Added plugin `detectindent.lua`

1 files changed, 64 insertions, 0 deletions

diff --git a/plugins/detectindent.lua b/plugins/detectindent.lua
new file mode 100644
index 0000000..9c473b5
--- /dev/null
+++ b/plugins/detectindent.lua
@@ -0,0 +1,64 @@
+local core = require "core"
+local command = require "core.command"
+local config = require "core.config"
+local DocView = require "core.docview"
+local Doc = require "core.doc"
+
+local cache = setmetatable({}, { __mode = "k" })
+
+
+local function detect_indent(doc)
+  for _, text in ipairs(doc.lines) do
+    local str = text:match("^  +")
+    if str then return "soft", #str end
+    local str = text:match("^\t+")
+    if str then return "hard" end
+  end
+end
+
+
+local function update_cache(doc)
+  local type, size = detect_indent(doc)
+  if type then
+    cache[doc] = { type = type, size = size }
+  end
+end
+
+
+local new = Doc.new
+function Doc:new(...)
+  new(self, ...)
+  update_cache(self)
+end
+
+local clean = Doc.clean
+function Doc:clean(...)
+  clean(self, ...)
+  update_cache(self)
+end
+
+
+local function with_indent_override(doc, fn, ...)
+  local c = cache[doc]
+  if not c then
+    return fn(...)
+  end
+  local type, size = config.tab_type, config.indent_size
+  config.tab_type, config.indent_size = c.type, c.size or config.indent_size
+  local r1, r2, r3 = fn(...)
+  config.tab_type, config.indent_size = type, size
+  return r1, r2, r3
+end
+
+
+local perform = command.perform
+function command.perform(...)
+  return with_indent_override(core.active_view.doc, perform, ...)
+end
+
+
+local draw = DocView.draw
+function DocView:draw(...)
+  return with_indent_override(self.doc, draw, self, ...)
+end
+