de.weltraumschaf.commons.shell

Class DefaultScanner

java.lang.Object

de.weltraumschaf.commons.shell.DefaultScanner

All Implemented Interfaces:

Scanner

 class DefaultScanner
extends Object
implements Scanner

Default implementation for scanning the input line from an interactive shell.

The scanner tokenizes:

• alpha numeric literals
• (signed) integer number literals
• (signed) float number literals
• boolean literals (true/false)
• and single/double quote delimited string literals

Since:

1.0.0

Author:

Sven Strittmatter

Field Summary

Fields

Modifier and Type	Field and Description
private LiteralCommandMap	commandMap Maps command literal strings to command types.

Constructor Summary

Constructors

Constructor and Description
DefaultScanner(LiteralCommandMap commandMap) Dedicated constructor.

Method Summary

Methods

Modifier and Type	Method and Description
private boolean	isAllowedInFloat(char c) Whether an character is allowed in float literals.
private boolean	isKeyword(String token) Determines if a token string is a keyword.
private void	scan(List<Token> tokens, CharacterStream characterStream) Loops over all characters of stream.
List<Token>	scan(String line) Scans give line and returns list of recognized tokens.
private Token	scanFloat(CharacterStream characterStream, StringBuilder value) Recognize float tokens until next white space character.
private Token	scanLiteral(CharacterStream characterStream) Recognize alpha numeric string tokens until next white space character.
private Token	scanLiteralOrKeyword(CharacterStream characterStream, StringBuilder value) Recognize alpha numeric string tokens until next white space character.
private Token	scanNumber(CharacterStream characterStream) Recognize numeric tokens until next white space character.
private Token	scanString(CharacterStream characterStream) Scan string tokens.

Methods inherited from class java.lang.Object

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

Field Detail

commandMap

private final LiteralCommandMap commandMap

Maps command literal strings to command types.

Constructor Detail

DefaultScanner

public DefaultScanner(LiteralCommandMap commandMap)

Dedicated constructor.

Parameters:

commandMap - map key word literals to command types

Method Detail

scan

public List<Token> scan(String line)
                 throws SyntaxException

Scans give line and returns list of recognized tokens.

Specified by:

scan in interface Scanner

Parameters:

line - must not be null

Returns:

never null, maybe empty

Throws:

SyntaxException - if syntax error occurred

scan

private void scan(List<Token> tokens,
        CharacterStream characterStream)
           throws SyntaxException

Loops over all characters of stream.

Parameters:

tokens - list to which recognized tokens will be add

characterStream - input line to scan

Throws:

SyntaxException - if string is not correct encapsulated by quotes

scanLiteral

private Token scanLiteral(CharacterStream characterStream)

Recognize alpha numeric string tokens until next white space character.

Parameters:

characterStream - input line to scan

Returns:

Return string type token

scanLiteralOrKeyword

private Token scanLiteralOrKeyword(CharacterStream characterStream,
                         StringBuilder value)

Recognize alpha numeric string tokens until next white space character.

Parameters:

characterStream - input line to scan

value - collects the token string, must not be null

Returns:

Return string type token

scanNumber

private Token scanNumber(CharacterStream characterStream)

Recognize numeric tokens until next white space character.

If this method recognizes a dot it will try to scan a float. If any not number character is detected it will treat the token as a literal/keyword.

Parameters:

characterStream - input line to scan

Returns:

integer or float or literal or keyword type token

scanFloat

private Token scanFloat(CharacterStream characterStream,
              StringBuilder value)

Recognize float tokens until next white space character.

If any not number character is detected it will treat the token as a literal/keyword.

Parameters:

characterStream - input line to scan

value - accumulates the token literal string

Returns:

float or literal or keyword type token

scanString

private Token scanString(CharacterStream characterStream)
                  throws SyntaxException

Scan string tokens. String tokens are everything encapsulated in single or double quotes.

Parameters:

characterStream - input line to scan

Returns:

integer type token

Throws:

SyntaxException - if string is not correct encapsulated by quotes

isKeyword

private boolean isKeyword(String token)

Determines if a token string is a keyword. Checks the string against LiteralCommandMap.isCommand(java.lang.String) and LiteralCommandMap.isSubCommand(java.lang.String).

Parameters:

token - string to check

Returns:

true if given string is a keyword else false

isAllowedInFloat

private boolean isAllowedInFloat(char c)

Whether an character is allowed in float literals.

Allowed are signs (+|-) and the exponential characters (E|e).

Parameters:

c - any character

Returns:

true if c is allowed, else false