fix(compat) OpenResty implementation of coroutine.wrap

.luacheckrc

@@ -4,10 +4,6 @@ max_line_length = false
 
 globals = {
     "ngx",
-    "coroutine._wrap",
-    "coroutine._yield",
-    "coroutine._create",
-    "coroutine._resume",
 }
 
 not_globals = {

CHANGELOG.md

@@ -1,10 +1,16 @@
 # Changelog
 
-## 1.x.x (upcoming)
+## 1.9.0 (2020-09-22)
+
+### New features
+
+  - `compat.wrap` a `coroutine.wrap` implementation that works like plain Lua
+    on OpenResty. (#342)
 
 ## Fixes
 
-  - In `pl.class`, `_init` can now be inherited from grandparent (or older ancestor) classes. (#289)
+  - In `pl.class`, `_init` can now be inherited from grandparent (or older ancestor) classes. [#289](https://github.com/lunarmodules/Penlight/pull/289)
+  - Using `compat.wrap` it now fixes `dir.dirtree`, `pl.lexer` on OpenResty. [#342](https://github.com/lunarmodules/Penlight/pull/342)
 
 ## 1.8.0 (2020-08-05)
 

lua/pl/compat.lua

@@ -145,6 +145,56 @@ else
     end
 end
 
+--- OpenResty compatibility (broken coroutines)
+-- @section openresty
+
+--- Wraps a function into a coroutine.
+-- This compatibility function is to restore `coroutine.wrap()` compatibility on
+-- OpenResty. On OpenResty, when a coroutine throws an error, the wrapper return
+-- `nil+err` instead of passing the hard error.
+-- This function will have traditional Lua behaviour on all implementations.
+-- @function compat.wrap
+-- @param func function to wrap into a coroutine
+-- @return a coroutine (thread type)
+do
+  -- coroutine.wrap compat, for bad openresty implementation
+  -- check by validating behaviour
+  local count do
+    local i = 0
+    function count()
+      while i < 10 do
+        i = i + 1
+        assert(i < 2) -- 1st pass succeeds, 2nd fails
+        coroutine.yield(i)
+      end
+    end
+  end
+  local test_coro = coroutine.wrap(count)
+  pcall(test_coro)  -- succeeds, 1st pass
+  local ok = pcall(test_coro) -- 2nd pass, should fail
+  if not ok then
+    -- it failed as expected, this is the right thing
+    compat.wrap = coroutine.wrap
+  else
+    -- the pcall returned success because the bad openresty implementation returns
+    -- nil+err instead of throwing a hard error, so we need to fix that.
+    -- Reimplemented coroutine.wrap to be original Lua compliant
+    compat.wrap = function(func)
+      local co = coroutine.create(func)
+      return function(...)
+        local results = table.pack(coroutine.resume(co, ...))
+        if results[1] then
+          -- success
+          return table.unpack(results, 2, results.n)
+        else
+          -- it failed
+          return error("coroutine failed with: " .. results[2])
+        end
+      end
+    end
+  end
+end
+
 --- Global exported functions (for Lua 5.1 & LuaJIT)
 -- @section lua52
 

lua/pl/dir.lua

@@ -17,9 +17,9 @@ local remove = os.remove
 local append = table.insert
 local assert_arg,assert_string,raise = utils.assert_arg,utils.assert_string,utils.raise
 
--- check on OpenResty coroutine versions, and use originals if possible
-local wrap = coroutine._wrap or coroutine.wrap
-local yield = coroutine._yield or coroutine.yield
+-- check for OpenResty coroutine versions
+local wrap = require("pl.compat").wrap
+local yield = coroutine.yield
 
 
 local dir = {}

lua/pl/lexer.lua

@@ -24,9 +24,9 @@ local strfind = string.find
 local strsub = string.sub
 local append = table.insert
 
--- check on OpenResty coroutine versions, and use originals if possible
-local wrap = coroutine._wrap or coroutine.wrap
-local yield = coroutine._yield or coroutine.yield
+-- check for OpenResty coroutine versions
+local wrap = require("pl.compat").wrap
+local yield = coroutine.yield
 
 
 local function assert_arg(idx,val,tp)

lua/pl/permute.lua

@@ -7,11 +7,9 @@ local utils = require 'pl.utils'
 local copy = tablex.deepcopy
 local append = table.insert
 local assert_arg = utils.assert_arg
-
--- check on OpenResty coroutine versions, and use originals if possible
-local co_create = coroutine._create or coroutine.create
-local co_yield = coroutine._yield or coroutine.yield
-local co_resume = coroutine._resume or coroutine.resume
+local co_create = coroutine.create
+local co_yield = coroutine.yield
+local co_resume = coroutine.resume
 
 
 local permute = {}