org.dellroad.stuff.string
Class ParseContext

java.lang.Object
  org.dellroad.stuff.string.ParseContext

All Implemented Interfaces:

Cloneable

public class ParseContext
extends Object
implements Cloneable

Utility class supporting parsing of strings.

Instances of this class are not thread safe.

Constructor Summary

ParseContext(String input)
Constructor.

Method Summary

IllegalArgumentException	buildException() Create a generic exception for rejecting the current input.
IllegalArgumentException	buildException(String message) Create an exception for rejecting the current input.
ParseContext	clone() Clone this instance.
void	expect(char ch) Read and advance past the next character, which must match ch.
int	getIndex() Get the current index into the original input string.
String	getInput() Get the current input.
String	getOriginalInput() Get the original input string as passed to the constructor.
boolean	isEOF() Determine if we are at the end of the input.
Matcher	matchPrefix(Pattern regex) Match the current input against the given regular expression and advance past it.
Matcher	matchPrefix(String regex) Match the current input against the given regular expression and advance past it.
char	peek() Read, but do not advance past, the next character.
char	read() Read and advance past the next character.
void	reset() Reset this instance.
void	setIndex(int index) Set the current index into the original input string.
void	skipWhitespace() Skip leading whitespace, if any.
boolean	tryLiteral(String prefix) Determine if the current input starts with the given literal prefix.
void	unread() Push back the previously read character.

Methods inherited from class java.lang.Object

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

Constructor Detail

ParseContext

public ParseContext(String input)

Constructor.

Parameters:

input - the input string to parse

Method Detail

getOriginalInput

public String getOriginalInput()

Get the original input string as passed to the constructor.

Returns:

original input string

getInput

public String getInput()

Get the current input.

Returns:

substring of the original input string starting at the current parse position

getIndex

public int getIndex()

Get the current index into the original input string.

Returns:

current parse position

See Also:

setIndex(int)

setIndex

public void setIndex(int index)

Set the current index into the original input string.

Parameters:

index - new parse position

Throws:

IllegalArgumentException - if index is greater than the original string length

See Also:

getIndex()

reset

public void reset()

Reset this instance. This instance will return to the state it was in immediately after construction.

This method just invokes:

setIndex(0)

matchPrefix

public Matcher matchPrefix(String regex)

Match the current input against the given regular expression and advance past it.

Parameters:

regex - regular expression to match against the current input

Throws:

IllegalArgumentException - if the current input does not match

matchPrefix

public Matcher matchPrefix(Pattern regex)

Match the current input against the given regular expression and advance past it.

Parameters:

regex - regular expression to match against the current input

Throws:

IllegalArgumentException - if the current input does not match

tryLiteral

public boolean tryLiteral(String prefix)

Determine if the current input starts with the given literal prefix. If so, advance past it. If not, do not advance.

Parameters:

prefix - literal string to try to match against the current input

Returns:

whether the current input matched prefix

isEOF

public boolean isEOF()

Determine if we are at the end of the input.

read

public char read()

Read and advance past the next character.

Returns:

the next character of input

Throws:

IllegalArgumentException - if there are no more characters

peek

public char peek()

Read, but do not advance past, the next character.

Returns:

the next character of input

Throws:

IllegalArgumentException - if there are no more characters

unread

public void unread()

Push back the previously read character.

Throws:

IllegalStateException - if the beginning of the original string has been reached

expect

public void expect(char ch)

Read and advance past the next character, which must match ch.

Parameters:

ch - the expected next character of input

Throws:

IllegalArgumentException - if there are no more characters or the next character read is not ch

skipWhitespace

public void skipWhitespace()

Skip leading whitespace, if any.

See Also:

Character.isWhitespace(char)

clone

public ParseContext clone()

Clone this instance.

Overrides:

clone in class Object

buildException

public IllegalArgumentException buildException()

Create a generic exception for rejecting the current input.

buildException

public IllegalArgumentException buildException(String message)

Create an exception for rejecting the current input.

Parameters:

message - problem description, or null for none