# This file is part of NIT ( http://www.nitlanguage.org ).
#
-# Copyright 2013-2014 Alexis Laferrière <alexis.laf@xymus.net>
-#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Business logic of a calculator
module calculator_logic
+import json::dynamic
+
+# Hold the state of the calculator and its services
class CalculatorContext
+ # Result of the last operation
var result: nullable Numeric = null
+ # Last operation pushed with `push_op`, to be executed on the next push
var last_op: nullable Char = null
+ # Value currently being entered
var current: nullable FlatBuffer = null
+
+ # Text to display on screen
fun display_text: String
do
var result = result
return buf.to_s
end
- fun push_op( op : Char )
+ # Push operation `op`, will usually execute the last operation
+ fun push_op(op: Char)
do
apply_last_op_if_any
if op == 'C' then
self.current = null
end
- fun push_digit( digit : Int )
+ # Push a digit
+ fun push_digit(digit: Int)
do
var current = current
if current == null then current = new FlatBuffer
end
end
+ # Switch entry mode from integer to decimal
fun switch_to_decimals
do
var current = current
self.current = current
end
- fun apply_last_op_if_any
+ # Execute the last operation it not null
+ protected fun apply_last_op_if_any
do
var op = last_op
else if op == '*' then
result = result.mul(current.to_n)
end
+
self.result = result
self.current = null
end
+
+ # Serialize calculator state to Json
+ fun to_json: String
+ do
+ # Do not save NaN nor inf
+ var result = self.result
+ if result != null and (result.to_f.is_nan or result.to_f.is_inf != 0) then result = null
+
+ var self_last_op = self.last_op
+ var last_op
+ if self_last_op == null then
+ last_op = "null"
+ else last_op = "\"{self_last_op}\""
+
+ var self_current = self.current
+ var current
+ if self_current == null then
+ current = "null"
+ else current = "\"{self_current}\""
+
+ return """
+{
+ "result": {{{result or else "null"}}},
+ "last_op": {{{last_op}}},
+ "current": {{{current}}}
+}"""
+ end
+
+ # Load calculator state from Json
+ init from_json(json_string: String)
+ do
+ var json = json_string.to_json_value
+ if json.is_error then
+ print "Loading state failed: {json.to_error}"
+ return
+ end
+
+ var result = json["result"]
+ if result.is_numeric then self.result = result.to_numeric
+
+ var last_op = json["last_op"]
+ if last_op.is_string then self.last_op = last_op.to_s.chars.first
+
+ var current = json["current"]
+ if current.is_string then self.current = new FlatBuffer.from(current.to_s)
+ end
end
redef universal Float