dk.brics.grammar.parser
Class Parser

java.lang.Object
  dk.brics.grammar.parser.Parser

public class Parser
extends Object

Parser.

Based on a variant of Earley's algorithm.

Constructor Summary

Parser(Grammar g, PrintWriter out)
Constructs a new parser.

Method Summary

boolean	check(String x, Production start) Checks whether the given string can be parsed without syntax errors.
long	getMaxMemory() Returns maximal memory usage during last parsing.
long	getMaxStates() Returns maximal number of parse states during last parsing.
long	getTotalStates() Returns total number of parse states during last parsing.
AST	parse(String x) Parses the given string.
AST	parse(String x, String file) Parses the given string.
AST	parse(String x, String file, Production start) Parses the given string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Parser

public Parser(Grammar g,
              PrintWriter out)

Constructs a new parser.

Parameters:

g - grammar

out - print writer for verbose messages (null if none)

Method Detail

check

public boolean check(String x,
                     Production start)

Checks whether the given string can be parsed without syntax errors.

Parameters:

x - string to parse

start - start production (if null, all productions of the start nonterminal are used)

Returns:

true iff the string can be parsed by the grammar

getMaxMemory

public long getMaxMemory()

Returns maximal memory usage during last parsing. (Note: garbage collection might reduce this number.)

Returns:

memory usage

getMaxStates

public long getMaxStates()

Returns maximal number of parse states during last parsing.

Returns:

number of parse states

getTotalStates

public long getTotalStates()

Returns total number of parse states during last parsing.

Returns:

number of parse states

parse

public AST parse(String x)
          throws ParseException

Parses the given string. Same as parse(x, null, null).

Parameters:

x - string to parse

Returns:

an abstract syntax tree for x

Throws:

ParseException - in case of parse error

parse

public AST parse(String x,
                 String file)
          throws ParseException

Parses the given string. Same as parse(x, file, null).

Parameters:

x - string to parse

file - path or URL of string to parse (null if unknown)

Returns:

an abstract syntax tree for x

Throws:

ParseException - in case of parse error

parse

public AST parse(String x,
                 String file,
                 Production start)
          throws ParseException

Parses the given string.

Parameters:

x - string to parse

file - path or URL of string to parse (null if unknown)

start - start production (if null, all productions of the start nonterminal are used)

Returns:

an abstract syntax tree for x

Throws:

ParseException - in case of parse error