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lex.ts
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lex.ts
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import Lexer, {Matcher} from './Lexer';
import type {Token} from './Lexer';
export const Tokens = {
AMPERSAND: 'AMPERSAND',
AT: 'AT',
BANG: 'BANG',
BAR: 'BAR',
BLOCK_STRING_VALUE: 'BLOCK_STRING_VALUE',
CLOSING_BRACE: 'CLOSING_BRACE',
CLOSING_BRACKET: 'CLOSING_BRACKET',
CLOSING_PAREN: 'CLOSING_PAREN',
COLON: 'COLON',
COMMA: 'COMMA',
COMMENT: 'COMMENT',
DOLLAR: 'DOLLAR',
ELLIPSIS: 'ELLIPSIS',
EQUALS: 'EQUALS',
FLOAT_VALUE: 'FLOAT_VALUE',
INT_VALUE: 'INT_VALUE',
LINE_TERMINATOR: 'LINE_TERMINATOR',
NAME: 'NAME',
OPENING_BRACE: 'OPENING_BRACE',
OPENING_BRACKET: 'OPENING_BRACKET',
OPENING_PAREN: 'OPENING_PAREN',
STRING_VALUE: 'STRING_VALUE',
UNICODE_BOM: 'UNICODE_BOM',
WHITESPACE: 'WHITESPACE',
} as const;
type TokenName = keyof typeof Tokens;
/**
* @see https://graphql.github.io/graphql-spec/draft/
*/
export default function lex(input: string) {
const lexer = new Lexer<unknown, unknown>((api) => {
const {a, an, choose, match, maybe, oneOf, repeat, sequence} = api;
oneOf(
match('\\"""'),
a('SOURCE_CHARACTER').except(oneOf(match('"""'), match('\\"""'))),
).name('BLOCK_STRING_CHARACTER');
sequence(match('#'), a('SOURCE_CHARACTER').until('LINE_TERMINATOR')).name(
'COMMENT',
);
match(/\\["\\\/bfnrt]/).name('ESCAPED_CHARACTER');
match(/\\u[0-9A-Fa-f]{4}/i).name('ESCAPED_UNICODE');
match(/[eE][+-]?\d+/).name('EXPONENT_PART');
match(/\.\d+/).name('FRACTIONAL_PART');
match(/-?(?:0|[1-9]\d*)/).name('INTEGER_PART');
match(/(?:\n|\r\n|\r)/).name('LINE_TERMINATOR');
match(/[\u0009\u000a\u000d\u0020-\uffff]/).name('SOURCE_CHARACTER');
oneOf(
a('SOURCE_CHARACTER').except(
oneOf(match('"'), match('\\'), 'LINE_TERMINATOR'),
),
'ESCAPED_UNICODE',
'ESCAPED_CHARACTER',
).name('STRING_CHARACTER');
const FLOAT_VALUE = sequence(
'INTEGER_PART',
oneOf(
sequence('FRACTIONAL_PART', 'EXPONENT_PART'),
'EXPONENT_PART',
'FRACTIONAL_PART',
),
);
const INT_VALUE = an('INTEGER_PART');
const NAME = match(/[_A-Za-z][_0-9A-Za-z]*/);
const BLOCK_STRING_VALUE = sequence(
match('"""'),
maybe(repeat('BLOCK_STRING_CHARACTER')),
match('"""'),
);
const STRING_VALUE = sequence(
match('"'),
maybe(repeat('STRING_CHARACTER')),
match('"'),
);
const choices: {[K in TokenName]: Matcher<unknown, unknown>} = {
//
// Punctuators (2.1.8).
//
BANG: match('!'),
DOLLAR: match('$'),
AMPERSAND: match('&'),
OPENING_PAREN: match('('),
CLOSING_PAREN: match(')'),
ELLIPSIS: match('...'),
COLON: match(':'),
EQUALS: match('='),
AT: match('@'),
OPENING_BRACKET: match('['),
CLOSING_BRACKET: match(']'),
OPENING_BRACE: match('{'),
BAR: match('|'),
CLOSING_BRACE: match('}'),
//
// (Other) lexical tokens (2.1.6).
//
NAME,
FLOAT_VALUE, // these two are
INT_VALUE, // ambiguous
BLOCK_STRING_VALUE,
STRING_VALUE,
//
// Ignored tokens (2.1.7).
//
UNICODE_BOM: match('\ufeff'),
WHITESPACE: match(/[\t ]+/),
LINE_TERMINATOR: a('LINE_TERMINATOR'),
COMMENT: a('COMMENT'),
COMMA: match(','),
};
return choose(choices);
});
return lexer.lex(input);
}
const IGNORED = new Set<string>([
Tokens.COMMA,
Tokens.COMMENT,
Tokens.LINE_TERMINATOR,
Tokens.UNICODE_BOM,
Tokens.WHITESPACE,
]);
export function isIgnored(token: Token) {
return IGNORED.has(token.name);
}