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  • Grammar/own-written parser?

    - by wvd
    Hello all, I'm doing some small projects which involve having different syntaxis for something, however sometimes these syntaxis are so easy that using a parser generator might be overkill. Now, when should I use a own-made parser, and when should I use a parser generator? Thanks, William van Doorn

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  • PHP: Recursive array function

    - by Industrial
    Hi everybody, I want to create a function that returns the full path from a set node, back to the root value. I tried to make a recursive function, but ran out of luck totally. What would be an appropriate way to do this? I assume that a recursive function is the only way? Here's the array: Array ( [0] => Array ( [id] => 1 [name] => Root category [_parent] => ) [1] => Array ( [id] => 2 [name] => Category 2 [_parent] => 1 ) [2] => Array ( [id] => 3 [name] => Category 3 [_parent] => 1 ) [3] => Array ( [id] => 4 [name] => Category 4 [_parent] => 3 ) ) The result I want my function to output when getting full path of node id#4: Array ( [0] => Array ( [id] => 1 [name] => Root category [_parent] => ) [1] => Array ( [id] => 3 [name] => Category 3 [_parent] => 1 ) [2] => Array ( [id] => 4 [name] => Category 4 [_parent] => 3 ) ) The notoriously bad example of my recursive skills: function recursive ($id, $array) { $innerarray = array(); foreach ($array as $k => $v) { if ($v['id'] === $id) { if ($v['_parent'] !== '') { $innerarray[] = $v; recursive($v['id'], $array); } } } return $innerarray; } Thanks!

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  • Generic rule parser for RPG board game rules - how to do it?

    - by burzum
    I want to build a generic rule parser for pen and paper style RPG systems. A rule can involve usually 1 to N entities 1 to N roles of a dice and calculating values based on multiple attributes of an entity. For example: Player has STR 18, his currently equipped weapon gives him a bonus of +1 STR but a malus of DEX -1. He attacks a monster entity and the game logic now is required to run a set of rules or actions: Player rolls the dice, if he gets for example 8 or more (base attack value he needs to pass is one of his base attributes!) his attack is successfully. The monster then rolls the dice to calculate if the attack goes through it's armor. If yes the damage is taken if not the attack was blocked. Besides simple math rules can also have constraints like applying only to a certain class of user (warrior vs wizzard for example) or any other attribute. So this is not just limited to mathematical operations. If you're familiar with RPG systems like Dungeon and Dragons you'll know what I'm up to. My issue is now that I have no clue how to exactly build this the best possible way. I want people to be able to set up any kind of rule and later simply do an action like selecting a player and a monster and run an action (set of rules like an attack). I'm asking less for help with the database side of things but more about how to come up with a structure and a parser for it to keep my rules flexible. The language of choice for this is php by the way.

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  • Right recursive grammar or left recursive?

    - by user2485710
    I have little to no knowledge of what I'm about to ask, so I would like a suggestion based on the level of skills required to implemented a parser for the given grammar ( since I'm a beginner in this kind of formal approach to parsers and languages ). Just by going back of a couple of years, this situation reminds me a little of Pascal grammar vs C/C++ grammar, this left vs right stuff. But I'm not going to do any of that, my purpose is to implement a simple parser for a markup language for documents like Markdown. So considering that I'm starting with a markup language in mind, I want to keep things simple, which is the easiest one to handle between this 2 options and why . Another kind of grammar could be an easier option for me ? If yes which one do you suggest ?

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  • Recursive move utility on Unix?

    - by Thomas Vander Stichele
    Sometimes I have two trees that used to have the same content, but have grown out of sync (because I moved disks around or whatever). A good example is a tree where I mirror upstream packages from Fedora. I want to merge those two trees again by moving all of the files from tree1 into tree2. Usually I do this with: rsync -arv tree1/* tree2 Then delete tree1. However, this takes an awful lot of time and disk space, and it would be much easier to be able to do: mv -r tree1/* tree2 In other words, a recursive move. It would be faster because first of all it would not even copy, just move the inodes, and second I wouldn't need a delete at the end. Does this exist ? As a test case, consider the following sequence of commands: $ mkdir -p a/b $ touch a/b/c1 $ rsync -arv a/ a2 sending incremental file list created directory ./ b/ b/c1 b/c2 sent 173 bytes received 57 bytes 460.00 bytes/sec total size is 0 speedup is 0.00 $ touch a/b/c2 What command would now have the effect of moving a/b/c2 to a2/b/c2 and then deleting the a subtree (since everything in it is already in the destination tree) ?

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  • How to test if Scala combinator parser matches a string

    - by W.P. McNeill
    I have a Scala combinator parser that handles comma-delimited lists of decimal numbers. object NumberListParser extends RegexParsers { def number: Parser[Double] = """\d+(\.\d*)?""".r ^^ (_.toDouble) def numbers: Parser[List[Double]] = rep1sep(number, ",") def itMatches(s: String): Boolean = parseAll(numbers, s) match { case _: Success[_] => true case _ => false } } The itMatches function returns true when given a string that matches the pattern. For example: NumberListParser.itMatches("12.4,3.141") // returns true NumberListParser.itMatches("bogus") // returns false Is there a more terse way to do this? I couldn't find one in the documentation, but my function sees a bit verbose, so I wonder if I'm overlooking something.

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  • RapidXML - does not compile ?

    - by milan
    Hi, I am novice to rapidXML but first impresion was not positive, I made simple Visual Studio 6 C++ Hello World Application and added RapidXML hpp files to project and in main.cpp I put: #include "stdafx.h" #include < iostream > #include < string > #include "rapidxml.hpp" using namespace std; using namespace rapidxml; int main ( ) { char x[] = "<Something>Text</Something>\0" ; //<<<< funktioniert, aber mit '*' nicht xml_document<> doc ; doc.parse<0>(x) ; cout << "Name of my first node is: " << doc.first_node()->name() << endl ; xml_node<>* node = doc.first_node("Something") ; cout << "Node 'Something' has value: " << node->value() << endl ; } And it does not compile, any help ? Is RapidXML possible to run with Visual Studio 6 ? Error I am getting are: --------------------Configuration: aaa - Win32 Debug-------------------- Compiling... rapidxml.cpp c:\Parser\rapidxml.cpp(310) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(320) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(320) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(385) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(417) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(417) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(448) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(448) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(476) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(579) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(599) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(639) : see reference to class template instantiation 'rapidxml::memory_pool<Ch>' being compiled c:\Parser\rapidxml.cpp(681) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(790) : see reference to class template instantiation 'rapidxml::xml_base<Ch>' being compiled c:\Parser\rapidxml.cpp(700) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(790) : see reference to class template instantiation 'rapidxml::xml_base<Ch>' being compiled c:\Parser\rapidxml.cpp(721) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(790) : see reference to class template instantiation 'rapidxml::xml_base<Ch>' being compiled c:\Parser\rapidxml.cpp(751) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(790) : see reference to class template instantiation 'rapidxml::xml_base<Ch>' being compiled c:\Parser\rapidxml.cpp(786) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(790) : see reference to class template instantiation 'rapidxml::xml_base<Ch>' being compiled c:\Parser\rapidxml.cpp(787) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(790) : see reference to class template instantiation 'rapidxml::xml_base<Ch>' being compiled c:\Parser\rapidxml.cpp(836) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(876) : see reference to class template instantiation 'rapidxml::xml_attribute<Ch>' being compiled c:\Parser\rapidxml.cpp(856) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(876) : see reference to class template instantiation 'rapidxml::xml_attribute<Ch>' being compiled c:\Parser\rapidxml.cpp(936) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(1345) : see reference to class template instantiation 'rapidxml::xml_node<Ch>' being compiled c:\Parser\rapidxml.cpp(958) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(1345) : see reference to class template instantiation 'rapidxml::xml_node<Ch>' being compiled c:\Parser\rapidxml.cpp(981) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(1345) : see reference to class template instantiation 'rapidxml::xml_node<Ch>' being compiled c:\Parser\rapidxml.cpp(1004) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(1345) : see reference to class template instantiation 'rapidxml::xml_node<Ch>' being compiled c:\Parser\rapidxml.cpp(1025) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(1345) : see reference to class template instantiation 'rapidxml::xml_node<Ch>' being compiled c:\Parser\rapidxml.cpp(1045) : error C2039: 'size_t' : is not a member of 'std' c:\Parser\rapidxml.cpp(1345) : see reference to class template instantiation 'rapidxml::xml_node<Ch>' being compiled Error executing cl.exe. rapidxml.obj - 25 error(s), 0 warning(s)

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  • Best json parser for qt?

    - by Martin
    I'm using QT for Symbian and need a simple json parser. I need to be able to go from json to Qt-variant and the other way around. Is there a simple json parser that I can use? I don't want to write my own. What is the best way to go? Thanks!

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  • running Sax parser

    - by apoorva
    Am new to using SAX parser .Can anyone tell me how to run it .and what all are required to run it (jdk )..Can i have a sax parser that can parse both android xml and a normal xml

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  • 'javadoc' look-a-like, using parser generator?

    - by wvd
    Hello all, I'm going to create a javadoc look-a-like for the language I'm mainly using, but I was wondering - is it worth to use a parser generator for this? The main idea to use a parser generator was because I could use templates for the HTML code which could be exported then. Also I could also use PDF templates if I need it. Thanks, William v. Doorn

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  • Scala parser combinators: how to parse "if(x)" if x can contain a ")"

    - by Germán
    I'm trying to get this to work: def emptyCond: Parser[Cond] = ("if" ~ "(") ~> regularStr <~ ")" ^^ { case s => Cond("",Nil,Nil) } where regularStr is defined to accept a number of things, including ")". Of course, I want this to be an acceptable input: if(foo()). But for any if(x) it is taking the ")" as part of the regularStr and so this parser never succeeds. What am I missing?

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  • How does a parser LL(*) works?

    - by freezer878
    Hi, I cannot find any complete description about LL() parser, such as ANTLR, on Internet. I'm wondering what is the difference between an LL(k) parser and an LL() one and why they can't support left-recusrive grammars despite their flexibility. Thanks in advance. Fabio.

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  • Looking for a CSS Parser in java

    - by Richard
    Hi, I'm looking for a CSS Parser in java. In particular my requirement is, for a given node/element in an HTML document, to be able to ask/get the css styles for that element from the Parser. I know there is the W3C SAC interface and one or 2 implementations based on this - but turorials/examples appear non-existant. Any help/points in rigth direction much appreciated. Thanks

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  • I need to develop a parser. Can I use Lex and Yacc for the purpose?

    - by Scrooge
    I need to extract very particular data from log files(of different types and formats). Since I am a recent college passout; my mind ran to using Lex and Yacc for the purpose. Now I have the following Questions 1. Will it be legal to do so ? (This product I am working for belongs to one of the biggest tech companies in the world.) 2. Also ; I would like to know if I am being too afraid to write my own parser? 3. How can I use Lex and Yacc if my product is Windows based? Please tell me if you need any clarification or extra information.

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  • Coding a parser for a domain specific language in Java

    - by Bruno Rothgiesser
    We want to design a simple domain specific language for writing test scripts to automatically test a XML-based interface of one of our applications. A sample test would be: Get an input XML file from network shared folder or subversion repository Import the XML file using the interface Check if the import result message was successfull Export the XML corresponding to the object that was just imported using the interface and check if it correct. If the domain specific language can be declarative and its statements look as close as my sentences in the sample above as possible, it will be awesome because people won't necessarily have to be programmers to understand/write/maintain the tests. Something like: newObject = GET FILE "http://svn/repos/template1.xml" reponseMessage = IMPORT newObject newObjectID = GET PROPERTY '/object/id/' FROM responseMessage (..) But then I'm not sure how to implement a simple parser for that languange in Java. Back in school, 10 years ago, I coded a language parser using Lex and Yacc for the C language. Maybe an approach would be to use some equivalent for Java? Or, I could give up the idea of having a declarative language and choose an XML-based language instead, which would possibly be easier to create a parser for? What approach would you recommend?

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  • Use of SAX parser in Android - OutOfMemory Issue

    - by Sephy
    Hi everybody, I have been using a SAX parser for a while now to get data from various XML, but today i'm banging my head on a new problem with a hudge XML (compared to the previous ones . here around 12k lines) with a lot of repetitive items in it. Most of the time, the items are part of a block : <content> <item lbl="blabla"> <item lbl="blabla"/> <item lbl="blabla"/> </item> <item lbl="blabla"> <item lbl="blabla"/> <item lbl="blabla"/> <item lbl="blabla"/> <item lbl="blabla"/> <item lbl="blabla"/> <item lbl="blabla"/> </item> </content> The blabla part is of course changing...But, I would like to keep the structure of items (they are titles and subtitles). And for that, I append each blabla with a starting and ending tag blabla, where x is the position in the tree of items (1, 2, 3 or 4). The slightly problematic part is that with that, I'm creating thousands of useless objects and the garbage collector doesn't have time to clean after the parser, and the inevitable OutOfMemory comes in my face... I have no idea of how to deal with it; The best technique would be if I could take the whole content of , but i'm not sure that this is possible with a SAX parser. Any help is welcome and any solution deeply thanked...

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  • php run function on all images from one dir in recursive mode (noob)

    - by Steve
    hey guyz i have a function $result = create_watermark( 'input_file_name' ,'output_file_name'); i have dir called /images n have 500 images in it and all images are link images_(some_unknown_numbers).png (all png) now i want run them thru function in loop and want out put like /markedimage/images_1.png images_2.png images_3.png i need help how can i run them in loop and how out put name can change want run script on Ubuntu so we can use shell too if any body want check function it is here http://paste2.org/p/789149 plz provide me code because i m newbie thanks in advance

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  • hand coding a parser

    - by John Leidegren
    For all you compiler gurus, I wanna write a recursive descent parser and I wanna do it with just code. No generating lexers and parsers from some other grammar and don't tell me to read the dragon book, i'll come around to that eventually. I wanna get into the gritty details about implementing a lexer and parser for a reasonable simple langauge, say CSS. And I wanna do this right. This will probably end up being a series of questions but right now I'm starting with a lexer. Tokenization rules for CSS can be found here. I find my self writing code like this (hopefully you can infer the rest from this snippet): public CssToken ReadNext() { int val; while ((val = _reader.Read()) != -1) { var c = (char)val; switch (_stack.Top) { case ParserState.Init: if (c == ' ') { continue; // ignore } else if (c == '.') { _stack.Transition(ParserState.SubIdent, ParserState.Init); } break; case ParserState.SubIdent: if (c == '-') { _token.Append(c); } _stack.Transition(ParserState.SubNMBegin); break; What is this called? and how far off am I from something reasonable well understood? I'm trying to balence something which is fair in terms of efficiency and easy to work with, using a stack to implement some kind of state machine is working quite well, but I'm unsure how to continue like this. What I have is an input stream, from which I can read 1 character at a time. I don't do any look a head right now, I just read the character then depending on the current state try to do something with that. I'd really like to get into the mind set of writing reusable snippets of code. This Transition method is currently means to do that, it will pop the current state of the stack and then push the arguments in reverse order. That way, when I write Transition(ParserState.SubIdent, ParserState.Init) it will "call" a sub routine SubIdent which will, when complete, return to the Init state. The parser will be implemented in much the same way, currently, having everyhing in a single big method like this allows me to easily return a token when I found one, but it also forces me to keep everything in one single big method. Is there a nice way to split these tokenization rules into seperate methods? Any input/advice on the matter would be greatly appriciated!

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  • How to get lookahead symbol when constructing LR(1) NFA for parser?

    - by greenoldman
    I am reading an explanation (awesome "Parsing Techniques" by D.Grune and C.J.H.Jacobs; p.292 in the 2nd edition) about how to construct an LR(1) parser, and I am at the stage of building the initial NFA. What I don't understand is how to get/compute a lookahead symbol. Here is the example from the book, the grammar: S -> E E -> E - T E -> T T -> ( E ) T -> n n is terminal. The "weird" transitions for me are is the sequence: 1) S -> . E eof 2) E -> . E - T eof 3) E -> . E - T - 4) E -> E . - T - 5) E -> E - . T - (Note: In the above table, the state numbers are in front and the lookahead symbol is at the end.) What puzzles me is that transition from (4) to (5) means reading - token, right? So how is it that - is still a lookahead symbol and even more important why is it that eof is no longer a lookahead symbol? After all in an input such as n - n eof there is only one - symbol. My naive thinking tells me (5) should be written as: 5) E -> E - . T - eof And another thing -- n is terminal. Why it is not used at all as a lookahead symbol? I mean -- we expect to see - or (, it is ok, but lack of n means we are sure it won't appear in input? Update: after more reading I am only more confused ;-) I.e. what is really a lookahead? Because I see such state as (p.292, 2nd column, 2nd row): E -> E . - T eof Lookahead says eof but the incoming input says -. Isn't it a contradiction? And it is not only in this book.

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  • exception occured in java compiler

    - by user2892977
    I am a beginner in Java.I have JDK1.7.0 installed on windows 7 OS.I just wrote a sample java file where the file was not getting compiled and throws the below error. Sam.java:5: ';' expected Sample p = New Sample(); An exception has occurred in the compile r (1.7.0-ea). Please file a bug at the Java Developer Connection (http://java.su n.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you. java.lang.StringIndexOutOfBoundsException: String index out of range: 26 at java.lang.String.charAt(String.java:694) at com.sun.tools.javac.util.Log.printErrLine(Log.java:251) at com.sun.tools.javac.util.Log.writeDiagnostic(Log.java:343) at com.sun.tools.javac.util.Log.report(Log.java:315) at com.sun.tools.javac.util.AbstractLog.error(AbstractLog.java:96) at com.sun.tools.javac.parser.Parser.reportSyntaxError(Parser.java:295) at com.sun.tools.javac.parser.Parser.accept(Parser.java:326) at com.sun.tools.javac.parser.Parser.blockStatements(Parser.java:1599) at com.sun.tools.javac.parser.Parser.block(Parser.java:1500) at com.sun.tools.javac.parser.Parser.block(Parser.java:1514) at com.sun.tools.javac.parser.Parser.methodDeclaratorRest(Parser.java:25 69) at com.sun.tools.javac.parser.Parser.classOrInterfaceBodyDeclaration(Par ser.java:2518) at com.sun.tools.javac.parser.Parser.classOrInterfaceBody(Parser.java:24 45) at com.sun.tools.javac.parser.Parser.classDeclaration(Parser.java:2290) at com.sun.tools.javac.parser.Parser.classOrInterfaceOrEnumDeclaration(P arser.java:2228) at com.sun.tools.javac.parser.Parser.typeDeclaration(Parser.java:2217) at com.sun.tools.javac.parser.Parser.compilationUnit(Parser.java:2163) at com.sun.tools.javac.main.JavaCompiler.parse(JavaCompiler.java:530) at com.sun.tools.javac.main.JavaCompiler.parse(JavaCompiler.java:571) at com.sun.tools.javac.main.JavaCompiler.parseFiles(JavaCompiler.java:82 2) at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:748) at com.sun.tools.javac.main.Main.compile(Main.java:386) at com.sun.tools.javac.main.Main.compile(Main.java:312) at com.sun.tools.javac.main.Main.compile(Main.java:303) at com.sun.tools.javac.Main.compile(Main.java:82) at com.sun.tools.javac.Main.main(Main.java:67) Below is the code for Sam.java file class sam { public static void main(String args[]) { Sample p = New Sample(); p.show(); p.display(); } } I researched in google with the various compiler options but that did not help.I would like to understand the below errors. 1 - Sam.java:5: ';' expected 2 - An exception has occurred in the compiler (1.7.0-ea)

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  • How to further improve error messages in Scala parser-combinator based parsers?

    - by rse
    I've coded a parser based on Scala parser combinators: class SxmlParser extends RegexParsers with ImplicitConversions with PackratParsers { [...] lazy val document: PackratParser[AstNodeDocument] = ((procinst | element | comment | cdata | whitespace | text)*) ^^ { AstNodeDocument(_) } [...] } object SxmlParser { def parse(text: String): AstNodeDocument = { var ast = AstNodeDocument() val parser = new SxmlParser() val result = parser.parseAll(parser.document, new CharArrayReader(text.toArray)) result match { case parser.Success(x, _) => ast = x case parser.NoSuccess(err, next) => { tool.die("failed to parse SXML input " + "(line " + next.pos.line + ", column " + next.pos.column + "):\n" + err + "\n" + next.pos.longString) } } ast } } Usually the resulting parsing error messages are rather nice. But sometimes it becomes just sxml: ERROR: failed to parse SXML input (line 32, column 1): `"' expected but `' found ^ This happens if a quote characters is not closed and the parser reaches the EOT. What I would like to see here is (1) what production the parser was in when it expected the '"' (I've multiple ones) and (2) where in the input this production started parsing (which is an indicator where the opening quote is in the input). Does anybody know how I can improve the error messages and include more information about the actual internal parsing state when the error happens (perhaps something like a production rule stacktrace or whatever can be given reasonably here to better identify the error location). BTW, the above "line 32, column 1" is actually the EOT position and hence of no use here, of course.

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