Delete function.

manual.md

@@ -376,7 +376,7 @@ Parameter:
 - "start_condition" is a string that has the name of the nonterminal where is the start condition, or nil that means "main".
 
 Return:
-- false if the phrase syntax fail to add into the instance due to some errors.
+- ID for the syntax added into the phrase, or nil if the phrase syntax fail to add into the phrase generator due to some errors.
 
 Errors:
 - Invalid parameter error if the parameter is neither a string or a compiled data.
@@ -386,6 +386,19 @@ Errors:
 Note:
 - output_error() and output_compile_error() is called if some errors are detected.
 
+### delete(self, id)
+
+It deletes a phrase syntax from the instance.
+
+Parameter:
+- "id" is the ID for the phrase syntax to delete from the instance.
+
+Return:
+- true if the syntax is deleted.
+
+Note:
+- This is an O(n) function, because it's assumed that the function is not used frequently.
+
 ### generate(self, ext_context)
 
 It generates a phrase text.

scripts/phrase.lua

@@ -59,7 +59,7 @@ end
    param: text_or_compiled  A text or a compiled data of the phrase syntax.
           start_condition  A string that has the name of the nonterminal where is the start condition, or nil that means "main".
 
-   return: false if the phrase syntax fail to add into the phrase generator due to some errors.
+   return: ID for the syntax added into the phrase, or nil if the phrase syntax fail to add into the phrase generator due to some errors.
 
    note: output_error() and output_compile_error() is if when some errors are detected.
 --]]
@@ -74,7 +74,7 @@ function phrase:add(text_or_compiled, start_condition)
       syntax = text_or_compiled.data:clone()
    else
       phrase.output_error("Invalid parameter type.\n")
-      return false
+      return nil
    end
    if err_msg == "" then
       if start_condition == nil then
@@ -87,12 +87,25 @@ function phrase:add(text_or_compiled, start_condition)
    end
    if err_msg ~= "" then
       self.output_compile_error(text, err_msg)
-      return false
+      return nil
    else
-      return true
+      return syntax
    end
 end
 
+--[[
+   Delete the phrase syntax from the instance.
+
+   param: ID for the syntax.
+
+   return: true if the syntax is deleted.
+
+   note: This is an O(n) function, because it's assumed that the function is not used frequently.
+--]]
+function phrase:delete(id)
+   return self.data:delete(id)
+end
+
 --[[
    Generate a phrase.
 

scripts/phrase/data.lua

@@ -661,6 +661,7 @@ end
    .generate(): generate a text.
 
    .add(): add a syntax into the phrase.
+   .delete(): delete a syntax into the phrase.
    .equalize_chance(): Equalize the chance to select each phrase syntax.
    .get_number_of_syntax(): The number of the syntaxes in the phrase.
    .get_weight(): The sum of the weight of the syntaxes.
@@ -710,6 +711,29 @@ function data.new_phrase_data ()
       return true
    end
 
+   phrase.delete = function (self, id)
+      local deleted = false
+      local sum = 0.0
+      for i, v in ipairs(self.syntaxes) do
+         if deleted then
+            self.syntaxes[i - 1] = self.syntaxes[i]
+            sum = sum + self.syntaxes[i - 1]:get_weight()
+            self.weights[i - 1] = sum
+         elseif v == id then
+            deleted = true
+            if i >= 2 then
+               sum = self.weights[i - 1]
+            end
+         end
+      end
+      if deleted then
+         local last = #self.syntaxes
+         self.syntaxes[last] = nil
+         self.weights[last] = nil
+      end
+      return deleted
+   end
+
    phrase.equalize_chance = function (self, enable)
       if enable == nil then
          self.equalized_chance = true

test/test_functions.lua

@@ -239,6 +239,108 @@ function test_functions.run_test()
          ph:generate() == "2"
    end
 
+   function tests.phrase_delete_first()
+      ut:set_random_sequence({ 0.9, 0.9, 0.9, 0.9, 0.9, 0.9 })
+      local ph = phrase.new()
+      local id1 = ph:add([[main = "1" 2 | 2 | 3]])
+      local id2 = ph:add([[main = A | "B" 3 | C]])
+      local id3 = ph:add([[main = あ | い | "う" 4]])
+      local r3 = ph:generate()
+      local n3 = ph:get_number_of_syntax()
+      local c3 = ph:get_combination_number()
+      local w3 = ph:get_weight()
+      local del3 = ph:delete(id1)
+      local r2 = ph:generate()
+      local n2 = ph:get_number_of_syntax()
+      local c2 = ph:get_combination_number()
+      local w2 = ph:get_weight()
+      local del2 = ph:delete(id2)
+      local r1 = ph:generate()
+      local n1 = ph:get_number_of_syntax()
+      local c1 = ph:get_combination_number()
+      local w1 = ph:get_weight()
+      local del1 = ph:delete(id3)
+      local r0 = ph:generate()
+      local n0 = ph:get_number_of_syntax()
+      local c0 = ph:get_combination_number()
+      local w0 = ph:get_weight()
+      return
+         del1 and del2 and del3 and
+         id1 and id2 and id3 and
+         r3 == "う" and r2 == "う" and r1 == "う" and r0 == "nil" and
+         n3 == 3 and n2 == 2 and n1 == 1 and n0 == 0 and
+         c3 == 9 and c2 == 6 and c1 == 3 and c0 == 0 and
+         w3 == 15 and w2 == 11 and w1 == 6 and w0 == 0
+   end
+
+   function tests.phrase_delete_last()
+      ut:set_random_sequence({ 0.9, 0.9, 0.9, 0.9, 0.9, 0.9 })
+      local ph = phrase.new()
+      local id1 = ph:add([[main = "1" 2 | 2 | 3]])
+      local id2 = ph:add([[main = A | "B" 3 | C]])
+      local id3 = ph:add([[main = あ | い | "う" 4]])
+      local r3 = ph:generate()
+      local n3 = ph:get_number_of_syntax()
+      local c3 = ph:get_combination_number()
+      local w3 = ph:get_weight()
+      local del3 = ph:delete(id3)
+      local r2 = ph:generate()
+      local n2 = ph:get_number_of_syntax()
+      local c2 = ph:get_combination_number()
+      local w2 = ph:get_weight()
+      local del2 = ph:delete(id2)
+      local r1 = ph:generate()
+      local n1 = ph:get_number_of_syntax()
+      local c1 = ph:get_combination_number()
+      local w1 = ph:get_weight()
+      local del1 = ph:delete(id1)
+      local r0 = ph:generate()
+      local n0 = ph:get_number_of_syntax()
+      local c0 = ph:get_combination_number()
+      local w0 = ph:get_weight()
+      return
+         del1 and del2 and del3 and
+         id1 and id2 and id3 and
+         r3 == "う" and r2 == "C" and r1 == "3" and r0 == "nil" and
+         n3 == 3 and n2 == 2 and n1 == 1 and n0 == 0 and
+         c3 == 9 and c2 == 6 and c1 == 3 and c0 == 0 and
+         w3 == 15 and w2 == 9 and w1 == 4 and w0 == 0
+   end
+
+   function tests.phrase_delete_middle()
+      ut:set_random_sequence({ 0.9, 0.9, 0.9, 0.9, 0.9, 0.9 })
+      local ph = phrase.new()
+      local id1 = ph:add([[main = "1" 2 | 2 | 3]])
+      local id2 = ph:add([[main = A | "B" 3 | C]])
+      local id3 = ph:add([[main = あ | い | "う" 4]])
+      local r3 = ph:generate()
+      local n3 = ph:get_number_of_syntax()
+      local c3 = ph:get_combination_number()
+      local w3 = ph:get_weight()
+      local del3 = ph:delete(id2)
+      local r2 = ph:generate()
+      local n2 = ph:get_number_of_syntax()
+      local c2 = ph:get_combination_number()
+      local w2 = ph:get_weight()
+      local del2 = ph:delete(id1)
+      local r1 = ph:generate()
+      local n1 = ph:get_number_of_syntax()
+      local c1 = ph:get_combination_number()
+      local w1 = ph:get_weight()
+      local del1 = ph:delete(id3)
+      local r0 = ph:generate()
+      local n0 = ph:get_number_of_syntax()
+      local c0 = ph:get_combination_number()
+      local w0 = ph:get_weight()
+      return
+         del1 and del2 and del3 and
+         id1 and id2 and id3 and
+         r3 == "う" and r2 == "う" and r1 == "う" and r0 == "nil" and
+         n3 == 3 and n2 == 2 and n1 == 1 and n0 == 0 and
+         c3 == 9 and c2 == 6 and c1 == 3 and c0 == 0 and
+         w3 == 15 and w2 == 10 and w1 == 6 and w0 == 0
+   end
+
    function tests.compile_add_1()
       local compiled = phrase.compile()
       local result = compiled:add([[B = 2]])