refactor(toml): split symbol parser (#6563)

Author: timreichen

toml/_parser.ts

@@ -197,8 +197,13 @@ export function deepAssignWithTable(target: Record<string, unknown>, table: {
 // Parser combinators and generators
 // ---------------------------------
 
-function or<T>(parsers: ParserComponent<T>[]): ParserComponent<T> {
-  return (scanner: Scanner): ParseResult<T> => {
+// deno-lint-ignore no-explicit-any
+function or<T extends readonly ParserComponent<any>[]>(
+  parsers: T,
+): ParserComponent<
+  ReturnType<T[number]> extends ParseResult<infer R> ? R : Failure
+> {
+  return (scanner: Scanner) => {
     for (const parse of parsers) {
       const result = parse(scanner);
       if (result.ok) return result;
@@ -533,22 +538,41 @@ export function multilineLiteralString(
   return success(acc.join(""));
 }
 
-const symbolPairs: [string, unknown][] = [
-  ["true", true],
-  ["false", false],
+const BOOLEAN_REGEXP = /(?:true|false)\b/y;
+export function boolean(scanner: Scanner): ParseResult<boolean> {
+  scanner.skipWhitespaces();
+  const match = scanner.match(BOOLEAN_REGEXP);
+  if (!match) return failure();
+  const string = match[0];
+  scanner.next(string.length);
+  const value = string === "true";
+  return success(value);
+}
+
+const INFINITY_MAP = new Map<string, number>([
   ["inf", Infinity],
   ["+inf", Infinity],
   ["-inf", -Infinity],
-  ["nan", NaN],
-  ["+nan", NaN],
-  ["-nan", NaN],
-];
-export function symbols(scanner: Scanner): ParseResult<unknown> {
+]);
+const INFINITY_REGEXP = /[+-]?inf\b/y;
+export function infinity(scanner: Scanner): ParseResult<number> {
   scanner.skipWhitespaces();
-  const found = symbolPairs.find(([str]) => scanner.startsWith(str));
-  if (!found) return failure();
-  const [str, value] = found;
-  scanner.next(str.length);
+  const match = scanner.match(INFINITY_REGEXP);
+  if (!match) return failure();
+  const string = match[0];
+  scanner.next(string.length);
+  const value = INFINITY_MAP.get(string)!;
+  return success(value);
+}
+
+const NAN_REGEXP = /[+-]?nan\b/y;
+export function nan(scanner: Scanner): ParseResult<number> {
+  scanner.skipWhitespaces();
+  const match = scanner.match(NAN_REGEXP);
+  if (!match) return failure();
+  const string = match[0];
+  scanner.next(string.length);
+  const value = NaN;
   return success(value);
 }
 
@@ -683,7 +707,9 @@ export const value = or([
   multilineLiteralString,
   basicString,
   literalString,
-  symbols,
+  boolean,
+  infinity,
+  nan,
   dateTime,
   localTime,
   binary,

toml/parse_test.ts

@@ -5,22 +5,24 @@ import {
   bareKey,
   basicString,
   binary,
+  boolean,
   dateTime,
   deepAssignWithTable,
   dottedKey,
   float,
   hex,
+  infinity,
   inlineTable,
   integer,
   literalString,
   localTime,
   multilineBasicString,
   multilineLiteralString,
+  nan,
   octal,
   pair,
   parserFactory,
   Scanner,
-  symbols,
   table,
   value,
 } from "./_parser.ts";
@@ -181,14 +183,38 @@ Violets are\\tblue'''`),
 });
 
 Deno.test({
-  name: "parse() handles symbols",
+  name: "parse() handles boolean",
   fn() {
-    const parse = parserFactory(symbols);
+    const parse = parserFactory(boolean);
     assertEquals(parse("true"), true);
-    assertEquals(parse("nan"), NaN);
+    assertEquals(parse("false"), false);
+    assertThrows(() => parse("truetrue"));
+    assertThrows(() => parse("false "));
+  },
+});
+
+Deno.test({
+  name: "parse() handles infinity",
+  fn() {
+    const parse = parserFactory(infinity);
     assertEquals(parse("inf"), Infinity);
-    assertThrows(() => parse(""));
-    assertThrows(() => parse("_"));
+    assertEquals(parse("+inf"), Infinity);
+    assertEquals(parse("-inf"), -Infinity);
+    assertThrows(() => parse("infinf"));
+    assertThrows(() => parse("+inf "));
+    assertThrows(() => parse("-inf_"));
+  },
+});
+Deno.test({
+  name: "parse() handles nan",
+  fn() {
+    const parse = parserFactory(nan);
+    assertEquals(parse("nan"), NaN);
+    assertEquals(parse("+nan"), NaN);
+    assertEquals(parse("-nan"), NaN);
+    assertThrows(() => parse("nannan"));
+    assertThrows(() => parse("+nan "));
+    assertThrows(() => parse("-nan_"));
   },
 });