add support for unary plus/minus

lib/ruby_algebra/expression.rb

@@ -151,23 +151,6 @@ module RubyAlgebra
     end
   end
 
-  class Subtraction < Addition
-    attr_reader :lhs, :rhs
-
-    def to_s
-      need_parentheses_left = lhs.op_priority < op_priority || (lhs.op_priority == op_priority && op_assoc_type == :right)
-      need_parentheses_right = rhs.op_priority < op_priority || (rhs.op_priority == op_priority && op_assoc_type == :left)
-
-      result = need_parentheses_left ? "(#{lhs}) - " : "#{lhs} - "
-      result + (need_parentheses_right ? "(#{rhs})" : rhs.to_s)
-    end
-
-    def type
-      :sub
-    end
-
-  end
-
   class Constant < Expression
     attr_reader :value
 

lib/ruby_algebra/parser.rb

@@ -24,7 +24,7 @@ module RubyAlgebra
       end
     end
 
-    class OperatorToken < Token
+    class BinaryOperatorToken < Token
       attr_reader :op
 
       def initialize(op)
@@ -33,6 +33,15 @@ module RubyAlgebra
       end
     end
 
+    class UnaryOperatorToken < Token
+      attr_reader :op
+
+      def initialize(op)
+        @type = :unary_op
+        @op = op
+      end
+    end
+
     class ParenthesisToken < Token
       attr_reader :closing
 
@@ -54,34 +63,42 @@ module RubyAlgebra
       while i < e.length
         c = e[i]
         if c.match?(/\p{Alpha}/)
-          yield OperatorToken.new(:mult) if add_implicit_mul
+          yield BinaryOperatorToken.new(:mult) if add_implicit_mul
           j = i + 1
           j += 1 while j < e.length && e[j].match?(/\p{Alnum}/)
           add_implicit_mul = true
           yield IdentifierToken.new(e[i...j])
           i = j
         elsif c.match?(/[+\-*\/^()]/)
-          yield OperatorToken.new(:mult) if c == "(" && add_implicit_mul
+          yield BinaryOperatorToken.new(:mult) if c == "(" && add_implicit_mul
           i += 1
-          add_implicit_mul = c == ")"
           case c
           when "+"
-            yield OperatorToken.new(:add)
+            if add_implicit_mul
+              yield BinaryOperatorToken.new(:add)
+            else
+              yield UnaryOperatorToken.new(:positive)
+            end
           when "-"
-            yield OperatorToken.new(:sub)
+            if add_implicit_mul
+              yield BinaryOperatorToken.new(:sub)
+            else
+              yield UnaryOperatorToken.new(:negative)
+            end
           when "*"
-            yield OperatorToken.new(:mult)
+            yield BinaryOperatorToken.new(:mult)
           when "/"
-            yield OperatorToken.new(:div)
+            yield BinaryOperatorToken.new(:div)
           when "^"
-            yield OperatorToken.new(:pow)
+            yield BinaryOperatorToken.new(:pow)
           when "("
             yield ParenthesisToken.new(false)
           when ")"
             yield ParenthesisToken.new(true)
           end
+          add_implicit_mul = c == ")"
         elsif c.match?(/\p{Digit}|\./)
-          yield OperatorToken.new(:mult) if add_implicit_mul
+          yield BinaryOperatorToken.new(:mult) if add_implicit_mul
           j = i + 1
           j += 1 while j < e.length && e[j].match?(/\p{Digit}|\./)
           s = e[i...j]
@@ -109,16 +126,15 @@ module RubyAlgebra
     def parse(expr)
       operators = []
       out_stack = []
-      prev = nil
       tokenize(expr) do |token|
+        pp token
         if token.type == :num
           out_stack.push(Constant.new(token.value))
         elsif token.type == :end
-          # тут надо обработку незакрытых (
           _parse_make_op(operators, out_stack) until operators.empty?
-        elsif token.type == :op
+        elsif token.type == :op || token.type == :unary_op
           p = _parse_op_prio token
-          while operators.length != 0 && operators.last.type == :op && (_parse_op_prio(operators.last) > p || (_parse_op_prio(operators.last) == p && token.op != :pow))
+          while operators.length != 0 && (operators.last.type == :op || operators.last.type == :unary_op) && (_parse_op_prio(operators.last) > p || (_parse_op_prio(operators.last) == p && token.op != :pow && token.op != :positive && token.op != :negative))
             _parse_make_op(operators, out_stack)
           end
           operators.push(token)
@@ -128,7 +144,7 @@ module RubyAlgebra
               _parse_make_op(operators, out_stack)
             end
             if operators.empty? || operators.last.type != :paren || operators.last.closing
-              puts "Missing ( in expression"
+              raise Exception.new
             else
               operators.pop
             end
@@ -138,17 +154,21 @@ module RubyAlgebra
         elsif token.type == :id
           out_stack.push(Variable.new(token.name))
         end
-        prev = token
       end
       out_stack[0]
     end
 
     def _parse_make_op(operators, out_stack)
       oper = operators.pop
-      raise Exception.new unless oper.type == :op
-      raise Exception.new unless out_stack.length >= 2
-      b = out_stack.pop
+      unless (oper.type == :op && out_stack.length >= 2) || (oper.type == :unary_op && out_stack.length >= 1)
+        raise Exception.new
+      end
+      b = out_stack.pop if oper.type == :op
       a = out_stack.pop
+
+      puts "make unary op #{oper.op} from (#{a})" if oper.type == :unary_op
+      puts "make binary op #{oper.op} from (#{a}), (#{b})" if oper.type == :op
+
       case oper.op
       when :add
         out_stack.push Addition.new(a, b)
@@ -160,6 +180,10 @@ module RubyAlgebra
         out_stack.push Division.new(a, b)
       when :pow
         out_stack.push Power.new(a, b)
+      when :positive
+        out_stack.push a
+      when :negative
+        out_stack.push Multiplication.new(Constant.new(-1), a)
       end
     end
 
@@ -169,7 +193,7 @@ module RubyAlgebra
         1
       when :mult, :div
         2
-      when :pow
+      when :pow, :positive, :negative
         3
       end
     end