tr: Utilize TRY more

This converts the local functions to return ErrorOr<T> and utilizes TRY
more.

Userland/Utilities/tr.cpp

@@ -17,60 +17,62 @@ static bool is_octal(int c)
     return c == '0' || c == '1' || c == '2' || c == '3' || c == '4' || c == '5' || c == '6' || c == '7';
 }
 
-static void generate_character_class(Function<int(int)> oracle, StringBuilder& out)
+static ErrorOr<void> generate_character_class(Function<int(int)> oracle, StringBuilder& out)
 {
     for (int i = 0; i < 128; i++) {
         if (oracle(i))
-            out.append(static_cast<char>(i));
+            TRY(out.try_append(static_cast<char>(i)));
     }
+
+    return {};
 }
 
-static String build_set(StringView specification)
+static ErrorOr<String> build_set(StringView specification)
 {
     StringBuilder out;
     GenericLexer lexer(specification);
 
     while (!lexer.is_eof()) {
         if (lexer.consume_specific("[:alnum:]"sv))
-            generate_character_class(isalnum, out);
+            TRY(generate_character_class(isalnum, out));
         else if (lexer.consume_specific("[:blank:]"sv))
-            generate_character_class(isblank, out);
+            TRY(generate_character_class(isblank, out));
         else if (lexer.consume_specific("[:digit:]"sv))
-            generate_character_class(isdigit, out);
+            TRY(generate_character_class(isdigit, out));
         else if (lexer.consume_specific("[:lower:]"sv))
-            generate_character_class(islower, out);
+            TRY(generate_character_class(islower, out));
         else if (lexer.consume_specific("[:punct:]"sv))
-            generate_character_class(ispunct, out);
+            TRY(generate_character_class(ispunct, out));
         else if (lexer.consume_specific("[:upper:]"sv))
-            generate_character_class(isupper, out);
+            TRY(generate_character_class(isupper, out));
         else if (lexer.consume_specific("[:alpha:]"sv))
-            generate_character_class(isalpha, out);
+            TRY(generate_character_class(isalpha, out));
         else if (lexer.consume_specific("[:cntrl:]"sv))
-            generate_character_class(iscntrl, out);
+            TRY(generate_character_class(iscntrl, out));
         else if (lexer.consume_specific("[:graph:]"sv))
-            generate_character_class(isgraph, out);
+            TRY(generate_character_class(isgraph, out));
         else if (lexer.consume_specific("[:print:]"sv))
-            generate_character_class(isprint, out);
+            TRY(generate_character_class(isprint, out));
         else if (lexer.consume_specific("[:space:]"sv))
-            generate_character_class(isspace, out);
+            TRY(generate_character_class(isspace, out));
         else if (lexer.consume_specific("[:xdigit:]"sv))
-            generate_character_class(isxdigit, out);
+            TRY(generate_character_class(isxdigit, out));
         else if (lexer.consume_specific("\\\\"sv))
-            out.append('\\');
+            TRY(out.try_append('\\'));
         else if (lexer.consume_specific("\\a"sv))
-            out.append('\a');
+            TRY(out.try_append('\a'));
         else if (lexer.consume_specific("\\b"sv))
-            out.append('\b');
+            TRY(out.try_append('\b'));
         else if (lexer.consume_specific("\\f"sv))
-            out.append('\f');
+            TRY(out.try_append('\f'));
         else if (lexer.consume_specific("\\n"sv))
-            out.append('\n');
+            TRY(out.try_append('\n'));
         else if (lexer.consume_specific("\\r"sv))
-            out.append('\r');
+            TRY(out.try_append('\r'));
         else if (lexer.consume_specific("\\t"sv))
-            out.append('\t');
+            TRY(out.try_append('\t'));
         else if (lexer.consume_specific("\\v"sv))
-            out.append('\v');
+            TRY(out.try_append('\v'));
         else if (lexer.next_is('\\') && is_octal(lexer.peek(1))) {
             lexer.consume_specific('\\');
             int max_left_over = 3;
@@ -81,9 +83,9 @@ static String build_set(StringView specification)
             int value = 0;
             for (char ch : octal_digits)
                 value = value * 8 + (ch - '0');
-            out.append(static_cast<char>(value));
+            TRY(out.try_append(static_cast<char>(value)));
         } else
-            out.append(lexer.consume(1));
+            TRY(out.try_append(lexer.consume(1)));
     }
 
     return out.to_string();
@@ -125,18 +127,18 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    String from_str = build_set(from_chars);
+    auto from_str = TRY(build_set(from_chars));
     if (complement_flag) {
         StringBuilder complement_set;
         for (int ch = 0; ch < 256; ch++) {
             if (!from_str.contains(static_cast<char>(ch)))
-                complement_set.append(static_cast<char>(ch));
+                TRY(complement_set.try_append(static_cast<char>(ch)));
         }
         from_str = complement_set.to_string();
     }
 
-    auto to_str = build_set(to_chars);
+    auto to_str = TRY(build_set(to_chars));
-    String squeeze_string = build_set(to_chars ? to_chars : from_chars);
+    auto squeeze_string = TRY(build_set(to_chars ? to_chars : from_chars));
     Optional<char> last_char;
 
     for (;;) {