Add hooks to define the source per buffer in mini.diff

[nicoe]

Contributing guidelines

• I have read CONTRIBUTING.md
• I have read CODE_OF_CONDUCT.md

Module(s)

mini.diff

Description

I started to use mini.diff and it works great, thanks for all the work!

In my job, I'm using both mercurial and git, so I quickly felt the need to have a source for mercurial.
But I didn't found a way to select the right source from the detected VCS managing the file in the buffer.

I ended up creating a source that is handling both but I find it quite ugly. I wonder if it wouldn't be interesting to plug a function somewhere so that the source used by the buffer can be programmatically decided.

For the record here is what I've written (it might be useful to someone) but it's a quick hack and this is nearly my first time writing some lua so I've probably made a lot of mistakes :)

    {
        "echasnovski/mini.diff",
        version=false,
        opts = function(_, opts)
            local MiniDiff = require("mini.diff")
            local git_hg = { name = 'git_hg' }
            local git_source = MiniDiff.gen_source.git()

            git_or_hg = function(path)
                local vcs = { type = nil }
                local cwd = vim.fn.fnamemodify(path, ':h')
                local hg_run = vim.system({ 'hg', 'root' }, { cwd = cwd, stdin = false, stdout = false, stderr = false }):wait()
                local git_run = vim.system({ 'git', 'rev-parse' }, { cwd = cwd, stdin = false, stdout = false, stderr = false }):wait()
                if hg_run.code == 0 then
                    return 'hg'
                elseif git_run.code == 0 then
                    return 'git'
                else
                    return nil
                end
            end

            git_hg.attach = function(buf_id)
                local path = vim.api.nvim_buf_get_name(buf_id)
                if path == '' or vim.fn.filereadable(path) ~= 1 then return false end
                local vcs = git_or_hg(path)
                if vcs == 'git' then
                    git_source.attach(buf_id)
                elseif vcs == 'hg' then
                    local p, stdout_feed = nil, {}
                    local on_exit = function(exit_code)
                        p:close()
                        if exit_code ~= 0 or stdout_feed[1] == nil then
                            vim.schedule_wrap(function()
                                MiniDiff.disable(buf_id)
                            end)()
                            return
                        end
                        vim.schedule_wrap(function()
                            MiniDiff.set_ref_text(buf_id, table.concat(stdout_feed, ''))
                        end)()
                    end
                    local stdout = vim.uv.new_pipe()
                    p = vim.uv.spawn('hg', { args = { 'cat', '--rev', 's0', path }, stdio = { nil, stdout, nil } }, on_exit)

                    local git_read_stream = function(stream, feed)
                        local callback = function(err, data)
                            if data ~= nil then return table.insert(feed, data) end
                            if err then feed[1] = nil end
                            stream:close()
                        end
                        stream:read_start(callback)
                    end
                    git_read_stream(stdout, stdout_feed)
                else
                    vim.schedule_wrap(function()
                        MiniDiff.disable(buf_id)
                    end)()
                end
            end

            git_hg.detach = function(buf_id)
                local path = vim.api.nvim_buf_get_name(buf_id)
                if path == '' or vim.fn.filereadable(path) ~= 1 then return false end
                local vcs = git_or_hg(path)
                if vcs == 'git' then
                    git_source.detach(buf_id)
                end
            end

            return {
                source=git_hg,
            }
        end,
        config = function(_, opts)
            require("mini.diff").setup(opts)
        end,
    },

[echasnovski]

Thanks for the suggestion! Glad you're liking 'mini.diff' so far :)

I ended up creating a source that is handling both but I find it quite ugly. I wonder if it wouldn't be interesting to plug a function somewhere so that the source used by the buffer can be programmatically decided.

Yes, this was the intended solution for this kind of problems. I'll take a look at how this can be made easier, but it will probably happen after the next stable 'mini.nvim' release.