public class PropertiesLexer extends AbstractLexer implements PropertiesTokens
PropertiesLexer is an implementation of the
Lexer interface for a *.properties or *.rts file.
Although *.rts are somewhat compatible with *.properties files, the
lexing rules provided by this module is tailored to *.properties
files. The format of an *.rts file is described by the following
excerpt from the RTS JavaDoc documentation: Specification of the RTS source file format: An RTS source file is a text file description of a set of string resources. Each such resource consists of an identifying key and its associated string.
The format of an RTS source file has been designed for compatibility with java ".properties" files" so that a java ".properties" file may serve as a valid RTS source file. RTS source files differ from ".properties" files by allowing keys to be any Unicode string and by providing rules for associating comments with resources.
Each line in a source file may represent a resource, a comment or be blank. Any line consisting only of whitespace is considered blank. Any line in which the first non-whitespace character is a # or a ! is a comment. All other lines represent string resources.
A line representing a string resource consists of a key/value pair. The key is represented by the text beginning with the first non-whitespace character continuing up to (but not including) the the next non-escaped whitespace, =, or : character. To represent a key that contains whitespace, =, or :'s, one may escape any such character by preceding it with a \. The precise escape mechanism is as follows: \ followed by any character is treated as the character itself (with no syntactic meaning attached) except in cases where that character is a:
Comments in an RTS source file may be associated with resources so that a comment can contain information about a particular entry. A resource is associated with the comment that immediately preceeds it. There may be blank lines between the comment and the resource -- however, blank line lines between comment lines cause the separated lines to be treated as different comments -- so that only the last comment is associated with a subsequent resource. A line containg only a # or ! is not treated as a blank.
In the following example, key1 is associated with comment lines 1-3 while key 2 is associated with comment lines 5 and 6 (but not 4).
# Example RTS source file
# comment_line_1
# comment_line_2
# comment_line_3
key1 = string_1
# comment_line_4
# comment_line_5
# comment_line_6
key2 = string_2
There are a couple quirks of the *.properties files (at least based
on the implementation of PropertyResourceBundle) which
are followed here:
This lexer does not assist in the deciphering of the contents of the actual property definition. Use the DefinitionLexer for this purpose.
This lexer requires a normalized buffer with only '\n' EOL characters.
Lexer,
PropertiesTokensAbstractLexer.DefaultLexerTokencurrentPos, textBufferTK_COMMENT, TK_DEFINITIONTK_EOF, TK_NOT_FOUND| Constructor and Description |
|---|
PropertiesLexer()
Constructs a default
PropertiesLexer with a starting
position of 0. |
PropertiesLexer(PropertyFileLexerSetup lexerSetup)
A constructor that parameterizes the lexerSetup object.
|
| Modifier and Type | Method and Description |
|---|---|
void |
backup()
Unlexes the last found token.
|
int |
lex(LexerToken lexedToken)
Scans the text buffer at the current position and returns the
token that was found.
|
void |
setPosition(int offset)
Sets the current lex (read) position to the given offset in the
buffer.
|
void |
setSkipComments(boolean skipComments)
Sets whether the
PropertiesLexer should generate
tokens for comments in the *.properties and *.rts files. |
static java.lang.String |
tokenToString(int token)
Utility routine to map the token to a string representation of
the token (for debug printing.)
|
static java.lang.String |
tokenToText(int token)
Utility routine to map the token to the original text (if
retrievable) of the token (for debug printing.)
|
createLexerToken, getTextBuffer, setTextBufferpublic PropertiesLexer()
PropertiesLexer with a starting
position of 0. Clients must call setTextBuffer() to
initialize the text buffer used for the Lexer. To start lexing
from an offset other than 0, call setPosition().public PropertiesLexer(PropertyFileLexerSetup lexerSetup)
lexerSetup - public void setSkipComments(boolean skipComments)
PropertiesLexer should generate
tokens for comments in the *.properties and *.rts files.skipComments - true to ignore comments in token generationpublic int lex(LexerToken lexedToken)
lexedToken instance passed in to the
call.lex in interface Lexerlex in class AbstractLexerlexedToken - the instance passed in where token info is storedlexedToken.getToken() (for convenience)public void backup()
lex()
will return the last token and offset information found.backup in interface Lexerbackup in class AbstractLexerpublic void setPosition(int offset)
setPosition in interface LexersetPosition in class AbstractLexeroffset - the offset for the next lex() operation.public static java.lang.String tokenToString(int token)
token - the token to mappublic static java.lang.String tokenToText(int token)
token - the token to map