1 files changed, 84 insertions, 0 deletions
diff --git a/runtime/lua/vim/glob.lua b/runtime/lua/vim/glob.lua
new file mode 100644
index 0000000000..ad4a915a94
--- /dev/null
+++ b/runtime/lua/vim/glob.lua
@@ -0,0 +1,84 @@
+local lpeg = vim.lpeg
+local P, S, V, R, B = lpeg.P, lpeg.S, lpeg.V, lpeg.R, lpeg.B
+local C, Cc, Ct, Cf = lpeg.C, lpeg.Cc, lpeg.Ct, lpeg.Cf
+
+local M = {}
+
+local pathsep = P('/')
+
+--- Parses a raw glob into an |lua-lpeg| pattern.
+---
+--- This uses glob semantics from LSP 3.17.0: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#pattern
+---
+--- Glob patterns can have the following syntax:
+--- - `*` to match one or more characters in a path segment
+--- - `?` to match on one character in a path segment
+--- - `**` to match any number of path segments, including none
+--- - `{}` to group conditions (e.g. `*.{ts,js}` matches TypeScript and JavaScript files)
+--- - `[]` to declare a range of characters to match in a path segment (e.g., `example.[0-9]` to match on `example.0`, `example.1`, …)
+--- - `[!...]` to negate a range of characters to match in a path segment (e.g., `example.[!0-9]` to match on `example.a`, `example.b`, but not `example.0`)
+---
+---@param pattern string The raw glob pattern
+---@return vim.lpeg.Pattern pattern An |lua-lpeg| representation of the pattern
+function M.to_lpeg(pattern)
+  local function class(inv, ranges)
+    local patt = R(unpack(vim.tbl_map(table.concat, ranges)))
+    if inv == '!' then
+      patt = P(1) - patt
+    end
+    return patt
+  end
+
+  local function add(acc, a)
+    return acc + a
+  end
+
+  local function mul(acc, m)
+    return acc * m
+  end
+
+  local function star(stars, after)
+    return (-after * (P(1) - pathsep)) ^ #stars * after
+  end
+
+  local function dstar(after)
+    return (-after * P(1)) ^ 0 * after
+  end
+
+  local p = P({
+    'Pattern',
+    Pattern = V('Elem') ^ -1 * V('End'),
+    Elem = Cf(
+      (V('DStar') + V('Star') + V('Ques') + V('Class') + V('CondList') + V('Literal'))
+        * (V('Elem') + V('End')),
+      mul
+    ),
+    DStar = (B(pathsep) + -B(P(1)))
+      * P('**')
+      * (pathsep * (V('Elem') + V('End')) + V('End'))
+      / dstar,
+    Star = C(P('*') ^ 1) * (V('Elem') + V('End')) / star,
+    Ques = P('?') * Cc(P(1) - pathsep),
+    Class = P('[')
+      * C(P('!') ^ -1)
+      * Ct(Ct(C(P(1)) * P('-') * C(P(1) - P(']'))) ^ 1 * P(']'))
+      / class,
+    CondList = P('{') * Cf(V('Cond') * (P(',') * V('Cond')) ^ 0, add) * P('}'),
+    -- TODO: '*' inside a {} condition is interpreted literally but should probably have the same
+    -- wildcard semantics it usually has.
+    -- Fixing this is non-trivial because '*' should match non-greedily up to "the rest of the
+    -- pattern" which in all other cases is the entire succeeding part of the pattern, but at the end of a {}
+    -- condition means "everything after the {}" where several other options separated by ',' may
+    -- exist in between that should not be matched by '*'.
+    Cond = Cf((V('Ques') + V('Class') + V('CondList') + (V('Literal') - S(',}'))) ^ 1, mul)
+      + Cc(P(0)),
+    Literal = P(1) / P,
+    End = P(-1) * Cc(P(-1)),
+  })
+
+  local lpeg_pattern = p:match(pattern) --[[@as vim.lpeg.Pattern?]]
+  assert(lpeg_pattern, 'Invalid glob')
+  return lpeg_pattern
+end
+
+return M