Module: mona/core

Methods

bind(parser, fun)

Returns a parser that calls fun on the value resulting from running parser on the current parsing state. Fails without executing fun if parser fails.

Parameters:

Name	Type	Description
parser	Parser	The parser to execute.
fun	Function	Function called with the resulting value of parser. Must return a parser.

Source:

• mona.js, line 226

Example

parse(bind(token(), function(x) { return value(x+"!"); }), "a"); // => "a!"

delay(constructor, args)

Delays calling of a parser constructor function until parse-time. Useful for recursive parsers that would otherwise blow the stack at construction time.

Parameters:

Name	Type	Argument	Description
constructor	Function		A function that returns a Parser.
args	*	<repeatable>	Arguments to apply to the constructor.

Source:

• mona.js, line 366

Example

// The following would usually result in an infinite loop:
function foo() {
  return or(x(), foo());
}
// But you can use delay() to remedy this...
function foo() {
  return or(x(), delay(foo));
}

eof()

Returns a parser that succeeds with a value of true if there is no more input to consume.

Source:

• mona.js, line 337

Example

parse(eof(), ""); // => true

fail(msg, type)

Returns a parser that always fails without consuming input. Automatically includes the line and column positions in the final ParserError.

Parameters:

Name	Type	Description
msg	String	Message to report with the failure.
type	String	A type to apply to the ParserError.

Source:

• mona.js, line 249

is(predicate, parser)

Returns a parser that succeeds if predicate returns true when called on a parser's result.

Parameters:

Name	Type	Argument	Default	Description
predicate	Function			Tests a parser's result.
parser	Parser	<optional>	token()	Parser to run.

Source:

• mona.js, line 461

Example

parse(is(function(x) { return x === "a"; }), "a"); // => "a"

isNot(predicate, parser)

Returns a parser that succeeds if predicate returns false when called on a parser's result.

Parameters:

Name	Type	Argument	Default	Description
predicate	Function			Tests a parser's result.
parser	Parser	<optional>	token()	Parser to run.

Source:

• mona.js, line 479

Example

parse(isNot(function(x) { return x === "a"; }), "b"); // => "b"

label(parser, msg)

Returns a parser that will label a parser failure by replacing its error messages with msg.

Parameters:

Name	Type	Description
parser	Parser	Parser whose errors to replace.
msg	String	Error message to replace errors with.

Source:

• mona.js, line 275

Example

parse(token(), ""); // => unexpected eof
parse(label(token(), "thing"), ""); // => expected thing

log(parser, tag, level)

Debugger parser that logs the ParserState with a tag.

Parameters:

Name	Type	Argument	Default	Description
parser	Parser			Parser to wrap.
tag	String			Tag to use when logging messages.
level	String	<optional>	"log"	'log', 'info', 'debug', 'warn', 'error'.

Source:

• mona.js, line 382

lookAhead(test)

Returns a parser that runs a given parser without consuming input, while still returning a success or failure.

Parameters:

Name	Type	Description
test	Parser	Parser to execute.

Source:

• mona.js, line 440

Example

parse(and(lookAhead(token()), token()), "a"); // => "a"

map(transformer, parser)

Returns a parser that transforms the resulting value of a successful application of its given parser. This function is a lot like bind, except it always succeeds if its parser succeeds, and is expected to return a transformed value, instead of another parser.

Parameters:

Name	Type	Description
transformer	Function	Function called on parser's value. Its return value will be used as the map parser's value.
parser	Parser	Parser that will yield the input value.

Source:

• mona.js, line 407

Example

parse(map(parseFloat, text()), "1234.5"); // => 1234.5

tag(parser, tag)

Returns a parser that returns an object with a single key whose value is the result of the given parser.

Parameters:

Name	Type	Description
parser	Parser	Parser whose value will be tagged.
tag	String	String to use as the object's key.

Source:

• mona.js, line 425

Example

parse(tag(token(), "myToken"), "a"); // => {myToken: "a"}

token(count)

Returns a parser that consumes a single item from the input, or fails with an unexpected eof error if there is no input left.

Parameters:

Name	Type	Argument	Default	Description
count	Integer	<optional>	1	number of tokens to consume. Must be > 0.

Source:

• mona.js, line 300

Example

parse(token(), "a"); // => "a"

value(val)

Returns a parser that always succeeds without consuming input.

Parameters:

Name	Type	Argument	Default	Description
val		<optional>	undefined	value to use as this parser's value.

Source:

• mona.js, line 204

Example

parse(value("foo"), ""); // => "foo"

Type Definitions

Parser(state) → {ParserState}

A function accepting parserState as input that transforms it and returns a new parserState.

Parameters:

Name	Type	Description
state	ParserState	Current parser state.

Source:

• mona.js, line 181

Returns:

state' - Transformed parser state.

Type

ParserState