feat: scripts/Modulize.lean (#10460)

This PR introduces a simple script that adjusts module headers in a
package for use of the module system, without further minimizing import
or annotation use.

---------

Co-authored-by: Kim Morrison <477956+kim-em@users.noreply.github.com>

lean.code-workspace

@@ -8,6 +8,9 @@
 		},
 		{
 			"path": "tests"
+		},
+		{
+			"path": "script"
 		}
 	],
 	"settings": {

script/Modulize.lean

@@ -0,0 +1,91 @@
+import Lake.CLI.Main
+
+/-!
+A simple script that inserts `module` and `@[expose] public section` into un-modulized files and
+bumps their imports to `public`.
+-/
+
+open Lean Parser.Module
+
+def main (args : List String) : IO Unit := do
+  initSearchPath (← findSysroot)
+  let mods := args.toArray.map (·.toName)
+
+  -- Determine default module(s) to run modulize on
+  let defaultTargetModules : Array Name ← try
+    let (elanInstall?, leanInstall?, lakeInstall?) ← Lake.findInstall?
+    let config ← Lake.MonadError.runEIO <| Lake.mkLoadConfig { elanInstall?, leanInstall?, lakeInstall? }
+    let some workspace ← Lake.loadWorkspace config |>.toBaseIO
+      | throw <| IO.userError "failed to load Lake workspace"
+    let defaultTargetModules := workspace.root.defaultTargets.flatMap fun target =>
+      if let some lib := workspace.root.findLeanLib? target then
+        lib.roots
+      else if let some exe := workspace.root.findLeanExe? target then
+        #[exe.config.root]
+      else
+        #[]
+    pure defaultTargetModules
+  catch _ =>
+    pure #[]
+
+  -- the list of root modules
+  let mods := if mods.isEmpty then defaultTargetModules else mods
+  -- Only submodules of `pkg` will be edited or have info reported on them
+  let pkg := mods[0]!.components.head!
+
+  -- Load all the modules
+  let imps := mods.map ({ module := · })
+  let env ← importModules imps {}
+
+  let srcSearchPath ← getSrcSearchPath
+
+  for mod in env.header.moduleNames do
+    if !pkg.isPrefixOf mod then
+      continue
+
+    -- Parse the input file
+    let some path ← srcSearchPath.findModuleWithExt "lean" mod
+      | throw <| .userError "error: failed to find source file for {mod}"
+    let mut text ← IO.FS.readFile path
+    let inputCtx := Parser.mkInputContext text path.toString
+    let (header, parserState, msgs) ← Parser.parseHeader inputCtx
+    if !msgs.toList.isEmpty then -- skip this file if there are parse errors
+      msgs.forM fun msg => msg.toString >>= IO.println
+      throw <| .userError "parse errors in file"
+    let `(header| $[module%$moduleTk?]? $imps:import*) := header
+      | throw <| .userError s!"unexpected header syntax of {path}"
+    if moduleTk?.isSome then
+      continue
+
+    let looksMeta := mod.components.any (· ∈ [`Tactic, `Linter])
+
+    -- initial whitespace if empty header
+    let startPos := header.raw.getPos? |>.getD parserState.pos
+
+    -- insert section if any trailing text
+    if header.raw.getTrailingTailPos?.all (· < text.endPos) then
+      let insertPos := header.raw.getTailPos? |>.getD startPos  -- empty header
+      let mut sec := if looksMeta then
+        "public meta section"
+      else
+        "@[expose] public section"
+      if !imps.isEmpty then
+        sec := "\n\n" ++ sec
+      if header.raw.getTailPos?.isNone then
+        sec := sec ++ "\n\n"
+      text := text.extract 0 insertPos ++ sec ++ text.extract insertPos text.endPos
+
+    -- prepend each import with `public `
+    for imp in imps.reverse do
+      let insertPos := imp.raw.getPos?.get!
+      let prfx := if looksMeta then "public meta " else "public "
+      text := text.extract 0 insertPos ++ prfx ++ text.extract insertPos text.endPos
+
+    -- insert `module` header
+    let mut initText := text.extract 0 startPos
+    if !initText.trim.isEmpty then
+      -- If there is a header comment, preserve it and put `module` in the line after
+      initText := initText.trimRight ++ "\n"
+    text := initText ++ "module\n\n" ++ text.extract startPos text.endPos
+
+    IO.FS.writeFile path text

script/lakefile.toml

@@ -0,0 +1,5 @@
+name = "scripts"
+
+[[lean_exe]]
+name = "modulize"
+root = "Modulize"

script/lean-toolchain

@@ -0,0 +1 @@
+lean4