Program Parse
| program | → | PROGRAM identifier IS |
| { instruction } | ||
| BEGIN | ||
| block | ||
| END identifier | ||
| instruction | → | INSTRUCTION identifier IS |
| block | ||
| END identifier |
Statement Parse
| block | → | { statement } |
| statement | → | if | while | call |
| if | → | IF condition THEN |
| block | ||
| [ ELSE | ||
| block ] | ||
| END IF | ||
| while | → | WHILE condition DO |
| block | ||
| END WHILE | ||
| call | → | identifier |
Tokenizer
| identifier | → | letter { letter | digit | - } |
| letter | → | a | b | ... | z | A | B | ... | Z |
| digit | → | 0 | 1 | ... | 9 |
| keyword | → | BEGIN | DO | ELSE | END | |
| IF | INSTRUCTION | IS | | ||
| PROGRAM | THEN | WHILE | ||
| condition | → | next-is-empty | next-is-not-empty | |
| next-is-wall | next-is-not-wall | | ||
| next-is-enemy | next-is-not-enemy | | ||
| next-is-friend | next-is-not-friend | | ||
| random | true |
Note 1: The special symbols { and } mean that the enclosed sequence of symbols occurs zero or more times, and the special symbols [ and ] mean that the enclosed sequence of symbols occurs zero or one times.
Note 2: Even though the rewrite rules for identifier do not rule this out explicitly, keywords and conditions are not considered identifiers (as defined by the mathematical subtype IDENTIFIER in the StatementKernel interface).