Update README

README.md

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+# revolver.nvim
+
+This Neovim plugin makes it easy to rotate between related files in a common directory. This enables "header flipping"
+in C/C++ and other languages where semantically related information is split between different files. revolver.nvim
+alternates between files that share a common prefix after stripping away one of the predetermined suffixes. This suffix
+is typically the file extension, but can include a part of the filename as well. Classic Vim is not supported.
+
+## Configuration
+
+This plugin can be configured by calling the `setup` function. A set of file suffixes is provided to override the
+defaults shown below.
+
+```lua
+require('revolver').setup({
+    '.c',
+    '.cpp',
+    '.h',
+    '.hpp',
+    '.inl'
+})
+```
+
+## Commands
+
+For the following examples, imagine that you have the files `foo.cpp`, `foo.h`, and `foo.inl` in a directory and are
+currently editing `foo.cpp`.
+
+#### `Revolver`
+Invoking the `Revolver` command will open `foo.h`. Subsequent invocation will cause `foo.h` and `foo.inl` to open before
+wrapping back around to `foo.cpp`. The order that files are opened in corresponds to the ordering of suffixes provided
+to the `setup` function.
+
+#### `RevolverBack`
+This command is similar to `Revolver` with the difference being that suffix rotation occurs backwards. The first file to
+be opened would be `foo.inl`, followed by `foo.h`, and finally `foo.cpp` again.

lua/hflip.lua

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-local function split_ext(path)
-    return path:match('^(.+)(%..+)$')
-end
-
-local function file_exists(path)
-    return vim.loop.fs_stat(path) ~= nil
-end
-
-local function locate_flip_path(name, exts)
-    for key, _ in pairs(exts) do
-        local path = name .. key
-        if file_exists(path) then
-            return path
-        end
-
-        local path_upper = name .. key:upper()
-        if file_exists(path_upper) then
-            return path_upper
-        end
-    end
-end
-
-local function hflip()
-    local header_exts = {
-        ['.h'] = true,
-        ['.hpp'] = true,
-        ['.lua'] = true,
-    }
-
-    local source_exts = {
-        ['.c'] = true,
-        ['.cpp'] = true
-    }
-
-    local index = vim.api.nvim_get_current_buf()
-    local path = vim.api.nvim_buf_get_name(index)
-    local name, ext = split_ext(path)
-
-    if ext ~= nil then
-        local ext_lower = ext:lower()
-
-        local flip_path
-        if header_exts[ext_lower] then
-            flip_path = locate_flip_path(name, source_exts)
-        elseif source_exts[ext_lower] then
-            flip_path = locate_flip_path(name, header_exts)
-        end
-
-        if flip_path then
-            vim.cmd(string.format('e %s', flip_path))
-        end
-    end
-end
-
-return {
-    hflip = hflip
-}

lua/revolver.lua

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+local RevolverSuffixes = {
+    '.c',
+    '.cpp',
+    '.h',
+    '.hpp',
+    '.inl',
+}
+
+local function setup(config)
+    if config then
+        RevolverSuffixes = config
+    end
+end
+
+local function escape(s)
+    return s:gsub('[%-%.%+%[%]%(%)%$%^%%%?%*]','%%%1')
+end
+
+local function file_exists(path)
+    return vim.loop.fs_stat(path) ~= nil
+end
+
+local function path_pivot(path, suffix)
+    local start, stop = path:find(escape(suffix) .. '$')
+    if start and stop == #path then
+        return path:sub(0, start - 1)
+    end
+end
+
+local function revolve(back)
+    local path = vim.api.nvim_buf_get_name(vim.api.nvim_get_current_buf())
+
+    local suffix_index = nil
+    local prefix = nil
+    for i, s in ipairs(RevolverSuffixes) do
+        prefix = path_pivot(path, s)
+        if prefix then
+            suffix_index = i
+            break
+        end
+    end
+
+    if prefix then
+        local start = 1
+        local stop = #RevolverSuffixes - 1
+        local step = 1
+        if back then
+            start, stop = stop, start
+            step = -1
+        end
+
+        for i = start, stop, step do
+            local j = (i + suffix_index - 1) % #RevolverSuffixes + 1
+            local next_path = prefix .. RevolverSuffixes[j]
+            if path ~= next_path and file_exists(next_path) then
+                vim.cmd(string.format('e %s', next_path))
+                break
+            end
+        end
+    end
+end
+
+return {
+    revolve = revolve,
+    setup = setup,
+}

plugin/hflip.vim

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-" in plugin/hflip.vim
-if exists('g:loaded_hflip') | finish | endif " prevent loading file twice
-
-let s:save_cpo = &cpo " save user coptions
-set cpo&vim " reset them to defaults
-
-" command to run our plugin
-command! HFlip lua require'hflip'.hflip()
-
-let &cpo = s:save_cpo " and restore after
-unlet s:save_cpo
-
-let g:loaded_hflip = 1

plugin/revolver.lua

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+if not vim.g.hflip then
+    local revolver = require('revolver')
+
+    local function reload()
+        package.loaded.revolver = nil
+        revolver = require('revolver')
+    end
+
+    local function revolve()
+        revolver.revolve(false)
+    end
+
+    local function revolve_back()
+        revolver.revolve(true)
+    end
+
+    vim.api.nvim_create_user_command('Revolver', revolve, {})
+    vim.api.nvim_create_user_command('RevolverBack', revolve_back, {})
+    vim.api.nvim_create_user_command('RevolverReload', reload, {})
+
+    vim.g.revolver = true
+end