     local dict = {}
     for k,v in env:iter() do
         dict[k] = v
@@ -130,7 +126,6 @@ end
 -- @return Error object on failure.
 function environment.tofile(env, file)
     assertIsTable(env)
-    assertIsTable(env.sorted)
     assertIsString(file)
     local rc, re, e, out
 
-- 
2.39.5