Parser:
- startrule: <rule>
regularrule: <rule>
Lexer:
// if a something is matched for two or more tokens, it will be matched as the highest of them here, so order of appearance matters
RULENAME: `regex`
// comment (must be seperate line)Parser:
// + and * can currently only be used to wrap a complete rule, so something like 'rule: rul1 rule2+ rule3' is not alowed.
- block: variable+ // * is supported as well!
variable: GLOBAL? ID EQ expr SEMICOLON
expr: add | neg
neg: ADD mul
add: (add ADD mul) | mul
mul: (mul MUL pow) | pow
pow: (pow POW atom) | atom
paren: LPAREN expr RPAREN
atom: NUM | ID | paren
Lexer:
GLOBAL: `global`
ID: `[a-zA-Z_][a-zA-Z0-9_]*`
SEMICOLON: `;`
EQ: `=`
NUM: `[0-9]+`
ADD: `\+|\-`
MUL: `\*|\/`
POW: `\^`
LPAREN: `\(`
RPAREN: `\)`class Parser(String[] lexerRules, String[] parserRules);
class Parser(String ruleFileContent);And to directly read from a file, use:
Parser Parser.fromFile(String filePath);Then, to parse a string, use:
ParserToken Parser.parse(String input);
ParserToken Parser.parse(String input, List<String> skipSingle);Input is the input string to be parsed, and skipSingle are parser rule names that should be skipped when only having one child, for example, if we put mul, pow in skipSingle, then the following parsing tree:
add(mul(pow(atom(NUM(1)))), ADD(+), mul(pow(atom(NUM(2)))))
will be translated into add(atom(NUM(1)), ADD(+), atom(NUM(2))).
Example usage:
Parser parser = Parser.fromFile("test/example.txt");
System.out.println(parser.parse("global x = 5 + 3; y = 2 * (3 + 4) ^ 7;", Arrays.asList("add", "mul", "pow")));Attributes:
String name; // Rule name
String value; // Original text in the input string
int start; // Start index in the input string (not line relative)
int end; // End index in the input string (not line relative)
int line; // Line number in the input string
List<ParserToken> children; // Child tokens