48 lines
1.1 KiB
TypeScript
48 lines
1.1 KiB
TypeScript
import type { Token } from "./lexer.ts";
|
|
import { is_digit } from "./utils.ts";
|
|
|
|
/**
|
|
* Scans a number, at the given position in the input string.
|
|
* This function assumes that the character at the given position is a digit.
|
|
* It follows this grammar:
|
|
*
|
|
* @param input the input string
|
|
* @param pos the position to start scanning from
|
|
* @returns
|
|
*/
|
|
export function lex_number(input: string, pos: number): [Token, number] {
|
|
const [token_value, next] = scan_decimal(input, pos);
|
|
|
|
return [{ v: token_value, token_type: "number" }, next];
|
|
}
|
|
|
|
function scan_decimal(input: string, starting_position: number): [string, number] {
|
|
let current_value = "";
|
|
let pos = starting_position;
|
|
|
|
while (pos < input.length) {
|
|
const c = input[pos];
|
|
|
|
if (c === ".") {
|
|
// todo
|
|
throw new Error("Not implemented");
|
|
}
|
|
else if (c == "e" || c == "E") {
|
|
// todo
|
|
throw new Error("Not implemented");
|
|
}
|
|
else if (is_digit(c)) {
|
|
current_value += c;
|
|
pos += 1;
|
|
}
|
|
else {
|
|
break;
|
|
}
|
|
|
|
}
|
|
|
|
return [current_value, pos];
|
|
}
|
|
|
|
|