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Changed the Constructor API (for loading of custom types) to

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make it easier to load custom classes/structs. Updated API docs,
tutorials and examples accordingly.
This commit is contained in:
Ferdinand Majerech 2011-10-17 12:53:38 +02:00
parent 5547f62176
commit 548480b06b
19 changed files with 371 additions and 396 deletions
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61
docsrc/tutorials/custom_types.rst
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@ -20,8 +20,9 @@ Constructor
D:YAML uses the `Constructor <../api/dyaml.constructor.html>`_ class to process
each node to hold data type corresponding to its tag. *Constructor* stores a
function for each supported tag to process it. These functions are supplied by
the user using the *addConstructor()* method. *Constructor* is then passed to
*Loader*, which parses YAML input.
the user using the *addConstructorXXX()* methods, where *XXX* is *Scalar*,
*Sequence* or *Mapping*. *Constructor* is then passed to *Loader*, which parses
YAML input.
Struct types have no specific requirements for YAML support. Class types should
define the *opEquals()* operator, as this is used in equality comparisons of
@ -41,17 +42,20 @@ following struct:
}
First, we need a function to construct our data type. It must take two *Mark*
structs, which store position of the node in the file, and either a *string*, an
array of *Node* or of *Node.Pair*, depending on whether we're constructing our
value from a scalar, sequence, or mapping, respectively. In this tutorial, we
have functions to construct a color from a scalar, using HTML-like format,
RRGGBB, or from a mapping, where we use the following format:
{r:RRR, g:GGG, b:BBB} . Code of these functions:
structs, which store position of the node in the file, and a reference to *Node*
to construct from. The node is guaranteed to contain either a *string*, an array
of *Node* or of *Node.Pair*, depending on whether we're constructing our value
from a scalar, sequence, or mapping, respectively. In this tutorial, we have
functions to construct a color from a scalar, using CSS-like format, RRGGBB, or
from a mapping, where we use the following format: {r:RRR, g:GGG, b:BBB} . Code
of these functions:
.. code-block:: d
Color constructColorScalar(Mark start, Mark end, string value)
Color constructColorScalar(Mark start, Mark end, ref Node node)
{
string value = node.get!string;
if(value.length != 6)
{
throw new ConstructorException("Invalid color: " ~ value, start, end);
@ -82,30 +86,21 @@ RRGGBB, or from a mapping, where we use the following format:
return result;
}
Color constructColorMapping(Mark start, Mark end, Node.Pair[] pairs)
Color constructColorMapping(Mark start, Mark end, ref Node node)
{
int r, g, b;
r = g = b = -1;
bool error = pairs.length != 3;
int r,g,b;
bool error = false;
foreach(ref pair; pairs)
//Might throw if a value is missing or is not an integer.
try
{
//Key might not be a string, and value might not be an int,
//so we need to check for that
try
{
switch(pair.key.get!string)
{
case "r": r = pair.value.get!int; break;
case "g": g = pair.value.get!int; break;
case "b": b = pair.value.get!int; break;
default: error = true;
}
}
catch(NodeException e)
{
error = true;
}
r = node["r"].get!int;
g = node["g"].get!int;
b = node["b"].get!int;
}
catch(NodeException e)
{
error = true;
}
if(error || r < 0 || r > 255 || g < 0 || g > 255 || b < 0 || b > 255)
@ -146,8 +141,8 @@ Finally, the code to put it all together:
{
auto constructor = new Constructor;
//both functions handle the same tag, but one handles scalar, one mapping.
constructor.addConstructor("!color", &constructColorScalar);
constructor.addConstructor("!color-mapping", &constructColorMapping);
constructor.addConstructorScalar("!color", &constructColorScalar);
constructor.addConstructorMapping("!color-mapping", &constructColorMapping);
auto loader = Loader("input.yaml");
loader.constructor = constructor;
@ -284,7 +279,7 @@ With the following code, we will add support for dumping the our Color type.
}
First we get the *Color* from the node. Then we convert it to a string with the
HTML-like format we've used before. Finally, we use the *representScalar()*
CSS-like format we've used before. Finally, we use the *representScalar()*
method of *Representer* to get a scalar node ready for output.
There are corresponding *representMapping()* and *representSequence()* methods
as well, with examples in the