* ext/dl: Added documentation. Patch by Vincent Batts.

  [ruby-trunk - Bug #6496]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35846 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

4 files changed, 102 insertions, 1 deletions

diff --git a/ext/dl/lib/dl.rb b/ext/dl/lib/dl.rb
index 80d46b685a..b34bb82f41 100644
--- a/ext/dl/lib/dl.rb
+++ b/ext/dl/lib/dl.rb
@@ -6,6 +6,7 @@ rescue LoadError
 end
 
 module DL
+  # Returns true if DL is using Fiddle, the libffi wrapper.
   def self.fiddle?
     Object.const_defined?(:Fiddle)
   end
diff --git a/ext/dl/lib/dl/cparser.rb b/ext/dl/lib/dl/cparser.rb
index 7aae9ea4eb..e70e0f1dc1 100644
--- a/ext/dl/lib/dl/cparser.rb
+++ b/ext/dl/lib/dl/cparser.rb
@@ -1,5 +1,13 @@
 module DL
+  # Methods for parsing C struct and C prototype signatures.
   module CParser
+    # Parses a C struct's members
+    #
+    # Example:
+    #
+    #   parse_struct_signature(['int i', 'char c'])
+    #   => [[DL::TYPE_INT, DL::TYPE_CHAR], ["i", "c"]]
+    #
     def parse_struct_signature(signature, tymap=nil)
       if( signature.is_a?(String) )
         signature = signature.split(/\s*,\s*/)
@@ -35,6 +43,16 @@ module DL
       return tys, mems
     end
 
+    # Parses a C prototype signature
+    #
+    # Example:
+    #
+    #   include DL::CParser
+    #   => Object
+    #
+    #   parse_signature('double sum(double, double)')
+    #   => ["sum", DL::TYPE_DOUBLE, [DL::TYPE_DOUBLE, DL::TYPE_DOUBLE]]
+    #
     def parse_signature(signature, tymap=nil)
       tymap ||= {}
       signature = signature.gsub(/\s+/, " ").strip
@@ -56,6 +74,25 @@ module DL
       end
     end
 
+    # Given a String of C type +ty+, return the corresponding DL constant.
+    #
+    # +ty+ can also accept an Array of C type Strings, and will returned in a
+    # corresponding Array.
+    #
+    # If Hash +tymap+ is provided, +ty+ is expected to be the key, and the
+    # value will be the C type to be looked up.
+    #
+    # Example:
+    #
+    #   parse_ctype('int')
+    #   => DL::TYPE_INT
+    #
+    #   parse_ctype('double')
+    #   => DL::TYPE_DOUBLE
+    #
+    #   parse_ctype('unsigned char')
+    #   => -DL::TYPE_CHAR
+    #
     def parse_ctype(ty, tymap=nil)
       tymap ||= {}
       case ty
diff --git a/ext/dl/lib/dl/import.rb b/ext/dl/lib/dl/import.rb
index eec65cdfd6..a318430b73 100644
--- a/ext/dl/lib/dl/import.rb
+++ b/ext/dl/lib/dl/import.rb
@@ -179,11 +179,17 @@ module DL
       f
     end
 
+    # Creates a class to wrap the C struct described by +signature+.
+    #
+    #   MyStruct = struct ['int i', 'char c']
     def struct(signature)
       tys, mems = parse_struct_signature(signature, @type_alias)
       DL::CStructBuilder.create(CStruct, tys, mems)
     end
 
+    # Creates a class to wrap the C union described by +signature+.
+    #
+    #   MyUnion = union ['int i', 'char c']
     def union(signature)
       tys, mems = parse_struct_signature(signature, @type_alias)
       DL::CStructBuilder.create(CUnion, tys, mems)
diff --git a/ext/dl/lib/dl/struct.rb b/ext/dl/lib/dl/struct.rb
index b8becca6b6..27f6b42fd2 100644
--- a/ext/dl/lib/dl/struct.rb
+++ b/ext/dl/lib/dl/struct.rb
@@ -2,19 +2,50 @@ require 'dl'
 require 'dl/pack.rb'
 
 module DL
+  # C struct shell
   class CStruct
+    # accessor to DL::CStructEntity
     def CStruct.entity_class()
       CStructEntity
     end
   end
 
+  # C union shell
   class CUnion
+    # accessor to DL::CUnionEntity
     def CUnion.entity_class()
       CUnionEntity
     end
   end
 
+  # Used to construct C classes (CUnion, CStruct, etc)
+  #
+  # DL::Importer#struct and DL::Importer#union wrap this functionality in an
+  # easy-to-use manner.
   module CStructBuilder
+    # Construct a new class given a C:
+    # * class +klass+ (CUnion, CStruct, or other that provide an
+    #   #entity_class)
+    # * +types+ (DL:TYPE_INT, DL::TYPE_SIZE_T, etc., see the C types
+    #   constants)
+    # * corresponding +members+
+    #
+    # DL::Importer#struct and DL::Importer#union wrap this functionality in an
+    # easy-to-use manner.
+    #
+    # Example:
+    #
+    #   require 'dl/struct'
+    #   require 'dl/cparser'
+    #
+    #   include DL::CParser
+    #
+    #   types, members = parse_struct_signature(['int i','char c'])
+    #
+    #   MyStruct = DL::CStructBuilder.create(CUnion, types, members)
+    #
+    #   obj = MyStruct.allocate
+    #
     def create(klass, types, members)
       new_class = Class.new(klass){
         define_method(:initialize){|addr|
@@ -43,15 +74,23 @@ module DL
     module_function :create
   end
 
+  # A C struct wrapper
   class CStructEntity < CPtr
     include PackInfo
     include ValueUtil
 
+    # Allocates a C struct the +types+ provided.  The C function +func+ is
+    # called when the instance is garbage collected.
     def CStructEntity.malloc(types, func = nil)
       addr = DL.malloc(CStructEntity.size(types))
       CStructEntity.new(addr, types, func)
     end
 
+    # Given +types+, returns the offset for the packed sizes of those types
+    #
+    #   DL::CStructEntity.size([DL::TYPE_DOUBLE, DL::TYPE_INT, DL::TYPE_CHAR,
+    #                           DL::TYPE_VOIDP])
+    #   => 24
     def CStructEntity.size(types)
       offset = 0
       max_align = 0
@@ -76,15 +115,22 @@ module DL
       offset
     end
 
+    # Wraps the C pointer +addr+ as a C struct with the given +types+.  The C
+    # function +func+ is called when the instance is garbage collected.
+    #
+    # See also DL::CPtr.new
     def initialize(addr, types, func = nil)
       set_ctypes(types)
       super(addr, @size, func)
     end
 
+    # Set the names of the +members+ in this C struct
     def assign_names(members)
       @members = members
     end
 
+    # Given +types+, calculate the offsets and sizes for the types in the
+    # struct.
     def set_ctypes(types)
       @ctypes = types
       @offset = []
@@ -112,6 +158,7 @@ module DL
       @size = offset
     end
 
+    # Fetch struct member +name+
     def [](name)
       idx = @members.index(name)
       if( idx.nil? )
@@ -145,6 +192,7 @@ module DL
       end
     end
 
+    # Set struct member +name+, to value +val+
     def []=(name, val)
       idx = @members.index(name)
       if( idx.nil? )
@@ -164,19 +212,27 @@ module DL
       end
     end
 
-    def to_s()
+    def to_s() # :nodoc:
       super(@size)
     end
   end
 
+  # A C union wrapper
   class CUnionEntity < CStructEntity
     include PackInfo
 
+    # Allocates a C union the +types+ provided.  The C function +func+ is
+    # called when the instance is garbage collected.
     def CUnionEntity.malloc(types, func=nil)
       addr = DL.malloc(CUnionEntity.size(types))
       CUnionEntity.new(addr, types, func)
     end
 
+    # Given +types+, returns the size needed for the union.
+    #
+    #   DL::CUnionEntity.size([DL::TYPE_DOUBLE, DL::TYPE_INT, DL::TYPE_CHAR,
+    #                          DL::TYPE_VOIDP])
+    #   => 8
     def CUnionEntity.size(types)
       size   = 0
       types.each_with_index{|t,i|
@@ -191,6 +247,7 @@ module DL
       }
     end
 
+    # Given +types+, calculate the necessary offset and for each union member
     def set_ctypes(types)
       @ctypes = types
       @offset = []