User:OrenBochman/ParserNG/Preprocessor Antlr
The Preprocessor[edit]
This is a Lexer for the Preprocessor in ANTLR
grammar wikiParser;
options
{
language=Java; // Default
// Tell ANTLR to make the generated lexer class extend the
// the named class, which is where any supporting code and
// variables will be placed.
//
superClass = AbstractTLexer;
// charVocabulary='\u0000'..'\uFFFE';
output=AST;
backtrack=true;
k=6;
}
wikiParser : WIKITEXT_L1*;
// $<EBNS
ALPHA
// A-Z | a-z
: '\u0041'..'\u005A' | '\u0061'..'\u007A'
;
BIT
: '0' | '1'
;
CHAR
// any 7-bit US-ASCII character, excluding NUL
: '\u0001'..'\u007F'
;
CR
// carriage return
: '\u000D'
;
CRLF
// Internet standard newline
: CR LF
;
CTL
// controls
: '\u0000'..'\u001F' | '\u007F'
;
DIGIT
// 0-9
: '\u0030'..'\u0039'
;
HEXDIG
: DIGIT | 'A' | 'B' | 'C' | 'D' | 'E' | 'F'
;
HTAB
// horizontal tab
: '\u0009'
;
LF
// linefeed
: '\u000A'
;
OCTET
// 8 bits of data
: '\u0000'..'\u00FF'
;
SP
// space
: '\u0020'
;
VCHAR
// visible (printing) characters
: '\u0021'..'\u007E'
;
// $>
//reserved characters
GT : '>';
LT : '<';
EQ : '=';
QUOTE : '\'';
DQUOTE
// " (Double Quote)
: '\u0022'
;
PIPE : '|';
HASH : '#';
RBRACE : ']';
LBRACE : '[';
M_RESERVED : EQ | QUOTE | DQUOTE | HASH | PIPE |
;
L_RESERVED
:LT| LBRACE;
R_RESERVED
:
GT | RBRACE
;
RESERVED
: L_RESERVED | M_RESERVED | R_RESERVED;
WS
//Whitesace
: SP
| HTAB
| LF
| CR
| CRLF
;
LS
//line space
: SP | HTAB ;
L_LIT
//everything except ;' (%x3E)
: ~(L_RESERVED | WS )
;
fragment
UNI_CHAR
// any Unicode character, excluding the surrogate blocks, FFFE, and FFFF.
// this is like . - must be reduced
//'\u0000'..'\uFFFD'
: ~(RESERVED | WS )
;
LITERAL
: UNI_CHAR //single character
| ~(L_RESERVED | WS)~( WS)+ //any non Left reserved char with any other chars
;
ATTR
: LITERAL? // can this be factored out
;
TITLE
: WIKITEXT_L3
;
PART_NAME
: WIKITEXT_L3
;
PART_VALUE
: WIKITEXT_L3
;
PART_LITERAL
//A litteral with no equal
: UNI_CHAR //single character
| ~(L_RESERVED | EQ | WS)~( WS)+ //any reserved char not on it's own
;
PART
: (PART_LITERAL+ EQ)? LITERAL+
;
PARTS
: TITLE ( PIPE PART )*
;
TPL_ARG
: '{{{' PARTS '}}}'
;
TEMPLATE
: '{{' PARTS '}}'
; //TODO: the closing token needs to match the inner token
LINK
: '[[' WIKITEXT_L3 ']]'
;
COMMENT
: '<!--'! (LITERAL | WS)* '-->'!
; //todo: make non greedy
//UNCLOSED_COMMENT : '<!--' LITERAL EOF ;
//LF_REWRITE : LF -> LINE_END LF LINE_START;
//LINE_EATING_COMMENT: LF SP* comment:COMMENT SP* LF!;
LINE_EATING_COMMENT
: LF LS* COMMENT LS* LF {emit("LF");}
;
NOWIKI_ELEMENT : '<nowiki' ATTR ( '/>'
| ( '>' LITERAL
( '</nowiki>'
| EOF ) ) )
;
EXTENTIONS : LT '/'? SP* 'ref' SP* GT
| LT '/'? SP* 'references' SP* GT
| LT SP*'references' SP*'/' SP* GT
;
// and similar rules added by XML-style EXTENTIONS.
XMLiS_ELEMENT : NOWIKI_ELEMENT | EXTENTIONS ;
HEADING : LF HEADING_INNER ( LS* COMMENT )? LS* ;
HEADING_INNER : '======' LS* h6=(LITERAL LS*)+'======'!
| '=====' LS* h5=(LITERAL LS*)+'====='!
| '====' LS* h4=(LITERAL LS)+'===='!
| '===' LS* h3=(LITERAL LS*)+'==='!
| '==' LS* h2=(LITERAL LS*)+'=='!
| '=' LS* h1=(LITERAL LS*)+'='!
;
// WIKITEXT_L1 is a simple proxy to WIKITEXT_L2, except in INCLUSION mode, where it
// has a role in <onlyinclude> syntax (see below)
WIKITEXT_L1 : WIKITEXT_L2
;
WIKITEXT_L2 : HEADING
| WIKITEXT_L3
;
WIKITEXT_L3
: LITERAL
| TEMPLATE
| TPL_ARG
| LINK
| COMMENT
| LINE_EATING_COMMENT
| UNCLOSED_COMMENT
| XMLiS_ELEMENT
;
////INC MODE/////////////////////////////////////////////////////////////////////////////////////////
NOINCLUDE_ELEMENT : '<noinclude' ATTR
( '/>'
| ( '>' LITERAL ( '</noinclude>'
| EOF ) ) )
;
INCLUSION_IGNORED_TAG : ('<' 'includeonly' '>'!)
| ('</'! 'includeonly' '>'!)
;
CLOSED_ONLYINCLUDE_ITEM : IGNORED_TEXT '<'! 'onlyinclude' '>'! WIKITEXT_L2 '</'! 'onlyinclude' '>'
;
UNCLOSED_ONLYINCLUDE_ITEM : IGNORED_TEXT '<' 'onlyinclude' '>' WIKITEXT_L2 ;
IGNORED_TEXT : LITERAL ;
ONLY_INCLUDE_SEQUENCE : CLOSED_ONLYINCLUDE_ITEM* UNCLOSED_ONLYINCLUDE_ITEM* ;
INC_XMLiS_ELEMENT : XMLiS_ELEMENT | NOINCLUDE_ELEMENT ;
INC_WIKITEXT_L1 : WIKITEXT_L1 | ONLY_INCLUDE_SEQUENCE;
INC_WIKITEXT_L3 : WIKITEXT_L3 | INCLUSION_IGNORED_TAG | ONLY_INCLUDE_SEQUENCE ;
////NO INC MODE/////////////////////////////////////////////////////////////////////////////////////
INCLUDE_ONLY_ELEMENT : '<includeonly' ATTR
( '/>'
| ( '>' LITERAL ( '</includeonly>'
| EOF ) ) )
;
NONINCLUSION_IGNORED_TAG
: '<'! '/'? 'noinclude' '>'!
| '<'! '/'? 'onlyinclude' '>'!
;
NI_XMLiS_ELEMENT
: XMLiS_ELEMENT
| INCLUDE_ONLY_ELEMENT
;
NI_WIKITEXT_L3
: NONINCLUSION_IGNORED_TAG
| WIKITEXT_L3
;
//associativity of sequences/////////////////////////////////////////////////////////////////////////////
//P1 ANGLE_BRACKET expressions have associativity from the Left
//i.e. left most opening tag in a sequence is the sequence root
ANGLE_BRACKET
: COMMENT
| ONLY_INCLUDE_SEQUENCE
// | UNCLOSED_COMMENT
| LINE_EATING_COMMENT
| INCLUSION_IGNORED_TAG
| NONINCLUSION_IGNORED_TAG
| XMLiS_ELEMENT
;
//based on [1]
Test Sets[edit]
EOF and broken xxx rules[edit]
Antlr offers some remedies. However issue is not so well explained.
The problem with {{ [[ }} ]] is a poor choice since it looks like a syntax error. If we consider {{a [[b | {{c|d}} ]] }} it is easier to see that the inner most element should be evaluated before the outer ones. Inner most element also starts furthest on the right. If we consider {{a [[b | {{c|d}} | {{e|f}} ]] }} it seemes that the parse tree should become something like:
Parse Tree[edit]
TMPL:e|f
/\
null |
/\
null TMPL:c|d
/\
null |
/\
null LNK:b
/\
null TMPL:a
- where:
- | are pipes
- /\ are branches
- null are empty place holders
- once parsed it should than be processed (and inverted) into an AST by further tree building rules.
EOF rules[edit]
As mentioned in the EBNF speck it inefficent to run a test till the end of file fpr on closed tokens. However is the parse tree is built as above it should take a single pass.
Premature eof[edit]
- in case of {{ [[ }} ]]EOF the EOF is premature and the {{ should wither be treeted as a syntax error or as a literal. (the former makes more sense)
The End Of File Condition[edit]
A method is available for reacting to the end of file condition as if it were an event; e.g., you might want to pop the lexer state at the end of an include file. This method, CharScanner.uponEOF(), is called from nextToken() right before the scanner returns an EOF_TYPE token object to parser:
public void uponEOF()|
throws TokenStreamException, CharStreamException;
This event is not generated during a syntactic predicate evaluation (i.e., when the parser is guessing) nor in the middle of the recognition of a lexical rule (that would be an IO exception). This event is generated only after the complete evaluation of the last token and upon the next request from the parser for a token.
You can throw exceptions from this method like "Heh, premature eof" or a retry stream exception. See the includeFile/P.g for an example usage.
Tests[edit]
Parser tests are in maintenece tests
- empty syntax
- [[{{]]}} is parsed as [[{{]}}
- {{[[}}]] is parsed as {{[[}}]]
- a{{b[[c}}d]]e is parsed as a{{b[[c}}d]]e
- using real link and template