Just like the usage of Parser Combinator in Haskell, jparser does not generate AST, so you need to use the map method to map the results to a custom class. You can see how it's done specifically from the implementation of JsonParser.
<dependency>
<groupId>io.github.janlely</groupId>
<artifactId>jparser</artifactId>
<version>1.0.6</version>
</dependency>gramma: be careful not to write it as left-recursive.
<expr> ::= <term> | <term> "+" <expr> | <term> "-" <expr>
<term> ::= <factor> | <factor> "*" <term> | <factor> "/" <term>
<factor> ::= <number> | "(" <expr> ")"
<number> ::= <digit> | <digit> <number>
<digit> ::= "0" | "1" | "2" | ... | "9"public class Calculator {
@Test
public void testCalc() {
Result result = expr().parse(Buffer.builder().data("(1+2)*3-(4*2)".getBytes()).build());
assert result.<Double>get(0).compareTo(1.0) == 0;
result = expr().parse(Buffer.builder().data("1+2*3-(4*2)".getBytes()).build());
assert result.<Double>get(0).compareTo(-1.0) == 0;
result = expr().parse(Buffer.builder().data("1+2*3-(4*(2+1))".getBytes()).build());
assert result.<Double>get(0).compareTo(-5.0) == 0;
}
public Parser expr() {
return Parser.choose(
() -> term().chain(TextParsers.one('+').ignore())
.chain(expr()).map(s -> (double)s.get(0) + (double)s.get(1)),
() -> term().chain(TextParsers.one('-').ignore())
.chain(expr()).map(s -> (double)s.get(0) - (double)s.get(1)),
() -> term()
);
}
public Parser term() {
return Parser.choose(
() -> factor().chain(TextParsers.one('*').trim(false).ignore())
.chain(term()).map(s -> (double)s.get(0) * (double)s.get(1)),
() -> factor().chain(TextParsers.one('/').trim(false).ignore())
.chain(term()).map(s -> (double)s.get(0) / (double)s.get(1)),
() -> factor()
);
}
public Parser factor() {
return Parser.choose(
TextParsers.one('(').ignore()
.chain(expr())
.chain(TextParsers.one(')').ignore()),
number()
);
}
public Parser number() {
return NumberParsers.anyDoubleStr();
}
}ByteParsers::satisfy //parse a byte based on a condition.
ByteParsers::any //parse any byte
ByteParsers::one //parse a specified byte
ByteParsers::take //parse N arbitrary bytes.
ByteParsers::skip //skip N arbitrary bytes.
ByteParsers::takeWhile //parse any number of bytes that meet a certain condition.
ByteParsers::skipWhile //skip any number of bytes that meet a certain condition.
TextParsers::satisfy //parse a character that satisfies a condition according to the given encoding.
TextParsers::one //parse a character according to the given encoding
TextParsers::oneOf //parse a character which is one of the given string
TextParsers::noneOf //parse a character which is none of the given string
TextParsers::string //parse a given string according to the given encoding.
TextParsers::any //parse any n characters according to the specified encoding.
TextParsers::take //parse any n characters according to the specified encoding.
TextParsers::takeWhile //parse characters that satisfy a condition according to the given encoding and return a string.
TextParsers::skip //skip n characters of the given encoding.
TextParsers::skipWhile //skip characters that satisfy a condition according to the given encoding
TextParsers::eof //end of line
TextParsers::space //parse one whitespace character, excluding newline characters.
TextParsers::spaces //parse whitespace characters, excluding newline characters.
TextParsers::white //parse one whitespace character
TextParsers::whites //parse whitespace characters
NumberParsers::intStr //parse a specified integer encoded as a string.
NumberParsers::anyIntStr //parse a any integer encoded as a string.
NumberParsers::intLE //parse a specified integer encoded in little-endian format
NumberParsers::intBE //parse a specified integer encoded in big-endian format
NumberParsers::longLE //parse a specified long integer encoded in little-endian format
NumberParsers::longBE //parse a specified long integer encoded in big-endian format
NumberParsers::anyIntLE //parse any integer encoded in little-endian format
NumberParsers::anyIntBE //parse any integer encoded in big-endian format
NumberParsers::anyLongLE //parse any long integer encoded in little-endian format
NumberParsers::andLongBE //parse any long integer encoded in big-endian formatParser::chain //chain another parser
Parser::btChain //chain another parser with backtrace enabled
Parser::chainWith //chain another parser generator(res -> Parser)
Parser::or //if this parser failed than try another
Parser::ignore //do parse, but ignore result
Parser::map //do parse and map the result
Parser::sepBy //parse multiply times seperate by another parser
Parser::scan //continuously reduce the input and attempt to parse it.
Parser::optinal //make this parser optional
Parser::trim //ignore leading and trailing whitespace and attempt to parse.
Parser::many //parse zero or more times
Parser::manyTill //implement with repeatTill
Parser::some //parse one or more times
Parser::someTill //implement with someTill
Parser::repeat //parse n times
Parser::repeatTill //parse several time till subparser matched
Parser::range //parse bettwen m and n times
Parser::attempt //parse zero to n times
Parser::must //add a predicate on the result.
Parser::choose //chain of Parser::or- to parse any input: implement IBuffer
- Parser a simple csv line:
@Test
public void testSimpleCsv() {
Parser csvLineParser = TextParsers.satisfy(Character::isLetterOrDigit)
.many().map(Mapper.toStr())
.sepBy(TextParsers.one(',').ignore());
Result result = csvLineParser.runParser(Buffer.builder()
.data("field1,field2,field3,field4".getBytes())
.build());
assert result.<String>get(0).equals("field1");
assert result.<String>get(1).equals("field2");
assert result.<String>get(2).equals("field3");
assert result.<String>get(3).equals("field4");
}- Parser a standard csv see CSVParser
public static Parser jsonParser() {
return stringParser()
.or(() -> objectParser().trim(true))
.or(() -> arrayParser().trim(true))
.or(() -> nullParser().trim(true))
.or(() -> boolParser().trim(true))
.or(() -> numberParser().trim(true))
.trim(true);
}
public static Parser objectParser() {
return TextParsers.one('{').ignore()
.chain(() -> membersParser())
.chain(() -> TextParsers.one('}').ignore());
}
public static Parser arrayParser() {
return TextParsers.one('[').ignore()
.chain(() -> jsonParser().sepBy(TextParsers.one(',').ignore()))
.chain(() -> TextParsers.one(']').ignore())
.map(ary -> JsonValue.builder()
.type(JsonType.ARRAY)
.value(new JsonArray().addAll(ary))
.build());
}
public static Parser membersParser() {
...
}
...
@Test
public void test() {
String source1 = " {\"hello\":\"world\",\"array\":[\"a\",{\"b\":\"c\"},null,123.4],\"name\":\"jay\"} ";
Result result1 = JsonParser.parser().runParser(Buffer.builder()
.data(source1.getBytes())
.build());
assert result1.isSuccess();
}see JsonPaser
/**
* Parse a full xml: <tag> content or children node </tag>
* @return
*/
public static Parser fullParser() {
return headParser()
.chain(() -> nodeParser().some().or(() -> contentParser()))
.chainWith(result -> {
String name = result.<XmlNode>get(0).getName();
return TextParsers.string("</").ignore()
.chain(() -> TextParsers.string(name).trim(true))
.chain(() -> TextParsers.string(">").ignore())
.ignore();
}).map(values -> {
...
}
@Test
public void testNode() {
String src = "<note hello=\"world\">\n" +
"<to>Tove</to>\n" +
"<from>Jani</from>\n" +
"<heading>Reminder</heading>\n" +
"<body>Don't forget me this weekend!</body>\n" +
"</note>";
Result result1 = XmlParser.parser().runParser(Buffer.builder()
.data(src.getBytes())
.build());
assert result1.isSuccess();
}see XmlPaser
public Parser parser() {
return Parser.choose(
() -> many(),
() -> some(),
() -> range(),
() -> repeat(),
() -> optional(),
() -> validToken()
).many().map(s -> {
...
}
@Test
public void testMatch() {
RegexParser regexParser = new RegexParser();
regexParser.compile("(a+)(b+)c?$");
Optional<String> result = regexParser.match("aaaabbbbc");
assert result.isPresent();
}
@Test
public void testGroup() {
RegexParser regexParser = new RegexParser();
regexParser.compile("(a+)b\\1");
Optional<String> result = regexParser.match("aabaa");
assert result.isPresent();
List<String> searchResult = regexParser.search("aaabaaa");
assert searchResult.size() == 2;
}see RegexPaser