feat(path): add expandvars

Author: haithium

spec/ntpath_spec.lua

@@ -18,14 +18,6 @@ local tbl = mods.tbl
 local tbl_keys = tbl.keys
 local fmt = string.format
 
-local function with_env(env, fn)
-  stub(os, "getenv", function(name)
-    return env[name]
-  end)
-  fn()
-  os.getenv:revert() ---@diagnostic disable-line: undefined-field
-end
-
 describe("mods.ntpath", function()
   local cwd = lfs.currentdir()
 
@@ -517,6 +509,30 @@ describe("mods.ntpath", function()
         { "~"    , { [[C:\Users\eric]]                         }},
         { "~test", { nil, "home directory for user is not set" }},
       }
+    },
+    expandvars = {
+      {
+        env = { foo = "bar", ["{foo"] = "baz1", ["{foo}"] = "baz2" },
+        { "foo"            , { "foo"         }},
+        { "$foo bar"       , { "bar bar"     }},
+        { "${foo}bar"      , { "barbar"      }},
+        { "$[foo]bar"      , { "$[foo]bar"   }},
+        { "$bar bar"       , { "$bar bar"    }},
+        { "$?bar"          , { "$?bar"       }},
+        { "$foo}bar"       , { "bar}bar"     }},
+        { "${foo"          , { "${foo"       }},
+        { "${{foo}}"       , { "baz1}"       }},
+        { "$foo$foo"       , { "barbar"      }},
+        { "$bar$bar"       , { "$bar$bar"    }},
+        { "%foo% bar"      , { "bar bar"     }},
+        { "%foo%bar"       , { "barbar"      }},
+        { "%foo%%foo%"     , { "barbar"      }},
+        { "%%foo%%foo%foo%", { "%foo%foobar" }},
+        { "%?bar%"         , { "%?bar%"      }},
+        { "%foo%%bar"      , { "bar%bar"     }},
+        { "'%foo%'%bar"    , { "'%foo%'%bar" }},
+        { "bar'%foo%"      , { "bar'%foo%"   }},
+      },
     }
   }
 

spec/path_spec.lua

@@ -617,4 +617,20 @@ describe("mods.path", function()
       end
     end
   end
+
+  it("expandvars()", function()
+    with_env({ foo = "bar", ["{foo"] = "baz1", ["{foo}"] = "baz2" }, function()
+      assert.are_same({ "foo" }, { posixpath.expandvars("foo") })
+      assert.are_same({ "bar bar" }, { posixpath.expandvars("$foo bar") })
+      assert.are_same({ "barbar" }, { posixpath.expandvars("${foo}bar") })
+      assert.are_same({ "$[foo]bar" }, { posixpath.expandvars("$[foo]bar") })
+      assert.are_same({ "$bar bar" }, { posixpath.expandvars("$bar bar") })
+      assert.are_same({ "$?bar" }, { posixpath.expandvars("$?bar") })
+      assert.are_same({ "bar}bar" }, { posixpath.expandvars("$foo}bar") })
+      assert.are_same({ "${foo" }, { posixpath.expandvars("${foo") })
+      assert.are_same({ "baz1}" }, { posixpath.expandvars("${{foo}}") })
+      assert.are_same({ "barbar" }, { posixpath.expandvars("$foo$foo") })
+      assert.are_same({ "$bar$bar" }, { posixpath.expandvars("$bar$bar") })
+    end)
+  end)
 end)

src/mods/ntpath.lua

@@ -485,6 +485,47 @@ function M.commonpath(paths)
   return first_drive .. first_root .. concat(common, SEP)
 end
 
+function M._expand_percent_vars(p)
+  local out = {}
+  local i = 1
+  local n = #p
+
+  while i <= n do
+    local ch = sub(p, i, i)
+    if ch ~= "%" then
+      out[#out + 1] = ch
+      i = i + 1
+    else
+      if i > 1 and sub(p, i - 1, i - 1) == "'" then
+        local close = find(p, "%", i + 1, true)
+        if close then
+          out[#out + 1] = sub(p, i, close)
+          i = close + 1
+        else
+          out[#out + 1] = "%"
+          i = i + 1
+        end
+      elseif i < n and sub(p, i + 1, i + 1) == "%" then
+        out[#out + 1] = "%"
+        i = i + 2
+      else
+        local close = find(p, "%", i + 1, true)
+        if not close then
+          out[#out + 1] = "%"
+          i = i + 1
+        else
+          local name = sub(p, i + 1, close - 1)
+          local v = getenv(name)
+          out[#out + 1] = v and v or ("%" .. name .. "%")
+          i = close + 1
+        end
+      end
+    end
+  end
+
+  return concat(out)
+end
+
 setmetatable(M, {
   __index = function(t, k)
     local v = path[k]

src/mods/path.lua

@@ -19,6 +19,7 @@ local rfind = str.rfind
 local concat = table.concat
 local find = string.find
 local fmt = string.format
+local getenv = os.getenv
 local gmatch = string.gmatch
 local gsub = string.gsub
 local lower = string.lower
@@ -109,6 +110,13 @@ local function match_part(name, pattern, case_sensitive)
   return match(name, "^" .. s .. "$") ~= nil
 end
 
+local function expandvars(getenv_fn, str, pattern, prefix, suffix)
+  return gsub(str, pattern, function(name)
+    local v = getenv_fn(name)
+    return v and v or (prefix .. name .. suffix)
+  end)
+end
+
 function M._splitext(p, sep, altsep, extsep)
   local sep_index = rfind(p, sep) or 0
   if altsep then
@@ -161,6 +169,13 @@ function M.drive(p)
   return (splitroot(p))
 end
 
+function M.expandvars(p)
+  assert_arg(1, p, "string")
+  local res = expandvars(getenv, p, "%${([^}]*)}", "${", "}")
+  res = expandvars(getenv, res, "%$([%w_]+)", "$", "")
+  return is_win and mods.ntpath._expand_percent_vars(res) or res
+end
+
 function M.is_relative_to(p, other)
   assert_arg(1, p, "string")
   assert_arg(2, other, "string")
@@ -330,6 +345,7 @@ if _TEST then
   -- stylua: ignore start
   function M._set_windows_semantics() set_semantics(true) end
   function M._set_posix_semantics() set_semantics(false) end
+  getenv = function(name) return os.getenv(name) end
 end
 
 return M

types/ntpath.lua

@@ -21,6 +21,14 @@
 ---@class mods.ntpath:mods.path
 local M = {}
 
+---@ignore
+---
+---Expand percent-style variables in a string.
+---
+---@param p string
+---@return string expanded
+---@private
+function M._expand_percent_vars(p) end
 ---
 ---Return `true` when `path` points to a mount root.
 ---

types/path.lua

@@ -199,6 +199,21 @@ function M.dirname(path) end
 ---@nodiscard
 function M.expanduser(path) end
 
+---
+---Expand vars in a path (`$VAR`/`${VAR}` everywhere, `%VAR%` on Windows).
+---
+---```lua
+---path.expandvars("$HOME/bin")               --> "/home/me/bin"
+---path.expandvars("${XDG_CONFIG_HOME}/nvim") --> "/home/me/.config/nvim"
+---path.expandvars("%USERPROFILE%\\bin")      --> "C:\\Users\\me\\bin"
+---path.expandvars("$UNKNOWN/bin")            --> "$UNKNOWN/bin"
+---```
+---
+---@param path string Path containing variable placeholders.
+---@return string expandedPath Path with variable values substituted.
+---@nodiscard
+function M.expandvars(path) end
+
 ---
 ---Return the current user's home directory path.
 ---
@@ -483,7 +498,7 @@ function M.match(path, pattern, case_sensitive) end
 ---Convert a `file://` URI to a local absolute path.
 ---
 ---```lua
----path.from_uri("file://localhost/tmp/a.txt") --> "/tmp/a.txt", nil
+---path.from_uri("file://localhost/tmp/a.txt") --> "/tmp/a.txt"
 ---```
 ---
 ---@param uri string URI value.