ts-antlr4-scanner

!Alt Text

> A scanner for antlr4-based lexers.

!Alt Text

Features

- Lookahead support
- Lookback support
- Advance to position
- Advance to token type

Installation

``shell
yarn add ts-antlr4-scanner


or


npm install ts-antlr4-scanner
`

Usage

`typescript
import { CommonTokenStream, ANTLRInputStream } from 'antlr4ts'
import { MySQLLexer } from 'ts-mysql-parser'
import { Scanner } from 'ts-antlr4-scanner'

const text = 'SELECT * FROM users'

const inputStream = new ANTLRInputStream(text)
const lexer = new MySQLLexer(inputStream) // Or any antlr4 lexer
const tokenStream = new CommonTokenStream(lexer)
const scanner = new Scanner(tokenStream)

// Move to character L of SELECT
scanner.advanceToPosition(3)

const tokenText = scanner.tokenText()
console.log(tokenText) // SELECT
`

API

$3

Creates a new instance of Scanner with the given token stream.

#### .next()

Advances to the next token.

`typescript
scanner.next()
`

#### .previous()

Returns to the previous token.

`typescript
scanner.previous()
`

#### .advanceToPosition(offset)

Advances to the token that covers the given zero-based offset.

`typescript
scanner.advanceToPosition(4)
`

#### .advanceToType(type)

Advances to the next token with the given lexical type.

`typescript
scanner.advanceToType(14)
`

#### .skipTokenSequence(sequence)

Steps over a number of tokens and positions.

`typescript
scanner.skipTokenSequence([1, 5, 8])
`

#### .lookAhead()

Returns the type of the next token without changing the internal state.

`typescript
scanner.lookAhead()
`

#### .lookBack()

Look back in the stream (physical order) what was before the current token, without modifying the current position.

`typescript
scanner.lookBack()
`

#### .reset()

Resets the walker to be at the original location.

`typescript
scanner.reset()
`

#### .push()

Store the current node on the stack, so we can easily come back when needed.

`typescript
scanner.push()
`

#### .pop()

Returns to the location at the top of the token stack (if any).

`typescript
scanner.pop()
`

#### .tokenText()

Returns the textual expression of the current token.

`typescript
scanner.tokenText()
`

#### .tokenType()

Returns the type of the current token.

`typescript
scanner.tokenType()
`

#### .tokenIndex()

Returns the (zero-based) index of the current token within the input.

`typescript
scanner.tokenIndex()
`

#### .tokenLine()

Returns the (one-based) line number of the token.

`typescript
scanner.tokenLine()
`

#### .tokenStart()

Returns the offset of the current token in its source string.

`typescript
scanner.tokenStart()
`

#### .tokenLength()

Returns the length of the current token in bytes.

`typescript
scanner.tokenLength()
`

#### .tokenChannel()

Returns the channel of the current token.

`typescript
scanner.tokenChannel()
`

#### .tokenSubText()

Returns all the input text from the current token to the end.

`typescript
scanner.tokenSubText()
``

Related

- ts-mysql-parser - A standalone, grammar-complete MySQL parser
- ts-mysql-analyzer - A MySQL query analyzer
- ts-mysql-schema - A schema extractor for MySQL
- ts-mysql-uri - Parse a MySQL connection URI

License

MIT

---

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