Package com.blackrook.expression.struct

Class Lexer.Parser

java.lang.Object

com.blackrook.expression.struct.Lexer.Parser

Enclosing class:

Lexer

public abstract static class Lexer.Parser
extends Object

Abstract parser class. This class aids in the creation of top-down (AKA recursive-descent) parsers.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Lexer.Parser.Exception	Thrown when a Parser has a problem.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Parser(Lexer lexer)	Constructs the parser and binds a Lexer to it.

Method Summary

Modifier and Type	Method	Description
protected Lexer.Token	currentToken()	Gets the token read from the last nextToken() call.
protected boolean	currentType(int... tokenTypes)	Attempts to match the type of the current token.
Lexer	getLexer()	Gets the Lexer that this Parser uses.
String	getTokenInfoLine(String message)	Returns a stock error line for when an error/warning or whatever occurs during parse.
protected boolean	matchType(int tokenType)	Matches the current token.
protected void	nextToken()	Reads and sets the current token to the next token.

Methods inherited from class java.lang.Object

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

Constructor Detail

Parser

protected Parser(Lexer lexer)

Constructs the parser and binds a Lexer to it.

Parameters:

lexer - the lexer that this reads from.

Method Detail

getLexer

public Lexer getLexer()

Gets the Lexer that this Parser uses.

Returns:

the underlying Lexer.

currentToken

protected Lexer.Token currentToken()

Gets the token read from the last nextToken() call.

Returns:

the current token.

matchType

protected boolean matchType(int tokenType)

Matches the current token. If matched, this returns true and advances to the next token. Else, this returns false.

Parameters:

tokenType - the type to match.

Returns:

true if matched, false if not.

currentType

protected boolean currentType(int... tokenTypes)

Attempts to match the type of the current token. If matched, this returns true. This DOES NOT ADVANCE to the next token.

Parameters:

tokenTypes - the list of types.

Returns:

true if one was matched, false if not.

nextToken

protected void nextToken()

Reads and sets the current token to the next token. If the current token is null, it is the end of the Lexer's stream.

Throws:

Lexer.Parser.Exception - if the next token can't be read.

getTokenInfoLine

public String getTokenInfoLine(String message)

Returns a stock error line for when an error/warning or whatever occurs during parse. For convenience only - not called by any of the current methods.

Parameters:

message - the message to append.

Returns:

the error message.