rune-langium / core/src / RuneDslParser

Class: RuneDslParser

Defined in: packages/core/src/services/rune-dsl-parser.ts:47

Custom Langium parser for the Rune DSL that pre-processes input text to insert implicit [ and ] brackets around bare expressions after extract, filter, and reduce operators.

Remarks

In the original Xtext-based Rune DSL, extract/filter/reduce can accept both bracket-delimited inline functions (extract [body]) and bare expressions (extract FuncName(item)), using the => syntactic predicate to resolve the ambiguity. Langium's LL(k) parser (Chevrotain) cannot replicate this — adding both alternatives causes the parser builder to hang indefinitely during FIRST(k) set computation.

This class works around the limitation by transforming the input text before parsing via insertImplicitBrackets: bare expressions after extract/filter/reduce are wrapped in [ and ] so the standard InlineFunction grammar rule handles them transparently.

Pitfalls

• The text pre-processor is regex-based and operates on raw source text before tokenization. It cannot correctly handle multi-line bare expressions that span a block boundary — always use explicit [ ] brackets in those cases.
• Do NOT regenerate ast.ts while TypeScript is watching the project — the generated file will be partially written and TypeScript will pick up an inconsistent version, causing spurious type errors. Stop the watcher first, regenerate, then restart.

Use When

• This is used automatically by createRuneDslServices() — you do not need to instantiate it directly.

Avoid When

• Subclassing for grammar experiments — prefer creating a separate grammar variant and a new services container instead.

See

• createRuneDslParser
• insertImplicitBrackets

Extends

• LangiumParser

Constructors

Constructor

new RuneDslParser(services): RuneDslParser;

Defined in: packages/core/src/services/rune-dsl-parser.ts:48

Parameters

Parameter	Type
services	LangiumCoreServices

Returns

RuneDslParser

Overrides

LangiumParser.constructor

Properties

Property	Modifier	Type	Inherited from	Defined in
_unorderedGroups	protected	Map<string, boolean[]>	LangiumParser._unorderedGroups	node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:89
allRules	protected	Map<string, RuleResult>	LangiumParser.allRules	node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:90
lexer	readonly	Lexer	LangiumParser.lexer	node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:87
mainRule	protected	RuleResult	LangiumParser.mainRule	node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:91
wrapper	readonly	ChevrotainWrapper	LangiumParser.wrapper	node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:88

Accessors

definitionErrors

Get Signature

get definitionErrors(): IParserDefinitionError[];

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:144

Returns

IParserDefinitionError[]

Inherited from

LangiumParser.definitionErrors

---

unorderedGroups

Get Signature

get unorderedGroups(): Map<string, boolean[]>;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:103

Current state of the unordered groups

Returns

Map<string, boolean[]>

Inherited from

LangiumParser.unorderedGroups

Methods

action()

action($type, action): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:138

Parameters

Parameter	Type
$type	string
action	Action

Returns

void

Inherited from

LangiumParser.action

---

alternatives()

alternatives(idx, choices): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:93

Performs alternatives parsing (the | operation in EBNF/Langium)

Parameters

Parameter	Type
idx	number
choices	IOrAlt<any>[]

Returns

void

Inherited from

LangiumParser.alternatives

---

atLeastOne()

atLeastOne(idx, callback): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:96

Parses the callback 1 or more times (the + operation in EBNF/Langium)

Parameters

Parameter	Type
idx	number
callback	DSLMethodOpts<unknown>

Returns

void

Inherited from

LangiumParser.atLeastOne

---

consume()

consume(
   idx, 
   tokenType, 
   feature): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:128

Parameters

Parameter	Type
idx	number
tokenType	TokenType
feature	AbstractElement

Returns

void

Inherited from

LangiumParser.consume

---

finalize()

finalize(): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:105

Returns

void

Inherited from

LangiumParser.finalize

---

getRule()

getRule(name): RuleResult | undefined;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:101

Returns the executable rule function for the specified rule name

Parameters

Parameter	Type
name	string

Returns

RuleResult | undefined

Inherited from

LangiumParser.getRule

---

getRuleStack()

getRuleStack(): number[];

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:104

The rule stack indicates the indices of rules that are currently invoked, in order of their invocation.

Returns

number[]

Inherited from

LangiumParser.getRuleStack

---

isRecording()

isRecording(): boolean;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:102

Whether the parser is currently actually in use or in "recording mode". Recording mode is activated once when the parser is analyzing itself. During this phase, no input exists and therefore no AST should be constructed

Returns

boolean

Inherited from

LangiumParser.isRecording

---

many()

many(idx, callback): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:95

Parses the callback 0 or more times (the * operation in EBNF/Langium)

Parameters

Parameter	Type
idx	number
callback	DSLMethodOpts<unknown>

Returns

void

Inherited from

LangiumParser.many

---

optional()

optional(idx, callback): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:94

Parses the callback as optional (the ? operation in EBNF/Langium)

Parameters

Parameter	Type
idx	number
callback	DSLMethodOpts<unknown>

Returns

void

Inherited from

LangiumParser.optional

---

parse()

parse<T>(input, options?): ParseResult<T>;

Defined in: packages/core/src/services/rune-dsl-parser.ts:52

Type Parameters

Type Parameter	Default type
T extends AstNode	AstNode

Parameters

Parameter	Type
input	string
options?	ParserOptions

Returns

ParseResult<T>

Overrides

LangiumParser.parse

---

rule()

rule(rule, impl): RuleResult;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:121

Parameters

Parameter	Type
rule	InfixRule | ParserRule
impl	RuleImpl

Returns

RuleResult

Inherited from

LangiumParser.rule

---

subrule()

subrule(
   idx, 
   rule, 
   fragment, 
   feature, 
   args): void;

Defined in: node_modules/.pnpm/langium@4.2.2/node_modules/langium/lib/parser/langium-parser.d.ts:136

Parameters

Parameter	Type
idx	number
rule	RuleResult
fragment	boolean
feature	AbstractElement
args	Args

Returns

void

Inherited from

LangiumParser.subrule