Start on simple resolving. We don't try to fix conflicts yet to keep …

…things simple, so for now that's up to the user.

examples/Podfile

@@ -1,13 +1,18 @@
+#dependency 'ASIHTTPRequest', '1.8'
+dependency 'ASIWebPageRequest', '= 1.8'
+
 # is part of ASIHTTPRequest 1.8 and 1.8.1
 dependency 'Reachability' #, '>= 2.0'
 
 # is part of ASIHTTPRequest
-dependency 'ASIWebPageRequest', '>= 1.8'
+#dependency 'ASIWebPageRequest', '>= 1.8'
+#dependency 'ASIWebPageRequest', '= 1.8'
 
 # this should fail the ASIHTTPRequest 1.8.1 hard requirement
 #dependency 'ASIWebPageRequest', '1.8.0'
 
 # we have a hard requirement here so:
 # * the Reachability dependency should be taken from this version
 # * the ASIWebPageRequest dependency requirement matches this one so should work
-dependency 'ASIHTTPRequest', '1.8.1'
+#dependency 'ASIHTTPRequest', '1.8.1'
+dependency 'ASIHTTPRequest', '>= 1.8'

lib/cocoa_pods.rb

@@ -2,6 +2,7 @@ module Pod
   autoload :Command,       'cocoa_pods/command'
   autoload :Config,        'cocoa_pods/config'
   autoload :Dependency,    'cocoa_pods/dependency'
+  autoload :Resolver,      'cocoa_pods/resolver'
   autoload :Source,        'cocoa_pods/source'
   autoload :Spec,          'cocoa_pods/specification'
   autoload :Specification, 'cocoa_pods/specification'

lib/cocoa_pods/command/install.rb

@@ -4,7 +4,7 @@ class Install < Command
       def run
         if spec = Specification.from_podfile(podfile)
           p spec
-          spec.install!
+          Resolver.new(spec).resolve
         else
           $stderr.puts "No Podfile found in current working directory."
         end

lib/cocoa_pods/dependency.rb

@@ -4,6 +4,5 @@ module Gem
 
 module Pod
   class Dependency < Gem::Dependency
-
   end
 end

lib/cocoa_pods/source.rb

@@ -16,9 +16,7 @@ def initialize(repo)
 
     def search(dependency)
       if dir = @repo.children.find { |c| c.basename.to_s == dependency.name }
-        set = Specification::Set.new(dir)
-        set.add_dependency(dependency)
-        set
+        Specification::Set.new(dir)
       end
     end
   end

lib/cocoa_pods/specification.rb

@@ -62,7 +62,8 @@ def description(description)
     end
 
     def part_of(name, *version_requirements)
-      @part_of = Dependency.new(name, *version_requirements)
+      #@part_of = Dependency.new(name, *version_requirements)
+      dependency(name, *version_requirements)
     end
 
     def source_files(*patterns)
@@ -75,7 +76,6 @@ def source(remote)
 
     attr_reader :dependencies
     def dependency(name, *version_requirements)
-      #version = args || [">= 0"]
       @dependencies << Dependency.new(name, *version_requirements)
     end
 
@@ -87,31 +87,14 @@ def from_podfile?
 
     def to_s
       if from_podfile?
-        "#<#{self.class.name} for podfile at `#{@defined_in_file}'>"
+        "podfile at `#{@defined_in_file}'"
       else
-        "#<#{self.class.name} for `#{@name}' version `#{@version}'>"
+        "`#{@name}' version `#{@version}'"
       end
     end
-    alias_method :inspect, :to_s
 
-    # TODO move to seperate installer class
-    def install!
-      #p @name, @version, @authors, @dependencies
-      @dependency_sets = @dependencies.map { |dep| Source.search(dep) }.flatten
-      @dependency_sets.each do |set|
-        p set
-        p set.podspec
-      end
-    end
-
-    private
-
-    def attr(name, arg)
-      if arg.nil? || arg.empty?
-        instance_variable_get("@#{name}")
-      else
-        instance_variable_set("@#{name}", block_given? ? yield : arg)
-      end
+    def inspect
+      "#<#{self.class.name} for #{to_s}>"
     end
   end
 

lib/cocoa_pods/specification/set.rb

@@ -3,10 +3,21 @@ class Specification
     class Set
       def initialize(pod_dir)
         @pod_dir = pod_dir
+        @required_by = []
       end
 
-      def add_dependency(dependency)
-        @dependency = dependency
+      def required_by(specification, dependency)
+        unless @required_by.empty? || dependency.requirement.satisfied_by?(required_version)
+          # TODO add graph that shows which dependencies led to this.
+          required_by = @required_by.map(&:first).join(', ')
+          raise "#{specification} tries to activate `#{dependency}', " \
+                "but already activated version `#{required_version}' by #{required_by}."
+        end
+        @required_by << [specification, dependency]
+      end
+
+      def dependency
+        @required_by.inject(Dependency.new(name)) { |previous, (_, dep)| previous.merge(dep) }
       end
 
       def name
@@ -23,12 +34,16 @@ def podspec
 
       # Return the first version that matches the current dependency.
       def required_version
-        unless v = versions.find { |v| @dependency.match?(name, v) }
-          raise "Required version (#{@dependency}) not found for `#{name}'."
+        unless v = versions.find { |v| dependency.match?(name, v) }
+          raise "Required version (#{dependency}) not found for `#{name}'."
         end
         v
       end
 
+      def ==(other)
+        self.class === other && name == other.name
+      end
+
       def to_s
         "#<#{self.class.name} for `#{name}' with required version `#{required_version}'>"
       end
@@ -39,7 +54,7 @@ def to_s
       # Returns Pod::Version instances, for each version directory, sorted from
       # lowest version to highest.
       def versions
-        @pod_dir.children.map { |v| Version.new(v.basename) }.sort
+        @pod_dir.children.map { |v| Version.new(v.basename) }.sort.reverse
       end
     end
   end