Generator

The code generators are invoked when the installer has scanned the directories, selected the files and applied the installation rules to produce the content that must be embedded.

Ada Generator

The Ada code generator produces for each resource description an Ada package with the name of that resource. Sometimes, the Ada package specification is enough and it contains all necessary definitions including the content of files. In other cases, an Ada package body is also generated and it contains the generated files with a function that allows to query and retrieve the file content. The Ada code generator is driven by the resource description and also by the tool options.

The code generator supports several data format to access the file content.

Format	Ada type
binary	access constant Ada.Streams.Stream_Element_Array
string	access constant String
lines	array of access constant String

When the --content-only option is used, the code generator uses the following type to describe a file content in the binary format:

type Content_Access is
   access constant Ada.Streams.Stream_Element_Array;

for the string format it defines:

type Content_Access is access constant String;

and for the lines format it defines:

type Content_Array is
   array (Natural range <>) of access constant String;
type Content_Access is access constant Content_Array;

These type definitions give access to a readonly binary or string content and provides enough information to also indicate the size of that content. Then when the --name-access option is passed, the code generator declares and implements the following function:

function Get_Content (Name : String) return Content_Access;

That function will return either a content access or null if it was not found.

By default, when the --content-only option is not passed, the code generator provides more information about the embedded content such as the file name, the modification time of the file and the target file format. In that case, the following Ada record is declared in the Ada specification:

type Name_Access is access constant String;
type Format_Type is (FILE_RAW, FILE_GZIP);
type Content_Type is record
  Name    : Name_Access;
  Content : Content_Access;
  Modtime : Interfaces.C.long = 0;
  Format  : Format_Type := FILE_RAW;
end record;

The generated Get_Content function will return a Content_Type. You must compare the result with the Null_Content constant to check if the embedded file was found.

When the --list-access option is passed, the code generator emits a code that gives access to the list of file names embedded in the resource. The list of names is a simple Ada constant array. The array is sorted on the name. It is declared as follows:

type Name_Array is array (Natural range <>) of Name_Access;
Names : constant Name_Array;

C Generator

The C code generator produces for each resource description a C header and a C source file with the name of that resource. The header contains the public declaration and the C source file contains the generated files with an optional function that allows to query and retrieve the file content. The C code generator is driven by the resource description and also by the tool options.

The header file declares a C structure that describes the content information. The C structure gives access to the content, its size, the modification time of the file and the target file format. The structure name is prefixed by the resource name.

struct <resource>_content {
  const unsigned char* content;
  size_t size;
  time_t modtime;
  int format;
}

This type definition gives access to a readonly binary content and provides enough information to also indicate the size of that content. Then when the --name-access option is passed, the code generator declares and implements the following function:

extern const struct <resource>_content *
     <resource>_get_content(const char* name);

That function will return either a pointer to the resource description or null if the name was not found.

When the --list-access option is passed, the C code generator also declares two global constant variables:

extern const char* const <resource>_names[];
static const int <resource>_names_length = NNN;

The generated array gives access to the list of file names embedded in the resource. That list is sorted on the name so that a dichotomic search can be used to find an entry.

Go Generator

The Go code generator produces for each resource description a Go source file with the name of that resource. The header contains the public declaration and the C source file contains the generated files with an optional function that allows to query and retrieve the file content. The C code generator is driven by the resource description and also by the tool options.

The Go source file declares a structure that describes the content information. The structure is declared public so that it is visible outside the Go package. It gives access to the content, its size, the modification time of the file and the target file format.

type Content struct {
  Content []byte
  Size    int64
  Modtime int64
  Format  int
}

This type definition gives access to a binary content and provides enough information to also indicate the size of that content. Then when the --name-access option is passed, the code generator declares and implements the following function:

func Get_content(name string) (*Content)

That function will return either a pointer to the resource description or null if the name was not found.

When the --list-access option is passed, the Go code generator makes available the list of names by making the Names variable public:

var Names= []string {
...
}

The generated array gives access to the list of file names embedded in the resource. That list is sorted on the name so that a dichotomic search can be used to find an entry.