@lanexio/parser-grammar-csv

This page documents @lanexio/parser-grammar-csv, the CSV grammar package for parsing RFC 4180 compliant CSV and TSV (tab-separated values) with configurable delimiter, quoting, and header detection.

• Version: Stable
• Module name: parser-grammar-csv
• Package: @lanexio/parser-grammar-csv
• Import path: @lanexio/parser-grammar-csv
• Layer: 2 (Grammar)
• Runtime: Universal
• Module format: ESM
• Stability: Stable
• Primary use case: Parse CSV and TSV data into a flat AST.

Layer contract

Layer 2 dependency rules

This package depends only on Layer 1 core packages. It does not import from query, bridge, devtools, or entry packages. Grammar packs never depend on other grammar packs.

When to use this module

• You need to parse CSV (RFC 4180) data into a traversable AST.
• You need to parse TSV (tab-separated values) data.
• You need configurable delimiter, quoting, or header detection.

Module boundary

Boundary	Description
Inputs	Uint8Array (source bytes) + optional ParseCsvOptions
Outputs	LexTree (flat AST rooted at CsvKind.Document)
Side effects	None
Determinism	Yes
External dependencies	@lanexio/parser-core
Never-throw guarantee	Yes
Security surface	None (parse only, no output generation)

Installation

1. Install the package.

   pnpm

   pnpm add @lanexio/parser-grammar-csv

   npm

   npm install @lanexio/parser-grammar-csv

   yarn

   yarn add @lanexio/parser-grammar-csv

2. Import the named export.

   import { parseCsv } from '@lanexio/parser-grammar-csv';

Peer dependencies

Requirement	Required	Layer	Notes
@lanexio/parser-core	Yes	1	^1.0.0

Basic Usage

import { parseCsv } from '@lanexio/parser-grammar-csv';

const encoder = new TextEncoder();
const bytes = encoder.encode('name,age\nAlice,30\nBob,25');

const tree = parseCsv(bytes);

console.log(tree.nodeCount);
console.log(tree.root.kind);   // CsvKind.Document

Parse TSV

import { parseTsv } from '@lanexio/parser-grammar-csv';

const encoder = new TextEncoder();
const tree = parseTsv(encoder.encode('name\tage\nAlice\t30'));

Custom delimiter

import { parseCsv } from '@lanexio/parser-grammar-csv';

const encoder = new TextEncoder();
const tree = parseCsv(encoder.encode('name|age\nAlice|30'), { delimiter: 0x7c });

Exports

Export	Type	Description
parseCsv	(bytes: Uint8Array, options?: ParseCsvOptions) => LexTree	Parse CSV. Never throws.
parseTsv	(source: Uint8Array, opts?: ParseTsvOptions) => LexTree	Parse TSV (tab-separated values).
CsvKind	const object	Numeric kind IDs for all CSV node types.
CsvField	const object	Numeric field IDs for CSV value slots.
CSV_FLAG_HEADER	4	Per-node flag: this record is the header row. Set on the first CsvKind.Record node when header option is true.
CSV_FLAG_QUOTED	2	Per-node flag: field is enclosed in double quotes. Set on CsvKind.Field nodes whose value is quoted.
CSV_FIELD_NAMES_BY_ID	readonly string[]	Field name lookup by numeric field ID.
CSV_KIND_NAMES_BY_ID	readonly Record<number, string>	Kind-name lookup by numeric ID.
csvGrammar	LanexioParserPureGrammar	Grammar descriptor for CSV.
tsvGrammar	LanexioParserPureGrammar	Grammar descriptor for TSV.
csvRegistration	GrammarRegistration	Registration for CSV.
tsvRegistration	GrammarRegistration	Registration for TSV.
csvReuseOracle	ReuseOracle	Incremental reuse oracle for CSV.
tsvReuseOracle	ReuseOracle	Incremental reuse oracle for TSV.

Options

ParseCsvOptions

Field	Type	Required	Default	Description
delimiter	number	No	0x2C (,)	Field delimiter byte.
quote	number	No	0x22 (")	Quote character byte.
header	boolean	No	true	Whether the first record is a header row.
relaxQuotes	boolean	No	true	Allow unescaped quotes inside quoted fields (non-RFC dialects).

ParseTsvOptions

Field	Type	Required	Default	Description
header	boolean	No	true	Whether the first record is a header row.

Return shape

Property	Type	Description
root	LexNode	Root node (CsvKind.Document or CsvKind.Error on pure invalid).
nodeCount	number	Total nodes in the tree.
source	Uint8Array	Original parsed bytes.

Exported types

Type	Purpose	Notes
ParseCsvOptions	Options for parseCsv	See options table above.
ParseTsvOptions	Options for parseTsv	{ header?: boolean }
CsvKindType	Union of all CsvKind values	Type-safe kind reference
CsvFieldType	Union of all CsvField values	Type-safe field reference

Configuration and Extension

Delimiter customization

parseCsv accepts any byte as delimiter. Use parseTsv for tab-delimited data (delegates to CSV parser with delimiter: 0x09, quote: -1).

Accessibility

Accessibility requirements

• No direct accessibility surface. The CSV parser produces flat AST data structures.

Accessibility checklist

Concern	Status
Generated output semantics	Not applicable (data format)
ARIA attributes in serialized output	Not applicable
Semantic element round-trip	Not applicable

Security

Security considerations

• parseCsv and parseTsv never throw on any byte sequence.

Threat	Mitigation	Status
Malformed input byte sequence	Panic-free guarantee: all inputs accepted, errors produce CsvKind.Error AST nodes	Implemented

Companion packages

Package	Relationship	Layer	Notes
@lanexio/parser-core	Requires	1	Provides LexTree, LexNode, LexCursor
@lanexio/parser	Consumes	6	Unified entry point

Changelog

Version	Date	Status	Notable changes
1.0.0	2026-05-29	Current	Initial stable release. Apache-2.0.

Migration notes

• None.

Related Content

Flat AST How the 16-byte node layout works.

Stability Guarantees Never-throw, panic-free, and 3-token recovery.