Merge pull request #37 from mohawkjohn/issue_33

Adds SymEngine::symbols() and allows Symbol.new to take a Ruby symbol

Author: certik

ext/symengine/ruby_symbol.c

@@ -1,10 +1,20 @@
 #include "ruby_symbol.h"
 
-VALUE csymbol_init(VALUE self, VALUE name) {
-    Check_Type(name, T_STRING);
-    basic_struct *this;
-    char *str_ptr = StringValueCStr(name);
+VALUE csymbol_init(VALUE self, VALUE name_or_id) {
+    char *str_ptr;
+
+    switch (TYPE(name_or_id)) {
+    case T_STRING:
+      str_ptr = StringValueCStr(name_or_id);
+      break;
+    case T_SYMBOL:
+      str_ptr = rb_id2name(rb_to_id(name_or_id));
+      break;      
+    default:
+      rb_raise(rb_eTypeError, "wrong argument type %s (expected Symbol or String)", rb_obj_classname(name_or_id));
+    }
 
+    basic_struct *this;
     Data_Get_Struct(self, basic_struct, this);
 
     symbol_set(this, str_ptr);

lib/symengine.rb

@@ -1,3 +1,36 @@
+module SymEngine
+  class << self
+
+    # Defines a shortcut for SymEngine::Symbol.new() allowing multiple symbols
+    # to be created all at once.
+    #
+    # Examples:
+    #
+    #    x, y = SymEngine.symbols(%i{x y})
+    #    x, y = SymEngine.symbols(%w{x y})
+    #    x, y = SymEngine.symbols([:x, :y])
+    #    x, y = SymEngine.symbols(['x', 'y'])
+    #    x, y = SymEngine.symbols('x', 'y')
+    #    x, y = SymEngine.symbols('x y')
+    #    
+    def symbols ary_or_string, *params
+      # Want to make sure we can accept an array or a bunch of splatted arguments
+      if params.size > 0
+        ary_or_string = (ary_or_string.is_a?(String) ? [ary_or_string] : ary_or_string).concat(params)
+      elsif ary_or_string.is_a?(String)
+        # or accept a string
+        ary_or_string = ary_or_string.split
+      end
+
+      # Make an Array of SymEngine::Symbols from the parameters we received,
+      # now that they're normalized.
+      ary_or_string.map do |symbol_or_string| 
+        SymEngine::Symbol.new(symbol_or_string)
+      end
+    end
+  end
+end
+
 require 'symengine/symengine'
 require 'symengine/iruby'
 require 'symengine/basic'

spec/symbol_spec.rb

@@ -1,9 +1,53 @@
 require 'spec_helper'
 
+
+
 describe SymEngine do
   before :each do
   end
 
+  describe '.symbols' do
+    before :all do
+
+      # Create a shortcut Proc to DRY up code.
+      #
+      # Call this with the number of symbols we expect to get out
+      # and the argument we want to provide it.
+      @test_symbols_method = Proc.new do |count_symbols, *args|
+        symbols = SymEngine.symbols(*args)
+        symbols.each do |symbol|
+          expect(symbol).to be_an_instance_of SymEngine::Symbol
+        end
+        expect(symbols.size).to eql(count_symbols)
+      end
+    end
+
+    context 'with a white-space separated string as an argument' do
+      it 'returns an Enumerable of Symbol objects' do
+        @test_symbols_method.call(2, 'x y')
+      end
+    end
+
+    context 'with an array of Ruby Symbols as an argument' do
+      it 'returns an Enumerable of Symbol objects' do
+        # @test_symbols_method.call(2, %i{x y}) # Ruby 2.0 and higher only
+        @test_symbols_method.call(2, [:x, :y])
+      end
+    end
+
+    context 'with an array of Ruby Strings as an argument' do
+      it 'returns an Enumerable of Symbol objects' do
+        @test_symbols_method.call(2, %w{x y})
+      end
+    end
+
+    context 'with a splatted argument' do
+      it 'returns an Enumerable of Symbol objects' do
+        @test_symbols_method.call(2, 'x', 'y')
+      end
+    end
+  end
+
   describe SymEngine::Symbol do
     before :each do
     end
@@ -15,6 +59,13 @@
           expect(symbol).to be_an_instance_of SymEngine::Symbol
         end
       end
+
+      context 'with a Ruby symbol as an argument' do
+        it 'returns a Symbol object' do
+          symbol = SymEngine::Symbol.new(:x)
+          expect(symbol).to be_an_instance_of SymEngine::Symbol
+        end
+      end
     end
   end
 end