proguard.classfile.attribute.signature.parsing

Class ParserContext

java.lang.Object

proguard.classfile.attribute.signature.parsing.ParserContext

public final class ParserContext
extends java.lang.Object

An object for storing the data of a currently running parsing operation. Wraps the input string and also stores the current offset that is being parsed.

Constructor Summary

Constructors

Constructor and Description
ParserContext(java.lang.String input) Initialize a new parser context from the given input string.

Method Summary

Modifier and Type	Method and Description
void	advance(int amount) Consume the given number of characters.
java.lang.String	chopFront(int length) Consume length characters from the input string, return them in a newly constructed string.
void	commit() Drop the last snapshot, use the currently valid parser state.
int	indexOf(char c) Returns first index of a given character in the remaining part of the input string.
char	peekChar(int offset) Look-ahead at the input string.
char	peekCharUnchecked(int offset) Same as peekChar(int), but doesn't check for the end of the string.
int	remainingLength()
void	revert() Reverts to the last valid snapshot.
void	snapshot() Take a snapshot of the current state of the parser.
boolean	startsWith(java.lang.String prefix) Tests whether the current state starts with the given string.

Methods inherited from class java.lang.Object

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

Constructor Detail

ParserContext

public ParserContext(java.lang.String input)

Initialize a new parser context from the given input string. Used for starting a new parser pass.

Parameters:

input - The input string to parse.

Method Detail

snapshot

public void snapshot()

Take a snapshot of the current state of the parser. Useful for handling recursion, where children could fail parsing.

Always MUST be paired with one of revert() or commit().

commit

public void commit()

Drop the last snapshot, use the currently valid parser state.

revert

public void revert()

Reverts to the last valid snapshot.

peekChar

public char peekChar(int offset)
              throws java.io.EOFException

Look-ahead at the input string.

Parameters:

offset - The number of characters that should be skipped. E.g. 0 means look at the currently parsed character.

Returns:

The character at the proper offset in the input.

Throws:

java.io.EOFException - When the read attempts to read anything past the end of the input string.

peekCharUnchecked

public char peekCharUnchecked(int offset)

Same as peekChar(int), but doesn't check for the end of the string. Useful in loops bounded by remainingLength() to avoid the need for a try-catch block.

Parameters:

offset - The offset of the character to look at.

Returns:

The character at the given position.

advance

public void advance(int amount)

Consume the given number of characters.

Parameters:

amount - The number of characters to consider parsed.

remainingLength

public int remainingLength()

Returns:

The remaining length of the input string.

chopFront

public java.lang.String chopFront(int length)

Consume length characters from the input string, return them in a newly constructed string.

Parameters:

length - The number of characters to consume from the beginning. (The method just calls advance(int) internally with this number.)

Returns:

A string of length length that appears at the current position in the input.

startsWith

public boolean startsWith(java.lang.String prefix)

Tests whether the current state starts with the given string.

Parameters:

prefix - The prefix we are checking for.

Returns:

True if the current input at the current offset starts with the given string.

indexOf

public int indexOf(char c)

Returns first index of a given character in the remaining part of the input string.

Parameters:

c - The character to search for.

Returns:

The offset of the character from the current position, or -1 if not found.