Initial markdown support

Markdown doesnt have a language server, so do this manually
Closes #43

lua/symbols-outline.lua

@@ -5,6 +5,7 @@ local ui = require('symbols-outline.ui')
 local writer = require('symbols-outline.writer')
 local config = require('symbols-outline.config')
 local utils = require('symbols-outline.utils.lsp_utils')
+local markdown = require('symbols-outline.markdown')
 
 local M = {}
 
@@ -58,12 +59,14 @@ end
 
 function M._refresh()
     if M.state.outline_buf ~= nil then
-        vim.lsp.buf_request_all(0, "textDocument/documentSymbol", getParams(),
-                                function(response)
+        local function refresh_handler(response)
             if response == nil or type(response) ~= 'table' then
                 return
             end
-            if not utils.is_buf_attached_to_lsp(vim.api.nvim_get_current_buf()) then
+
+            local current_buf = vim.api.nvim_get_current_buf()
+            if (not utils.is_buf_markdown(current_buf)) and
+                (not utils.is_buf_attached_to_lsp(current_buf)) then
                 return
             end
 
@@ -75,7 +78,13 @@ function M._refresh()
 
             writer.parse_and_write(M.state.outline_buf,
                                    M.state.flattened_outline_items)
-        end)
+        end
+
+        if vim.api.nvim_buf_get_option(0, 'ft') == 'markdown' then
+            refresh_handler(markdown.handle_markdown())
+        end
+        vim.lsp.buf_request_all(0, "textDocument/documentSymbol", getParams(),
+                                refresh_handler)
     end
 end
 
@@ -96,7 +105,10 @@ function M._highlight_current_item(winnr)
 
     local doesnt_have_outline_buf = not M.state.outline_buf
 
-    local should_exit = doesnt_have_lsp or doesnt_have_outline_buf or
+    local is_not_markdown = not utils.is_buf_markdown(0)
+
+    local should_exit = (doesnt_have_lsp and is_not_markdown) or
+                            doesnt_have_outline_buf or
                             is_current_buffer_the_outline
 
     -- Make a special case if we have a window number
@@ -250,15 +262,17 @@ end
 
 function M.toggle_outline()
     if M.state.outline_buf == nil then
-        vim.lsp.buf_request_all(0, "textDocument/documentSymbol", getParams(),
-                                handler)
+        M.open_outline()
     else
-        vim.api.nvim_win_close(M.state.outline_win, true)
+        M.close_outline()
     end
 end
 
 function M.open_outline()
     if M.state.outline_buf == nil then
+        if vim.api.nvim_buf_get_option(0, 'ft') == 'markdown' then
+            handler(markdown.handle_markdown())
+        end
         vim.lsp.buf_request_all(0, "textDocument/documentSymbol", getParams(),
                                 handler)
     end

lua/symbols-outline/config.lua

@@ -65,9 +65,7 @@ function M.get_position_navigation_direction()
     end
 end
 
-function M.get_width_percentage()
-    return M.options.width / 100
-end
+function M.get_width_percentage() return M.options.width / 100 end
 
 function M.get_split_command()
     if M.options.position == 'left' then
@@ -90,6 +88,7 @@ end
 
 function M.is_client_blacklisted(client_id)
     local client = vim.lsp.get_client_by_id(client_id)
+    if not client then return false end
     return has_value(M.options.lsp_blacklist, client.name)
 end
 

lua/symbols-outline/markdown.lua

@@ -0,0 +1,37 @@
+local M = {}
+
+---Parses markdown files and returns a table of SymbolInformation[] which is
+-- used by the plugin to show the outline.
+-- We do this because markdown does not have a LSP.
+-- Note that the headings won't have any heirarchy (as of now).
+---@return table
+function M.handle_markdown()
+    local lines = vim.api.nvim_buf_get_lines(0, 0, -1, false)
+    local results = {}
+
+    for line, value in ipairs(lines) do
+        if string.find(value, "^#+") then
+            if #results > 0 then
+               results[#results].selectionRange["end"].line = line - 1
+               results[#results].range["end"].line = line - 1
+            end
+
+            table.insert(results, {
+                kind = 13,
+                name = value,
+                selectionRange = {
+                    start = {character = 1, line = line - 1},
+                    ["end"] = {character = 1, line = line - 1}
+                },
+                range = {
+                    start = {character = 1, line = line - 1},
+                    ["end"] = {character = 1, line = line - 1}
+                }
+            })
+        end
+    end
+
+    return {[1000000]={result=results}}
+end
+
+return M

lua/symbols-outline/utils/lsp_utils.lua

@@ -7,4 +7,8 @@ function M.is_buf_attached_to_lsp(bufnr)
     return clients ~= nil and #clients > 0
 end
 
+function M.is_buf_markdown(bufnr)
+   return vim.api.nvim_buf_get_option(bufnr, 'ft') == 'markdown'
+end
+
 return M