add basic include-code.lua script

fixtures/inc.sql

@@ -0,0 +1,3 @@
+DROP SCHEMA IF EXISTS maryam CASCADE;
+
+CREATE SCHEMA maryam;

fixtures/include-code.md

@@ -0,0 +1,9 @@
+
+```{.sql include=fixtures/inc.sql ranges=2-$ }
+will be removed by include
+```
+
+```sql
+SELECT * FROM source;
+```
+

include-code.lua

@@ -0,0 +1,58 @@
+local system = require 'pandoc.system'
+
+local function get_file(filename)
+    local sysdir = system.get_working_directory()
+    for k,v in pairs(PANDOC_STATE.resource_path) do
+      local path = sysdir.."/"..v.."/"..filename
+      local f = io.open(path, "r")
+      if f ~= nil then
+        return f
+      else
+        io.stderr:write(string.format("file not found, content of code block not replaced: %s", filename))
+        return nil
+      end
+    end
+end
+
+local function get_content(file, ranges)
+  if ranges == nil then
+    return file:read "*a"
+  end
+  print(ranges)
+
+  local intervals = {}
+  for interval in ranges:gmatch('[^,%s]+') do
+    table.insert(intervals, interval)
+  end
+
+  local current_line = 0
+  for k, interval in pairs(intervals) do
+    print("handling interval", interval)
+    local first = 0
+    local last  = 0
+    -- inspect interval
+      if string.find(interval, '-') then
+        -- we have an interval
+        first, last = interval:match("([0-9]+)-([0-9]+)")
+        print(first, last)
+      end
+  end
+
+  return ""
+end
+
+
+function CodeBlock(elem)
+  if (elem.attributes['include'] ~= nil) then
+    local filename = elem.attributes['include']
+    local f = get_file(filename)
+
+    if (f == nil) then
+      return elem
+    end
+
+    elem.text = get_content(f, elem.attributes['ranges'])
+    io.close(f)
+  end
+  return elem
+end