This module parses YAML serialized data into a Prolog term with
structure that is compatible with the JSON library. This library is a
wrapper around the C library libyaml
. This library forms the basis of
the YAML support in several languages and thus guarantees compatibility
of our YAML support with other languages.
- yaml_read(+Input, -DOM) is det
- Parse Input to a YAML DOM. The DOM representation uses the following
mapping:
- A YAML sequence is mapped to a Prolog List.
- A YAML mapping is mapped to a Prolog dict.
- Untagged scalars follow the implicit tag rules defined by
YAML, providing numbers (int, float and special floats),
null
and the booleans true
and false
. Other untagged
values are returned as a Prolog string. Tagged values are
returned as tag(Tag, String)
which is processed by
yalm_tagged/3. This internal predicate calls the user hook
yaml:tagged/3 with the same arguments and, if the hook fails,
provides the following defaults:
!!binary
converts the Base64 to a string of bytes.
!!str
explicitly keeps a string
!!null
translates "null" to null
!!bool
translates to true
and false
!!int
translates to an integer
!!float
translates to a float
- Anything else is returned as
tag(Tag, String)
- Arguments:
-
Input | - is one of (1) a stream, (2) a term string(Data) or
(3) a file name. |
- bug
- - YAML defines that floats do not require a digit after the
decimal dot. We use the Prolog parser which does require the
decimal dot to be followed by at least one digit. Because the
YAML spec intends to match JSON which does require a digit,
we ignore this incompatibility, expecting it will be addressed
in the next YAML version.
- yaml_write(+Out:stream, +DOM) is det
- yaml_write(+Out:stream, +DOM, +Options) is det
- Emit a YAML DOM object as a serialized YAML document to the stream
Out. Options processed are:
- canonical(+Boolean)
- Use canonical representation. Default is
false
.
- unicode(+Boolean)
- Use unicode Default is
true
.
- implicit(+Boolean)
- Use implicit or explicit representation. Currently only
affects the opening and closing the document. Default is
true
. Use false
for embedded documents.
- factorize(+Boolean)
- If
true
, minimize the term by factoring out common
structures and use &anchor
and *anchor
. Factorization
is always used if DOM is a cyclic term.
Re-exported predicates
The following predicates are exported from this file while their implementation is defined in imported modules or non-module files loaded by this module.
- yaml_write(+Out:stream, +DOM) is det
- yaml_write(+Out:stream, +DOM, +Options) is det
- Emit a YAML DOM object as a serialized YAML document to the stream
Out. Options processed are:
- canonical(+Boolean)
- Use canonical representation. Default is
false
.
- unicode(+Boolean)
- Use unicode Default is
true
.
- implicit(+Boolean)
- Use implicit or explicit representation. Currently only
affects the opening and closing the document. Default is
true
. Use false
for embedded documents.
- factorize(+Boolean)
- If
true
, minimize the term by factoring out common
structures and use &anchor
and *anchor
. Factorization
is always used if DOM is a cyclic term.