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// Copyright Ferdinand Majerech 2011.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
/**
* Implements a class that resolves YAML tags. This can be used to implicitly
* resolve tags for custom data types, removing the need to explicitly
* specify tags in YAML. A tutorial can be found
* $(LINK2 ../tutorials/custom_types.html, here).
*
* Code based on $(LINK2 http://www.pyyaml.org, PyYAML).
*/
module dyaml.resolver;
import std.conv;
import std.regex;
import std.typecons;
import std.utf;
import dyaml.node;
import dyaml.exception;
/// Type of `regexes`
private alias RegexType = Tuple!(string, "tag", const Regex!char, "regexp", string, "chars");
private immutable RegexType[] regexes = [
RegexType("tag:yaml.org,2002:bool",
regex(r"^(?:yes|Yes|YES|no|No|NO|true|True|TRUE" ~
"|false|False|FALSE|on|On|ON|off|Off|OFF)$"),
"yYnNtTfFoO"),
RegexType("tag:yaml.org,2002:float",
regex(r"^(?:[-+]?([0-9][0-9_]*)\\.[0-9_]*" ~
"(?:[eE][-+][0-9]+)?|[-+]?(?:[0-9][0-9_]" ~
"*)?\\.[0-9_]+(?:[eE][-+][0-9]+)?|[-+]?" ~
"[0-9][0-9_]*(?::[0-5]?[0-9])+\\.[0-9_]" ~
"*|[-+]?\\.(?:inf|Inf|INF)|\\." ~
"(?:nan|NaN|NAN))$"),
"-+0123456789."),
RegexType("tag:yaml.org,2002:int",
regex(r"^(?:[-+]?0b[0-1_]+" ~
"|[-+]?0[0-7_]+" ~
"|[-+]?(?:0|[1-9][0-9_]*)" ~
"|[-+]?0x[0-9a-fA-F_]+" ~
"|[-+]?[1-9][0-9_]*(?::[0-5]?[0-9])+)$"),
"-+0123456789"),
RegexType("tag:yaml.org,2002:merge", regex(r"^<<$"), "<"),
RegexType("tag:yaml.org,2002:null",
regex(r"^$|^(?:~|null|Null|NULL)$"), "~nN\0"),
RegexType("tag:yaml.org,2002:timestamp",
regex(r"^[0-9][0-9][0-9][0-9]-[0-9][0-9]-" ~
"[0-9][0-9]|[0-9][0-9][0-9][0-9]-[0-9]" ~
"[0-9]?-[0-9][0-9]?[Tt]|[ \t]+[0-9]" ~
"[0-9]?:[0-9][0-9]:[0-9][0-9]" ~
"(?:\\.[0-9]*)?(?:[ \t]*Z|[-+][0-9]" ~
"[0-9]?(?::[0-9][0-9])?)?$"),
"0123456789"),
RegexType("tag:yaml.org,2002:value", regex(r"^=$"), "="),
//The following resolver is only for documentation purposes. It cannot work
//because plain scalars cannot start with '!', '&', or '*'.
RegexType("tag:yaml.org,2002:yaml", regex(r"^(?:!|&|\*)$"), "!&*"),
];
/**
* Resolves YAML tags (data types).
*
* Can be used to implicitly resolve custom data types of scalar values.
*/
struct Resolver
{
private:
// Default tag to use for scalars.
string defaultScalarTag_ = "tag:yaml.org,2002:str";
// Default tag to use for sequences.
string defaultSequenceTag_ = "tag:yaml.org,2002:seq";
// Default tag to use for mappings.
string defaultMappingTag_ = "tag:yaml.org,2002:map";
/*
* Arrays of scalar resolver tuples indexed by starting character of a scalar.
*
* Each tuple stores regular expression the scalar must match,
* and tag to assign to it if it matches.
*/
Tuple!(string, const Regex!char)[][dchar] yamlImplicitResolvers_;
package:
static auto withDefaultResolvers() @safe
{
Resolver resolver;
foreach(pair; regexes)
{
resolver.addImplicitResolver(pair.tag, pair.regexp, pair.chars);
}
return resolver;
}
public:
@disable bool opEquals(ref Resolver);
@disable int opCmp(ref Resolver);
/**
* Add an implicit scalar resolver.
*
* If a scalar matches regexp and starts with any character in first,
* its _tag is set to tag. If it matches more than one resolver _regexp
* resolvers added _first override ones added later. Default resolvers
* override any user specified resolvers, but they can be disabled in
* Resolver constructor.
*
* If a scalar is not resolved to anything, it is assigned the default
* YAML _tag for strings.
*
* Params: tag = Tag to resolve to.
* regexp = Regular expression the scalar must match to have this _tag.
* first = String of possible starting characters of the scalar.
*
*/
void addImplicitResolver(string tag, const Regex!char regexp, string first)
pure @safe
{
foreach(const dchar c; first)
{
if((c in yamlImplicitResolvers_) is null)
{
yamlImplicitResolvers_[c] = [];
}
yamlImplicitResolvers_[c] ~= tuple(tag, regexp);
}
}
/// Resolve scalars starting with 'A' to !_tag
@safe unittest
{
import std.file : write;
import std.regex : regex;
import dyaml.loader : Loader;
import dyaml.resolver : Resolver;
write("example.yaml", "A");
auto loader = Loader.fromFile("example.yaml");
loader.resolver.addImplicitResolver("!tag", regex("A.*"), "A");
auto node = loader.load();
assert(node.tag == "!tag");
}
package:
/**
* Resolve tag of a node.
*
* Params: kind = Type of the node.
* tag = Explicit tag of the node, if any.
* value = Value of the node, if any.
* implicit = Should the node be implicitly resolved?
*
* If the tag is already specified and not non-specific, that tag will
* be returned.
*
* Returns: Resolved tag.
*/
string resolve(const NodeID kind, const string tag, const string value,
const bool implicit) @safe
{
import std.array : empty, front;
if((tag !is null) && (tag != "!"))
{
return tag;
}
final switch (kind)
{
case NodeID.scalar:
if(!implicit)
{
return defaultScalarTag_;
}
//Get the first char of the value.
const dchar first = value.empty ? '\0' : value.front;
auto resolvers = (first in yamlImplicitResolvers_) is null ?
[] : yamlImplicitResolvers_[first];
//If regexp matches, return tag.
foreach(resolver; resolvers)
{
if(!(match(value, resolver[1]).empty))
{
return resolver[0];
}
}
return defaultScalarTag_;
case NodeID.sequence:
return defaultSequenceTag_;
case NodeID.mapping:
return defaultMappingTag_;
case NodeID.invalid:
assert(false, "Cannot resolve an invalid node");
}
}
@safe unittest
{
auto resolver = Resolver.withDefaultResolvers;
bool tagMatch(string tag, string[] values) @safe
{
const string expected = tag;
foreach(value; values)
{
const string resolved = resolver.resolve(NodeID.scalar, null, value, true);
if(expected != resolved)
{
return false;
}
}
return true;
}
assert(tagMatch("tag:yaml.org,2002:bool",
["yes", "NO", "True", "on"]));
assert(tagMatch("tag:yaml.org,2002:float",
["6.8523015e+5", "685.230_15e+03", "685_230.15",
"190:20:30.15", "-.inf", ".NaN"]));
assert(tagMatch("tag:yaml.org,2002:int",
["685230", "+685_230", "02472256", "0x_0A_74_AE",
"0b1010_0111_0100_1010_1110", "190:20:30"]));
assert(tagMatch("tag:yaml.org,2002:merge", ["<<"]));
assert(tagMatch("tag:yaml.org,2002:null", ["~", "null", ""]));
assert(tagMatch("tag:yaml.org,2002:str",
["abcd", "9a8b", "9.1adsf"]));
assert(tagMatch("tag:yaml.org,2002:timestamp",
["2001-12-15T02:59:43.1Z",
"2001-12-14t21:59:43.10-05:00",
"2001-12-14 21:59:43.10 -5",
"2001-12-15 2:59:43.10",
"2002-12-14"]));
assert(tagMatch("tag:yaml.org,2002:value", ["="]));
assert(tagMatch("tag:yaml.org,2002:yaml", ["!", "&", "*"]));
}
///Returns: Default scalar tag.
@property string defaultScalarTag() const pure @safe nothrow {return defaultScalarTag_;}
///Returns: Default sequence tag.
@property string defaultSequenceTag() const pure @safe nothrow {return defaultSequenceTag_;}
///Returns: Default mapping tag.
@property string defaultMappingTag() const pure @safe nothrow {return defaultMappingTag_;}
}
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