44The YAML Format
55===============
66
7- According to the official `YAML `_ website, YAML is "a human friendly data
8- serialization standard for all programming languages".
9-
10- Even if the YAML format can describe complex nested data structure, this
11- article only describes the minimum set of features needed to use YAML as a
12- configuration file format.
13-
14- YAML is a simple language that describes data. As PHP, it has a syntax for
15- simple types like strings, booleans, floats, or integers. But unlike PHP, it
16- makes a difference between arrays (sequences) and hashes (mappings).
7+ According to the official `YAML website `_, YAML is "a human friendly data
8+ serialization standard for all programming languages". The Symfony Yaml
9+ component implements a subset of the `YAML specification `_. Specifically, it
10+ implements the minimum set of features needed to use YAML as a configuration
11+ file format.
1712
1813Scalars
1914-------
@@ -171,8 +166,8 @@ Collections
171166-----------
172167
173168A YAML file is rarely used to describe a simple scalar. Most of the time, it
174- describes a collection. A collection can be a sequence or a mapping of
175- elements. Both sequences and mappings are converted to PHP arrays .
169+ describes a collection. YAML collections can be a sequence (indexed arrays in PHP)
170+ or a mapping of elements (associative arrays in PHP) .
176171
177172Sequences use a dash followed by a space:
178173
@@ -318,4 +313,20 @@ The YAML specification defines some tags to set the type of any data explicitly:
318313 Pz7Y6OjuDg4J+fn5OTk6enp
319314 56enmleECcgggoBADs=
320315
321- YAML : http://yaml.org/
316+
317+ -------------------------
318+
319+ The following YAML features are not supported by the Symfony Yaml component:
320+
321+ * Multi-documents (``--- `` and ``... `` markers);
322+ * Complex mapping keys and complex values starting with ``? ``;
323+ * Tagged values as keys;
324+ * The following tags and types: `!!set `, `!!omap `, `!!pairs `, `!!set `, `!!seq `,
325+ `!!bool `, `!!int `, `!!merge `, `!!null `, `!!timestamp `, `!!value`, `!!yaml `;
326+ * Tags (``TAG `` directive; example: ``%TAG ! tag:example.com,2000:app/ ``)
327+ and tag references (example: ``!<tag:example.com,2000:app/foo> ``);
328+ * Using sequence-like syntax for mapping elements (example: ``{foo, bar} ``; use
329+ ``{foo: ~, bar: ~} `` instead).
330+
331+ .. _`YAML website` : http://yaml.org/
332+ .. _`YAML specification` : http://www.yaml.org/spec/1.2/spec.html
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