Package com.gengoai.parsing

Class Parser

java.lang.Object

com.gengoai.parsing.Parser

All Implemented Interfaces:

TokenStream, Serializable

public class Parser
extends Object
implements TokenStream, Serializable

An implementation of a Pratt Parser inspired by Pratt Parsers: Expression Parsing Made Easy. An instance of a Parser is tied to a specific Grammar and TokenStream. This implementation allows for operator precedence to be defined for each ParserHandler and allows the precedence to be specified when retrieving the next expression.

Author:

David B. Bracewell

See Also:

Serialized Form

Field Summary

Fields inherited from interface com.gengoai.parsing.TokenStream

EOF, EOF_TOKEN

Constructor Summary

Constructors

Constructor	Description
Parser(Grammar grammar, TokenStream tokenStream)	Instantiates a new Parser.

Method Summary

Modifier and Type	Method	Description
ParserToken	consume()	Consumes a token from the stream.
<O> O	evaluate(Evaluator<? extends O> evaluator)	Parses the given resource and evaluates it with the given evaluator.
<O> List<O>	evaluateAll(Evaluator<? extends O> evaluator)	Parses the given string and evaluates it with the given evaluator.
List<Expression>	parseAllExpressions()	Parse all expressions list.
Expression	parseExpression()	Parses the token stream to get the next expression
Expression	parseExpression(int precedence)	Parses the token stream to get the next expression
Expression	parseExpression(int precedence, boolean isRightAssociative)	Parses the token stream to get the next expression
<T extends Expression> T	parseExpression(int precedence, Class<T> tClass)
Expression	parseExpression(ParserToken precedence)	Parses the token stream to get the next expression
Expression	parseExpression(ParserToken token, boolean isRightAssociative)	Parses the token stream to get the next expression
<T extends Expression> T	parseExpression(ParserToken precedence, Class<T> tClass)
<T extends Expression> T	parseExpression(Class<T> tClass)
<T extends Expression> List<T>	parseExpressionList(Tag endOfList, Tag separator)	Parses a list of tokens ending with the endOfList tag and values separated using the separator tag.
<T extends Expression> List<T>	parseExpressionList(Tag startOfList, Tag endOfList, Tag separator)	Parses a list of tokens ending with the endOfList tag and values separated using the separator tag.
ParserToken	peek()	Peeks at the next token on the stream.
ParserToken	token()	Returns the last token extracted via the call to consume.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.gengoai.parsing.TokenStream

consume, hasNext

Constructor Detail

Parser

public Parser(Grammar grammar,
              TokenStream tokenStream)

Instantiates a new Parser.

Parameters:

grammar - the grammar to use for parsing

tokenStream - the TokenStream to parse from

Method Detail

consume

public ParserToken consume()

Description copied from interface: TokenStream

Consumes a token from the stream.

Specified by:

consume in interface TokenStream

Returns:

the consumed token.

evaluate

public <O> O evaluate(Evaluator<? extends O> evaluator)
               throws ParseException

Parses the given resource and evaluates it with the given evaluator. Requires that the parse result in a single expression.

Type Parameters:

O - the return type of the evaluator

Parameters:

evaluator - the evaluator to use for transforming expressions

Returns:

the single return values from the evaluator

Throws:

ParseException - the parse exception

evaluateAll

public <O> List<O> evaluateAll(Evaluator<? extends O> evaluator)
                        throws ParseException

Parses the given string and evaluates it with the given evaluator.

Type Parameters:

O - the return type of the evaluator

Parameters:

evaluator - the evaluator to use for transforming expressions

Returns:

A list of objects relating to the transformation of expressions by the given evaluator.

Throws:

ParseException - Something went wrong parsing

parseAllExpressions

public List<Expression> parseAllExpressions()
                                     throws ParseException

Parse all expressions list.

Returns:

the list

Throws:

ParseException - the parse exception

parseExpression

public Expression parseExpression()
                           throws ParseException

Parses the token stream to get the next expression

Returns:

the next expression in the parse

Throws:

ParseException - Something went wrong parsing

parseExpression

public <T extends Expression> T parseExpression(Class<T> tClass)
                                         throws ParseException

Throws:

ParseException

parseExpression

public <T extends Expression> T parseExpression(ParserToken precedence,
                                                Class<T> tClass)
                                         throws ParseException

Throws:

ParseException

parseExpression

public <T extends Expression> T parseExpression(int precedence,
                                                Class<T> tClass)
                                         throws ParseException

Throws:

ParseException

parseExpression

public Expression parseExpression(ParserToken precedence)
                           throws ParseException

Parses the token stream to get the next expression

Parameters:

precedence - Uses the associated precedence of the handler associated with the given token or 0 if no precedence is defined.

Returns:

the next expression in the parse

Throws:

ParseException - Something went wrong parsing

parseExpression

public Expression parseExpression(ParserToken token,
                                  boolean isRightAssociative)
                           throws ParseException

Parses the token stream to get the next expression

Parameters:

token - Uses the associated precedence of the handler associated with the given token or 0 if no precedence is defined.

isRightAssociative - True - if this is a right associative rule

Returns:

the next expression in the parse

Throws:

ParseException - Something went wrong parsing

parseExpression

public Expression parseExpression(int precedence)
                           throws ParseException

Parses the token stream to get the next expression

Parameters:

precedence - The precedence of the next prefix expression

Returns:

the next expression in the parse

Throws:

ParseException - Something went wrong parsing

parseExpression

public Expression parseExpression(int precedence,
                                  boolean isRightAssociative)
                           throws ParseException

Parses the token stream to get the next expression

Parameters:

precedence - The precedence of the next prefix expression

isRightAssociative - True - if this is a right associative rule

Returns:

the next expression in the parse

Throws:

ParseException - Something went wrong parsing

parseExpressionList

public <T extends Expression> List<T> parseExpressionList(Tag endOfList,
                                                          Tag separator)
                                                   throws ParseException

Parses a list of tokens ending with the endOfList tag and values separated using the separator tag.

Parameters:

endOfList - the Tag indicating the end of the list has been reached.

separator - the Tag separating values of the list (null value means no separator).

Returns:

the list of parsed expressions

Throws:

ParseException - Something went wrong parsing the token stream

parseExpressionList

public <T extends Expression> List<T> parseExpressionList(Tag startOfList,
                                                          Tag endOfList,
                                                          Tag separator)
                                                   throws ParseException

Parses a list of tokens ending with the endOfList tag and values separated using the separator tag.

Type Parameters:

T - the type parameter

Parameters:

startOfList - the start of list

endOfList - the Tag indicating the end of the list has been reached.

separator - the Tag separating values of the list (null value means no separator).

Returns:

the list of parsed expressions

Throws:

ParseException - Something went wrong parsing the token stream

peek

public ParserToken peek()

Description copied from interface: TokenStream

Peeks at the next token on the stream.

Specified by:

peek in interface TokenStream

Returns:

the next token on the stream (special EOF token if no more tokens exists)

token

public ParserToken token()

Description copied from interface: TokenStream

Returns the last token extracted via the call to consume.

Specified by:

token in interface TokenStream

Returns:

the last extracted token via consume