182 lines
6.1 KiB
Plaintext
182 lines
6.1 KiB
Plaintext
===============
|
|
Getting started
|
|
===============
|
|
|
|
Welcome to D:YAML! D:YAML is a `YAML <http://en.wikipedia.org/wiki/YAML>`_
|
|
parser library for the `D programming language <http://dlang.org>`_.
|
|
This tutorial will explain how to set D:YAML up and use it in your projects.
|
|
|
|
This is meant to be the **simplest possible** introduction to D:YAML. Some of
|
|
this information might already be known to you. Only basic usage is covered.
|
|
|
|
|
|
----------
|
|
Setting up
|
|
----------
|
|
|
|
^^^^^^^^^^^^^^^^^^^^^^^^
|
|
Install the DMD compiler
|
|
^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
Digital Mars D compiler, or DMD, is the most commonly used D compiler. You can
|
|
find its newest version `here <http://dlang.org/download.html>`_.
|
|
Download the version of DMD for your operating system and install it.
|
|
|
|
.. note::
|
|
Other D compilers exist, such as
|
|
`GDC <http://gdcproject.org/>`_ and
|
|
`LDC <http://bitbucket.org/goshawk/gdc/wiki/Home>`_.
|
|
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
Download and compile D:YAML
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
The newest version of D:YAML can be found
|
|
`here <https://github.com/Kiith-Sa/D-YAML>`_. Download a source archive, extract
|
|
it, and move to the extracted directory.
|
|
|
|
D:YAML uses a modified version of the `CDC <http://dsource.org/projects/cdc/>`_
|
|
script for compilation. To compile D:YAML, you first need to build CDC.
|
|
Do this by typing the following command into the console::
|
|
|
|
dmd cdc.d
|
|
|
|
Now compile D:YAML with CDC.
|
|
To do this on Unix/Linux, use the following command::
|
|
|
|
./cdc
|
|
|
|
On Windows::
|
|
|
|
cdc.exe
|
|
|
|
This will compile the library to a file called ``libdyaml.a`` on Unix/Linux or
|
|
``libdyaml.lib`` on Windows.
|
|
|
|
|
|
-------------------------
|
|
Your first D:YAML project
|
|
-------------------------
|
|
|
|
Create a directory for your project and in that directory, create a file called
|
|
``input.yaml`` with the following contents:
|
|
|
|
.. code-block:: yaml
|
|
|
|
Hello World :
|
|
- Hello
|
|
- World
|
|
Answer: 42
|
|
|
|
This will serve as input for our example.
|
|
|
|
Now we need to parse it. Create a file called ``main.d``. Paste following code
|
|
into the file:
|
|
|
|
.. code-block:: d
|
|
|
|
import std.stdio;
|
|
import yaml;
|
|
|
|
void main()
|
|
{
|
|
//Read the input.
|
|
Node root = Loader("input.yaml").load();
|
|
|
|
//Display the data read.
|
|
foreach(string word; root["Hello World"])
|
|
{
|
|
writeln(word);
|
|
}
|
|
writeln("The answer is ", root["Answer"].as!int);
|
|
|
|
//Dump the loaded document to output.yaml.
|
|
Dumper("output.yaml").dump(root);
|
|
}
|
|
|
|
|
|
^^^^^^^^^^^^^^^^^^^^^^^
|
|
Explanation of the code
|
|
^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
First, we import the *yaml* module. This is the only D:YAML module you
|
|
need to import - it automatically imports all needed modules.
|
|
|
|
Next we load the file using the *Loader.load()* method. *Loader* is a struct
|
|
used for parsing YAML documents. The *load()* method loads the file as
|
|
**one** YAML document, or throws *YAMLException*, D:YAML exception type, if the
|
|
file could not be parsed or does not contain exactly one document. Note that we
|
|
don't do any error checking here in order to keep the example as simple as
|
|
possible.
|
|
|
|
*Node* represents a node in a YAML document. It can be a sequence (array),
|
|
mapping (associative array) or a scalar (value). Here the root node is a
|
|
mapping, and we use the index operator to get subnodes with keys "Hello World"
|
|
and "Answer". We iterate over the first, as it is a sequence, and use the
|
|
*Node.as()* method on the second to read its value as an integer.
|
|
|
|
You can iterate over a mapping or sequence as if it was an associative or normal
|
|
array. If you try to iterate over a scalar, it will throw a *YAMLException*.
|
|
|
|
You can iterate over subnodes using *Node* as the iterated type, or specify
|
|
the type subnodes are expected to have. D:YAML will automatically convert
|
|
iterated subnodes to that type if possible. Here we specify the *string* type,
|
|
so we iterate over the "Hello World" sequence as an array of strings. If it is
|
|
not possible to convert to iterated type, a *YAMLException* is thrown. For
|
|
instance, if we specified *int* here, we would get an error, as "Hello"
|
|
cannot be converted to an integer.
|
|
|
|
The *Node.as()* method is used to read value of a scalar node as specified type.
|
|
D:YAML will try to return the scalar as this type, converting if needed,
|
|
throwing *YAMLException* if not possible.
|
|
|
|
Finally we dump the document we just read to ``output.yaml`` with the
|
|
*Dumper.dump()* method. *Dumper* is a struct used to dump YAML documents.
|
|
The *dump()* method writes one or more documents to a file, throwing
|
|
*YAMLException* if the file could not be written to.
|
|
|
|
D:YAML doesn't preserve style information in documents, so even though
|
|
``output.yaml`` will contain the same data as ``input.yaml``, it might be
|
|
formatted differently. Comments are not preserved, either.
|
|
|
|
|
|
^^^^^^^^^
|
|
Compiling
|
|
^^^^^^^^^
|
|
|
|
To compile your project, DMD needs to know which directories contain the
|
|
imported modules and the library. You also need to tell it to link with D:YAML.
|
|
The import directory should be the ``source`` subdirectory of the D:YAML
|
|
directory. You can specify it using the ``-I`` option of DMD. The library
|
|
directory should point to the compiled library. On Unix/Linux you can specify
|
|
it using the ``-L-L`` option, and link with D:YAML using the ``-L-l`` option.
|
|
On Windows, the import directory is used as the library directory. To link with
|
|
the library on Windows, just add the path to it relative to the current
|
|
directory.
|
|
|
|
For example, if you extracted and compiled D:YAML in ``/home/xxx/dyaml``, your
|
|
project is in ``/home/xxx/dyaml-project``, and you are currently in that
|
|
directory, compile the project with the following command on Unix/Linux::
|
|
|
|
dmd -I../dyaml/source -L-L../dyaml -L-ldyaml main.d
|
|
|
|
And the following on Windows::
|
|
|
|
dmd -I../dyaml/source ../dyaml/libdyaml.lib main.d
|
|
|
|
This will produce an executable called ``main`` or ``main.exe`` in your
|
|
directory. When you run it, it should produce the following output::
|
|
|
|
Hello
|
|
World
|
|
The answer is 42
|
|
|
|
|
|
^^^^^^^^^^
|
|
Conclusion
|
|
^^^^^^^^^^
|
|
|
|
You should now have a basic idea about how to use D:YAML. To learn more, look at
|
|
the `API documentation <../api/index.html>`_ and other tutorials. You can find code for this
|
|
example in the ``example/getting_started`` directory in the package.
|