blob: 9558443991aa293cbf2b9277a693657680d3d24d [file] [log] [blame]
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
/**
* Takes a parsed YAML document (what the spec calls the "serialization tree")
* and resolves aliases, resolves tags, and parses scalars to produce the
* "representation graph".
*/
class _Composer extends _Visitor {
/** The root node of the serialization tree. */
_Node root;
/**
* Map from anchor names to the most recent representation graph node with
* that anchor.
*/
Map<String, _Node> anchors;
/**
* The next id to use for the represenation graph's anchors. The spec doesn't
* use anchors in the representation graph, but we do so that the constructor
* can ensure that the same node in the representation graph produces the same
* native object.
*/
int idCounter;
_Composer(this.root) : this.anchors = <String, _Node>{}, this.idCounter = 0;
/** Runs the Composer to produce a representation graph. */
_Node compose() => root.visit(this);
/** Returns the anchor to which an alias node refers. */
_Node visitAlias(_AliasNode alias) {
if (!anchors.containsKey(alias.anchor)) {
throw new YamlException("no anchor for alias ${alias.anchor}");
}
return anchors[alias.anchor];
}
/**
* Parses a scalar node according to its tag, or auto-detects the type if no
* tag exists. Currently this only supports the YAML core type schema.
*/
_Node visitScalar(_ScalarNode scalar) {
if (scalar.tag.name == "!") {
return setAnchor(scalar, parseString(scalar.content));
} else if (scalar.tag.name == "?") {
for (var fn in [parseNull, parseBool, parseInt, parseFloat]) {
var result = fn(scalar.content);
if (result != null) return result;
}
return setAnchor(scalar, parseString(scalar.content));
}
// TODO(nweiz): support the full YAML type repository
var tagParsers = {
'null': parseNull, 'bool': parseBool, 'int': parseInt,
'float': parseFloat, 'str': parseString
};
for (var key in tagParsers.keys) {
if (scalar.tag.name != _Tag.yaml(key)) continue;
var result = tagParsers[key](scalar.content);
if (result != null) return setAnchor(scalar, result);
throw new YamlException('invalid literal for $key: "${scalar.content}"');
}
throw new YamlException('undefined tag: "${scalar.tag.name}"');
}
/** Assigns a tag to the sequence and recursively composes its contents. */
_Node visitSequence(_SequenceNode seq) {
var tagName = seq.tag.name;
if (tagName != "!" && tagName != "?" && tagName != _Tag.yaml("seq")) {
throw new YamlException("invalid tag for sequence: ${tagName}");
}
var result = setAnchor(seq, new _SequenceNode(_Tag.yaml("seq"), null));
result.content = super.visitSequence(seq);
return result;
}
/** Assigns a tag to the mapping and recursively composes its contents. */
_Node visitMapping(_MappingNode map) {
var tagName = map.tag.name;
if (tagName != "!" && tagName != "?" && tagName != _Tag.yaml("map")) {
throw new YamlException("invalid tag for mapping: ${tagName}");
}
var result = setAnchor(map, new _MappingNode(_Tag.yaml("map"), null));
result.content = super.visitMapping(map);
return result;
}
/**
* If the serialization tree node [anchored] has an anchor, records that
* that anchor is pointing to the representation graph node [result].
*/
_Node setAnchor(_Node anchored, _Node result) {
if (anchored.anchor == null) return result;
result.anchor = '${idCounter++}';
anchors[anchored.anchor] = result;
return result;
}
/** Parses a null scalar. */
_ScalarNode parseNull(String content) {
if (!const RegExp("^(null|Null|NULL|~|)\$").hasMatch(content)) return null;
return new _ScalarNode(_Tag.yaml("null"), value: null);
}
/** Parses a boolean scalar. */
_ScalarNode parseBool(String content) {
var match = const RegExp("^(?:(true|True|TRUE)|(false|False|FALSE))\$").
firstMatch(content);
if (match == null) return null;
return new _ScalarNode(_Tag.yaml("bool"), value: match.group(1) != null);
}
/** Parses an integer scalar. */
_ScalarNode parseInt(String content) {
var match = const RegExp("^[-+]?[0-9]+\$").firstMatch(content);
if (match != null) {
return new _ScalarNode(_Tag.yaml("int"),
value: Math.parseInt(match.group(0)));
}
match = const RegExp("^0o([0-7]+)\$").firstMatch(content);
if (match != null) {
// TODO(nweiz): clean this up when Dart can parse an octal string
var n = 0;
for (var c in match.group(1).charCodes) {
n *= 8;
n += c - 48;
}
return new _ScalarNode(_Tag.yaml("int"), value: n);
}
match = const RegExp("^0x[0-9a-fA-F]+\$").firstMatch(content);
if (match != null) {
return new _ScalarNode(_Tag.yaml("int"),
value: Math.parseInt(match.group(0)));
}
return null;
}
/** Parses a floating-point scalar. */
_ScalarNode parseFloat(String content) {
var match = const RegExp(
"^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?\$").
firstMatch(content);
if (match != null) {
// YAML allows floats of the form "0.", but Dart does not. Fix up those
// floats by removing the trailing dot.
var matchStr = match.group(0).replaceAll(new RegExp(r"\.$"), "");
return new _ScalarNode(_Tag.yaml("float"),
value: Math.parseDouble(matchStr));
}
match = const RegExp("^([+-]?)\.(inf|Inf|INF)\$").firstMatch(content);
if (match != null) {
var infinityStr = match.group(1) == "-" ? "-Infinity" : "Infinity";
return new _ScalarNode(_Tag.yaml("float"),
value: Math.parseDouble(infinityStr));
}
match = const RegExp("^\.(nan|NaN|NAN)\$").firstMatch(content);
if (match != null) {
return new _ScalarNode(_Tag.yaml("float"),
value: Math.parseDouble("NaN"));
}
return null;
}
/** Parses a string scalar. */
_ScalarNode parseString(String content) =>
new _ScalarNode(_Tag.yaml("str"), value: content);
}