We define a custom Error class for parsing errors.
The possible sources of errors are defined in the enumeration below.
export enum ErrorSource {
Input = "Input",
Lexer = "Lexer",
Parser = "Parsing"
}
The ParseError class contains information about the parsing error in an easily accessible form.
export class ParseError extends Error {
constructor(
The source of the error.
readonly source: ErrorSource,
The position where the error happened.
readonly position: number,
Input found at position.
readonly found: string,
Input expected at position. There can be multiple terminals.
readonly expected: string[] = []) {
Constructor formats the error message using the parameters provided.
super(`${source} error at position ${position + 1}.\n` +
`\tFound: "${found}"\n` +
`\tExpected: ${expected.map(s => `"${s}"`).join(", ")}`);
}
}