feat: add utility function to write data in path

src/lua/zencode_data.lua

@@ -672,3 +672,102 @@ function apply_encoding(src_name, src_enc, dest_enc)
   if not f_dest_enc then error("Destination encoding format not found: "..dest_enc, 2) end
   return deepmap(f_dest_enc.fun, encoded_src)
 end
+
+-- READ and WRITE to ACK memory
+
+-- extract an element from deep down
+-- works both in IN and ACK memory
+-- @param path path to variable separated by points
+-- @return element found following the path
+-- @return name of the destination
+function read_from_path(path, no_dest)
+  local path_array = strtok(uscore(path), CONF.path.separator)
+  local root = path_array[1]
+  table.remove(path_array, 1)
+  local dest = path_array[#path_array]
+  if not no_dest then empty(dest) end
+  -- should works both in given and when phase
+  -- IN is checked firstly since in the When phase IN will be empty
+  local res = IN[root] or ACK[root]
+  for _,v in pairs(path_array) do
+      zencode_assert(luatype(res) == 'table', "Object is not a table: "..root)
+      if res[v] == nil then
+          local v_number = tonumber(v)
+          zencode_assert(v_number and res[v_number] ~= nil, "Key "..v.." not found in "..root)
+          res = res[v_number]
+      else
+          res = res[v]
+      end
+      root = v
+  end
+  return res, dest
+end
+
+-- set an element deep down
+-- @param path to dest separated by points
+-- @param value to set in path
+function write_to_path(path, value)
+  local path_array <const> = strtok(uscore(path), CONF.path.separator)
+  if #path_array == 0 then
+      error("write_to_path path input is empty", 2)
+  end
+  local current_path = ""
+  local current = ACK
+
+  for i = 1, #path_array - 1 do
+      local raw_key = path_array[i]
+      local key = tonumber(raw_key) or raw_key
+      current_path = fif(i == 1, "", current_path .. ".") .. raw_key
+
+      -- Current must always be a table
+      if luatype(current) ~= "table" then
+          error("Path error at segment '" .. current_path .. "': not a table")
+      end
+      -- Handle array case
+      if luatype(key) == "number" then
+          local arr_length = isarray(current)
+          if not arr_length then
+              error("Path error at '" .. current_path .. "': expected array, found " .. luatype(current[key]))
+          end
+          if current[key] == nil then
+              if key ~= arr_length + 1 then
+                  error("Invalid array index at '" .. current_path .. "': expected position between 1 and " .. (arr_length + 1))
+              end
+              current[key] = {}
+          end
+      else
+          if current[key] ~= nil then
+              local ltc <const> = luatype(current[key])
+              if ltc ~= "table" then
+                  error("Path conflict at '" .. current_path .. "': expected table, found " .. ltc)
+              end
+          else
+              current[key] = {}
+          end
+      end
+      current = current[key]
+  end
+
+  local final_raw = path_array[#path_array]
+  local final_key = tonumber(final_raw) or final_raw
+  current_path = current_path.."."..final_raw
+
+  if luatype(current) ~= "table" then
+      error("Cannot assign at path '" .. current_path .. "': parent is not a table")
+  end
+  -- Make sure to not overwrite existing value
+  if current[final_key] ~= nil then
+      error("Cannot overwrite existing value at path '" .. current_path .. "'")
+  end
+  -- Final value: if it's an array index, make sure it's next free position
+  if luatype(final_key) == "number" then
+      local arr_length = isarray(current)
+      if not arr_length then
+          error("Path error at '" .. current_path .. "': expected array, found " .. luatype(current))
+      end
+      if final_key ~= arr_length + 1 then
+          error("Invalid array index at '" .. current_path .. "': expected position " .. (arr_length + 1))
+      end
+  end
+  current[final_key] = value
+end

src/lua/zencode_given.lua

@@ -445,15 +445,15 @@ Given("'' part of '' before string suffix ''", function(enc, src, sfx_name)
 end)
 
 Given("'' in path ''", function(enc, path)
-    local ele_from_path, dest = pick_from_path(path)
+    local ele_from_path, dest = read_from_path(path)
     ZEN.TMP = guess_conversion(ele_from_path, enc)
     ZEN.TMP.name = dest
     ack(dest)
     gc()
 end)
 
 Given("'' part of path '' after string prefix ''", function(enc, path, pfx_name)
-          local ele_from_path, dest = pick_from_path(path)
+          local ele_from_path, dest = read_from_path(path)
           local pfx = IN[pfx_name] or pfx_name
           local plen = #pfx
           elelen = #ele_from_path
@@ -470,7 +470,7 @@ end)
 
 
 Given("'' part of path '' before string suffix ''", function(enc, path, sfx_name)
-          local ele_from_path, dest = pick_from_path(path)
+          local ele_from_path, dest = read_from_path(path)
           local sfx = IN[sfx_name] or sfx_name
           local slen = #sfx
           elelen = #ele_from_path

src/lua/zencode_math.lua

@@ -150,7 +150,7 @@ local function _rpn_eval(rpn)
                 res = v
             else
                 -- handle path divided by conf separator in value name
-                res = pick_from_path(v, true)
+                res = read_from_path(v, true)
             end
         end
         insert(values, res)

src/lua/zencode_merkle.lua

@@ -23,7 +23,7 @@
 local MT = require'crypto_merkle'
 
 local function _zencode_merkle_root(name, hashtype)
-    local data = pick_from_path(name, true)
+    local data = read_from_path(name, true)
     if not data or type(data) ~= 'table' then
         error("Table not found in path: "..name, 2)
     end
@@ -39,7 +39,7 @@ When("create merkle root of dictionary path '' using hash ''", _zencode_merkle_r
 -- Function to verify the integrity of a Merkle root
 local function _verify_merkle_root(root, name)
     local merkle_root = have(root)
-    local data_table = pick_from_path(name, true)
+    local data_table = read_from_path(name, true)
     if not data_table or type(data_table) ~= 'table' then
         error("Table not found in path: "..name, 2)
     end

src/lua/zencode_table.lua

@@ -255,7 +255,7 @@ end)
 
 local function take_out_f(path, dest, format)
     if dest then path = path..CONF.path.separator..dest end
-    local ele <const>, dest <const> = pick_from_path(path)
+    local ele <const>, dest <const> = read_from_path(path)
     ACK[dest] = ele
     if format then
         new_codec(dest, guess_conversion(ACK[dest], format))

src/lua/zencode_when.lua

@@ -116,6 +116,13 @@ When("write string '' in ''", function(content, dest)
 			   zentype = 'e' })
 end)
 
+When("write string '' in path ''", function(content, dest_path)
+    local maybe = mayhave(dest_path)
+    local path = maybe and maybe:octet():string() or dest_path
+    have(string.match(path, "^[^%.]+"))
+    write_to_path(path, O.from_string(content))
+end)
+
 -- ... and from a number
 When("write number '' in ''", function(content, dest)
 	empty(dest)

src/lua/zenroom_common.lua

@@ -420,34 +420,6 @@ function zip(...)
     end
 end
 
--- extract an element from deep down
--- works both in IN and ACK memory
--- @param path path to variable separated by points
--- @return element found following the path
--- @return name of the destination
-function pick_from_path(path, no_dest)
-    local path_array = strtok(uscore(path), CONF.path.separator)
-    local root = path_array[1]
-    table.remove(path_array, 1)
-    local dest = path_array[#path_array]
-    if not no_dest then empty(dest) end
-    -- should works both in given and when phase
-    -- IN is checked firstly since in the When phase IN will be empty
-    local res = IN[root] or ACK[root]
-    for _,v in pairs(path_array) do
-        zencode_assert(luatype(res) == 'table', "Object is not a table: "..root)
-        if res[v] == nil then
-            local v_number = tonumber(v)
-            zencode_assert(v_number and res[v_number] ~= nil, "Key "..v.." not found in "..root)
-            res = res[v_number]
-        else
-            res = res[v]
-        end
-        root = v
-    end
-    return res, dest
-end
-
 -- -- MULTIBASE
 
 -- Unicode, character, encoding, description, status

test/zencode/cookbook_when.bats

@@ -1847,7 +1847,7 @@ Then print 'random dictionary'
 EOF
     save_output when_random_from_table.out.json
     assert_output '{"random_array":[1,3],"random_dictionary":{"str3":"world","str4":"!"},"random_pick":"world"}'
-}  
+}
 
 @test "hash to point on a curve" {
     cat <<EOF | save_asset when_hash_to_point.data.json
@@ -1869,4 +1869,30 @@ Then print 'hash to point ecp'
 EOF
     save_output when_hash_to_point.out.json
     assert_output '{"hash_to_point_ecp":"AxAXy/Tldf0HPLWpeby/p9r5N5KWsRtyOOhupzDyD+zgpiyIM9ET0sBhcfXQyxD2Iw==","hash_to_point_ecp2":"EKDkY8NZoPBUrXbCKuGTfACzGhYjDN1ukN4WFeC1KruGArzmM2GjcNl540ccj1NwBmJripsCB8dKAZdHsPExCa2bd1HXbCvOIlaT0+yvl8Zb+MjzPAuvOs2y9rpKK/+GBGkYvsUr8aoHyijjv34XjG+6APolthn9+RA3p+Eluos5RjoIiPsYcgixpF+8rj4OEWDf3to6w2qomLHGf0lwhEzMZbPZ67zGYXUkJHSR2cGT/jdPufs7M9Havmq0iCiY"}'
-}  
+}
+
+@test "write string in path" {
+    cat <<EOF | save_asset write_string_in_path.data.json
+{
+    "path": "a.b.c.1.1.d",
+    "a": {
+        "b": {
+        }
+    }
+}
+EOF
+    cat <<EOF | zexe write_string_in_path.zen write_string_in_path.data.json
+Given I have a 'string' named 'path'
+Given I have a 'string dictionary' named 'a'
+
+When I write string 'hello' in path 'path'
+When I write string 'hello' in path 'a.b.e'
+When I write string 'hello' in path 'a.b.c.2'
+When I write string 'hello' in path 'a.b.c.1.2'
+
+Then print 'a'
+
+EOF
+    save_output write_string_in_path.out.json
+    assert_output '{"a":{"b":{"c":[[{"d":"hello"},"hello"],"hello"],"e":"hello"}}}'
+}