org.stekikun.dolmen.codegen

Class LexBuffer.Position

java.lang.Object

org.stekikun.dolmen.codegen.LexBuffer.Position

Enclosing class:

LexBuffer

public static final class LexBuffer.Position
extends Object

Instances of this class describe a position in some input (most frequently a file, but could be a string or any char sequence). A position is given by the description of the input, the absolute position in said input, the line number in the input where this position occurs, and the offset of said line in the input. The column number can be retrieved via column().

LexBuffer uses LexBuffer.Position to register the positions in the current input of the last lexeme start and the current position (which happens to be the last lexeme end when in a semantic action). LexBuffers do not manage line numbers by themselves, only absolute character offsets, so that updating line and bol is the responsibility of the lexer's semantic actions. See LexBuffer.newline().

Instances of this class are immutable so the lexer must create new ones when updating them, but a parser using this lexer or semantic actions can safely use positions without having to copy them defensively.

Author:

Stéphane Lescuyer

See Also:

LexBuffer.newline(), LexBuffer.getLexemeStart(), LexBuffer.getLexemeEnd()

Field Summary

Fields

Modifier and Type	Field and Description
int	bol The offset of the beginning of the line of this position
String	filename The filename that this position relates to, or a description of the input if not a regular file
int	line The line of this position, starting at 1
int	offset The character offset of this position, starting at 0

Constructor Summary

Constructors

Constructor and Description
Position(String filename) Returns the initial position in the given file
Position(String filename, int offset, int line, int bol) Builds a position from the given parameters

Method Summary

Modifier and Type	Method and Description
int	column()
@NonNull String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

filename

public final String filename

The filename that this position relates to, or a description of the input if not a regular file

offset

public final int offset

The character offset of this position, starting at 0

line

public final int line

The line of this position, starting at 1

bol

public final int bol

The offset of the beginning of the line of this position

Constructor Detail

Position

public Position(String filename)

Returns the initial position in the given file

Parameters:

filename -

Position

public Position(String filename,
                int offset,
                int line,
                int bol)

Builds a position from the given parameters

Parameters:

filename -

offset -

line -

bol -

Method Detail

column

public int column()

Returns:

the column offset (1-based) of this position

toString

public @NonNull String toString()

Overrides:

toString in class Object