feat: Lua 5.1+ support (1.3.0) + Lua 5.1-5.4 matrix CI

.github/workflows/test.yml

@@ -13,6 +13,26 @@ jobs:
       - uses: actions/checkout@v4
       - run: docker compose run --rm test
 
+  matrix:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        lua: ["5.1", "5.2", "5.3", "5.4"]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: leafo/gh-actions-lua@v10
+        with:
+          luaVersion: ${{ matrix.lua }}
+      - uses: leafo/gh-actions-luarocks@v4
+      - run: |
+          luarocks install lpeg
+          luarocks install dkjson
+          luarocks install argparse
+          luarocks install busted
+      - run: luarocks make ./parse_sdp-1.3.0-1.rockspec
+      - run: busted spec/
+
   conformance:
     runs-on: ubuntu-latest
     steps:

CHANGELOG.md

@@ -9,17 +9,51 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+- _(none yet; 1.3.0 just shipped)_
+
+## [1.3.0] — 2026-05-26
+
+### Added
+
+- **Lua 5.1 and Lua 5.2 support.** Rockspec dependency relaxed from
+  `lua >= 5.3, < 5.6` to `lua >= 5.1, < 5.6`. No additional rocks
+  required on any Lua version — Lua 5.3+ uses native bitwise
+  operators (`&` / `>>` / `<<`); Lua 5.1 and 5.2 use a pure-Lua
+  arithmetic backend in `parse_sdp.grammar.bitops_compat`. The
+  backend is selected at `require` time by the dispatcher in
+  `parse_sdp.grammar.bitops`, so the 5.3+ path is unchanged.
+- **CI matrix across Lua 5.1 / 5.2 / 5.3 / 5.4.** The existing
+  Docker-based Lua 5.5 job continues to mirror local development;
+  the new matrix job uses `leafo/gh-actions-lua@v10` and runs the
+  full hermetic suite on each version. Conformance fixtures still
+  run on the 5.5 image only.
+
 ### Changed
 
-- **Bitwise operations isolated behind a dispatcher (`parse_sdp.grammar.bitops`).**
-  `int_to_ipv4` and `ipv6_add` in `parse_sdp/grammar/addresses.lua` no
-  longer contain `&` / `>>` syntax — they call `bitops.band` /
-  `bitops.rshift` via a shim that loads the native-operator backend on
-  Lua 5.3+ and a pure-Lua arithmetic backend on 5.1/5.2. Behavior is
-  unchanged on every Lua version the project supports today; this is
-  the refactor that unblocks the planned Lua 5.1/5.2 support without
-  compromising the 5.3+ code path. The rockspec floor is still
-  `lua >= 5.3, < 5.6` in this entry; the next entry will relax it.
+- **Bitwise operations isolated behind a dispatcher
+  (`parse_sdp.grammar.bitops`).** `int_to_ipv4` and `ipv6_add` in
+  `parse_sdp/grammar/addresses.lua` no longer contain `&` / `>>`
+  syntax — they call `bitops.band` / `bitops.rshift` via a shim that
+  loads the native-operator backend on Lua 5.3+ and a pure-Lua
+  arithmetic backend on 5.1/5.2. Behavior is unchanged on every
+  Lua version.
+- **`spec/cli_spec.lua` `run()` helper captures exit codes via a
+  subshell-emitted temp file** instead of relying on the 5.2+
+  three-value return from `io.popen():close()`. Same observable
+  behavior on every Lua version; the rewrite is required for the
+  Lua 5.1 entry above.
+
+### Fixed
+
+- `spec/grammar_base_spec.lua` uses `(table.unpack or unpack)` for
+  Lua 5.1 compatibility (5.1 has `unpack` as a global; 5.2+ has
+  `table.unpack`).
+
+### Verification
+
+- Full hermetic suite (1208 tests) passes under Lua 5.1, 5.2, 5.3,
+  5.4 (via hererocks-built local envs) and Lua 5.5 (via the
+  existing Docker image).
 
 ## [1.2.1] — 2026-05-22
 

CLAUDE.md

@@ -4,7 +4,7 @@ Context and conventions for Claude Code working in this repo.
 
 ## Project Purpose
 
-`parse_sdp` is a Lua 5.5 + LPEG library that parses, validates, and serializes SDP
+`parse_sdp` is a Lua 5.1+ + LPEG library that parses, validates, and serializes SDP
 (Session Description Protocol) files. Three validation tiers:
 RFC 8866 (generic SDP; obsoletes RFC 4566) → SMPTE ST 2110 → IPMX.
 
@@ -21,11 +21,11 @@ Prefer fewer, well-named things over many small helpers.
 
 | Concern | Choice |
 | --- | --- |
-| Language | Lua 5.5 |
+| Language | Lua 5.1+ (tested on 5.1, 5.2, 5.3, 5.4, 5.5) |
 | Parsing | LPEG |
 | JSON | dkjson (pure Lua, LuaRocks) |
 | Tests | busted — `busted spec/` |
-| Container | Docker |
+| Container | Docker (Lua 5.5) |
 
 ## Repository Layout
 
@@ -290,7 +290,13 @@ confirmed-against-primary-source findings get fixed.
 - **Strict by default.** If RFC 8866 says a field is required, the parser rejects
   input that omits it — no silent defaults, no forgiveness.
 - **dkjson** is the only external runtime dependency beyond LPEG.
-- Lua 5.5: use `local` and `global` declarations explicitly; no implicit globals.
+- **Lua-version portability.** The library supports 5.1 through 5.5 in
+  a single source tree. Don't introduce 5.3+-only syntax (`&` / `>>` /
+  `<<`, integer division `//`, `string.pack`, `\u{}` escapes, `<const>`
+  / `<close>`, `goto`, etc.) outside the `parse_sdp.grammar.bitops_53`
+  module, which is only loaded on 5.3+. Don't reach for `table.unpack`
+  in spec code without the `(table.unpack or unpack)` fallback.
+  CI runs the full hermetic suite on each of 5.1, 5.2, 5.3, 5.4, 5.5.
 
 ## Check Taxonomy
 

GUIDE.md

@@ -20,7 +20,7 @@
 
 ## Introduction
 
-`parse_sdp` is a Lua 5.3-5.5 library for parsing, validating, and serializing SDP (Session Description Protocol) files used in professional media over IP workflows. It is built with [LPEG](https://www.inf.puc-rio.br/~roberto/lpeg/). Runtime dependencies: LPEG, [dkjson](https://github.com/LuaDist/dkjson), and argparse (CLI only — never loaded by `require("parse_sdp")`).
+`parse_sdp` is a Lua 5.1-5.5 library for parsing, validating, and serializing SDP (Session Description Protocol) files used in professional media over IP workflows. It is built with [LPEG](https://www.inf.puc-rio.br/~roberto/lpeg/). Runtime dependencies: LPEG, [dkjson](https://github.com/LuaDist/dkjson), and argparse (CLI only — never loaded by `require("parse_sdp")`). No bit-manipulation rock is required on any Lua version — Lua 5.3+ uses native bitwise operators, and Lua 5.1 / 5.2 use a pure-Lua arithmetic backend bundled with the library.
 
 **Strictness is a primary feature.** The library enforces RFC 8866 (which obsoletes RFC 4566) exactly: required fields must be present, optional fields must appear in the correct position, and values must conform to their specified formats. SDP files that are "mostly valid" but technically non-conformant are rejected with a precise error message. The library will never produce an invalid SDP file.
 
@@ -79,6 +79,10 @@ IPMX (IP Media Experience) is an interoperability profile layered on ST 2110. It
 
 ## Installation
 
+### Supported Lua versions
+
+Lua 5.1, 5.2, 5.3, 5.4, and 5.5. CI runs the full hermetic test suite on each version. No additional rocks are needed beyond the standard runtime deps; Lua 5.3+ uses native bitwise operators, and Lua 5.1 / 5.2 use a pure-Lua arithmetic backend (`parse_sdp.grammar.bitops_compat`) selected automatically at `require` time.
+
 ### LuaRocks
 
 ```sh

PLAN.md

@@ -18,7 +18,7 @@
 
 | Concern | Choice |
 | --- | --- |
-| Language | Lua 5.5 |
+| Language | Lua 5.1+ (tested on 5.1, 5.2, 5.3, 5.4, 5.5) |
 | Parsing | LPEG |
 | JSON | dkjson (pure Lua, LuaRocks) |
 | Tests | busted |
@@ -339,11 +339,15 @@ the AMWA conformance fixtures across the matrix.
    `addresses.lua` to call the shim. Rockspec still at `lua >= 5.3`.
    Suite grew 1197 → 1208 (+11 bitops cases). Verified passing under
    Docker Lua 5.5 and under hererocks-built Lua 5.1.
-3. [ ] **Compat slice**: relax rockspec to `lua >= 5.1`, register the
-   three new modules in `build.modules`, fix `table.unpack` in the
-   one spec file, add the matrix CI job. Bump version to 1.3.0.
-   Update CHANGELOG / GUIDE / README / CLAUDE per Migration & version
-   above.
+3. [x] **Compat slice**: rockspec floor relaxed to `lua >= 5.1`,
+   three new modules registered in `build.modules`, `table.unpack`
+   fixed via `(table.unpack or unpack)`, `spec/cli_spec.lua`'s
+   `run()` helper rewritten to capture exit codes via a subshell
+   (the 5.2+ `io.popen():close()` three-value return doesn't exist
+   on 5.1). Matrix CI job added using `leafo/gh-actions-lua@v10`
+   across 5.1 / 5.2 / 5.3 / 5.4. Version bumped to 1.3.0. CHANGELOG
+   / GUIDE / README / CLAUDE.md updated. All 1208 tests pass locally
+   under 5.1, 5.2, 5.3, 5.4, and 5.5.
 4. [ ] **Release slice**: tag `v1.3.0`, upload rockspec, publish.
 
 ## Known Deferred Items

README.md

@@ -2,7 +2,7 @@
 
 [![Tests](https://github.com/andrewstarks/parse_sdp/actions/workflows/test.yml/badge.svg)](https://github.com/andrewstarks/parse_sdp/actions/workflows/test.yml)
 
-A Lua 5.3 - 5.5 library for parsing, validating, and serializing SDP (Session Description Protocol) files, with support for SMPTE ST 2110 and IPMX extensions.
+A Lua 5.1 - 5.5 library for parsing, validating, and serializing SDP (Session Description Protocol) files, with support for SMPTE ST 2110 and IPMX extensions.
 
 Built with [LPEG](https://www.inf.puc-rio.br/~roberto/lpeg/) for precise, composable parsing and structured error reporting.
 
@@ -53,6 +53,9 @@ luarocks install parse_sdp
 
 `lpeg`, `dkjson`, and `argparse` are installed automatically as dependencies.
 `argparse` is only used by the CLI binary — `require("parse_sdp")` never loads it.
+No bit-manipulation rock is required on any Lua version: Lua 5.3+ uses
+native bitwise operators, and Lua 5.1/5.2 use a pure-Lua arithmetic
+implementation bundled with the library.
 
 **Docker:**
 

parse_sdp-1.2.1-1.rockspec → parse_sdp-1.3.0-1.rockspec

@@ -1,9 +1,9 @@
 package = "parse_sdp"
-version = "1.2.1-1"
+version = "1.3.0-1"
 
 source = {
   url  = "git+https://github.com/andrewstarks/parse_sdp.git",
-  tag  = "v1.2.1",
+  tag  = "v1.3.0",
 }
 
 description = {
@@ -31,8 +31,10 @@ round-trip, and registry inspection.
 
 -- argparse is only used by the CLI binary at bin/parse_sdp;
 -- require("parse_sdp") loads only the library and never pulls argparse in.
+-- Lua 5.1/5.2 get a pure-Lua arithmetic bitops backend; no extra rock
+-- is needed on any supported version (see parse_sdp/grammar/bitops.lua).
 dependencies = {
-  "lua >= 5.3, < 5.6",
+  "lua >= 5.1, < 5.6",
   "lpeg",
   "dkjson",
   "argparse",
@@ -41,14 +43,17 @@ dependencies = {
 build = {
   type    = "builtin",
   modules = {
-    parse_sdp                        = "parse_sdp/init.lua",
-    ["parse_sdp.errors"]             = "parse_sdp/errors.lua",
-    ["parse_sdp.serialize"]          = "parse_sdp/serialize.lua",
-    ["parse_sdp.grammar.patterns"]   = "parse_sdp/grammar/patterns.lua",
-    ["parse_sdp.grammar.addresses"]  = "parse_sdp/grammar/addresses.lua",
-    ["parse_sdp.grammar.base"]       = "parse_sdp/grammar/base.lua",
-    ["parse_sdp.grammar.st2110"]     = "parse_sdp/grammar/st2110.lua",
-    ["parse_sdp.grammar.ipmx"]       = "parse_sdp/grammar/ipmx.lua",
+    parse_sdp                            = "parse_sdp/init.lua",
+    ["parse_sdp.errors"]                 = "parse_sdp/errors.lua",
+    ["parse_sdp.serialize"]              = "parse_sdp/serialize.lua",
+    ["parse_sdp.grammar.patterns"]       = "parse_sdp/grammar/patterns.lua",
+    ["parse_sdp.grammar.addresses"]      = "parse_sdp/grammar/addresses.lua",
+    ["parse_sdp.grammar.bitops"]         = "parse_sdp/grammar/bitops.lua",
+    ["parse_sdp.grammar.bitops_53"]      = "parse_sdp/grammar/bitops_53.lua",
+    ["parse_sdp.grammar.bitops_compat"]  = "parse_sdp/grammar/bitops_compat.lua",
+    ["parse_sdp.grammar.base"]           = "parse_sdp/grammar/base.lua",
+    ["parse_sdp.grammar.st2110"]         = "parse_sdp/grammar/st2110.lua",
+    ["parse_sdp.grammar.ipmx"]           = "parse_sdp/grammar/ipmx.lua",
   },
   install = {
     bin = {

spec/cli_spec.lua

@@ -9,32 +9,43 @@ local dkjson = require("dkjson")
 -- stdin_text: optional string piped to the process's stdin.
 -- Returns stdout (string), stderr (string), exit_code (number).
 local function run(args_str, stdin_text)
-  local tmp_err = os.tmpname()
+  -- Subshell the CLI and capture its exit code via a temp file. The
+  -- 3-value return from `handle:close()` was added in Lua 5.2; on 5.1
+  -- the popen close returns only a status flag, so reading $? back
+  -- through the filesystem is the portable path.
+  local tmp_err  = os.tmpname()
+  local tmp_exit = os.tmpname()
   local tmp_in
 
-  local cmd
+  local inner
   if stdin_text then
     tmp_in = os.tmpname()
     local f = assert(io.open(tmp_in, "w"))
     f:write(stdin_text)
     f:close()
-    cmd = string.format("lua bin/parse_sdp %s < %s 2>%s", args_str, tmp_in, tmp_err)
+    inner = string.format("lua bin/parse_sdp %s < %s", args_str, tmp_in)
   else
-    cmd = string.format("lua bin/parse_sdp %s 2>%s", args_str, tmp_err)
+    inner = string.format("lua bin/parse_sdp %s", args_str)
   end
+  local cmd = string.format("(%s; echo $? > %s) 2>%s", inner, tmp_exit, tmp_err)
 
   local handle  = io.popen(cmd, "r")
   local stdout  = handle:read("*a")
-  local _, _, code = handle:close()
+  handle:close()
 
   local ef     = io.open(tmp_err, "r")
   local stderr = ef and ef:read("*a") or ""
   if ef then ef:close() end
 
+  local xf   = io.open(tmp_exit, "r")
+  local code = xf and tonumber(xf:read("*a")) or 0
+  if xf then xf:close() end
+
   os.remove(tmp_err)
+  os.remove(tmp_exit)
   if tmp_in then os.remove(tmp_in) end
 
-  return stdout, stderr, code or 0
+  return stdout, stderr, code
 end
 
 -- ── validate subcommand ─────────────────────────────────────────────────────

spec/grammar_base_spec.lua

@@ -1346,7 +1346,7 @@ describe("base SDP grammar — dynamic-PT requires rtpmap (Phase 3.B, RFC 8866 
       "v=0", "o=- 1 1 IN IP4 127.0.0.1", "s=X",
       "c=IN IP4 224.0.0.1/127",
       "t=0 0",
-      table.unpack(media_block),
+      (table.unpack or unpack)(media_block),
     })
   end