42 lines
2.1 KiB
Markdown
42 lines
2.1 KiB
Markdown
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# yaml-ast-parser
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[](https://travis-ci.org/mulesoft-labs/yaml-ast-parser)
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This is a fork of JS-YAML which supports parsing of YAML into AST.
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In additional to parsing YAML to AST, it has following features:
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* restoration after the errors and reporting errors as a part of AST nodes.
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* built-in support for `!include` tag used in RAML
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## Usage
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The type information below is relevant when using TypeScript, if using from JavaScript only the field/method information is relevant.
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`load` method can be used to load the tree and returns a `YAMLNode`.
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### YAMLNode
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`YAMLNode` class is an ancestor for all node kinds.
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It's `kind` field determine node kind, one of `Kind` enum:
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* `SCALAR`, `MAPPING`, `MAP`, `SEQ`, `ANCHOR_REF` or `INCLUDE_REF`.
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After node kind is determined, it can be cast to one of the `YAMLNode` descendants types:
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* `YAMLScalar`, `YAMLMapping`, `YamlMap`, `YAMLSequence` or `YAMLAnchorReference`.
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| class | important members |
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|-------|-------------------|
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| `YAMLNode` | `startPosition` and `endPosition` provide node range.|
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| `YAMLScalar` | `string` `value` field |
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| `YAMLMapping` |`YAMLScalar` `key` and `YAMLNode` `value` fields |
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| `YAMLSequence` | `YAMLNode[]` `items` field|
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| `YamlMap` | `YAMLMapping[]` `mappings` field|
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| `YAMLAnchorReference` | `string` `referencesAnchor` and `YAMLNode` `value`|
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### YAMLScalar
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Scalars are [one of the three main node types defined by YAML](http://www.yaml.org/spec/1.2/spec.html#scalar//) and are effectively leaf nodes.
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There are many factors that can influence the type of datum represent in scalar node (context, schema, tag, etc.).
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To help inspection of a `YAMLScalar` to determine its datatype when a document uses the [Core Schema](http://www.yaml.org/spec/1.2/spec.html#id2804923), you can pass the `YAMLScalar` to the `determineScalarType` function. It will return an enum value indicating `null`, `bool`, `int`, `float`, or `string`.
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Once you know the type, there are also some helper functions to help read the value by passing them the string, `value`: `parseYamlBoolean`, `parseYamlFloat`, and `parseYamlInteger`.
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