reStructuredText 的 ANTLR 语法(规则优先级) [英] ANTLR grammar for reStructuredText (rule priorities)
问题描述
第一个问题流
大家好,
这可能是这个问题的后续: 创建的图像.但是有更多的观众.一个不错的在线工具是这个,它似乎正在使用 kgraphviewer 在引擎盖"下.祝你好运!
First question stream
Hello everyone,
This could be a follow-up on this question: Antlr rule priorities
I'm trying to write an ANTLR grammar for the reStructuredText markup language.
The main problem I'm facing is : "How to match any sequence of characters (regular text) without masking other grammar rules?"
Let's take an example with a paragraph with inline markup:
In `Figure 17-6`_, we have positioned ``before_ptr`` so that it points to the element
*before* the insert point. The variable ``after_ptr`` points to the element *after* the
insert. In other words, we are going to put our new element **in between** ``before_ptr``
and ``after_ptr``.
I thought that writing rules for inline markup text would be easy. So I wrote a simple grammar:
grammar Rst;
options {
output=AST;
language=Java;
backtrack=true;
//memoize=true;
}
@members {
boolean inInlineMarkup = false;
}
// PARSER
text
: inline_markup (WS? inline_markup)* WS? EOF
;
inline_markup
@after {
inInlineMarkup = false;
}
: {!inInlineMarkup}? (emphasis|strong|litteral|link)
;
emphasis
@init {
inInlineMarkup = true;
}
: '*' (~'*')+ '*' {System.out.println("emphasis: " + $text);}
;
strong
@init {
inInlineMarkup = true;
}
: '**' (~'*')+ '**' {System.out.println("bold: " + $text);}
;
litteral
@init {
inInlineMarkup = true;
}
: '``' (~'`')+ '``' {System.out.println("litteral: " + $text);}
;
link
@init {
inInlineMarkup = true;
}
: inline_internal_target
| footnote_reference
| hyperlink_reference
;
inline_internal_target
: '_`' (~'`')+ '`' {System.out.println("inline_internal_target: " + $text);}
;
footnote_reference
: '[' (~']')+ ']_' {System.out.println("footnote_reference: " + $text);}
;
hyperlink_reference
: ~(' '|'\t'|'\u000C'|'_')+ '_' {System.out.println("hyperlink_reference: " + $text);}
| '`' (~'`')+ '`_' {System.out.println("hyperlink_reference (long): " + $text);}
;
// LEXER
WS
: (' '|'\t'|'\u000C')+
;
NEWLINE
: '\r'? '\n'
;
This simple grammar doesn't work. And I didn't even try to match regular text...
My questions:
- Could someone point to my errors and maybe give me a hint on how to match regular text?
- Is there a way to set priority on the grammar rules? Maybe this could be a lead.
Thanks in advance for your help :-)
Robin
Second question stream
Thank you very much for your help! I would have had a hard time figuring my errors... I'm not writing that grammar (only) to learn ANTLR, I'm trying to code an IDE plugin for eclipse. And for that, I need a grammar ;)
I managed to go further in the grammar and wrote a text
rule:
grammar Rst;
options {
output=AST;
language=Java;
}
@members {
boolean inInlineMarkup = false;
}
//////////////////
// PARSER RULES //
//////////////////
file
: line* EOF
;
line
: text* NEWLINE
;
text
: inline_markup
| normal_text
;
inline_markup
@after {
inInlineMarkup = false;
}
: {!inInlineMarkup}? {inInlineMarkup = true;}
(
| STRONG
| EMPHASIS
| LITTERAL
| INTERPRETED_TEXT
| SUBSTITUTION_REFERENCE
| link
)
;
link
: INLINE_INTERNAL_TARGET
| FOOTNOTE_REFERENCE
| HYPERLINK_REFERENCE
;
normal_text
: {!inInlineMarkup}?
~(EMPHASIS
|SUBSTITUTION_REFERENCE
|STRONG
|LITTERAL
|INTERPRETED_TEXT
|INLINE_INTERNAL_TARGET
|FOOTNOTE_REFERENCE
|HYPERLINK_REFERENCE
|NEWLINE
)
;
//////////////////
// LEXER TOKENS //
//////////////////
EMPHASIS
: STAR ANY_BUT_STAR+ STAR {System.out.println("EMPHASIS: " + $text);}
;
SUBSTITUTION_REFERENCE
: PIPE ANY_BUT_PIPE+ PIPE {System.out.println("SUBST_REF: " + $text);}
;
STRONG
: STAR STAR ANY_BUT_STAR+ STAR STAR {System.out.println("STRONG: " + $text);}
;
LITTERAL
: BACKTICK BACKTICK ANY_BUT_BACKTICK+ BACKTICK BACKTICK {System.out.println("LITTERAL: " + $text);}
;
INTERPRETED_TEXT
: BACKTICK ANY_BUT_BACKTICK+ BACKTICK {System.out.println("LITTERAL: " + $text);}
;
INLINE_INTERNAL_TARGET
: UNDERSCORE BACKTICK ANY_BUT_BACKTICK+ BACKTICK {System.out.println("INLINE_INTERNAL_TARGET: " + $text);}
;
FOOTNOTE_REFERENCE
: L_BRACKET ANY_BUT_BRACKET+ R_BRACKET UNDERSCORE {System.out.println("FOOTNOTE_REFERENCE: " + $text);}
;
HYPERLINK_REFERENCE
: BACKTICK ANY_BUT_BACKTICK+ BACKTICK UNDERSCORE {System.out.println("HYPERLINK_REFERENCE (long): " + $text);}
| ANY_BUT_ENDLINK+ UNDERSCORE {System.out.println("HYPERLINK_REFERENCE (short): " + $text);}
;
WS
: (' '|'\t')+ {$channel=HIDDEN;}
;
NEWLINE
: '\r'? '\n' {$channel=HIDDEN;}
;
///////////////
// FRAGMENTS //
///////////////
fragment ANY_BUT_PIPE
: ESC PIPE
| ~(PIPE|'\n'|'\r')
;
fragment ANY_BUT_BRACKET
: ESC R_BRACKET
| ~(R_BRACKET|'\n'|'\r')
;
fragment ANY_BUT_STAR
: ESC STAR
| ~(STAR|'\n'|'\r')
;
fragment ANY_BUT_BACKTICK
: ESC BACKTICK
| ~(BACKTICK|'\n'|'\r')
;
fragment ANY_BUT_ENDLINK
: ~(UNDERSCORE|' '|'\t'|'\n'|'\r')
;
fragment ESC
: '\\'
;
fragment STAR
: '*'
;
fragment BACKTICK
: '`'
;
fragment PIPE
: '|'
;
fragment L_BRACKET
: '['
;
fragment R_BRACKET
: ']'
;
fragment UNDERSCORE
: '_'
;
The grammar is working fine for inline_markup but normal_text is not matched.
Here is my test class:
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.tree.Tree;
public class Test {
public static void main(String[] args) throws RecognitionException, IOException {
InputStream is = Test.class.getResourceAsStream("test.rst");
Reader r = new InputStreamReader(is);
StringBuilder source = new StringBuilder();
char[] buffer = new char[1024];
int readLenght = 0;
while ((readLenght = r.read(buffer)) > 0) {
if (readLenght < buffer.length) {
source.append(buffer, 0, readLenght);
} else {
source.append(buffer);
}
}
r.close();
System.out.println(source.toString());
ANTLRStringStream in = new ANTLRStringStream(source.toString());
RstLexer lexer = new RstLexer(in);
CommonTokenStream tokens = new CommonTokenStream(lexer);
RstParser parser = new RstParser(tokens);
RstParser.file_return out = parser.file();
System.out.println(((Tree)out.getTree()).toStringTree());
}
}
And the input file I use:
In `Figure 17-6`_, we have positioned ``before_ptr`` so that it points to the element
*before* the insert point. The variable ``after_ptr`` points to the |element| *after* the
insert. In other words, `we are going`_ to put_ our new element **in between** ``before_ptr``
and ``after_ptr``.
And I get this output:
HYPERLINK_REFERENCE (short): 7-6`_
line 1:2 mismatched character ' ' expecting '_'
line 1:10 mismatched character ' ' expecting '_'
line 1:18 mismatched character ' ' expecting '_'
line 1:21 mismatched character ' ' expecting '_'
line 1:26 mismatched character ' ' expecting '_'
line 1:37 mismatched character ' ' expecting '_'
LITTERAL: `before_ptr`
line 1:86 no viable alternative at character '\r'
line 1:55 mismatched character ' ' expecting '_'
line 1:60 mismatched character ' ' expecting '_'
line 1:63 mismatched character ' ' expecting '_'
line 1:70 mismatched character ' ' expecting '_'
line 1:73 mismatched character ' ' expecting '_'
line 1:77 mismatched character ' ' expecting '_'
line 1:85 mismatched character ' ' expecting '_'
EMPHASIS: *before*
line 2:12 mismatched character ' ' expecting '_'
line 2:19 mismatched character ' ' expecting '_'
line 2:26 mismatched character ' ' expecting '_'
LITTERAL: `after_ptr`
line 2:30 mismatched character ' ' expecting '_'
line 2:39 mismatched character ' ' expecting '_'
line 2:90 no viable alternative at character '\r'
line 2:60 mismatched character ' ' expecting '_'
line 2:63 mismatched character ' ' expecting '_'
line 2:67 mismatched character ' ' expecting '_'
line 2:77 mismatched character ' ' expecting '_'
line 2:85 mismatched character ' ' expecting '_'
line 2:89 mismatched character ' ' expecting '_'
line 3:7 mismatched character ' ' expecting '_'
line 3:10 mismatched character ' ' expecting '_'
line 3:16 mismatched character ' ' expecting '_'
line 3:23 mismatched character ' ' expecting '_'
line 3:27 mismatched character ' ' expecting '_'
line 3:31 mismatched character ' ' expecting '_'
line 3:42 mismatched character ' ' expecting '_'
line 3:51 mismatched character ' ' expecting '_'
line 3:55 mismatched character ' ' expecting '_'
line 3:63 mismatched character ' ' expecting '_'
line 3:94 mismatched character '\r' expecting '*'
line 4:3 mismatched character ' ' expecting '_'
line 4:18 no viable alternative at character '\r'
line 4:18 mismatched character '\r' expecting '_'
HYPERLINK_REFERENCE (short): oing`_
HYPERLINK_REFERENCE (short): ut_
EMPHASIS: *in between*
LITTERAL: `after_ptr`
BR.recoverFromMismatchedToken
line 0:-1 mismatched input '<EOF>' expecting NEWLINE
null
Can you point to my error(s)? (the parser works for inline markup without errors when I add the filter=true; option to the grammar)
Robin
Here's a quick demo how you could parse this reStructeredText. Note that it just handles a minor set of all available markup-syntax, and by adding more to it, you will affect the existing parser/lexer rules: so there is much, much more work to be done!
Demo
grammar RST;
options {
output=AST;
backtrack=true;
memoize=true;
}
tokens {
ROOT;
PARAGRAPH;
INDENTATION;
LINE;
WORD;
BOLD;
ITALIC;
INTERPRETED_TEXT;
INLINE_LITERAL;
REFERENCE;
}
parse
: paragraph+ EOF -> ^(ROOT paragraph+)
;
paragraph
: line+ -> ^(PARAGRAPH line+)
| Space* LineBreak -> /* omit line-breaks between paragraphs from AST */
;
line
: indentation text+ LineBreak -> ^(LINE text+)
;
indentation
: Space* -> ^(INDENTATION Space*)
;
text
: styledText
| interpretedText
| inlineLiteral
| reference
| Space
| Star
| EscapeSequence
| Any
;
styledText
: bold
| italic
;
bold
: Star Star boldAtom+ Star Star -> ^(BOLD boldAtom+)
;
italic
: Star italicAtom+ Star -> ^(ITALIC italicAtom+)
;
boldAtom
: ~(Star | LineBreak)
| italic
;
italicAtom
: ~(Star | LineBreak)
| bold
;
interpretedText
: BackTick interpretedTextAtoms BackTick -> ^(INTERPRETED_TEXT interpretedTextAtoms)
;
interpretedTextAtoms
: ~BackTick+
;
inlineLiteral
: BackTick BackTick inlineLiteralAtoms BackTick BackTick -> ^(INLINE_LITERAL inlineLiteralAtoms)
;
inlineLiteralAtoms
: inlineLiteralAtom+
;
inlineLiteralAtom
: ~BackTick
| BackTick ~BackTick
;
reference
: Any+ UnderScore -> ^(REFERENCE Any+)
;
UnderScore
: '_'
;
BackTick
: '`'
;
Star
: '*'
;
Space
: ' '
| '\t'
;
EscapeSequence
: '\\' ('\\' | '*')
;
LineBreak
: '\r'? '\n'
| '\r'
;
Any
: .
;
When you generate a parser and lexer from the above, and let it parse the following input file:
***x*** **yyy** *zz* * a b c P2 ``*a*`b`` `q` Python_
(note the trailing line break!)
the parser will produce the following AST:
EDIT
The graph can be created by running this class:
import org.antlr.runtime.*;
import org.antlr.runtime.tree.*;
import org.antlr.stringtemplate.*;
public class Main {
public static void main(String[] args) throws Exception {
String source =
"***x*** **yyy** *zz* *\n" +
"a b c\n" +
"\n" +
"P2 ``*a*`b`` `q`\n" +
"Python_\n";
RSTLexer lexer = new RSTLexer(new ANTLRStringStream(source));
RSTParser parser = new RSTParser(new CommonTokenStream(lexer));
CommonTree tree = (CommonTree)parser.parse().getTree();
DOTTreeGenerator gen = new DOTTreeGenerator();
StringTemplate st = gen.toDOT(tree);
System.out.println(st);
}
}
or if your source comes from a file, do:
RSTLexer lexer = new RSTLexer(new ANTLRFileStream("test.rst"));
or
RSTLexer lexer = new RSTLexer(new ANTLRFileStream("test.rst", "???"));
where "???"
is the encoding of your file.
The class above will print the AST as a DOT file to the console. You can use a DOT viewer to display the AST. In this case, I posted an image created by kgraphviewer. But there are many more viewers around. A nice online one is this one, which appears to be using kgraphviewer under "the hood". Good luck!
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