antlr | 易学教程

String Template: make all variable declaration global

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问题 I am trying to implement a translator using ANTLR+StringTemplate. I have a starting language that is java like and multiple destination language. I used the example: http://www.antlr.org/wiki/display/ST/Language+Translation+Using+ANTLR+and+StringTemplate One of my destination language needs all variables to be declared globally. I wrote a grammar that recognizes variables, but i cannot find e way in my template for making a local variable to be declared globally. Of course if I would have

ANTLR: how to parse a region within matching brackets with a lexer

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问题 i want to parse something like this in my lexer: ( begin expression ) where expressions are also surrounded by brackets. it isn't important what is in the expression, i just want to have all what's between the (begin and the matching ) as a token. an example would be: (begin (define x (+ 1 2))) so the text of the token should be (define x (+ 1 2))) something like PROGRAM : LPAREN BEGIN .* RPAREN; does (obviously) not work because as soon as he sees a ")", he thinks the rule is over, but i

ANTLR Implicit Multiplication

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问题 I'm new to ANTLR, and I'm trying to expand upon the example of a simple calculator presented here. Specifically, I've tried adding some simple functions, negative numbers and so on, to familiarize myself with ANTLR. However, I've run into a bit of a problem trying to implement "implicit" multiplication (for example, 3cos(2)sin(2) would be interpreted as 3*cos(2)*sin(2)). I've found a question on Stack Overflow with the same kind of problem (here). The general form of the solution to that

Antlr Error Strategy to skip tokens until rule matches again

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问题 I tried this solution but it didn't seem to work for me Here's an excerpt from my grammer: module : BEGIN MODULE IDENT STRING module_element* END MODULE ; module_element : element_1 | element_2 | element_3 | ... ; There is a bigger tree below each element. Now when a RecognitionException occurs I want to consume tokens until either the next module_element matches or the parent END MODULE matches. Any hints on how to do this inside a class inheriting from DefaultErrorStrategy? edit: Here is a

Error handeling in antlr 3.0

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I need to Report customized error when ever user input does not match our defined rules. Here is my code: grammar second1; @lexer::members { @Override public void reportError(RecognitionException e) { System.out.println("Throwing Exception: "+ e.getMessage()); throw new IllegalArgumentException(e); } } @parser::members { private boolean inbounds(Token t, int min, int max, String methodName) { int n = Integer.parseInt(t.getText()); if(n >= min && n <= max) { return true; } else { System.out.println("The range for value accepted by " + methodName+" is "+min +"-" + max ); return false; } } } expr

Antlr lexer tokens that match similar strings, what if the greedy lexer makes a mistake?

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问题 It seems that sometimes the Antlr lexer makes a bad choice on which rule to use when tokenizing a stream of characters... I'm trying to figure out how to help Antlr make the obvious-to-a-human right choice. I want to parse text like this: d/dt(x)=a a=d/dt d=3 dt=4 This is an unfortunate syntax that an existing language uses and I'm trying to write a parser for. The "d/dt(x)" is representing the left hand side of a differential equation. Ignore the lingo if you must, just know that it is not

What does ^ and ! stand for in ANTLR grammar

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问题 I was having difficulty figuring out what does ^ and ! stand for in ANTLR grammar terminology. 回答1: Have a look at the ANTLR Cheat Sheet: ! don't include in AST ^ make AST root node And ^ can also be used in rewrite rules: ... -> ^( ... ) . For example, the following two parser rules are equivalent: expression : A '+'^ A ';'! ; and: expression : A '+' A ';' -> ^('+' A A) ; Both create the following AST: + / \ A A In other words: the + is made as root, the two A 's its children, and the ; is

ANTLR - NoViableAltException

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问题 I'm trying to learn ANTLR by writing a grammer (I'm using eclipse with the plugins for ANTLR), and it was going alright until I ran into the error: NoViableAltException: line 0:-1 no viable alternative at input '<EOF>' When I try to test my args parser rule; typedident : (INT|CHAR) IDENT; args : (typedident ( COMMA typedident)*)?; An ident is a letter followed by any character, this works, I've tested it. typedident also works for the test. I'm using the input of int a12q2efwe, char a12eqdsf

“FOLLOW_set_in_”… is undefined in generated parser

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问题 I have written a grammar for vaguely Java-like DSL. While there are still some issues with it (it doesn't recognize all the inputs as I would want it to), what concerns me most is that the generated C code is not compilable. I use AntlrWorks 1.5 with Antlr 3.5 (Antlr 4 apparently does not support C target). The problem is with expression rules. I have rules prio14Expression to prio0Expression which handle operator precedence. To problem is at priority 2, which evaluates prefix and postfix

How can i see the live parse tree using Antlr4 Ide in Eclipse?

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问题 I'm new using Antlr4 but I know that exist a plugin for Eclipse. I have a simple question...After I created the g4 file how can I visualize the live parse tree in order to see the tree of an input expression? Thanks 回答1: Currently there is no provision for viewing live parse tree in ANTLR 4 IDE for Eclipse. Meanwhile, you can see the parse tree using -gui switch in the command line. It also provides a feature of saving the parse tree as PNG. 回答2: After installing Antlr4Ide plugin in Eclipse: