From ecf1af2d8a42ca698040594327d379b7ffe04560 Mon Sep 17 00:00:00 2001
From: Daniel Silverstone <dsilvers@digital-scurf.org>
Date: Tue, 14 Jul 2015 15:27:53 +0100
Subject: Add support for retrieving the location of a clod key/value pair

---
 lib/clod.lua       | 32 +++++++++++++++++++++++++++++++-
 test/test-clod.lua | 25 +++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/lib/clod.lua b/lib/clod.lua
index 2416a80..ee6cd75 100644
--- a/lib/clod.lua
+++ b/lib/clod.lua
@@ -397,6 +397,36 @@ function methods:set_list(prefix, list)
    end
 end
 
+---
+-- Get the location of a given setting
+--
+-- Find where a given key is defined in the clod source.  Note that if
+-- you have added a new key, or removed an old key, since loading then
+-- you may not be able to retrieve data for those entries.
+--
+-- Also, note that this function will always return the original line number
+-- of an entry, which is not necessarily where the entry would be in a new
+-- serialisation if changes have been made.
+--
+-- @function locate
+-- @tparam string key The name of the key to locate
+-- @treturn number-or-false The line number that key is defined on, or nil.
+-- @treturn[opt] string The reason for the nil return
+function methods:locate(key)
+   local meta = metadata[self].settings
+   if meta[key] then
+      if meta[key].original_lineno then
+	 return meta[key].original_lineno
+      end
+      return nil, "Key is new, rather than from the input"
+   end
+   for k in pairs(meta) do
+      if k:sub(1,#key) == key then
+	 return nil, "Ambiguous key prefix"
+      end
+   end
+   return nil, "Not found"
+end
 ---
 -- The settings in this `clodfile` instance.
 --
@@ -462,7 +492,7 @@ local function parse_config(conf, confname, migrate_lists)
          key = calculate_wild_key({settings=settings}, wild_prefix)
       end
       local curline = getinfo(2 + (offset or 0), "Snlf").currentline
-      local entry = { key = key, value = value, lineno = curline }
+      local entry = { key = key, value = value, lineno = curline, original_lineno = curline }
       while last_entry.lineno < (curline - 1) do
          local empty = { 
             lineno = last_entry.lineno + 1,
diff --git a/test/test-clod.lua b/test/test-clod.lua
index b720ff6..fe18bf6 100644
--- a/test/test-clod.lua
+++ b/test/test-clod.lua
@@ -347,6 +347,31 @@ tab["*"] "world"
    assert(conf:serialise() == output_str)
 end
 
+function suite.locate_inputs()
+   local input_str = [[
+foo "bar"
+baz "meta"
+qux "fish"
+]]
+   local conf = assert(clod.parse(input_str, "@str", true))
+   assert(conf:locate("foo") == 1)
+   assert(conf:locate("baz") == 2)
+   assert(conf:locate("qux") == 3)
+end
+
+function suite.locate_inputs_even_after_delete()
+   local input_str = [[
+foo "bar"
+baz "meta"
+qux "fish"
+]]
+   local conf = assert(clod.parse(input_str, "@str", true))
+   assert(conf:locate("foo") == 1)
+   conf.settings["baz"] = nil
+   assert(conf:locate("qux") == 3)
+end
+
+
 local count_ok = 0
 for _, testname in ipairs(testnames) do
 --   print("Run: " .. testname)
-- 
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