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