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• LoadDictation with SAPI

  - by Naveen

  I am able to create alternate dictation grammars using the dictation resource kit or directions given here. I am not able to load the new dictation topic with c++. I am trying to modify the simpledict sample provided with the sapi5.1 sdk. The following doesn't work. std::wstring stemp = s2ws("grammar:dictation#Genre"); LPCWSTR mygrammar = stemp.c_str(); hr = m_cpDictationGrammar-LoadDictation(mygrammar, SPLO_STATIC);

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• Looking for a Java grammar in lex/yacc format

  - by Ben

  Does anyone know an online repository for lex/yacc format grammars? I'm looking for a Java grammar to make a quicky sourcecode converter. Thank you!

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• What are the benefits of using Boost.Phoenix?

  - by Denis Shevchenko

  Hello all! I can not understand what the real benefits of using Boost.Phoenix. When I use it with Boost.Spirit grammars, it's really useful: double_[ boost::phoenix::push_back( boost::phoenix::ref( v ), _1 ) ] When I use it for lambda functions, it's also useful and elegant: boost::range::for_each( my_string, if_ ( '\\' == arg1 ) [ arg1 = '/' ] ); But what are the benefits of everything else in this library? The documentation says: "Functors everywhere". I don't understand what is the good of it?

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• Parser generator for inline documentation

  - by Leonth

  To have a general-purpose documentation system that can extract inline documentation of multiple languages, a parser for each language is needed. A parser generator (which actually doesn't have to be that complete or efficient) is thus needed. http://antlr.org/ is a nice parser generator that already has a number of grammars for popular languages. Are there better alternatives i.e. simpler ones that support generating parsers for even more languages out-of-the-box?

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• What makes Ometa special?

  - by Brian

  Ometa is "a new object-oriented language for pattern matching." I've encountered pattern matching in languages like Oz tools to parse grammars like Lexx/Yacc or Pyparsing before. Despite looking at example code, reading discussions, and talking to a friend, I still am not able to get a real understanding of what makes Ometa special (or at least, why some people think it is). Any explanation?

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• What does the q in a q-grammar stand for?

  - by Aru

  So I've been reading sites and the classic books on compilers, reading about s-grammar and q-grammars I wondered what the s and q stand for, I think the s stands for simple grammar. While the q...well, I have no idea. What does the q in a q-grammar stand for?

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• standard C++ grammar

  - by eSKay

  Does the standard specify the official C++ grammar? I searched, but did not find it anywhere. Also, I wish to read a bit about C++ grammar in detail, like which category of grammars it falls in, etc. Any links pointing me in the right direction would be helpful. By category, I meant

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• How do LL(*) parsers work?

  - by freezer878

  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.

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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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• Why do programmers seem to be such bad spellers?

  - by Joel Etherton

  Programming languages are very precise tools based on explicit grammars. They're very picky, and when being used they require an exacting amount of detail. C#, for instance, is case sensitive so even getting the case of an argument wrong will cause an error. Questions asked all over the StackExchange are replete with misspellings, grammatical errors, and other problems that seem to indicate a lack of attention to detail when it comes to the language itself. Now, I understand there are a lot of programmers out there whose native language is not English, and I am not directing this question (rant one might say) at them. I'm referring to the individuals who are clearly from an English speaking background who refuse to pay attention to these simple details. I am not perfect by any means, but I try to use the language correctly so that my meaning will be understood correctly. I find programmers misspelling variable names, classes, and all manner of words in any kind of technical documentation they might write. I have had to withstand code where I am repeatedly referring to the subit[sic] button or HttpWebResponse reponse. The general complaint about bad spelling is one thing, and it will always be there. I accept that. But my question/comment is about the proclivity of bad spelling within the programming community. I would think that people who deal with such exacting tools to be more naturally predisposed towards proper spelling. Yet this doesn't seem to be the case.

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• How to implement string matching based on a pattern

  - by Vincent Rischmann

  I was asked to build a tool that can identify if a string match a pattern. Example: {1:20} stuff t(x) {a,b,c} would match: 1 stuff tx a 20 stuff t c It is a sort of regex but with a different syntax Parentheses indicate an optional value {1:20} is a interval; I will have to check if the token is a number and if it is between 1 and 20 {a,b,c} is just an enumeration; it can be either a or b or c Right now I implemented this with a regex, and the interval stuff was a pain to do. On my own time I tried implementing some kind of matcher by hand, but it turns out it's not that easy to do. By experimenting I ended up with a function that generates a state table from the pattern and a state machine. It worked well until I tried to implement the optional value, and I got stuck and how to generate the state table. After that I searched how I could do this, and that led me to stuff like LL parser, LALR parser, recursive-descent parser, context-free grammars, etc. I never studied any of this so it's hard to know what is relevant here, but I think this is what I need: A grammar A parser which generates states from the grammar and a pattern A state machine to see if a string match the states So my first question is: Is this right ? And second question, what do you recommend I read/study to be able to implement this ?

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• ANTLR lexer mismatches tokens

  - by Barry Brown

  I have a simple ANTLR grammar, which I have stripped down to its bare essentials to demonstrate this problem I'm having. I am using ANTLRworks 1.3.1. grammar sample; assignment : IDENT ':=' NUM ';' ; IDENT : ('a'..'z')+ ; NUM : ('0'..'9')+ ; WS : (' '|'\n'|'\t'|'\r')+ {$channel=HIDDEN;} ; Obviously, this statement is accepted by the grammar: x := 99; But this one also is: x := @!$()()%99***; Output from the ANTLRworks Interpreter: What am I doing wrong? Even other sample grammars that come with ANTLR (such as the CMinus grammar) exhibit this behavior.

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• How to correctly formalize the command line usage of GNU/Linux commands?

  - by Francesco Turco

  I'd like to write down a BNF-like formal grammar for describing the command line usage of some GNU/Linux tools. For example I can describe the usage of the cat command as: (cat-command) : 'cat' (arguments-list) (arguments-list) : (argument) (arguments-list) : (arguments-list) (argument) (argument) : (file) The problem is I can't write down a precise grammar for some commands such as md5sum. My first attempt at that would be the following: (md5sum-command) : 'md5sum' (arguments-list) (arguments-list) : (argument) (arguments-list) : (arguments-list) (argument) (argument) : (file) (argument) : '--check' But as you can see this grammar allows you to specify the --check argument as many times as you wish, which is incorrect as you should use it at most one time. How can I fix that? Also, what kind of formal grammars I should study for better treating this kind of problems? Thanks.

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• How do I generate different yyparse functions from lex/yacc for use in the same program?

  - by th

  Hi, I want to generate two separate parsing functions from lex/yacc. Normally yacc gives you a function yyparse() that you can call when you need to do some parsing, but I need to have several different yyparses each associated with different lexers and grammars. The man page seems to suggest the -p (prefix) flag, but this didn't work for me. I got errors from gcc that indicated that yylval was not properly being relabeled (i.e. it claims that several different tokens are not defined). Does anyone know the general rpocedure for generating these separate functions? thanks

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• The Definition of Regular Languages

  - by AraK

  Good Day, I have tried, and burned my brain to understand the definition of Regular Languages in Discrete Mathematics and its Applications(Rosen) without reaching the goal of understanding why the definition is like that in this book. On page(789), I am rephrasing the definition: Type 3 grammars are defined as: w1 --> w2 Where w1 is a non-terminal, and w2 is of the form: w2 = aB w2 = a Where B is a non-terminal, and a is a terminal. A special case is when w1 is the starting symbol and w2 is lambda(the empty string): w1 = S S --> lambda Two questions I couldn't find an answer for. First, Why can't w2 be of the form Ba. Second, Why lambda is only allowed for the starting symbol only. The book states that, regular languages are equivalent to Finite State Automaton, and we can easily see that a we can build FSA for both cases. I took a look at other resources, and these restrictions don't exist in these resources. Thanks,

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• Pyparsing CSV string with random quotes

  - by gtfx

  Hey, I have a string like the following: <118date=2010-05-09,time=16:41:27,device_id=FE-2KA3F09000049,log_id=0400147717,log_part=00,type=statistics,subtype=n/a,pri=information,session_id=o49CedRc021772,from="[email protected]",mailer="mta",client_name="example.org,[194.177.17.24]",resolved=OK,to="[email protected]",direction="in",message_length=6832079,virus="",disposition="Accept",classifier="Not,Spam",subject="=?windows-1255?B?Rlc6IEZ3OiDg5fDp5fog+fno5fog7Pf46eHp7S3u4+Tp7SE=?=" I tried using CSV module and it didn't fit, cause i haven't found a way to ignore what's quoted. Pyparsing looked like a better answer but i haven't found a way to declare all the grammars. Currently, i am using my old Perl script to parse it, but i want this written in Python. if you need my Perl snippet i will be glad to provide it. Any help is appreciated.

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• code throws std::bad_alloc, not enough memory or can it be a bug?

  - by Andreas

  I am parsing using a pretty large grammar (1.1 GB, it's data-oriented parsing). The parser I use (bitpar) is said to be optimized for highly ambiguous grammars. I'm getting this error: 1terminate called after throwing an instance of 'std::bad_alloc' what(): St9bad_alloc dotest.sh: line 11: 16686 Aborted bitpar -p -b 1 -s top -u unknownwordsm -w pos.dfsa /tmp/gsyntax.pcfg /tmp/gsyntax.lex arbobanko.test arbobanko.results Is there hope? Does it mean that it has ran out of memory? It uses about 15 GB before it crashes. The machine I'm using has 32 GB of RAM, plus swap as well. It crashes before outputting a single parse tree. The parser is an efficient CYK chart parser using bit vector representations; I presume it is already near the limit of memory efficiency. If it really requires too much memory I could sample from the grammar rules, but this will decrease parse accuracy of course.

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• If item not in the lst in scheme

  - by ms. sakura

  I'm working on context-free grammars, and I have a function that returns the (terminal values of grammar) for example: i have non-terminal function that results in (A B) , from calling say ((A cat) (B happy np) (A B sad)) so technically A and B are non terminals of the grammar. Now I want to be able to get the terminals (cat happy np sad) (define terminals (lambda (lsts) (cond ((null? lsts) lsts) ((not(member? (car(car lsts)) (n-terminals lsts))) (cons (car(car lsts)) (terminals (car (cdr lsts))))) (else (terminals (cdr lsts)))))) PS: functionality of n-terminals is described above. member? is a boolean function that returns true if an item is a member of the list, false otherwise. My function returns an empty lst. What am I missing here?

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• on coding style

  - by user12607414

  I vastly prefer coding to discussing coding style, just as I would prefer to write poetry instead of talking about how it should be written. Sometimes the topic cannot be put off, either because some individual coder is messing up a shared code base and needs to be corrected, or (worse) because some officious soul has decided, "what we really need around here are some strongly enforced style rules!" Neither is the case at the moment, and yet I will venture a post on the subject. The following are not rules, but suggested etiquette. The idea is to allow a coherent style of coding to flourish safely and sanely, as a humane, inductive, social process. Maxim M1: Observe, respect, and imitate the largest-scale precedents available. (Preserve styles of whitespace, capitalization, punctuation, abbreviation, name choice, code block size, factorization, type of comments, class organization, file naming, etc., etc., etc.) Maxim M2: Don't add weight to small-scale variations. (Realize that Maxim M1 has been broken many times, but don't take that as license to create further irregularities.) Maxim M3: Listen to and rely on your reviewers to help you perceive your own coding quirks. (When you review, help the coder do this.) Maxim M4: When you touch some code, try to leave it more readable than you found it. (When you review such changes, thank the coder for the cleanup. When you plan changes, plan for cleanups.) On the Hotspot project, which is almost 1.5 decades old, we have often practiced and benefited from such etiquette. The process is, and should be, inductive, not prescriptive. An ounce of neighborliness is better than a pound of police-work. Reality check: If you actually look at (or live in) the Hotspot code base, you will find we have accumulated many annoying irregularities in our source base. I suppose this is the normal condition of a lived-in space. Unless you want to spend all your time polishing and tidying, you can't live without some smudge and clutter, can you? Final digression: Grammars and dictionaries and other prescriptive rule books are sometimes useful, but we humans learn and maintain our language by example not grammar. The same applies to style rules. Actually, I think the process of maintaining a clean and pleasant working code base is an instance of a community maintaining its common linguistic identity. BTW, I've been reading and listening to John McWhorter lately with great pleasure. (If you end with a digression, is it a tail-digression?)

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• Help needed with pyparsing [closed]

  - by Zearin

  Overview So, I’m in the middle of refactoring a project, and I’m separating out a bunch of parsing code. The code I’m concerned with is pyparsing. I have a very poor understanding of pyparsing, even after spending a lot of time reading through the official documentation. I’m having trouble because (1) pyparsing takes a (deliberately) unorthodox approach to parsing, and (2) I’m working on code I didn’t write, with poor comments, and a non-elementary set of existing grammars. (I can’t get in touch with the original author, either.) Failing Test I’m using PyVows to test my code. One of my tests is as follows (I think this is clear even if you’re unfamiliar with PyVows; let me know if it isn’t): def test_multiline_command_ends(self, topic): output = parsed_input('multiline command ends\n\n',topic) expect(output).to_equal( r'''['multiline', 'command ends', '\n', '\n'] - args: command ends - multiline_command: multiline - statement: ['multiline', 'command ends', '\n', '\n'] - args: command ends - multiline_command: multiline - terminator: ['\n', '\n'] - terminator: ['\n', '\n']''') But when I run the test, I get the following in the terminal: Failed Test Results Expected topic("['multiline', 'command ends']\n- args: command ends\n- command: multiline\n- statement: ['multiline', 'command ends']\n - args: command ends\n - command: multiline") to equal "['multiline', 'command ends', '\\n', '\\n']\n- args: command ends\n- multiline_command: multiline\n- statement: ['multiline', 'command ends', '\\n', '\\n']\n - args: command ends\n - multiline_command: multiline\n - terminator: ['\\n', '\\n']\n- terminator: ['\\n', '\\n']" Note: Since the output is to a Terminal, the expected output (the second one) has extra backslashes. This is normal. The test ran without issue before this piece of refactoring began. Expected Behavior The first line of output should match the second, but it doesn’t. Specifically, it’s not including the two newline characters in that first list object. So I’m getting this: "['multiline', 'command ends']\n- args: command ends\n- command: multiline\n- statement: ['multiline', 'command ends']\n - args: command ends\n - command: multiline" When I should be getting this: "['multiline', 'command ends', '\\n', '\\n']\n- args: command ends\n- multiline_command: multiline\n- statement: ['multiline', 'command ends', '\\n', '\\n']\n - args: command ends\n - multiline_command: multiline\n - terminator: ['\\n', '\\n']\n- terminator: ['\\n', '\\n']" Earlier in the code, there is also this statement: pyparsing.ParserElement.setDefaultWhitespaceChars(' \t') …Which I think should prevent exactly this kind of error. But I’m not sure. Even if the problem can’t be identified with certainty, simply narrowing down where the problem is would be a HUGE help. Please let me know how I might take a step or two towards fixing this.

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• What Precalculus knowledge is required before learning Discrete Math Computer Science topics?

  - by Ein Doofus

  Below I've listed the chapters from a Precalculus book as well as the author recommended Computer Science chapters from a Discrete Mathematics book. Although these chapters are from two specific books on these subjects I believe the topics are generally the same between any Precalc or Discrete Math book. What Precalculus topics should one know before starting these Discrete Math Computer Science topics?: Discrete Mathematics CS Chapters 1.1 Propositional Logic 1.2 Propositional Equivalences 1.3 Predicates and Quantifiers 1.4 Nested Quantifiers 1.5 Rules of Inference 1.6 Introduction to Proofs 1.7 Proof Methods and Strategy 2.1 Sets 2.2 Set Operations 2.3 Functions 2.4 Sequences and Summations 3.1 Algorithms 3.2 The Growths of Functions 3.3 Complexity of Algorithms 3.4 The Integers and Division 3.5 Primes and Greatest Common Divisors 3.6 Integers and Algorithms 3.8 Matrices 4.1 Mathematical Induction 4.2 Strong Induction and Well-Ordering 4.3 Recursive Definitions and Structural Induction 4.4 Recursive Algorithms 4.5 Program Correctness 5.1 The Basics of Counting 5.2 The Pigeonhole Principle 5.3 Permutations and Combinations 5.6 Generating Permutations and Combinations 6.1 An Introduction to Discrete Probability 6.4 Expected Value and Variance 7.1 Recurrence Relations 7.3 Divide-and-Conquer Algorithms and Recurrence Relations 7.5 Inclusion-Exclusion 8.1 Relations and Their Properties 8.2 n-ary Relations and Their Applications 8.3 Representing Relations 8.5 Equivalence Relations 9.1 Graphs and Graph Models 9.2 Graph Terminology and Special Types of Graphs 9.3 Representing Graphs and Graph Isomorphism 9.4 Connectivity 9.5 Euler and Hamilton Ptahs 10.1 Introduction to Trees 10.2 Application of Trees 10.3 Tree Traversal 11.1 Boolean Functions 11.2 Representing Boolean Functions 11.3 Logic Gates 11.4 Minimization of Circuits 12.1 Language and Grammars 12.2 Finite-State Machines with Output 12.3 Finite-State Machines with No Output 12.4 Language Recognition 12.5 Turing Machines Precalculus Chapters R.1 The Real-Number System R.2 Integer Exponents, Scientific Notation, and Order of Operations R.3 Addition, Subtraction, and Multiplication of Polynomials R.4 Factoring R.5 Rational Expressions R.6 Radical Notation and Rational Exponents R.7 The Basics of Equation Solving 1.1 Functions, Graphs, Graphers 1.2 Linear Functions, Slope, and Applications 1.3 Modeling: Data Analysis, Curve Fitting, and Linear Regression 1.4 More on Functions 1.5 Symmetry and Transformations 1.6 Variation and Applications 1.7 Distance, Midpoints, and Circles 2.1 Zeros of Linear Functions and Models 2.2 The Complex Numbers 2.3 Zeros of Quadratic Functions and Models 2.4 Analyzing Graphs of Quadratic Functions 2.5 Modeling: Data Analysis, Curve Fitting, and Quadratic Regression 2.6 Zeros and More Equation Solving 2.7 Solving Inequalities 3.1 Polynomial Functions and Modeling 3.2 Polynomial Division; The Remainder and Factor Theorems 3.3 Theorems about Zeros of Polynomial Functions 3.4 Rational Functions 3.5 Polynomial and Rational Inequalities 4.1 Composite and Inverse Functions 4.2 Exponential Functions and Graphs 4.3 Logarithmic Functions and Graphs 4.4 Properties of Logarithmic Functions 4.5 Solving Exponential and Logarithmic Equations 4.6 Applications and Models: Growth and Decay 5.1 Systems of Equations in Two Variables 5.2 System of Equations in Three Variables 5.3 Matrices and Systems of Equations 5.4 Matrix Operations 5.5 Inverses of Matrices 5.6 System of Inequalities and Linear Programming 5.7 Partial Fractions 6.1 The Parabola 6.2 The Circle and Ellipse 6.3 The Hyperbola 6.4 Nonlinear Systems of Equations

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• T4 vs CodeDom vs Oslo

  - by Ryan Riley

  In an application scaffolding project on which I'm working, I'm trying to decide whether to use Oslo, T4 or CodeDom for generating code. Our goals are to keep dependencies to a minimum and drive code generation for a domain driven design from user stories. The first step will be to create the tests from the user stories, but we want the domain experts to be able to write their stories in a variety of different media (e.g. custom app, Word, etc.) and still generate the tests from the stories. What I know so far: CodeDom requires .NET but can only output .NET class files (e.g. .cs, .vb). Level of difficulty is fairly high. T4 requires CodeDom and VS Standard+. Level of difficulty is fairly reasonable, especially with the T4 Toolbox. Oslo is very new. I have no idea of the dependencies, but I imagine you must be on at least .NET 3.5. I'm also not certain as to the code generation abilities or the complexity for adding new grammars. However, domain experts could probably write user stories in Intellipad quite easily. Also not sure about ease of converting stories in Word to an MGrammar. What are your thoughts, experiences, etc. with any of the above tools. We want to stick with Microsoft or open source tools.

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• Parsing an arithmetic expression and building a tree from it in Java

  - by ChocolateBear

  Hi, I needed some help with creating custom trees given an arithmetic expression. Say, for example, you input this arithmetic expression: (5+2)*7 The result tree should look like: * / \ + 7 / \ 5 2 I have some custom classes to represent the different types of nodes, i.e. PlusOp, LeafInt, etc. I don't need to evaluate the expression, just create the tree, so I can perform other functions on it later. Additionally, the negative operator '-' can only have one child, and to represent '5-2', you must input it as 5 + (-2). Some validation on the expression would be required to ensure each type of operator has the correct the no. of arguments/children, each opening bracket is accompanied by a closing bracket. Also, I should probably mention my friend has already written code which converts the input string into a stack of tokens, if that's going to be helpful for this. I'd appreciate any help at all. Thanks :) (I read that you can write a grammar and use antlr/JavaCC, etc. to create the parse tree, but I'm not familiar with these tools or with writing grammars, so if that's your solution, I'd be grateful if you could provide some helpful tutorials/links for them.)

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• Big problem with regular expression in Lex (lexical analyzer)

  - by Nazgulled

  Hi, I have some content like this: author = "Marjan Mernik and Viljem Zumer", title = "Implementation of multiple attribute grammar inheritance in the tool LISA", year = 1999 author = "Manfred Broy and Martin Wirsing", title = "Generalized Heterogeneous Algebras and Partial Interpretations", year = 1983 author = "Ikuo Nakata and Masataka Sassa", title = "L-Attributed LL(1)-Grammars are LR-Attributed", journal = "Information Processing Letters" And I need to catch everything between double quotes for title. My first try was this: ^(" "|\t)+"title"" "*=" "*"\"".+"\"," Which catches the first example, but not the other two. The other have multiple lines and that's the problem. I though about changing to something with \n somewhere to allow multiple lines, like this: ^(" "|\t)+"title"" "*=" "*"\""(.|\n)+"\"," But this doesn't help, instead, it catches everything. Than I though, "what I want is between double quotes, what if I catch everything until I find another " followed by ,? This way I could know if I was at the end of the title or not, no matter the number of lines, like this: ^(" "|\t)+"title"" "*=" "*"\""[^"\""]+"," But this has another problem... The example above doesn't have it, but the double quote symbol (") can be in between the title declaration. For instance: title = "aaaaaaa \"X bbbbbb", And yes, it will always be preceded by a backslash (\). Any suggestions to fix this regexp?

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• Is there a standard lexer/parser tool for Python?

  - by Salim Fadhley

  A volunteer job requires us to convert a large number of LaTeX documents into ePub format. It's a series of open-source fiction book which has so far only been produced only on paper via a print on demand service. We'd like to be able to offer the book to users of book-reader devices (such as Kindle) which require the ePub format for best results. Fortunately, ePub is a very simple format, however there's no trivial way for LaTeX to produce the XHTML outut required. We experimented with alternative LaTeX compilers (e.g. plastex) but in the end we figured that it would probably be a lot easier to simply write our own compiler which understands a tiny subset of the LaTeX language and compiles directly to XHTML / ePub. Previously I used a tool on Windows called GOLD. This allowed me to go directly from BNF grammars to a stub parser. It also alllowed me to implement the parser in any language I liked. (I'd choose Python). This product has to work on Linux, so I'm wondering if there's an equivalent toolchain that works as well under Ubutnu / Eclipse / Python. The idea is that we will take the grammar of TeX and just implement a teeny subset of that, but we do not want to spend a huge amount of time worrying about grammar and parsing. A parser generator would obviously save us a great deal of time. Sal UPDATE 1: Bonus marks for a solution with excellent documentation or tutorials.

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