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-- Copyright 2019-2020 Mitchell. See LICENSE.
local M = {}
--[[ This comment is for LuaDoc.
---
-- Records buffer positions within Textadept views over time and allows for
-- navigating through that history.
--
-- This module listens for text edit events and buffer switch events. Each time
-- an insertion or deletion occurs, its location is recorded in the current
-- view's location history. If the edit is close enough to the previous record,
-- the previous record is amended. Each time a buffer switch occurs, the before
-- and after locations are also recorded.
-- @field minimum_line_distance (number)
-- The minimum number of lines between distinct history records.
-- The default value is `3`.
-- @field maximum_history_size (number)
-- The maximum number of history records to keep per view.
-- The default value is `100`.
module('textadept.history')]]
M.minimum_line_distance = 3
M.maximum_history_size = 100
-- Map of views to their history records.
-- Each record has a `pos` field that points to the current history position in
-- the associated view.
-- @class table
-- @name view_history
local view_history = setmetatable({}, {__index = function(t, view)
t[view] = {pos = 0}
return t[view]
end})
-- Listens for text insertion and deletion events and records their locations.
events.connect(events.MODIFIED, function(position, mod, text, length)
local buffer = buffer
-- Only interested in text insertion or deletion.
if mod & buffer.MOD_INSERTTEXT > 0 then
if length == buffer.length then return end -- ignore file loading
position = position + length
elseif mod & buffer.MOD_DELETETEXT > 0 then
if buffer.length == 0 then return end -- ignore replacing buffer contents
else
return
end
-- Ignore undo/redo.
if mod & (buffer.PERFORMED_UNDO | buffer.PERFORMED_REDO) > 0 then return end
M.record(nil, buffer:line_from_position(position), buffer.column[position])
end)
-- Do not record positions during buffer switches when jumping backwards or
-- forwards.
local jumping = false
-- Jumps to the given record in the current view's history.
-- @param record History record to jump to.
local function jump(record)
jumping = true
local filename = record.filename
if lfs.attributes(filename) then
io.open_file(filename)
else
for _, buffer in ipairs(_BUFFERS) do
if buffer.filename == filename or buffer._type == filename or
not buffer.filename and not buffer._type and
filename == _L['Untitled'] then
view:goto_buffer(buffer)
break
end
end
end
buffer:goto_pos(buffer:find_column(record.line, record.column))
jumping = false
end
---
-- Navigates backwards through the current view's history.
-- @name back
function M.back()
local history = view_history[view]
if #history == 0 then return end -- nothing to do
local record = history[history.pos]
local line = buffer:line_from_position(buffer.current_pos)
if buffer.filename ~= record.filename and buffer._type ~= record.filename or
math.abs(record.line - line) > M.minimum_line_distance then
-- When navigated away from the most recent record, and if that record is
-- not a soft record, jump back to it first, then navigate backwards.
if not record.soft then jump(record) return end
-- Otherwise, update the soft record with the current position and
-- immediately navigate backwards.
M.record(record.filename, nil, nil, record.soft)
end
if history.pos > 1 then history.pos = history.pos - 1 end
jump(history[history.pos])
end
---
-- Navigates forwards through the current view's history.
-- @name forward
function M.forward()
local history = view_history[view]
if history.pos == #history then return end -- nothing to do
local record = history[history.pos]
if record.soft then M.record(record.filename, nil, nil, record.soft) end
history.pos = history.pos + 1
jump(history[history.pos])
end
---
-- Records the given location in the current view's history.
-- @param filename Optional string filename, buffer type, or identifier of the
-- buffer to store. If `nil`, uses the current buffer.
-- @param line Optional Integer line number to store. If `nil`, uses the current
-- line.
-- @param column Optional integer column number on line *line* to store. If
-- `nil`, uses the current column.
-- @param soft Optional flag that indicates whether or not this record should be
-- skipped when navigating backward towards it, and updated when navigating
-- away from it. The default value is `false`.
-- @name record
function M.record(filename, line, column, soft)
if not assert_type(filename, 'string/nil', 1) then
filename = buffer.filename or buffer._type or _L['Untitled']
end
if not assert_type(line, 'number/nil', 2) then
line = buffer:line_from_position(buffer.current_pos)
end
if not assert_type(column, 'number/nil', 3) then
column = buffer.column[buffer.current_pos]
end
local history = view_history[view]
if #history > 0 then
local record = history[history.pos]
if filename == record.filename and
(math.abs(record.line - line) <= M.minimum_line_distance or
record.soft) then
-- If the most recent record is close enough (distance-wise), or if that
-- record is a soft record, update it instead of recording a new one.
record.line, record.column = line, column
record.soft = soft and record.soft
return
end
end
if history.pos < #history then
for i = history.pos + 1, #history do history[i] = nil end -- clear forward
end
history[#history + 1] = {
filename = filename, line = line, column = column, soft = soft
}
if #history > M.maximum_history_size then table.remove(history, 1) end
history.pos = #history
end
-- Softly record positions when switching between buffers.
local function record_switch()
if not jumping then M.record(nil, nil, nil, true) end
end
events.connect(events.BUFFER_BEFORE_SWITCH, record_switch)
events.connect(events.BUFFER_AFTER_SWITCH, record_switch)
events.connect(events.FILE_OPENED, record_switch)
---
-- Clears all view history.
-- @name clear
function M.clear()
for view in pairs(view_history) do view_history[view] = {pos = 0} end
end
return M
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