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pikuma_ps1/scripts/duffle_paths.lua
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2026-07-10 23:36:44 -04:00

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--- duffle_paths.lua — Single-line bootstrap helper for the tape-atom Lua scripts.
---
--- Each entry script (ps1_meta.lua, word_count_eval.lua, and the 5 passes/*.lua files) starts with:
--- ```lua
--- local duffle = dofile((arg[0]:match("(.*[/\\])") or "./") .. "duffle_paths.lua")
--- ```
--- That single line: (a) locates this helper via `arg[0]`,
--- (b) loads it (which sets `package.path` + `package.cpath` via `git rev-parse`),
--- (c) returns the `M` table (a wrapper around the setup function).
--- After this line, `require("duffle")` and `require("passes.X")` both resolve normally.
local M = {}
-- Cache key for the repo root. Stored in `package.loaded` (process-global) so all 8 entry scripts + passes scripts share one git call.
-- Without this cache, `git rev-parse --show-toplevel` runs once per script load = 8 × ~150ms = 1.2s wasted per build on Windows.
local CACHE_KEY = "__duffle_repo_root__"
--- Resolve the repo root via git (cached after first call).
--- Returns a normalized path with a trailing forward-slash, or nil if not in a git repo.
--- @return string|nil
local function find_repo_root()
if package.loaded[CACHE_KEY] then return package.loaded[CACHE_KEY] end
local p = io.popen("git rev-parse --show-toplevel 2>nul")
local root
if p then root = p:read("*l"); p:close() end
if not root or root == "" then return nil end
-- Normalize to forward slashes (Windows accepts both, but mixed `\` + `/` confuses LuaJIT's file APIs).
root = root:gsub("\\", "/")
if not root:match("/$") then root = root .. "/" end
package.loaded[CACHE_KEY] = root
return root
end
--- Set `package.path` (for `require("duffle")` + `require("passes.X")`) and `package.cpath` (for `lpeg.dll` on Windows).
--- Idempotent: safe to call multiple times (just re-sets the same paths).
function M.setup()
local repo_root = find_repo_root()
if not repo_root then
io.stderr:write("[duffle_paths] git rev-parse failed -- not in a git repo?\n")
os.exit(2)
end
local scripts_dir = repo_root .. "scripts/"
local passes_dir = repo_root .. "scripts/passes/"
package.path = scripts_dir .. "?.lua;"
.. scripts_dir .. "?/init.lua;"
.. passes_dir .. "?.lua;"
.. passes_dir .. "?/init.lua;"
.. package.path
if package.config:sub(1, 1) == "\\" then
package.cpath = repo_root .. "toolchain/luajit-2.1/lib/lua/5.1/?.dll;"
.. package.cpath
end
end
-- Run the setup as a side effect.
M.setup()
return M