Added the ability to do arithmetic on symbolic names :)

lib/n65/directives/bytes.rb

@@ -46,7 +46,7 @@ module N65
 
 
     ####
-    ##  Initialize with filename
+    ##  Initialize with a byte array
     def initialize(bytes_array)
       @bytes_array = bytes_array
     end
@@ -62,7 +62,7 @@ module N65
           when Fixnum
             byte
           when String
-            value = saved_assembler.symbol_table.resolve_symbol(byte)
+            saved_assembler.symbol_table.resolve_symbol(byte)
           else
             fail(InvalidByteValue, byte)
           end

lib/n65/regexes.rb

@@ -22,7 +22,7 @@ module N65
     Immediate  = "\##{Num8}"
 
     ##  Symbols, must begin with a letter, and supports dot syntax
-    Sym       = '([a-zA-Z][a-zA-Z\d_\.]*)'
+    Sym        = '([a-zA-Z][a-zA-Z\d_\.]*(?:[\+\-\*\/]\d+)*)'
 
 
     ##  The X or Y register

lib/n65/symbol_table.rb

@@ -56,10 +56,30 @@ module N65
 
 
     ####
-    ##
+    ##  Separate arithmetic from scope name
+    def find_arithmetic(name)
+      last_name = name.split('.').last
+      md = last_name.match(/([\+\-\*\/])(\d+)$/)
+      f = lambda{|v| v}
+
+      unless md.nil?
+        full_match, operator, argument = md.to_a
+        name.gsub!(full_match, '')
+        f = lambda {|value| value.send(operator.to_sym, argument.to_i) }
+      end
+
+      [name, f]
+    end
+
+
+    ####
+    ##  Resolve a symbol to its value
     def resolve_symbol(name)
+      name, arithmetic = find_arithmetic(name)
+
       method = name.include?('.') ? :resolve_symbol_dot_syntax : :resolve_symbol_scoped
       value = self.send(method, name)
+      value = arithmetic.call(value)
 
       fail(UndefinedSymbol, name) if value.nil?
       value

lib/n65/version.rb

@@ -1,3 +1,3 @@
 module N65
-  VERSION ||= "1.1.0"
+  VERSION ||= "1.5.0"
 end

test/test_arithmetic_symbols.rb

@@ -0,0 +1,78 @@
+gem 'minitest'
+require 'minitest/autorun'
+require 'minitest/unit'
+
+require_relative '../lib/n65.rb'
+
+
+class TestArithmeticSymbols < MiniTest::Test
+  include N65
+
+
+  def test_identify_plain_symbol
+    re = Regexp.new(Regexes::Sym)
+    assert_match(re, 'dog')
+    assert_match(re, 'animal.dog')
+    assert_match(re, 'global.animal.dog')
+  end
+
+
+  def test_symbol_values
+    st = SymbolTable.new
+    st.define_symbol('variable', 0xff)
+    assert_equal(0xff, st.resolve_symbol('variable'))
+  end
+
+
+  def test_perform_symbolic_arithmetic
+    st = SymbolTable.new
+    st.define_symbol('variable', 0x20)
+    assert_equal(0x21, st.resolve_symbol('variable+1'))
+    assert_equal(0x40, st.resolve_symbol('variable*2'))
+  end
+
+
+  def test_symbol_addition
+    program = <<-ASM
+    .ines {"prog": 1, "char": 0, "mapper": 0, "mirror": 0}
+
+    .org $0020
+    .scope struct
+      .space a 1
+      .space b 1
+    .
+
+    .org $8000
+    .scope main
+      sei
+      cld
+      lda struct+1 zp
+      lda struct*2 zp
+      rts
+    .
+    ASM
+
+    assembler = Assembler.new
+    program.split(/\n/).each do |line|
+      assembler.assemble_one_line(line)
+    end
+    assembler.fulfill_promises
+
+    binary = assembler.emit_binary_rom[16...23].split(//).map(&:ord)
+
+    ##  So yay, arithmetic on symbols works now :)
+    correct = [
+      0x78,         #  sei
+      0xd8,         #  cld
+      0xa5,         #  lda
+      0x21,         #  $20 + 1
+      0xa5,         #  lda
+      0x40,         #  $20 * 2
+      0x60          #  rts
+    ]
+    assert_equal(binary, correct)
+  end
+
+
+end
+

test/test_symbol_table.rb

@@ -74,7 +74,7 @@ class TestSymbolTable < MiniTest::Test
 
   ####
   ##  Test exiting a sub scope, and being able to access a symbol through a full path
-  def test_exit_scope
+  def test_exit_scope_full_path
     st = SymbolTable.new
     st.enter_scope('animals')
     st.define_symbol('dog', 'woof')