de.unkrig.commons.text.parser

Class AbstractParser<TT extends Enum<TT>>

java.lang.Object

de.unkrig.commons.text.parser.AbstractParser<TT>

Type Parameters:

TT - The enumerator representing the scanner's token types

Direct Known Subclasses:

JsonParser, Parser

public class AbstractParser<TT extends Enum<TT>>
extends Object

The base class for implementing parsers. Typically, you would declare methods named 'parse...()' which invoke each other and the 'peek...()', 'read...()' and 'peekRead...()' methods to parse a document.

Field Summary

Fields

Modifier and Type	Field and Description
protected ProducerWhichThrows<? extends AbstractScanner.Token<TT>,? extends ScanException>	scanner The source of tokens that are processed by this parser.

Constructor Summary

Constructors

Constructor and Description
AbstractParser(ProducerWhichThrows<? extends AbstractScanner.Token<TT>,? extends ScanException> scanner)

Method Summary

Modifier and Type	Method and Description
void	eoi() Asserts that the scanner is at end-of-input.
AbstractScanner.Token<TT>	peek() Checks the next token, but does not consume it.
int	peek(Object... tokenTypeOrText) Checks the next token, but does not consume it.
boolean	peek(String text) Checks the next token, but does not consume it.
String	peek(TT tokenType) Checks the next token, but does not consume it.
int	peekRead(String... texts) Checks the next token and consumes it if it matches.
boolean	peekRead(String text) Checks the next token and consumes it if it matches.
AbstractScanner.Token<TT>	peekRead(TT... tokenTypes) Checks the next token and consumes it if its type is one of the tokenTypes.
String	peekRead(TT tokenType) Checks the next token and consumes it if its type is tokenType.
<T extends Enum<T>> T	peekReadEnum(T... values) Checks the next token and consumes it if its text equals the return value of toString() of one of the values.
AbstractScanner.Token<TT>	read() Consumes the next token.
int	read(Object... tokenTypeOrText) Consumes the next token.
void	read(String text) Consumes the next token.
String	read(TT tokenType) Consumes the next token.
void	unread(AbstractScanner.Token<TT> t) Modifies this parser such that t will appear as the "next token" before the actual next token.

Methods inherited from class java.lang.Object

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

Field Detail

scanner

protected final ProducerWhichThrows<? extends AbstractScanner.Token<TT extends Enum<TT>>,? extends ScanException> scanner

The source of tokens that are processed by this parser.

Constructor Detail

AbstractParser

public AbstractParser(ProducerWhichThrows<? extends AbstractScanner.Token<TT>,? extends ScanException> scanner)

Parameters:

scanner - Its toString() method returns a human-readable indication of the scanner location

Method Detail

peek

@Nullable
public AbstractScanner.Token<TT> peek()
                                          throws ParseException

Checks the next token, but does not consume it.

Returns:

The next token, or null if the scanner is at end-of-input

Throws:

ParseException

peek

@Nullable
public String peek(TT tokenType)
                       throws ParseException

Checks the next token, but does not consume it.

Returns:

The next token's text, or null if the next token's type is not tokenType, or if the scanner is at end-of-input

Throws:

ParseException

peek

public boolean peek(@Nullable
                    String text)
             throws ParseException

Checks the next token, but does not consume it.

Returns:

Whether the next token's text equals text, or the scanner is not at end-of-input and text is null

Throws:

ParseException

peek

public int peek(Object... tokenTypeOrText)
         throws ParseException

Checks the next token, but does not consume it.

An element of tokenTypeOrText matches iff:

• the element equals the next token's type, or
• the element equals the next token's text, or
• the element is null and the scanner is at end-of-input

Returns:

The index of the first element of tokenTypeOrText that matches, or -1

Throws:

ParseException

peekRead

@Nullable
public String peekRead(TT tokenType)
                           throws ParseException

Checks the next token and consumes it if its type is tokenType.

Returns:

The text of the next token, or null if the next token's type is not tokenType, or if the scanner is at end-of-input

Throws:

ParseException

peekRead

public boolean peekRead(@Nullable
                        String text)
                 throws ParseException

Checks the next token and consumes it if it matches.

Returns:

Whether the next token's text equals text, or the scanner is at end-of-input and text is null

Throws:

ParseException

peekRead

public int peekRead(String... texts)
             throws ParseException

Checks the next token and consumes it if it matches.

An element of texts matches iff:

• the element equals the next token's text, or
• the element is null and the scanner is at end-of-input

Returns:

The index of the first element of texts that matches, or -1

Throws:

ParseException

peekReadEnum

@Nullable
public <T extends Enum<T>> T peekReadEnum(T... values)
                                              throws ParseException

Checks the next token and consumes it if its text equals the return value of toString() of one of the values.

Returns:

The matched value, or null if none match, or the scanner is at end-of-input

Throws:

ParseException

peekRead

@Nullable
public AbstractScanner.Token<TT> peekRead(TT... tokenTypes)
                                              throws ParseException

Checks the next token and consumes it if its type is one of the tokenTypes.

Returns:

The matched token, or null iff none match, or the scanner is at end-of-input

Throws:

ParseException

read

public AbstractScanner.Token<TT> read()
                               throws ParseException

Consumes the next token.

Returns:

The next token

Throws:

ParseException - The scanner is at end-of-input

read

public String read(TT tokenType)
            throws ParseException

Consumes the next token.

Returns:

The next token's text

Throws:

ParseException - The next token's type is not tokenType

ParseException - The scanner is at end-of-input

read

public void read(String text)
          throws ParseException

Consumes the next token.

Throws:

ParseException - The next token's text does not equal text

ParseException - The scanner is at end-of-input

See Also:

eoi()

read

public int read(Object... tokenTypeOrText)
         throws ParseException

Consumes the next token.

An element of tokenTypeOrText matches iff:

• the element is null and the scanner is at end-of-input
• the element equals the next token's type, or
• the element equals the next token's text, or

Returns:

The index of the first element of tokenTypeOrText that matches

Throws:

ParseException - Neither the next token's type nor its text equals any of tokenTypeOrText

ParseException - The scanner is at end-of-input

unread

public void unread(AbstractScanner.Token<TT> t)

Modifies this parser such that t will appear as the "next token" before the actual next token.

This operation is only permitted iff the next token has not been read-ahead.

Throws:

IllegalStateException - Another token has already been read-ahead, either by one of the peek() operations, or an unsuccessful peekRead() operation

eoi

public void eoi()
         throws ParseException

Asserts that the scanner is at end-of-input.

Throws:

ParseException - Iff the scanner is not at end-of-input