add lists support to babycode

lib/babycode.lua

@@ -1,16 +1,82 @@
 local babycode = {}
 
+local string_trim = require("lapis.util").trim
+
+local function s_split(s, delimiter, max_matches, trim, allow_empty)
+  local result = {}
+  if s == "" then
+    return result
+  end
+  trim = trim == nil and true or trim
+  local tr = function(subj)
+    if trim then return string_trim(subj) else return subj end
+  end
+  max_matches = max_matches or -1
+  allow_empty = allow_empty == nil and true or allow_empty
+  
+  if delimiter == "" then
+    for i=1, #s do
+      local c = s:sub(i, 1)
+      if allow_empty or c ~= "" then
+        table.insert(result, c)
+        if max_matches > 0 and #result == max_matches then
+          break
+        end
+      end
+    end
+    return result
+  end
+  
+  local current_pos = 1
+  local delim_len = #delimiter
+  
+  while true do
+    if max_matches > 0 and #result >= max_matches then
+      break
+    end
+---@diagnostic disable-next-line: param-type-mismatch
+    local start_pos, end_pos = s:find(delimiter, current_pos, true)
+    if not start_pos then
+      break
+    end
+    local substr = s:sub(current_pos, start_pos - 1)
+    if allow_empty or substr ~= "" then
+      table.insert(result, tr(substr))
+    end
+    current_pos = end_pos + 1
+  end
+  
+  local substr = s:sub(current_pos)
+  if allow_empty or substr ~= "" then
+    table.insert(result, tr(substr))
+  end
+  
+  return result
+end
+
+local function get_list_items(list_body, escape_html)
+  list_body = list_body:gsub("  +%s*\r?\n", "<br>")
+  list_body = list_body:gsub("(%S)(\r?\n\r?\n)\r?\n*", "%1\1")
+  local list_items = s_split(list_body, "\1")
+  local lis = ""
+  for _, li in ipairs(list_items) do
+    local rendered = babycode.to_html(li, escape_html)
+    lis = lis .. "<li>" .. rendered .. "</li>"
+  end
+  return lis
+end
+
 ---renders babycode to html
 ---@param s string input babycode
 ---@param escape_html fun(s: string): string function that escapes html
 function babycode.to_html(s, escape_html)
   if not s or s == "" then return "" end
-  -- extract code blocks first and store them as placeholders
+  local text = escape_html(s)
+  -- extract code blocks and store them as placeholders
   -- don't want to process bbcode embedded into a code block
   local code_blocks = {}
   local inline_codes = {}
-  s = escape_html(s)
-  local text = s:gsub("%[code%](.-)%[/code%]", function(code)
+  text = text:gsub("%[code%](.-)%[/code%]", function(code)
     local is_inline = code:match("\n") == nil
     if is_inline then
       table.insert(inline_codes, code)
@@ -23,10 +89,17 @@ function babycode.to_html(s, escape_html)
     end
   end)
   
-  text = text:gsub("  %s?\r?\n", "<br>")
-  -- normalize newlines
-  text = text:gsub("\r?\n\r?\n+", "<br>")
+  text = text:gsub("%[ul%](.-)%[/ul%]", function(list_body)
+    return "<ul>" .. get_list_items(list_body, escape_html) .. "</ul>"
+  end)
+  text = text:gsub("%[ol%](.-)%[/ol%]", function(list_body)
+    return "<ol>" .. get_list_items(list_body, escape_html) .. "</ol>"
+  end)
   
+  -- normalize newlines, attempt #4
+  text = text:gsub("  +%s*\r?\n", "<br>")
+  text = text:gsub("(%S)(\r?\n\r?\n)\r?\n*", "%1<br><br>")
+
   local url_tags = {}
   -- replace `[url=https://example.com]Example[/url] tags
   text = text:gsub("%[url=([^%]]+)%](.-)%[/url%]", function(url, label)
@@ -40,8 +113,6 @@ function babycode.to_html(s, escape_html)
   text = text:gsub("%[s%](.-)%[/s%]", "<del>%1</del>")
   
   -- these can be nested, so replace open and closed separately
-  -- text = text:gsub("%[quote%]", "<blockquote>")
-  -- text = text:gsub("%[/quote%]", "</blockquote>")
   text = text:gsub("%[(/?)quote%]", "<%1blockquote>")
 
   -- replace loose links