Enum SyntaxKind

Source

#[repr(u16)]pub enum SyntaxKind {
Show 50 variants    ROOT = 0,
    DOCUMENT = 1,
    SEQUENCE = 2,
    MAPPING = 3,
    SCALAR = 4,
    ALIAS = 5,
    TAGGED_NODE = 6,
    ERROR = 7,
    DASH = 8,
    PLUS = 9,
    COLON = 10,
    QUESTION = 11,
    LEFT_BRACKET = 12,
    RIGHT_BRACKET = 13,
    LEFT_BRACE = 14,
    RIGHT_BRACE = 15,
    COMMA = 16,
    PIPE = 17,
    GREATER = 18,
    AMPERSAND = 19,
    ASTERISK = 20,
    EXCLAMATION = 21,
    PERCENT = 22,
    AT = 23,
    BACKTICK = 24,
    QUOTE = 25,
    SINGLE_QUOTE = 26,
    DOC_START = 27,
    DOC_END = 28,
    KEY = 29,
    VALUE = 30,
    MAPPING_ENTRY = 31,
    SEQUENCE_ENTRY = 32,
    STRING = 33,
    UNTERMINATED_STRING = 34,
    INT = 35,
    FLOAT = 36,
    BOOL = 37,
    NULL = 38,
    TAG = 39,
    ANCHOR = 40,
    REFERENCE = 41,
    MERGE_KEY = 42,
    DIRECTIVE = 43,
    WHITESPACE = 44,
    NEWLINE = 45,
    INDENT = 46,
    COMMENT = 47,
    BOM = 48,
    EOF = 49,
}

Expand description

YAML Concrete Syntax Tree (CST) node types.

This enum defines all possible node types in the YAML syntax tree, representing both lexical tokens (from the lexer) and semantic nodes (created by the parser).

§Tree Hierarchy

The YAML syntax tree follows this general structure:

ROOT
├── DOCUMENT*
│   ├── DIRECTIVE* (optional, e.g., %YAML 1.2)
│   ├── DOC_START? (optional ---)
│   ├── MAPPING | SEQUENCE | SCALAR | TAGGED_NODE
│   └── DOC_END? (optional ...)
└── WHITESPACE | NEWLINE | COMMENT (between documents)

MAPPING
├── MAPPING_ENTRY*
│   ├── KEY
│   │   └── SCALAR | SEQUENCE | MAPPING (YAML 1.2 allows complex keys)
│   ├── COLON
│   ├── WHITESPACE?
│   └── VALUE
│       └── SCALAR | SEQUENCE | MAPPING | TAGGED_NODE
├── NEWLINE
├── INDENT
└── COMMENT?

SEQUENCE  
├── SEQUENCE_ENTRY*
│   ├── DASH
│   ├── WHITESPACE?
│   └── SCALAR | SEQUENCE | MAPPING | TAGGED_NODE
├── NEWLINE
├── INDENT
└── COMMENT?

SCALAR
└── STRING | INT | FLOAT | BOOL | NULL

TAGGED_NODE
├── TAG (e.g., !!str, !custom)
├── WHITESPACE?
└── SCALAR | MAPPING | SEQUENCE

§Node Categories

§Structural Nodes (created by parser)

ROOT: Top-level container for the entire document
DOCUMENT: A single YAML document (separated by — or …)
MAPPING: Key-value pairs {key: value} or block style
SEQUENCE: Lists [item1, item2] or block style with -
SCALAR: Leaf values (strings, numbers, booleans, null)
TAGGED_NODE: Values with explicit type tags !!str "hello"

§Container Nodes (created by parser)

MAPPING_ENTRY: A single key-value pair within a mapping
SEQUENCE_ENTRY: A single item within a sequence
KEY: The key part of a key-value pair (can contain complex types)
VALUE: The value part of a key-value pair

§Lexical Tokens (from lexer)

Punctuation: COLON, DASH, COMMA, etc.
Brackets: LEFT_BRACKET, RIGHT_BRACKET, LEFT_BRACE, RIGHT_BRACE
Literals: STRING, INT, FLOAT, BOOL, NULL
YAML-specific: TAG, ANCHOR, REFERENCE, MERGE_KEY
Document markers: DOC_START (—), DOC_END (…)
Formatting: WHITESPACE, NEWLINE, INDENT, COMMENT

§Special Cases

§Complex Keys (YAML 1.2.2)

Keys can be sequences or mappings, not just scalars:

[1, 2]: value        # Sequence key
{a: b}: value        # Mapping key

§Tagged Values

Values can have explicit type information:

number: !!int "123"  # Force string "123" to be treated as integer
binary: !!binary |   # Base64 encoded binary data
  R0lGODlhDAAMAIQ...

§Block Scalars

Multi-line strings with special parsing rules:

literal: |           # PIPE indicates literal scalar
  Line 1
  Line 2
folded: >            # GREATER indicates folded scalar  
  Long text that
  gets folded

The tree preserves all original formatting, comments, and whitespace, enabling lossless round-trip parsing and precise source location tracking.