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-rw-r--r--lua/buffer_browser.lua259
1 files changed, 259 insertions, 0 deletions
diff --git a/lua/buffer_browser.lua b/lua/buffer_browser.lua
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+++ b/lua/buffer_browser.lua
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+--[[
+BUFFER BROWSER
+Author: Marc Coquand
+
+The comments below the code can be used to test the functions. Run them in `lua %` or with a code runner, like sniprun.
+]]
+local api = vim.api
+
+--[[ STATE MANAGEMENT
+We make use of a Zipper to keep track of the state of the buffers
+(https://stackoverflow.com/questions/380438/what-is-the-zipper-data-structure-and-should-i-be-using-it)
+]]
+local function matchesFilter(filters, name)
+ if filters == nil then
+ return false
+ end
+
+ for _, filter in ipairs(filters) do
+ if name == filter then
+ return true
+ end
+ end
+ return false
+end
+
+
+local function StateAppend(bufNr, stateFiletype, state, filters)
+ if (state.current == bufNr) then
+ return state
+ end
+
+ -- if filters matches the filetype of the buffer we change from, don't add it to history
+ if (stateFiletype ~= nil and matchesFilter(filters, stateFiletype)) then
+ state.current = bufNr
+ return state
+ else
+ state.future = {}
+ table.insert(state.previous, 1, state.current)
+ state.current = bufNr
+
+ return state
+ end
+end
+
+local function StateGoBack(state)
+ -- Go back in the state by setting current to the first element of previous, and appending the current to the future
+ -- Check if past is empty, if so return state as is
+ if #state.previous == 0 then
+ return state
+ end
+
+ table.insert(state.future, 1, state.current)
+ state.current = table.remove(state.previous, 1)
+ return state
+end
+-- local state = { current = 1, previous = { 2, 3 }, future = { 4, 5 } }
+-- print(StateGoBack(StateGoBack(StateGoBack(state)))['current'])
+-- > 3
+
+local function StateGoForward(state)
+ -- Go forward in the state by setting current to the first element of future, and appending the current to the previous
+
+ -- Check if future is empty, if so return state as is
+ if #state.future == 0 then
+ return state
+ end
+
+ table.insert(state.previous, 1, state.current)
+ state.current = table.remove(state.future, 1)
+
+ return state
+end
+-- local state = { current = 1, previous = { 2, 3 }, future = { 4, 5 } }
+-- print(StateGoForward(StateGoForward(StateGoForward(state)))['current'])
+
+local function StateDelete(state, bufNr)
+ -- Delete bufNr from state.previous
+ for i, v in ipairs(state.previous) do
+ if v == bufNr then
+ table.remove(state.previous, i)
+ end
+ end
+
+ -- Delete bufNr from state.future
+ for i, v in ipairs(state.future) do
+ if v == bufNr then
+ table.remove(state.future, i)
+ end
+ end
+
+ -- If bufNr is current, set current to the first element of previous
+ if state.current == bufNr and #state.previous > 0 then
+ state.current = table.remove(state.previous, 1)
+ return state
+ end
+
+ -- If bufNr is current and we have a future
+ if state.current == bufNr and #state.future > 0 then
+ state.current = table.remove(state.future, 1)
+ return state
+ end
+
+ -- If bufNr is current, set current to the first element of future
+ if state.current == bufNr then
+ state.current = nil
+ return state
+ end
+ return state
+end
+-- local state = { current = 1, previous = { 2, 3 }, future = { 4, 5 } }
+-- print(StateDelete(state, 1)['current'])
+-- -- > 2
+
+local function stateIsEmpty(state)
+ return (state.current == nil and state.previous == nil and state.future == nil)
+end
+
+
+-- [[ EFFECTS ]]
+local function setState(state)
+ vim.w.buffer_browser_previous = state.previous
+ vim.w.buffer_browser_current = state.current
+ vim.w.buffer_browser_future = state.future
+end
+
+local function getState()
+ local current = vim.w.buffer_browser_current
+ local previous = vim.w.buffer_browser_previous
+ local future = vim.w.buffer_browser_future
+ return {
+ current = current,
+ previous = previous,
+ future = future,
+ }
+end
+
+local function initState(bufNr)
+ vim.w.buffer_browser_current = bufNr
+ vim.w.buffer_browser_previous = {}
+ vim.w.buffer_browser_future = {}
+end
+
+local function getBufNr()
+ local winnr = api.nvim_tabpage_get_win(0)
+ return api.nvim_win_get_buf(winnr)
+end
+
+local function getFiletype(bufnr)
+ if (bufnr == nil) then
+ return ''
+ end
+ return vim.bo[bufnr].filetype
+end
+
+--[[ AUTO COMMANDS ]]
+function BufferBrowserBufferEnter(args)
+ local bufNr = args.buf
+ local filters = vim.g.buffer_browser_filters
+
+ local state = getState()
+ if stateIsEmpty(state) then
+ initState(bufNr)
+ else
+ if (state.current ~= bufNr) then
+ local stateFiletype = getFiletype(state.current)
+ StateAppend(bufNr, stateFiletype, state, filters)
+ setState(state)
+ end
+ end
+end
+
+function BufferBrowserBufferWipeOut(args)
+ local buf = args.buf
+ local state = getState()
+ if not stateIsEmpty(state) then
+ StateDelete(state, buf)
+ setState(state)
+ end
+end
+
+local BufferBrowserGroup = api.nvim_create_augroup('BufferBrowser', { clear = true })
+
+api.nvim_create_autocmd({ 'WinEnter', 'BufEnter' },
+ {
+ group = BufferBrowserGroup,
+ pattern = '*',
+ callback = function(args)
+ BufferBrowserBufferEnter(args)
+ end
+ }
+)
+
+-- BufWipeout is called before deletion
+api.nvim_create_autocmd('BufWipeout',
+ {
+ group = BufferBrowserGroup,
+ pattern = '*',
+ callback = function(args)
+ BufferBrowserBufferWipeOut(args)
+ end
+ }
+)
+
+
+--[[ COMMANDS ]]
+local function next()
+ local bufnr = getBufNr()
+ local state = getState()
+
+ if stateIsEmpty(state) then
+ initState(bufnr)
+ else
+ StateGoForward(state)
+ setState(state)
+ end
+ api.nvim_command('buffer ' .. state.current)
+end
+
+local function prev()
+ local bufnr = getBufNr()
+ local state = getState()
+
+ if stateIsEmpty(state) then
+ initState(bufnr)
+ else
+ StateGoBack(state)
+ setState(state)
+ end
+ api.nvim_command('buffer ' .. state.current)
+end
+
+--[[ DEBUG ]]
+local function printBrowserHistory()
+ local state = getState()
+ print('Browser State Previous: ' .. vim.inspect(state.previous))
+ print('Browser State Current: ' .. vim.inspect(state.current))
+ print('Browser State Future: ' .. vim.inspect(state.future))
+end
+
+
+--[[ SETUP ]]
+local function setup(opts)
+ if (opts == nil) then
+ local default = {
+ '', 'netrw', 'gitcommit', 'TelescopePrompt'
+ }
+ vim.g.buffer_browser_filters = default
+ else
+ -- Filter is based on filetype
+ vim.g.buffer_browser_filters = opts.filetype_filters
+ end
+end
+
+return {
+ next = next,
+ prev = prev,
+ printBrowserHistory = printBrowserHistory,
+ setup = setup
+}